tag:blogger.com,1999:blog-7610957496050838672024-03-23T15:14:42.253+05:00Automotive MechanicsThis includes major type of engine fundamentals, assembly, Engine System, type of engines, Engines design according to fuels types used.Servicing Engines (Overhauling and troubleshooting, Transmissions types, hydraulic systems, Steering and brake systems and stereo systems and their servicing etc.Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.comBlogger51125tag:blogger.com,1999:blog-761095749605083867.post-76412604084390728382011-06-25T04:01:00.003+05:002011-07-08T04:16:04.862+05:00Scored piston<div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Scored piston </span></u></b></div><div style="text-align: justify;"><br />
</div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOdgEixwiMUTzu30s_0UZxeqQ66rLxUVsh5DDIiduVGYLRp-rtC2Un5Y0FXf6Y-Gdxm7NygFeO8lU8rFTx8jM06IiAjD0mxTfwOFqTa8llijYMypGdyUcTkGghWefNTWj48S9XhJBi6kk/s1600/Fig+7.27.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOdgEixwiMUTzu30s_0UZxeqQ66rLxUVsh5DDIiduVGYLRp-rtC2Un5Y0FXf6Y-Gdxm7NygFeO8lU8rFTx8jM06IiAjD0mxTfwOFqTa8llijYMypGdyUcTkGghWefNTWj48S9XhJBi6kk/s200/Fig+7.27.gif" width="187" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.27</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Scoring is an advanced stage of scuffing (Figure 7.27). As well as the original cause of scuffing, continued operation of the engine with scuffed pistons and cylinders will generate excessive heat and friction. This will exaggerate the problem, so that a large area of the piston becomes scored. <br />
Deep scoring in a cylinder can be the result of a mechanical failure, such as a broken piston ring, a broken circlip, or a loose piston pin. This type of damage could be confined to only one cylinder and the cause is easy to see. </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Abrasion is a type of light scoring that could be caused by dust and dirt entering the engine through a faulty or badly serviced air cleaner. <br />
There will be abrasive wear to the valve sterns and guides as well as to the pistons, rings and cylinders. The scoring will not be deep, but will be in the form of a mat finish of very fine score marks covering all the rubbing surfaces. All the cylinders would be affected.</span> <br />
<br style="mso-special-character: line-break;" /></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTBN_hfyhiP6W0ye7KqkvUubCssSfKonfNLPS4deoc_Y8I2s2Rh_-e5DHFYR7g6Kce_Qp6CE_qPpfunZefOA-h17XR3J7TjvjM4wiSDGVsemED2TVeuOLlqO50l2J4kcKJoeSqpiqNu4o/s1600/Fig+7.28.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTBN_hfyhiP6W0ye7KqkvUubCssSfKonfNLPS4deoc_Y8I2s2Rh_-e5DHFYR7g6Kce_Qp6CE_qPpfunZefOA-h17XR3J7TjvjM4wiSDGVsemED2TVeuOLlqO50l2J4kcKJoeSqpiqNu4o/s200/Fig+7.28.gif" width="197" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.28</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Seized piston</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;"> </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">With a seized piston, the entire thrust surfaces would be marked (Figure 7.28). A likely cause is insufficient lubrication. If this is the correct diagnosis, the bearings and journals will also be affected and the engine oil will be contaminated. <br />
Other factors that could cause a breakdown in the oil film between the piston and cylinder must also be considered, such as cooling-system problems, or blowby due to sticking rings.</span> <br />
<br style="mso-special-character: line-break;" /></div><div class="MsoNormal" style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">Scuffing, scoring and seizing are conditions that are closely related. In some cases, they could be three stages of damage from the same initial cause.</span></i></div><div style="text-align: justify;"><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCC0SbKoGqCoifzTN6vz9QikobdYMxI4A48zqZwj-Y3CVryDKbNhJCL1GthBNHxZejx8en4tDPFH8xRsVVYgbgQZFKzEAZYmTxLy_lTIA-qKo9nFiyqPyMrK7WdURnqqhsJNakFinrbo0/s1600/Fig+7.29.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCC0SbKoGqCoifzTN6vz9QikobdYMxI4A48zqZwj-Y3CVryDKbNhJCL1GthBNHxZejx8en4tDPFH8xRsVVYgbgQZFKzEAZYmTxLy_lTIA-qKo9nFiyqPyMrK7WdURnqqhsJNakFinrbo0/s200/Fig+7.29.gif" width="195" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.29</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Corrosion can affect a piston as shown in Figure 7.29. This can be the result of coolant leaking into the combustion chamber and finding its way down past the piston rings. This would affect cylinder-wall lubrication and could cause scuffing. <br />
A coolant leak can contaminate the engine oil and form sludge in the oil pan. This will further affect cylinder lubrication. Blowby can also contaminate the engine oil, and make the additives less effective. </span></div><div style="text-align: justify;"><span style="font-family: Arial;">Blowby will occur if the piston rings do not seal properly. The hot gases that blow past the piston will increase the temperature of the piston, piston rings and cylinder walls. </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> The tension of the piston rings could be lost because of overheating, and so the problem of blowby increased. Where the engine is continued in operation, this can destroy the piston lands and rings as shown in Figure 7.30. </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnm2GMS103MrVfM9ZQ_GE8cPu0nAJeXSVT6pZbMBDf9RI-bvJ1xWN6LyTS1Vta5KTW1PW0SUytXpYe-I3ViGaelgBnChVVyrNyKZ7q1dRg6wdEONYiWLsuXVcusNgQ3TRXHnhiQcqDa3E/s1600/Fig+7.30.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnm2GMS103MrVfM9ZQ_GE8cPu0nAJeXSVT6pZbMBDf9RI-bvJ1xWN6LyTS1Vta5KTW1PW0SUytXpYe-I3ViGaelgBnChVVyrNyKZ7q1dRg6wdEONYiWLsuXVcusNgQ3TRXHnhiQcqDa3E/s200/Fig+7.30.gif" width="173" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.30</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston damage </span></u></b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><span style="font-family: Arial;">Figure 7.31 shows damage to the piston-pin boss area of a piston. This has been caused by a loose circlip. Circlips must be a good fit in their grooves and should be renewed whenever an engine is dismantled. <br />
Misalignment of the connecting rod can cause side thrusts on the piston pin which are transmitted to the circlip. This could break the circlip, or damage the piston. If the circlip breaks, particles could score the piston and cylinder, or jam the piston rings, to eventually produce damage such as that illustrated. </span></div><div style="text-align: justify;"><br />
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<tr align="justify"><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFVKtWWVQwvXp6eYTaMSgNk9ZCGHlNxRYp06WdrhxF4RygrHsh2tpciP_o5N5JEYWwbMnQ4tpXIGtQRYcmmZm1RPLpgxRYqKiXl6Y2fy1rhhrr3haOatUMMhiwfNv7af2xDLF801DDeNY/s1600/Fig+7.31.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFVKtWWVQwvXp6eYTaMSgNk9ZCGHlNxRYp06WdrhxF4RygrHsh2tpciP_o5N5JEYWwbMnQ4tpXIGtQRYcmmZm1RPLpgxRYqKiXl6Y2fy1rhhrr3haOatUMMhiwfNv7af2xDLF801DDeNY/s200/Fig+7.31.gif" width="200" /></a></td></tr>
<tr align="center"><td class="tr-caption"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.31</span></td></tr>
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<div style="color: black; font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="color: black; font-family: Georgia;"><span style="font-family: "Courier New",Courier,monospace;">See General engine service>>>>>>>>>></span></span><i><span style="color: #cc0000; font-family: Georgia;"><br />
</span></i></span></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-81611696839250204852011-06-24T03:43:00.000+05:002011-07-08T04:01:01.446+05:00Connecting-rod aligner<div style="text-align: justify;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJgLgAueI0rSAfRlmXvjv4Xu8k68EzFAtT_Zjf8LOLzRv94Gm9nOeAME9GPmUSEnhVtsPBtQKg2jMlz5TN5izQooHeMKaP4JRnXdRBsjZ06Z7EH3zlvFDy26D4Fhqf_Dct6xggbR2DT-c/s1600/Fig+7.25.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJgLgAueI0rSAfRlmXvjv4Xu8k68EzFAtT_Zjf8LOLzRv94Gm9nOeAME9GPmUSEnhVtsPBtQKg2jMlz5TN5izQooHeMKaP4JRnXdRBsjZ06Z7EH3zlvFDy26D4Fhqf_Dct6xggbR2DT-c/s200/Fig+7.25.gif" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.25</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;"></span></u></b><span style="font-family: Arial;">This is a fixture that consists of a vertical faceplate, with a horizontal mandrel. The big end of the connecting rod is mounted on the mandrel and the rod alignment is checked against the faceplate. <br />
A specially-shaped jig or V-block is used — the V of the jig is shaped to sit on the piston pin. Small dowels that extend from the jig are checked against the faceplate to determine rod alignment (Figure <i>7.25).</i></span><i><span style="font-size: 11.0pt;"> </span></i></div><div> </div><div style="margin-top: 6pt; text-align: justify;"><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">Checking alignment </span></i></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Install the piston pin in the connecting rod, mount the rod on the mandrel of the aligner, and place the V of the jig over the piston pin. <br />
Slide the rod along the mandrel until the dowels of the jig just touch the surface of the faceplate. If the dowels do not touch the plate, then the rod is misaligned. <br />
The rod should be checked for bend and then for twist. To do this, the jig is mounted in two different positions on the piston pin: <br />
1. </span><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">with the dowels vertical</span></i></b><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">This will check for bend in the rod. If the rod is straight, both vertical dowels will be in contact with the faceplate (Figure <i><span style="mso-bidi-font-weight: bold;">7.25(a)).<b> </b></span></i>If only one dowel contacts the faceplate, then the rod is bent. <br />
2. </span><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">with the dowels horizontal</span></i></b><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">This will check for twist in the rod. If the rod is true, and not twisted, both horizontal dowels will be in contact with the faceplate (Figure 7.25(b)). If only one dowel contacts the faceplate, then the rod is twisted. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;"><span style="mso-spacerun: yes;"> </span>The allowable misalignment, for both bend and twist is around 0.10mm. This is checked with feeler gauges between the dowels and the faceplate.</span> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </i></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Straightening connecting rods</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Connecting rods that are slightly misaligned can be straightened in a special jig designed for this purpose. A press or bending bar can also be used. <br />
When straightening a connecting rod, it should be bent a little beyond the point where it is straight and then bent back to obtain correct alignment. This relieves the stress in the rod and it is less likely to tend to take up a permanent set and, for this reason, doubtful or badly misaligned rods should be replaced.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt;">Analyzing piston, ring and cylinder problems</span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 17.0pt;"> <br />
</span></b><span style="font-family: Arial;"> </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Engine noises, loss of engine power and exhaust smoke are indications that there could be problems with pistons and cylinders. While these could be due to wear in a vehicle with high kilometres, excessive wear or damage needs to be investigated. <br />
The cause of a fault must be located and corrected so that the problem does not occur again. For damaged pistons and cylinders, do not just blame the part that failed, but consider the following as possible causes: </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">1. Operating conditions of the vehicle </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">2. Lubrication <br />
3. Cooling <br />
4. Temperature </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">5. Connecting-rod alignment </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">6. Other possible cause. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Following are descriptions of a number of piston faults that are not the result of normal wear. These are shown as separate faults, but some are a more advanced stage of one of the other faults, The cylinders in which the pistons operate will also be damaged, but the piston will show more damage because it is made of softer material. <br />
When diagnosing a problem, consider whether it is related to the whole engine, or whether it is confined to only one cylinder. Also, consider whether the problem is related to the piston, the piston rings, or the cylinder, although one usually affects the others. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;"><span style="text-decoration: none;"><br />
</span></span></u></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Scuffed pistons</span></u></b></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0TwM2iuo-r0SjVOrDq8oCEdhGfoJdfvOZ2ATtklMoEoYGgtH5f0AbjrZfYgbdYfYB1bPI8HNeV1JVCr8NCAkfh5SQwTj7ulYOF8bHWbtyzzHY2j1Keu1Z2GIKs72WJmYrq-zLAQQSzgg/s1600/Fig+7.26.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0TwM2iuo-r0SjVOrDq8oCEdhGfoJdfvOZ2ATtklMoEoYGgtH5f0AbjrZfYgbdYfYB1bPI8HNeV1JVCr8NCAkfh5SQwTj7ulYOF8bHWbtyzzHY2j1Keu1Z2GIKs72WJmYrq-zLAQQSzgg/s200/Fig+7.26.gif" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;">Fig 7.26</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Scuffing is a light abrasion on the thrust sides of the piston (Figure 7.26). It is caused by heat. It occurs when two surfaces are rubbing together and the temperature rises until melting point is reached. Small particles of metal then weld together, leaving small deposits on one surface and small holes in the other. <br />
When scuffing starts, the damage can spread, being aggravated by the rough surfaces until an area of the piston is affected as shown. <br />
The following should be checked for possible causes of scuffing or other piston failure: </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">I. The water-jackets for restrictions or deposits that could cause hot spots on the cylinder walls or distortion of the cylinder. <br />
2. The lubrication system for correct pressure and type of oil. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">3. The piston for size and clearance. <br />
4. The connecting rod for alignment. </span></div><div style="text-align: justify;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial;"><span style="font-family: "Courier New",Courier,monospace; font-size: x-small;">See scored pistons>>>>>>>>>>>>>>>>>></span></span></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com1tag:blogger.com,1999:blog-761095749605083867.post-20553149708650835912011-06-23T03:15:00.008+05:002011-07-08T03:41:47.490+05:00Cont. Connecting rod beaing installation<div style="text-align: justify;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb2uC2xtN0HvfIn0BgXvuTUb28WMwumAw8IgSIM-z24z6JMwfr8SGyeHN1d-ufEYOdo_Jzt3uYKvFRlV4LMapfv39PhgQ9tkqOcp1P_PSr23GbpV4mCrvniwM1z-RjMt0R_s2kI_F7gw4/s1600/Fig+7.24.gif" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br />
</a></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5FlNzDFNE2NPVfdm6fQdA8KilHZ5htiD6aR3nbuXb0y5yny4S63ZTGpi_t7cCSP1qd9RK-Lbgj9rY6fVFiO4gqpBNJQyYLNIeZtdvE3ixJz7un_trqfXee3Ht5Uvpxgvs2iCvKNuAsrI/s1600/Fig+7.20.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="166" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5FlNzDFNE2NPVfdm6fQdA8KilHZ5htiD6aR3nbuXb0y5yny4S63ZTGpi_t7cCSP1qd9RK-Lbgj9rY6fVFiO4gqpBNJQyYLNIeZtdvE3ixJz7un_trqfXee3Ht5Uvpxgvs2iCvKNuAsrI/s200/Fig+7.20.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.20</span></td></tr>
</tbody></table><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--><span style="font-family: Arial;"></span><div style="text-align: justify;"><span style="font-family: Arial;">When bearings are to be installed, make sure that hand, workbench, tools and all engine parts are clean. Keep new bearings wrapped until ready to be installed and then handle them carefully. To avoid problems, wipe each bearing with a fresh piece of cleaning rag and install it into a clean bore (Figure 7.20). <br />
The bearings have locating tangs that fit into notches in the connecting rod and cap. Make sure that the tangs enter the notches correctly. See the comments about bearing spread and crush that follow. <br />
Bearing clearance cannot be adjusted. Any attempt to correct bearing clearance by filing the connecting-rod cap will destroy the original relationship between the cap and the rod. This will cause early bearing failure. </span></div><div> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Bearing spread and crush</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></b></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFuGI9ekgobjCQtZZv-G4swyRxR04CeuzsJ5Hb7Qw0HMvvcKa4pOuyjHuMxNttSdrdW42_IKMDrALLf61zUEBKPGKTC4OXMeNWHKfXyxZiMWepqhlqKX6O9e0Fj-DJuoWNsk_FEBdz7VI/s1600/Fig+7.21.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="93" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFuGI9ekgobjCQtZZv-G4swyRxR04CeuzsJ5Hb7Qw0HMvvcKa4pOuyjHuMxNttSdrdW42_IKMDrALLf61zUEBKPGKTC4OXMeNWHKfXyxZiMWepqhlqKX6O9e0Fj-DJuoWNsk_FEBdz7VI/s200/Fig+7.21.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.21</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Bearing inserts are provided with </span><i><span style="color: #cc0000; font-family: Georgia; mso-fareast-font-family: "Times New Roman";">spread</span></i><i><span style="font-family: Arial;"> </span></i><span style="font-family: Arial;">and </span><i><span style="color: #cc0000; font-family: Georgia; mso-fareast-font-family: "Times New Roman";">crush</span></i><i><span style="font-family: Arial; font-size: 11.0pt;"> </span></i><span style="font-family: Arial;">(Figure 7.21). With spread, the ends of the bearing are slightly wider than the bore of the rod or cap into which the bearing fits. When the bearing is being pushed into the cap or into the connecting rod, it will snap into place and the spread of the bearing will keep it there. </span><br />
<span style="font-family: Arial;"> Crush is caused because the edge of the bearing insert stands above the parting face of the connecting rod or cap. This additional height is ‘crushed’ when the cap is installed and the bolts tightened. Crushing pushes the inserts into the bore in the connecting rod and cap. This ensures that the backs of the inserts are in snug contact with the bore. Figure 7.22 shows </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs-djLR2MwATtYTyPfO02z_7C8ZlID5mOtfyvqgQu1whl66xtCQm7Zegvn07E8FwuYqeTDPOVcKJCio4fPOFIPmsudvvBxOML480REz1IdXeNYjW8aOtEonusatJnQ-NYtl6DRyaFhhOg/s1600/Fig+7.22.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="158" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs-djLR2MwATtYTyPfO02z_7C8ZlID5mOtfyvqgQu1whl66xtCQm7Zegvn07E8FwuYqeTDPOVcKJCio4fPOFIPmsudvvBxOML480REz1IdXeNYjW8aOtEonusatJnQ-NYtl6DRyaFhhOg/s200/Fig+7.22.gif" width="200" /></a></td></tr>
<tr align="center" style="background-color: #cfe2f3;"><td class="tr-caption"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.22</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">the top half of a bearing correctly installed in a connecting rod. <br />
Crush is a general term as described, but it can also refer to the distance that the edge of the bearing stands above the parting face.</span><span style="font-family: "Helvetica\, sans-serif";"> <br style="mso-special-character: line-break;" /> </span><br style="mso-special-character: line-break;" /><span style="font-family: "Helvetica, sans-serif";"> </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-bidi-font-style: italic; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia; mso-fareast-font-family: "Times New Roman";">New hearings will have the correct crush and must not be</span></i></div><div class="MsoNormal" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><i><span style="color: #cc0000; font-family: Georgia;">tampered with in any way. </span></i></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;">Checking connecting-rod bearings</span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 17.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Automotive engines are fitted with precision-insert bearings that are accurately finished to size and require no adjustment. In fact, adjustment should never be attempted as this will ruin the bearing. <br />
The clearance of a connecting-rod bearing can be found by using a telescopic gauge to measure the bearing and a micrometer to measure the journal. However, the easiest way is with Plastigage. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span><span style="font-family: "Helvetica\, sans-serif"; font-size: 11.0pt;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Plastigage </span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></b></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrAHOL3hrpPBn-Hqg-cz-iOmEpJAsIxw_mkdnGN00H50j91NyWAXJYOts2muV6BCbUBUt_3cdJ5NCZJMBlPDgKgoT0tAdc8XuEXiR8FhdU1JCRWrikDUExYH7VYhvy1GRO3Bztp08uuqo/s1600/Fig+7.23.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="120" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrAHOL3hrpPBn-Hqg-cz-iOmEpJAsIxw_mkdnGN00H50j91NyWAXJYOts2muV6BCbUBUt_3cdJ5NCZJMBlPDgKgoT0tAdc8XuEXiR8FhdU1JCRWrikDUExYH7VYhvy1GRO3Bztp08uuqo/s200/Fig+7.23.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.23</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Plastigage is a plastic material that comes in strips and flattens under pressure. It is used to check the clearance between bearings and shafts. <br />
When used to check the clearance of a connecting- rod bearing, a strip of the material is placed in the bearing in the cap. The cap is installed and the nuts are tightened to the correct torque. The bearing cap is then removed and the flattened Plastigage is measured</span><span style="font-family: "Helvetica\, sans-serif"; font-size: 11.0pt;"> </span><span style="font-family: Arial;">(Figure 7.23). If the Plastigage is flattened only a little, then there is a large-clearance, and vice versa. <br />
A printed scale is supplied with the Plastigage. The scale has bands of different widths which are marked to show the bearing clearance </span><span style="font-family: Arial; font-size: 4.0pt;">— </span><span style="font-family: Arial;">for example, 0.02 mm, 0.03 mm etc. The scale is placed against the flattened Plastigage to check its width as shown in the illustration. </span><b><span style="font-family: "Helvetica\, sans-serif";"></span></b></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The scale measures the width of the flattened Plastigage, but shows this as its thickness, which is the clearance between the bearing and the shaft. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">Using Plastigage </span></i></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">1. Wipe the crank-pin and bearing clean of oil. </span></div><div style="text-align: justify;"> </div><div style="margin-bottom: 6pt; text-align: justify;"><span style="font-family: Arial;">2. Position the crank-pin of the bearing to be checked about 30° before BDC, because this is where the bearing clearance is likely to be greatest. <br />
3. Place a small strip of Plastigage in the centre of the bearing and install the bearing cap on the connecting rod. <br />
4. Remove the bearing cap and check the thickness of the flattened Plastigage against the scale.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><div style="margin: 0in 0in 6pt; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">Do not move the crankshaft while the cap nuts are tight,- this would disturb the Plastigage and give an inaccurate measurement. </span><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </i></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;">Connecting-rod alignment</span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 17.0pt;"> <br />
</span></b><span style="font-family: Arial;"> </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb2uC2xtN0HvfIn0BgXvuTUb28WMwumAw8IgSIM-z24z6JMwfr8SGyeHN1d-ufEYOdo_Jzt3uYKvFRlV4LMapfv39PhgQ9tkqOcp1P_PSr23GbpV4mCrvniwM1z-RjMt0R_s2kI_F7gw4/s1600/Fig+7.24.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb2uC2xtN0HvfIn0BgXvuTUb28WMwumAw8IgSIM-z24z6JMwfr8SGyeHN1d-ufEYOdo_Jzt3uYKvFRlV4LMapfv39PhgQ9tkqOcp1P_PSr23GbpV4mCrvniwM1z-RjMt0R_s2kI_F7gw4/s200/Fig+7.24.gif" width="95" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Arial;">Fig</span></span><span style="font-size: x-small;"><span style="font-family: Arial;"> 7.24</span></span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">The connecting rod must be in alignment — that is, there should be no twist or bend in the rod. Any misalignment will cause side thrusts on the piston and irregular loading of the bearing. </span></div><div style="text-align: justify;"> <span style="font-size: small;"><span style="font-family: Arial;">Figure 7.24 shows the effects of a misaligned connecting rod. The heavy loading at points A and B on the bearing would cause bearing failure at these points. </span></span><br />
<span style="font-size: small;"><span style="font-family: Arial;"> The heavy-pressure spots C and D on the piston will cause heavy wear and possibly scoring</span></span><span style="font-size: small;"><span style="font-family: Arial;"> of the piston and cylinder wall. A basic inspection check is to look for uneven wear or shiny spots on the pistons, which will indicate misalignment. If this condition is found, the connecting rod should be checked and as necessary, straightened or replaced.</span></span><span style="font-family: "Times New Roman"; font-size: 10pt;"><span style="font-size: small;"> </span></span><br />
<span style="font-family: "Times New Roman"; font-size: 10pt;"><span style="font-size: small;"> </span></span></div><div style="text-align: justify;"><br style="mso-special-character: line-break;" /><span style="font-family: "Times New Roman"; font-size: 10.0pt; mso-ansi-language: EN-US; mso-bidi-language: AR-SA; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US;"> </span></div><div style="text-align: justify;"><div style="color: black; font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;"><span>Continued</span></span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="color: black; font-family: Georgia;"><span style="font-family: "Courier New",Courier,monospace;">See connecting rod aligner>>>>>>>>>></span></span></span><i><span style="color: #cc0000; font-family: Georgia;"><br />
</span></i></div><span style="font-family: "Times New Roman"; font-size: 10pt;"> </span></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0Islamabad, Pakistan33.718151 73.06054700000004233.639677 72.938652500000046 33.796625 73.182441500000039tag:blogger.com,1999:blog-761095749605083867.post-51323945089202432932011-06-22T02:16:00.078+05:002011-07-08T03:15:02.410+05:00Checking rings on a piston<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihSkHmTU05a6PhOnKerEE8pdLZEXayqePGSrWBvswOQMrpHhRFR2nFz0PQgK9CQX80vRaxsWfPY3NSrxx_j7PxTMvfLPHMiKTkroCayWP7NVPFFKP-f0zAOyC8lgddysy0w8NolVx7XLw/s1600/Fig7.12.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="178" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihSkHmTU05a6PhOnKerEE8pdLZEXayqePGSrWBvswOQMrpHhRFR2nFz0PQgK9CQX80vRaxsWfPY3NSrxx_j7PxTMvfLPHMiKTkroCayWP7NVPFFKP-f0zAOyC8lgddysy0w8NolVx7XLw/s200/Fig7.12.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.12</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"> </span></u></b><span style="font-family: Arial;">Rings are checked in their grooves to make sure that they are free and also that the groove is the right depth. The grooves must be clean, with all carbon removed. A groove-cleaning tool or a broken ring is used for this purpose. <br />
Place the face of the new ring in the groove, as shown in Figure 7.12, and roll it around the piston. it should be free in all parts of the groove. If the ring is tight in any spot, the groove should be cleaned and the ring tried again. </span></div><div></div><div style="text-align: justify;"><span style="font-family: Arial;">Check the ring-groove depth. With the face of the ring held into its groove, place a steel rule across the lands. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">There should be clearance between the rule and the ring. Average specifications are around 0.3 mm. Some replacement rings might require deeper grooves, and the instructions supplied by the manufacturer should be closely followed.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyt5uLnD4L3pIYoPKl5s-oLbXQtCULfszERnJaQEAnlXFGnnzGCodIIKN4gZq6-4Qaw_diS69sPI_n5M_rsNiWbx0al9YZndF8SDr34pU31JYpKHi5_GokGPZcbDOf5qtEg2KkFegfg70/s1600/Fig7.13.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="158" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyt5uLnD4L3pIYoPKl5s-oLbXQtCULfszERnJaQEAnlXFGnnzGCodIIKN4gZq6-4Qaw_diS69sPI_n5M_rsNiWbx0al9YZndF8SDr34pU31JYpKHi5_GokGPZcbDOf5qtEg2KkFegfg70/s200/Fig7.13.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.13</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Ring side clearance</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">The side clearance of the ring in the groove is checked with a feeler gauge (Figure 7.13). </span><span style="font-family: Arial;">This can be done by holding the ring in its groove, or with the ring installed on the piston. Average specifications for side clearance are 0.035 mm for petrol engines and 0.05 mm for diesel engines.</span><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Installing rings on a piston</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">The steel rails and separators of segmental rings are carefully wound into the groove in the piston, one piece at a time, making sure that they are correctly seated (Figure 7.14). The ring can be turned in its groove if it is correctly installed.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiL0nNKLxMXN-piKRkWbV5o6nbc_gBHp5D8RD2AXmrIa_1UirrvyMQ91KzTsRX2SwJnSu2PXh6xIxiox9cm6H_fNHuREbqsBwOm_4cZgxsQnXrmDiFf1wQbfdqYQsF1Y_ZVDCBAgrqwzXs/s1600/Fig7.14.gif" style="margin-left: auto; margin-right: auto;"><img border="0" height="129" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiL0nNKLxMXN-piKRkWbV5o6nbc_gBHp5D8RD2AXmrIa_1UirrvyMQ91KzTsRX2SwJnSu2PXh6xIxiox9cm6H_fNHuREbqsBwOm_4cZgxsQnXrmDiFf1wQbfdqYQsF1Y_ZVDCBAgrqwzXs/s200/Fig7.14.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.14</span></td></tr>
</tbody> </table><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;"> </span><br />
<span style="font-family: Arial;"> Cast iron compression rings can be installed in a similar way, but care must be taken that the</span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><span style="font-family: Arial;"> rings are not distorted, The best method for compression rings is with a ring-expanding tool (Figure 7.15). This supports the ring while it is being spread. The ring should be expanded just enough to allow it to pass over the piston. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
<b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Compression rings</span></i></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">A compression ring with a tapered face or counter-bore must be installed with the correct side of the ring to the top, as shown in Figure 7.15. If a ring is fitted upside down, its action will be reversed. A scraper ring, for example, would carry oil up the cylinder wall into the</span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja2adO8tuNufOvOR2Ng1FO4w105D631guXP5FnQO6mk8UApXDGRZSI6TQELvgwVhBYTVLmb822HKHuqKHV3JZreJ1VxtHX3ORGF1sonWTQQ-xxXhD867zn6CWoeBGQBus8oYUVEP7i47s/s1600/Fig7.15.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja2adO8tuNufOvOR2Ng1FO4w105D631guXP5FnQO6mk8UApXDGRZSI6TQELvgwVhBYTVLmb822HKHuqKHV3JZreJ1VxtHX3ORGF1sonWTQQ-xxXhD867zn6CWoeBGQBus8oYUVEP7i47s/s200/Fig7.15.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.15</span></td></tr>
</tbody></table><span style="font-family: Arial;"> combustion chamber. This would cause high oil consumption and associated problems.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> </span><br />
<span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Ring gaps</span></i></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;">When the rings are installed in their grooves, the ring gaps should be staggered so that all the gaps are not in line. The gaps are kept away from the thrust sides of the piston. Figure</span></div><div style="text-align: justify;"><span style="font-family: Arial;"> 7.16 shows a set of rings and how the gaps are arranged.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> </span><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Installing pistons in cyLinders</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> </span></b><span style="font-family: Arial;"></span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhI5ySuGLaL3gS-XoTeaIYNOzxQvlI6WDxu-KppSib4kPrrkvjhpDGi9JVdD8XoSfWPx3JUGlYrZmHrMRjDzDMHTn2blf8w1ZQF8i1d1BZ77QWbh9WRL4EbjNCP9EnP-EOxg3QXuxs-wLQ/s1600/Fig7.16.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhI5ySuGLaL3gS-XoTeaIYNOzxQvlI6WDxu-KppSib4kPrrkvjhpDGi9JVdD8XoSfWPx3JUGlYrZmHrMRjDzDMHTn2blf8w1ZQF8i1d1BZ77QWbh9WRL4EbjNCP9EnP-EOxg3QXuxs-wLQ/s200/Fig7.16.gif" width="198" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.16</span></td></tr>
</tbody></table><span style="font-family: Arial;">A piston-ring compressor is used to install the piston in the cylinder (Figure 7. 17). The compressor clamps around the piston rings and compresses them into their grooves so that they will enter the cylinder bore without being damaged. <br />
Following are related points: <br />
1. Oil the piston and rings and stagger the ring gaps. </span><br />
<span style="font-family: Arial;"> 2. Fit a piece of plastic tube over the connecting-rod bolts so that they will not scratch the crank-pin journal (Figure 7.18). </span></div><br />
<div style="text-align: justify;"><span style="font-family: Arial;"> 3. Fit the ring compressor over the piston and tighten it firmly so that the rings are compressed. </span></div><div style="text-align: justify;"></div><div style="margin-bottom: 12pt; text-align: justify;"><span style="font-family: Arial;">4. Place the piston and connecting rod in the cylinder, with the front mark of the piston towards the front of the engine. <br />
5. Insert the piston using light even taps with a hammer handle on the head of the piston. Only light taps will be needed if a good compressor is used and operated correctly. Heavy</span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTsKcnHgb2yXzAtQotzPz0Uxvw9y2RTDIZ8nesX9l4JOxbulZUsT8F7UqZzcjWgxEI48jQxVuiHEpgLoyUQ7jsubqZllZenhozBmasQhqmgd5j0ctnA-S9_xM67bunbPF4BW93cdYg1fU/s1600/Fig7.17.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="162" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTsKcnHgb2yXzAtQotzPz0Uxvw9y2RTDIZ8nesX9l4JOxbulZUsT8F7UqZzcjWgxEI48jQxVuiHEpgLoyUQ7jsubqZllZenhozBmasQhqmgd5j0ctnA-S9_xM67bunbPF4BW93cdYg1fU/s200/Fig7.17.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.17</span></td></tr>
</tbody></table><span style="font-family: Arial;"> blows will damage the piston and break the rings. <br />
6. Hold the compressor firmly against the surface of the cylinder block so that there is no gap for the rings to escape. </span></div><div style="text-align: justify;"></div><br />
<div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">The piston rings must be compressed to enter the cylinder. A ring that is not held by the compressor is likely to be broken. </span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;"></span></u></b></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Installing connecting-rod bearings</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">New precision connecting-rod bearings are required if the old ones are defective or have worn so much that clearances are excessive. New bearings will also be required if the crankpin journals have worn out-of- round or tapered to the extent that</span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjf9yhG7Hv-utu639ixoV5nMSJrD84XtpNqeA9B-SceRCWCDuClb13TZ7jEBOzWgaF96v73lWOu1jUjkG4DLIlih-6kAf2aJ_pBabeAwGYj3VdGfmLTxvMwyOCiaYFD-xSqwlmhe3fuEbk/s1600/Fig+7.18.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="146" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjf9yhG7Hv-utu639ixoV5nMSJrD84XtpNqeA9B-SceRCWCDuClb13TZ7jEBOzWgaF96v73lWOu1jUjkG4DLIlih-6kAf2aJ_pBabeAwGYj3VdGfmLTxvMwyOCiaYFD-xSqwlmhe3fuEbk/s200/Fig+7.18.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.18</span></td></tr>
</tbody></table><span style="font-family: Arial;"> the crankshaft has to be reground. In this case, the journals will be finished undersize and undersize bearings would be used. Undersize bearings would have some form of identification to show that they were not standard bearings (Figure 7.19). </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> Crank-pin journals should be checked with a micrometer for taper or eccentricity. If the journals are out-of-round or tapered more than 0.04 mm (example) the crankshaft must be replaced or the crank-pins reground. <br style="mso-special-character: line-break;" /> </span><br />
<br />
<span style="font-family: Arial;"> </span></div><div style="text-align: justify;"></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">For bearing faults, refer to the section ‘Analyzing bearing failures’ in previous posts</span></i><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjH9v5OaiXvJXe4tfgf5p7z0jZ_UXZdP1xswyvDU5Ycdvo7pMlMnDeQ1-pFlGlOM0fn-8ivT5NrMqyBhTrJeAnRfXFp-jDK78R8FeKJQUElqdreGak53yxcESFLeCRmD6v5EswcSnTc7gs/s1600/Fig+7.19.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjH9v5OaiXvJXe4tfgf5p7z0jZ_UXZdP1xswyvDU5Ycdvo7pMlMnDeQ1-pFlGlOM0fn-8ivT5NrMqyBhTrJeAnRfXFp-jDK78R8FeKJQUElqdreGak53yxcESFLeCRmD6v5EswcSnTc7gs/s200/Fig+7.19.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: #cfe2f3;">Fig 7.19</span></td></tr>
</tbody> </table><i><span style="color: #cc0000; font-family: Georgia;"> showing typical engine bearing problems.</span></i><br />
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<div style="font-family: "Courier New",Courier,monospace; text-align: center;"><br />
</div><div style="color: black; font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="color: #cc0000; font-family: Georgia; font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See Installing connecting rod bearings>>>>>>>>>></span></span><i><span style="color: #cc0000; font-family: Georgia;"><br />
</span></i></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-27433895619892251412011-06-21T03:21:00.006+05:002011-07-08T02:15:29.543+05:00Piston measurement and clearance<div dir="ltr" style="text-align: left;" trbidi="on"><span style="font-family: Arial;">A piston must be in good condition if it is to be reinstalled in the engine. This means that it must have no cracks, scores or scratches. It must be the correct size and have the correct clearance in the cylinder. <br />
The piston is measured with an outside micrometer or vernier calipers. The cylinder is measured with an inside micrometer and the two sets of measurements are compared to find the piston clearance. </span><br />
<div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Arial;"><span style="text-decoration: none;"> </span></span></u></b></div><div style="text-align: justify;"><br />
<b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Measuring the piston </span></u></b></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFHHcYk2zsKKOlL4qNnLgQ5qXOFdYsCNbpkPIi218w7-JFAk87iBHBveXxZTamiVCTQbufLzV0rT28vyvJ2OpZBn-ut2NVVj6xs6nOTfgV0ydI7r8AgLmjzoZVLXbPoJraCeRD7U_NBzw/s1600/pict11.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="53" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFHHcYk2zsKKOlL4qNnLgQ5qXOFdYsCNbpkPIi218w7-JFAk87iBHBveXxZTamiVCTQbufLzV0rT28vyvJ2OpZBn-ut2NVVj6xs6nOTfgV0ydI7r8AgLmjzoZVLXbPoJraCeRD7U_NBzw/s200/pict11.jpg" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 7.7</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Using a micrometer, measure the piston skirt across the thrust faces as shown in Figure 7.7. In most cases, the measurement is taken at a point which is approximately one-third of the skirt height. This is the nominal diameter of the piston and should be the greatest dimension. </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> Other measurements can be taken as a check and to make sure that the piston has not collapsed. A collapsed piston will have a reduced diameter at the lower end of the skirt. </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiwbyh1OlGSM8gIOwKRscjdBMkfFruwkWz5qWpTt5qS6q8OEhToRbdaPqx2rrS1l7f9RsKQSlJiGm7vTMQ54HnHfZoJC-MC7xKSXDM1UHG4FurTYY_ffttrf3tR-9hcV9iirTUEZAOURE/s1600/Fig7.8.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="89" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiwbyh1OlGSM8gIOwKRscjdBMkfFruwkWz5qWpTt5qS6q8OEhToRbdaPqx2rrS1l7f9RsKQSlJiGm7vTMQ54HnHfZoJC-MC7xKSXDM1UHG4FurTYY_ffttrf3tR-9hcV9iirTUEZAOURE/s200/Fig7.8.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 7.8</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">The engine manufacturer’s service manual should be consulted for piston dimensions and clearances. It will also have information on how to measure the piston. Some pistons are cam-ground, some have a tapered skirt and some are slightly barrel-shaped. All pistons are not measured in the same way. </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> Figure 7.8 is an example of piston measurement. It shows the places on a piston where measurements would be taken. These are as follows: </span></div><div style="text-align: justify;"><br />
<span style="font-family: Arial;">BB is the nominal piston diameter <br />
AA is the reduced diameter after cam grinding <br />
CC is the diameter at the top of the skirt <br />
DD is the diameter at the bottom of the skirt <br />
EE is the reduced diameter at the lands.</span> </div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><br />
<span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">These measurements enable the piston size, cam grinding, skirt taper and land </span></i><br />
<i><span style="color: #cc0000; font-family: Georgia;">relief to </span></i><i><span style="color: #cc0000; font-family: Georgia;">be determined. </span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
<b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Checking the piston in its cylinder</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjU8krJv9NjsIojd7XX90CsfLjAmUnZcjh58NoDqnQgdzGD8Rfh3wM5CO5T_wuIHberCNG8p6x6CqhUpHOOaxRA94QMfgNOE4WWCs-tR3AHCl_PCSXROqnuMiWRice7BgbgjxulMyIVX1U/s1600/Fig7.9.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="190" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjU8krJv9NjsIojd7XX90CsfLjAmUnZcjh58NoDqnQgdzGD8Rfh3wM5CO5T_wuIHberCNG8p6x6CqhUpHOOaxRA94QMfgNOE4WWCs-tR3AHCl_PCSXROqnuMiWRice7BgbgjxulMyIVX1U/s200/Fig7.9.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 7.9</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">The fit of the piston in the cylinder can be checked with a feeler-gauge strip. The following is a typical procedure. <br />
Place the piston in the cylinder upside down with the feeler strip, lightly oiled, placed 900 from the piston-pin holes. This is the greatest piston diameter. The feeler strip should extend the full length of the piston. Different thicknesses can be tried to determine the clearance. </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> A refinement of this procedure, which is more exact, requires the use of a spring scale. The force required to pull the feeler strip from between the piston and cylinder is measured (Figure 7.9). The following is an example: a strip of feeler 12 mm wide and 0.04 mm thick should be able to be withdrawn from between the piston and the cylinder wall with a pull of 20 to 40 newtons. If the feeler strip pulls out too easily, the fit is too loose, if it is too hard to pull, the fit is too tight. </span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Fitting piston rings</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">Replacement piston rings are supplied as a package kit to suit the particular engine being repaired. They can be obtained in various over sizes to suit oversize cylinder bores. <br />
Piston rings are supplied for a particular bore diameter. Their ends should not be filed to fit them to smaller bores because they will become oval-shaped when installed in the cylinder, if the cylinder has been re-bored or made oversize by honing, it will require oversize rings; if not, standard-sized rings must be used, irrespective of the wear that might have occurred to the upper portion of the cylinder.</span><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVBVih_KJXvuuV4PAGRy5dkyD8RUCd2RP7XLaU-mVropHjblmDp-aF5GXjN0d-YDRQrfmpTcGDuoIyrBc62pC76lK39ivmoR5-Uhi3SJ1CNZneijb1_bTeKSQCmJkvd762Ua9qv69Fca8/s1600/pict13.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="132" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVBVih_KJXvuuV4PAGRy5dkyD8RUCd2RP7XLaU-mVropHjblmDp-aF5GXjN0d-YDRQrfmpTcGDuoIyrBc62pC76lK39ivmoR5-Uhi3SJ1CNZneijb1_bTeKSQCmJkvd762Ua9qv69Fca8/s200/pict13.jpg" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 7.1</span></td></tr>
</tbody></table><div style="text-align: justify;"><br />
<b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Checking rings in the cylinder bore</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"><br />
</span></b><span style="font-family: Arial;">New piston rings should be checked in the cylinder to make sure that they are correct for the bore size (Figure 7.10). </span><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Arial;"></span></u></b></div><div style="text-align: justify;"><br />
<span style="font-family: Arial;">A quick check can be made with the ring near the top of the bore to make sure that it has a gap. However, before a measurement is actually taken, the ring is pushed down the cylinder with the head of a piston (Figure 7.11). This makes sure that the ring is sitting squarely in the bore. Worn bores will be tapered, and so the ring should be pushed down to the part of the bore that is least worn. This will be below the lower limit of ring travel. <br />
Check the gap between the ends of the ring with feeler gauges. A rule of thumb is that the</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi20sHanhFr3MWAJpbZ-8Dcy3u9-P5wGcAYf2jS4gg2qdHnB39Yo7oVdw4WpCFBI-AwBWVwklzz3E30bWvBV8vib85QaaNU-vxZsjcNdSpIa-F7tzAwgTIePTZUqqXZhjwda9Msh4citII/s1600/Fig7.11.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi20sHanhFr3MWAJpbZ-8Dcy3u9-P5wGcAYf2jS4gg2qdHnB39Yo7oVdw4WpCFBI-AwBWVwklzz3E30bWvBV8vib85QaaNU-vxZsjcNdSpIa-F7tzAwgTIePTZUqqXZhjwda9Msh4citII/s200/Fig7.11.gif" width="198" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 7.11</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">gap clearance should be 0.03 mm for each 10 mm of cylinder diameter, measured in the <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">unworn</span> </i>part of the bore.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> </span></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">The ring must not be measured at the top of the bore because its gap will close as it is moved towards the bottom of the cylinder. Without a gap, the ring will break or cause scuffing of the cylinder walls.</span></i></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><br />
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</div><div style="margin-left: 0in; text-indent: 0in;"><br />
</div><div style="margin-left: 0in; text-indent: 0in;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="font-family: Arial;"><span style="font-family: "Courier New",Courier,monospace;">See piston rings checking>>>>>></span></span></span></div><div style="margin-left: 0in; text-indent: 0in;"><br />
</div><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b><br />
<span style="font-family: Arial;"></span><span style="font-size: 11pt;"> </span></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-81439955457610469172011-06-20T02:17:00.005+05:002011-07-06T03:21:03.245+05:00Piston, connecting rod and bearing service<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">Satisfactory engine performance cannot be obtained unless the piston and connecting-rod assembly are in good condition. <br />
The piston must have correct clearance in the cylinder to avoid piston slap, the compression rings must seal to prevent pressure loss during compression and combustion, the oil ring must control the oil on the cylinder walls, and the piston pin must be the correct fit to prevent noise. <br />
The connecting-rod bearings must not be damaged or worn, and the crank-pin journals must be in good condition to prevent oil loss and noise. </span></div><div></div><div style="text-align: justify;"><u><span style="color: #7030a0; font-family: Arial;"><span style="text-decoration: none;"><br />
</span></span></u></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Dismantling the piston assembly</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">The following are points that relate to dismantling a piston and connecting-rod assembly: <br />
1. Remove the piston rings by winding them out of the grooves in the piston. A thick feeler gauge used under the rings will help. <br />
2. Push the halves of the bearing from the connecting rod and cap. Check for difference between the upper and lower halves. The upper half of the bearing may have an oil hole. <br />
3. Check the piston pin by trying to move the connecting rod in relation to the piston. <br />
4. If the piston is to be removed from the connecting rod, check for markings that identify the front of the piston in relation to the connecting rod. <br />
<i>5. </i>Separate the piston from the connecting rod by removing the piston pin. Depending on the type, the pin may have to be tapped or pressed out. <br />
6. Temporarily install the cap on the connecting rod so that the bearing and all the other parts of the assembly are together.</span><span style="font-size: 11pt;"> <br />
</span><span style="font-family: Arial;">7. Clean the various parts and check for wear. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">All parts must be kept to their original cylinders </span></i><span style="color: #cc0000; font-family: Georgia;">— <i>mark or label as necessary. </i></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><u><span style="color: #7030a0; font-family: Arial;"><span style="text-decoration: none;"><br />
</span></span></u></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Removing and replacing piston pins</span></u></b><b><span style="font-family: Tahoma; font-size: 17pt;"> </span></b><span style="font-family: Tahoma;"></span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvKNTdz5Fj3LAYjPjK_k7ysyIxHRxLRbrQpx0y0ZnJIUQdLsvzukK0hruz4SvGEJcizGMkXOwYBt5lg7iXM333sInXTDmvwhve8hnTc3MWqfpYv9V_UKxGuEA41NcRbGgU68g0bon-8ds/s1600/pict0.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="124" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvKNTdz5Fj3LAYjPjK_k7ysyIxHRxLRbrQpx0y0ZnJIUQdLsvzukK0hruz4SvGEJcizGMkXOwYBt5lg7iXM333sInXTDmvwhve8hnTc3MWqfpYv9V_UKxGuEA41NcRbGgU68g0bon-8ds/s200/pict0.jpg" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.1</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Normally, the piston and connecting rod are only separated if there seems to be looseness between the piston and the rod. To check the fit of the piston pin, hold the piston firmly and try to rock the connecting rod from side to side (Figure 7.1). There should be little or no movement. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">If there is obvious movement then the piston pin, the pin holes in the piston, or the bush in the connecting rod (where fitted) will be worn. The piston should be dismantled from the connecting rod so that the parts can be examined.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP2Dh5MUKCElUGBQGAK2uFcpzqhcga9hyphenhyphengnjfqiQ-BA3qQc8B0xSDNQkNsd7wHr1-olCZqGZM5EqVs1AhgrzWjRpkluHXMlUX2zEasmIAt-adrMZIjfzMLFqa6abYrW-eYQf-b1ZQoQ6M/s1600/Fig7.2.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP2Dh5MUKCElUGBQGAK2uFcpzqhcga9hyphenhyphengnjfqiQ-BA3qQc8B0xSDNQkNsd7wHr1-olCZqGZM5EqVs1AhgrzWjRpkluHXMlUX2zEasmIAt-adrMZIjfzMLFqa6abYrW-eYQf-b1ZQoQ6M/s200/Fig7.2.gif" width="91" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.2</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Floating piston pins </span></u></b><b><span style="font-family: "Helvetica, sans-serif";"><br />
</span></b><span style="font-family: Arial;">Removing and installing a floating piston pin is shown in Figure 7.2. This has circlips that have to be removed from the piston before the piston pin can be removed. <br />
The piston pin can be tapped out, using a light hammer and a punch. The piston must be suitably supported to prevent it from being damaged and the punch should have a pilot that fits into the hollow piston pin.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="font-size: small;"><span style="color: #cc0000; font-family: Symbol;">·<span style="-moz-font-feature-settings: normal; -moz-font-language-override: normal; font-family: "Times New Roman"; font-size-adjust: none; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal;"> </span></span></span><i><span style="font-size: 11pt;"><span style="font-size: small;"><span style="color: #cc0000;">If the piston pin is tight, the piston should be heated before the pin is </span></span></span></i><br />
<i><span style="font-size: 11pt;"><span style="font-size: small;"><span style="color: #cc0000;">removed. </span></span><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">When dismantled, the bush in the small end of the connecting rod should be checked for wear, as well as the piston pin and the pin holes in the piston. <br />
In some cases, a worn bush in the eye of a connecting rod can be replaced by pressing out the old bush and pressing in a new one. Figure 7.3 shows this operation for a connecting rod of a diesel engine. This is a rugged connecting rod with a relatively thick bush. The eye of the rod must be supported and a suitable pressing tool used. The bush has</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcO32FZwQhT4aHg9LRSt6Lk0EXetiZXtlPkmFX7pyponXic78ApADcsM03Ns5PcKWJ24lwPV56OUCJjnR_XysXdpfCof0LswR97aPqtIeVj6vDi1663KpjgmOx8qEWYO-Uj6oFXQ8zm1I/s1600/Fig7.3.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcO32FZwQhT4aHg9LRSt6Lk0EXetiZXtlPkmFX7pyponXic78ApADcsM03Ns5PcKWJ24lwPV56OUCJjnR_XysXdpfCof0LswR97aPqtIeVj6vDi1663KpjgmOx8qEWYO-Uj6oFXQ8zm1I/s200/Fig7.3.gif" width="194" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.3</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;"> an oil hole that must be aligned with the hole in the rod. </span><br />
<span style="font-family: Arial;"> Before installing the piston pin, the piston should be heated so that the pin can be installed without damage. New circlips should be used.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><u><span style="color: #7030a0; font-family: Arial;"><span style="text-decoration: none;"></span></span></u><br />
<u><span style="color: #7030a0; font-family: Arial;"><span style="text-decoration: none;"></span></span></u></div><div style="color: purple; font-family: Arial,Helvetica,sans-serif; text-align: justify;"><span style="font-size: 9pt;">Figure 7.2 Floating piston pin <br />
(a) the circlips are removed with a small <br />
screwdriver (b) the piston pin is installed to a heated piston (c) new circlips are fitted</span></div><div style="text-align: justify;"><u><span style="color: #7030a0; font-family: Arial;"><span style="text-decoration: none;"><br />
</span></span></u></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Press-fit piston pins</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">A pressing tool and a supporting tool are needed when removing or installing piston pins that are a press fit. </span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">This type of pin is free to move in the piston bosses, but is a press fit in the small end of the connecting rod. <br />
Figure 7.4 shows how the piston is being supported while the piston pin is being pressed out of the connecting rod. The pin must not be driven out. Before removing a piston pin, note its exact position in the connecting rod so that it can be replaced in the same position. </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBV_nlAzWcahSGBcTKlH7wj1o3I_8CvlyFXuZnBzhGeixcQf9dpzNdcM8FWLjlDV8Sm38b_DJGPHHdBSkzai_-CyBR6eOgyiW1jMF-TfYIFeAtYiTQZyT17xLAVDmD8Qn3eUtuTwkvN_k/s1600/pict4.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="184" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBV_nlAzWcahSGBcTKlH7wj1o3I_8CvlyFXuZnBzhGeixcQf9dpzNdcM8FWLjlDV8Sm38b_DJGPHHdBSkzai_-CyBR6eOgyiW1jMF-TfYIFeAtYiTQZyT17xLAVDmD8Qn3eUtuTwkvN_k/s200/pict4.jpg" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.4</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> Press-fit piston pins have an interference fit of about 0.02 mm in the eye of the connecting rod. When </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">a pin is to be installed, the eye of the rod can be heated carefully on a hotplate so that the piston pin can be easily fitted. <br />
The pressing tool and support arc used to press the pin back into the connecting rod. This must be done quickly so that the pin is in its correct position before the connecting rod cools and contracts. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><br />
<div style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Heating the piston or rod</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">To heat the piston, place it in a container of water and heat the water to almost boiling point (Figure <i>7.5). </i>This will expand the piston and make the piston pin easier to remove. This can be done before dismantling and also before reassembling. </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWYKoCowxgtdV7IYq16g_WLaUBtLqNnOAO9MBkL0BtJgZjVtD5NvNWXWGCV1YWEtxhdypGatEehcSYWYHwbcMUMVtZ0AszuVaegbaFDB64b2BX1HTx2dcLJ7hzReBT5FF9NKSPvnbvk1E/s1600/pict6.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="109" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWYKoCowxgtdV7IYq16g_WLaUBtLqNnOAO9MBkL0BtJgZjVtD5NvNWXWGCV1YWEtxhdypGatEehcSYWYHwbcMUMVtZ0AszuVaegbaFDB64b2BX1HTx2dcLJ7hzReBT5FF9NKSPvnbvk1E/s200/pict6.jpg" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.5</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;"> An alternative method, only for press-fit piston pins, is to carefully heat the end of the connecting rod on a hotplate. This will expand the eye of the connecting rod and allow the piston pin to be fitted. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">Direct flame should not he applied to a connecting <span style="mso-bidi-font-weight: bold;">rod<b>. </b></span></span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="margin-left: 0.5in; text-align: left; text-indent: -0.5in;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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<i><span style="color: #cc0000; font-family: Georgia;"><b> </b></span></i></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston-pin fit <br />
</span></u></b><span style="font-family: Arial;">A piston pin that is fitted too tightly could cause distortion, while a pin that is too loose could cause a knock. <br />
Engine manufacturers specify clearances, such as 0.002—0.008 mm between the piston pin and the piston, with a wear limit of 0.02 mm. These are very small clearances. The small clearances are possible by having the piston pin a selective fit in the piston. The piston pin and the hole in the piston have extremely fine surface-finishes and this reduces wear. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="margin-bottom: 6pt; text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Types of piston pins fit</span></i></b><b style="mso-bidi-font-weight: normal;"><i style="mso-bidi-font-style: normal;"><span style="font-family: Georgia; font-size: 12pt;"></span></i></b></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_A6magzlkl-bDCJ86EPAYMvgh5eMaH-eloFhqZd-OlszTn_YDB_SDxMkr_X7xzHCwgAjj65GucfIFsOMBGbbBJZ9NnKfV2E6EC7Ij5gNTEcehp4uhPCB-a_FvyCt-3yy0FuJRsDenrls/s1600/Fig7.6.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_A6magzlkl-bDCJ86EPAYMvgh5eMaH-eloFhqZd-OlszTn_YDB_SDxMkr_X7xzHCwgAjj65GucfIFsOMBGbbBJZ9NnKfV2E6EC7Ij5gNTEcehp4uhPCB-a_FvyCt-3yy0FuJRsDenrls/s200/Fig7.6.gif" width="73" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">7.6</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">During manufacture of parts, special gauges are used and these are capable of measuring to an accuracy of 0.0002 mm. In service workshops, where clearances have to be checked, such accuracy is not needed and micrometers, calipers and dial gauges are used. <br />
There are also ways of describing the fits between parts — three descriptions of the fit of piston pins are illustrated in Figure 7.6. In order of tightness, these are</span> <i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">hand-push</span></i><i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial;">fit,</span> <i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">thumb-push</span></i><i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial;">fit and </span><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">finger-push</span></i><i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial;">fit</span>. <span style="font-family: Arial;">There are other descriptions that can be used, such as</span><i><span style="color: #cc0000; font-family: Georgia;"> tap fit, light-tap fit </span></i><span style="font-family: Arial;">and</span><i><span style="color: #cc0000; font-family: Georgia;"> drive fit. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></i></div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;"> While these fits are not measurements, they are useful as workshop</span></i></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><i><span style="color: #cc0000; font-family: Georgia;">descriptions. </span></i></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="font-family: Arial;"><span style="font-family: "Courier New",Courier,monospace;">See piston measurements and clearance>>>>>></span></span></span></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><br />
</div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com1tag:blogger.com,1999:blog-761095749605083867.post-43525088383227994002011-06-19T01:45:00.005+05:002011-07-06T02:24:43.119+05:00Connecting rods<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWHgKhIlchh-JWYSHMAi5uDaICXNTHrlAxQFst10yEjnDSNWmdnbIjk60chkdynuucMJkiHriyHqi5JllTO7biDoGAzyZaSSMSGYeQ04n9650mNO_rkC6oG6zqZrrHDKvFPEUKHzfosCw/s1600/Fig+6.25.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br />
</a></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisSVTj-efocE67qiSh8zHwARlZKTVJ0M_bqYakuXoO2TujDzTKSkaJ0l0TMHmPxHbC7SjQbiyzipxr674mVNd_dy34Ml1bD9v0MYof8yp3ihRKUR6BOwQ6pdM9ToCFQGYVZE95zJcCi98/s1600/Fig+6.22.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisSVTj-efocE67qiSh8zHwARlZKTVJ0M_bqYakuXoO2TujDzTKSkaJ0l0TMHmPxHbC7SjQbiyzipxr674mVNd_dy34Ml1bD9v0MYof8yp3ihRKUR6BOwQ6pdM9ToCFQGYVZE95zJcCi98/s200/Fig+6.22.gif" width="119" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 6.23</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">The connecting rod must be very strong and rigid, but it must also be as light as possible. Connecting rods are highly stressed, being subjected to stretching, compression and bending. They are made as a forging of H-section, because this shape provides greater strength than a solid rod of the same mass (Figure 6.23).</span></div><div></div><div class="MsoNormal" style="text-align: justify;"><br />
<span style="font-family: Arial;">The crank-pin end is the larger end of the connecting rod and is often referred to as the </span><i><span style="color: #cc0000; font-family: Georgia;">big end</span></i><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">The piston end is much smaller and so is referred to as the <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">small end</span>, </i>or sometimes as the </span><i><span style="color: #cc0000; font-family: Georgia;">little end</span></i><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">The big end of the connecting rod has a bearing cap that enables it to be installed on the crank-pin. The big end also carries the two halves of the bearing. </span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"></div><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh71SOFOVA7yRe8gjrBtS9o5sceNWUKAiqBdMPH4yomkX5r7xYnKXjOvrzT_n7uICCyUDjAupL3ToCcLpSXV6wlcHyF5HW5m44HRvGynRcxH50ibossmafSx4q0T9I0LZd4IDj0uW4GWUU/s1600/Fig+6.24.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh71SOFOVA7yRe8gjrBtS9o5sceNWUKAiqBdMPH4yomkX5r7xYnKXjOvrzT_n7uICCyUDjAupL3ToCcLpSXV6wlcHyF5HW5m44HRvGynRcxH50ibossmafSx4q0T9I0LZd4IDj0uW4GWUU/s200/Fig+6.24.gif" width="200" /></a></td></tr>
<tr style="background-color: #cfe2f3;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 6.24</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Connecting-rod features</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">To maintain engine balance, all the connecting rods in an engine are matched for mass. The cylinder number is stamped on most rods and caps so that they will not become mixed up when the engine is dismantled (Figure 6.24). </span><br />
<span style="font-family: Arial;"> During the manufacture of most connecting rods, the parting faces of both the bearing cap and the connecting rod are machined as flat surfaces. The cap is bolted to the rod, and the</span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> bore for the bearing is then finished to an accurate size. </span><br />
<span style="font-family: Arial;"> Another process uses a <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">fracture</span> </i>method. The connecting rod is made as a single piece and the cap is then broken away from the rod. The cap is reassembled to the rod and the bore for the bearing is machined. With this process, the parting faces of the cap and the connecting rod are irregular, but they fit together so closely that the parting line can barely be seen. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;"><br />
</span><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Connecting-rod bolts</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Some connecting rods have cap bolts with nuts, similar to those in Figure 6.23. The bolts are a neat fit in the connecting rod and are not usually removed unless they are to be replaced. Other connecting rods have cap bolts that are threaded into the connecting rod. <br />
Some bolts have their shank reduced in diameter so that it is less than the thread and this actually increases their strength. In a normal bolt, the root of the thread is the smallest diameter and so takes the greatest stress. When the shank of a bolt is reduced in size, the stress is distributed over a different part of the bolt and so prevents failure at the thread.</span> <br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><span style="color: red; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="font-family: Georgia;"><span style="color: red;">The cap bolts are subjected to a tensile stress (stretching) caused by the piston inertia</span></span></i></div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><i><span style="font-family: Georgia;"><span style="color: red;"> at the top of the stroke.</span> </span></i><span style="font-family: Georgia;"></span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Forces in a connecting-rod assembly</span></u></b></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWHgKhIlchh-JWYSHMAi5uDaICXNTHrlAxQFst10yEjnDSNWmdnbIjk60chkdynuucMJkiHriyHqi5JllTO7biDoGAzyZaSSMSGYeQ04n9650mNO_rkC6oG6zqZrrHDKvFPEUKHzfosCw/s1600/Fig+6.25.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWHgKhIlchh-JWYSHMAi5uDaICXNTHrlAxQFst10yEjnDSNWmdnbIjk60chkdynuucMJkiHriyHqi5JllTO7biDoGAzyZaSSMSGYeQ04n9650mNO_rkC6oG6zqZrrHDKvFPEUKHzfosCw/s200/Fig+6.25.gif" width="126" /></a></td></tr>
<tr style="background-color: #cfe2f3; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;">Fig 6.24</td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Forces in a connecting-rod </span><span style="font-family: Arial; font-size: 12pt;">assembly </span><span style="font-family: Arial;"></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">The connecting-rod and piston assembly are subjected to various forces. These are caused by combustion pressure, piston inertia and centrifugal force. <br />
An example of the way in which inertia forces act on the various parts of the assembly can be seen in Figure 6.25<i>. </i>The piston in the illustration is almost at the end of an upstroke (exhaust stroke) and at TDC will produce an inertia force that will be transmitted to other</span><span style="font-family: Arial;"> parts of the assembly. </span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">On the down-stroke, when the piston reaches BDC, the direction of most of the forces due to inertia will be the reverse of those shown. <br />
The piston provides an inertia force at TDC and BDC where the piston changes its stroke. In effect, the piston tries to keep moving but is held by the connecting rod. This places the connecting rod in <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">tension</span> </i>when the piston is at TDC and in </span><i><span style="color: #cc0000; font-family: Georgia;">compression</span></i><i><span style="font-family: Arial;"> </span></i><span style="font-family: Arial;">when the piston is at BDC. </span><span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif; font-size: 10pt;"> </span></div><div style="text-align: justify;"><div style="text-align: justify;"><div style="background-color: white;"><br />
<span style="background-color: white; color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 6.25<u> </u>Effects of inertia of the piston at the end of the exhaust stroke </span><span style="background-color: white; color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif; font-size: 4pt;">— </span><span style="background-color: #fce5cd; font-family: "Helvetica, sans-serif"; font-size: 10pt;"><span style="color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="background-color: white;">the assembly is for a diesel engine</span> </span></span></div><span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"><span style="color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"> 1 piston inertia, 2 toad on upper half of small-end bush, </span></span><br />
<span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"><span style="color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"> 3 connecting rod in tension, 4 bolts in tension, 5 toad on </span></span><br />
<span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"><span style="color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"> tower half of big-end bearing, 6 toad on upper half of main </span></span><br />
<span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"><span style="color: purple; font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"> bearing </span></span></div><span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"></span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: "Helvetica, sans-serif"; font-size: 10pt;"> <br style="mso-special-character: line-break;" /> </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">There are many forces acting at different times. On the compression stroke, compression pressure will have an influence on the forces, as will combustion pressure during the power stroke. The effects of centrifugal force, due to crankshaft rotation, will increase with engine speed. <br />
The assembly shown in Figure 6.25 is for a larger diesel engine. The parts are bigger and have a greater mass than those of a petrol engine, so greater stress can be created. However, the engine rotational speeds (and piston speeds) will be much lower than those of a petrol engine. </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Connecting-rod bearings </span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"><br />
</span></b><span style="font-family: Arial;">Connecting-rod bearings are split-sleeve bearings of the precision-insert type. One half of the bearing is carried in the connecting rod and the other half in the connecting-rod cap. <br />
Various points relating to crankshaft bearings were discussed in last posts, and there is more information related to bearings in the posts that follows.</span></div><div style="text-align: justify;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: left;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="font-family: Arial;"><span style="font-family: "Courier New",Courier,monospace;">See piston, Connecting rod and bearing service>>>>>>>>>>>>>>>>>></span></span></span></div><div style="text-align: justify;"><span style="font-family: Arial;"> </span><span style="font-size: 11pt;"> </span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-28049079803430960032011-06-18T02:00:00.000+05:002011-07-05T02:13:55.431+05:00Piston ring sets and piston pins<div dir="ltr" style="text-align: left;" trbidi="on"><div><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;"></span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 18.0pt;"></span></b><span style="font-size: 18.0pt;"></span></div><div style="text-align: justify;"> </div><div style="margin-bottom: 12pt; text-align: justify;"><span style="font-size: 11.0pt;"><span style="font-family: Arial,Helvetica,sans-serif;">The engines of most passenger cars and light commercial vehicles have pistons with a set of three rings. Typical ring sets are shown in Figures 6.18 and 6.20. There are various combinations of compression rings and oil rings. Usually, there is a top compression ring, a scraper ring, and a segmental oil ring. </span></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b><i style="mso-bidi-font-style: normal;"><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">Piston-ring coatings</span></i></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Some piston rings are coated with a soft material to assist them to ‘bed in’. New rings and cylinders have very small irregularities and when these wear off, the rings will provide a better seal. To assist this process, the rings can be coated with phosphate, graphite or iron oxide. These are relatively soft substances which wear more quickly than the ring material. The coatings also absorb oil and help with ring lubrication. This prevents scuffing of the cylinder walls. <br />
To prevent wear, the face of the piston ring can be coated with chromium. This is a relatively hard material, but it operates well against the cast-iron cylinder walls without scuffing. </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Molybdenum is also used as a coating for compression rings. It has properties that give quick bedding-in. Rings coated with molybdenum resist abrasive wear much better than uncoated cast iron rings, but not as well as chromium-plated rings.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFjZUzGWrabyfq7eEduJZpLI0noJh_7UDYlcFdVMubbjR9Xn0FUoMq0jT88v4WxESoHIKDF4JrizM2yifykG46nDEJ5-t7X0Ui2mz0inqf7uOHujWiEspU-PoWZOo8nD2aP41Bvz1Jw9w/s1600/Fig+6.20.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="126" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFjZUzGWrabyfq7eEduJZpLI0noJh_7UDYlcFdVMubbjR9Xn0FUoMq0jT88v4WxESoHIKDF4JrizM2yifykG46nDEJ5-t7X0Ui2mz0inqf7uOHujWiEspU-PoWZOo8nD2aP41Bvz1Jw9w/s200/Fig+6.20.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial; font-size: 11.0pt;"></span><span style="font-family: Arial;"> 6.21</span></td></tr>
</tbody></table><div style="margin-bottom: 6pt; text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;">Piston pins</span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 17.0pt;"> <br />
</span></b><span style="font-family: Arial;">The piston pin secures the piston to the small end of the connecting rod and also provides the wrist-like action that is needed between the two parts. <br />
There are different methods used to retain the piston pin, but two that are commonly used are shown in Figure</span><span style="font-family: Arial; font-size: 11.0pt;"> </span><span style="font-family: Arial;">6.21. These are:</span><span style="font-family: Arial; font-size: 11.0pt;"> </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;">1<span style="font-size: 11.0pt;">. </span><i><span style="color: #cc0000; font-family: Georgia;">Press fit pin</span></i><i><span style="font-size: 11.0pt;">. </span></i><span style="font-family: Arial;">The piston pin is a press fit in the eye of the connecting rod and floats in the piston. The fit in the connecting rod is tight enough to retain the pin and prevent it from moving. This is the method most commonly used for engines in passenger cars and light commercial vehicles.</span><span style="font-family: Arial; font-size: 11.0pt;"> <br />
</span>2<span style="font-size: 11.0pt;">. </span><i><span style="color: #cc0000; font-family: Georgia;">Floating pin</span></i><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">The piston pin is arranged to float in both the eye of the connecting rod and the piston. Circlips in grooves in the piston bosses retain the piston pin and prevent it from coming into contact with the cylinder walls. <br />
There are variations of the designs shown. With some floating piston pins, thrust pads of soft metal are fitted in the ends of the pins. The pin floats in the piston and in the connecting rod. The thrust pads are allowed to come into contact with the cylinder wall, but being soft and lightly loaded, they do no hanu. <br />
With another design, the piston pin is clamped in the connecting rod. The eye of the rod is split and a bolt is used to form it into a clamp. This design increases the mass at the small end of the connecting rod, which is not desirable because it adds to the mass of the reciprocating parts.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">The piston pin is also referred to as a wrist pin, and sometimes as a gudgeon pin</span><span style="color: #cc0000;">. </span></i><span style="color: #cc0000; font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitMCCz1B6lFxPJVSmo9SzGfxYeU4q47CAKwyghkwZUMsShEuZlO9h7uDVQhQYe1lTm5r94ogCODrE_B5XaI3vdePXOrY6FodAaUQqI0h6U12mwu7CezjL4XsLQchddEBDf5VZW210uZrE/s1600/Fig+6.22.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitMCCz1B6lFxPJVSmo9SzGfxYeU4q47CAKwyghkwZUMsShEuZlO9h7uDVQhQYe1lTm5r94ogCODrE_B5XaI3vdePXOrY6FodAaUQqI0h6U12mwu7CezjL4XsLQchddEBDf5VZW210uZrE/s200/Fig+6.22.gif" width="119" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.22</span></td></tr>
</tbody></table><div style="margin-bottom: 6pt; text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Piston-pin lubrication</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Most piston pins depend on splash and oil mist for lubrication, but some piston pins are pressure- lubricated. For this, an oil passage is drilled the full length of the connecting rod. Oil from the connecting- rod bearing passes through the passage to the piston pin. <br />
Most engines have a connecting rod with a ‘spit hole’, or oil jet, in the crank-pin end. This hole lines up with the oil hole in the crank-pin once on each revolution of the crankshaft. When this occurs, a squirt of oil is directed onto the cylinder walls as shown in Figure 6.22. This also lubricates the piston pin. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">In engines with piston cooling jets, the oil directed from the jet cools the piston and also lubricates the piston pin (previous Figure 6.9).</span></div><div style="text-align: justify;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See Connecting rods>>>>>>>>>>>>>>>>>></span></span></span></div><div style="text-align: justify;"><span style="font-family: Arial;"></span></div><div style="text-align: justify;"><span style="font-family: Arial;"></span></div><div style="text-align: justify;"><span style="font-family: Arial;"><span style="color: #cc0000;"></span></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-75898759839794061932011-06-17T00:49:00.009+05:002011-07-05T01:59:58.906+05:00Piston rings<div dir="ltr" style="text-align: left;" trbidi="on"><!--[if gte mso 10]> <style>
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</style> <![endif]--> <div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt;"></span></u></b><span style="font-family: Arial;">There are two general types of piston rings: <i><span style="color: #cc0000;">compression rings</span> </i>and <i><span style="color: #cc0000;">oil rings</span>. </i>They fit accurately into the grooves in the pistons. Compression rings provide a gas seal against the cylinder walls, while oil rings control the oil on the cylinder walls and return excess oil to the oil pan.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div> </div><div class="MsoNormal" style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-bidi-font-style: italic; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Oil rings are also referred to as oil-control rings. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></i></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK5eNBza4Q0EBWNDso8Ha6BoNbInGlAVux9d9yyZ_f9jMxNx28rcdqaruDlyxsMtteaU9OmZKDCdTk4PUirTKFhdzmWx2S58Rd9h7OlpZnL5xfJYxnd_jqWuw1Vqpmg8cEOY5nEdS4MEA/s1600/Fig+6.13.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK5eNBza4Q0EBWNDso8Ha6BoNbInGlAVux9d9yyZ_f9jMxNx28rcdqaruDlyxsMtteaU9OmZKDCdTk4PUirTKFhdzmWx2S58Rd9h7OlpZnL5xfJYxnd_jqWuw1Vqpmg8cEOY5nEdS4MEA/s200/Fig+6.13.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.13</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Figure 6.13 shows a basic compression ring and a basic oil ring with their parts named, but there are a number of variations in design. Piston rings are split so that they expand against the cylinder walls. This also enables them to be fitted into the grooves in the piston. <br />
When removed from the engine, piston rings are larger in diameter than the cylinder, but when installed, they are compressed so that the gap is almost closed. The tension within the rings keeps them against the cylinder walls.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5waZS20p-wyOMaaKSMHU0M044pbZ3NQXpcMarU-zBnUQteyo6prwM2FWpPqKCbDmgF-AVVDmqqkXcZLSIwg6e4VFKMvUyIYS3nDxqv1ilvtImvAvlsV5s28HmSdMPxZr2pXKdgpkM55M/s1600/Fig+6.14.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="176" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5waZS20p-wyOMaaKSMHU0M044pbZ3NQXpcMarU-zBnUQteyo6prwM2FWpPqKCbDmgF-AVVDmqqkXcZLSIwg6e4VFKMvUyIYS3nDxqv1ilvtImvAvlsV5s28HmSdMPxZr2pXKdgpkM55M/s200/Fig+6.14.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.14</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-size: large;"><b><u><span style="color: #006600; font-family: Tahoma;">Compression rings</span></u></b></span><b><span style="font-family: "Helvetica\, sans-serif";"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;">Compression rings have to provide a seal that prevents loss of air during the compression stroke and loss of gas pressure during the power stroke. If the rings do not seal properly on the compression stroke there will be loss of compression and engine power. If the rings do not seal properly during the power stroke then combustion gases will be forced past the piston into the crankcase. This condition occurs in a worn engine and is known as </span><i style="color: #cc0000;"><span style="font-family: Georgia; mso-bidi-font-family: Arial;">blowby</span></i><i><span style="font-family: Arial;">.</span></i><i><span style="font-size: 11.0pt;"> </span></i></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="margin-bottom: 12pt; text-align: justify;"><span style="font-size: large;"><b><i><span style="color: #cc0000;">Types of compression rings</span><span style="color: #cc0000;"> </span></i></b></span><i><span style="font-size: 11.0pt;"></span></i><br />
<i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial;">Figure 6.14 shows the shape of the cross-section of a number of compression rings. They all depend on the tension within the ring to hold them outwards against the cylinder walls, but</span></div><div class="MsoNormal" style="margin-bottom: 12pt; text-align: justify;"><span style="font-family: Arial;"> some have features that provide additional pressure in operation. Some have a torsional action. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">1</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Tapered ring</span><span style="color: #cc0000;"> </span></i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">has a slightly tapered face that helps to scrape oil from the cylinder walls.</span> <br />
<span style="font-family: Arial;">2</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Chamfered ring</span> </i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">the chamfer on the back of the ring produces an increased pressure against the cylinder walls.</span> <br />
<span style="font-family: Arial;">3</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Counter-bored ring</span> </i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">a back edge of the ring is cut away to give a torsional action. </span><br />
<span style="font-family: Arial;"> 4</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Undercut ring</span> </i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">the face is slightly tapered and its lower part cut away to give a torsional</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTzlcTWODnpWPNm4jtVn_lqBbXwoVgKfSgM19ljpLlMFaU2uzUkcK_h85JB_A06fgt0maUnbhbjcENpV5ub937CUpuXGbDFyE5djeLTL4sVkHbfLsi80RQjUxgXgq3MN27UBuq5auYEdo/s1600/Fig+6.15.gif" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="155" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTzlcTWODnpWPNm4jtVn_lqBbXwoVgKfSgM19ljpLlMFaU2uzUkcK_h85JB_A06fgt0maUnbhbjcENpV5ub937CUpuXGbDFyE5djeLTL4sVkHbfLsi80RQjUxgXgq3MN27UBuq5auYEdo/s200/Fig+6.15.gif" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial;">Fig </span><span style="font-family: Arial;"><span style="background-color: cyan;">6.15 (a & b)</span></span></td></tr>
</tbody> </table><div style="text-align: justify;"><span style="font-family: Arial;"> action.</span> <br />
<span style="font-family: Arial;">5</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Plain ring</span> </i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">has a rectangular section and is held against the cylinder wall by its own tension.</span> <br />
<span style="font-family: Arial;">6</span>. <i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">Faced ring</span> </i><span style="font-family: "Helvetica\, sans-serif";">— </span><span style="font-family: Arial;">the facing resists heat and wear.</span> </div><div style="text-align: justify;"> </div><br />
<div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Torsional rings</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> </span></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Figure 6.15 shows the torsional action of compression rings with shaped cross-sections. This is shown on both the </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">intake </span></i><i style="mso-bidi-font-style: normal;"><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">stroke</span></i><span style="font-family: Arial;"> and the </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">power </span></i><i style="mso-bidi-font-style: normal;"><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">stroke</span></i><span style="font-family: Arial;">. </span><br />
<span style="font-family: Arial;"> During the </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">intake stroke</span></i><i><span style="font-family: Arial;">, </span></i><span style="font-family: Arial;">internal forces in the ring (due to removing a corner of the ring) cause the ring to twist slightly (Figure <i>6.15(a)). </i>As the piston moves down the cylinder</span><span style="font-size: 11.0pt;">, </span><span style="font-family: Arial;">the rings have a scraping action that removes surplus oil from the cylinder walls. On the piston</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVm5B-LXMXPvcGC57-PBypOtMTV_vAYn4IOXMyTQPHfLJnhdFklD4KdW6BvmMn0qrBtcOvzFoFfTlWbUPa5vt0ADR5QjJnU_1-U9Co_De0dBZwz_ZDmum6mdbGWYZned78Md58sYC81uM/s1600/pict18.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVm5B-LXMXPvcGC57-PBypOtMTV_vAYn4IOXMyTQPHfLJnhdFklD4KdW6BvmMn0qrBtcOvzFoFfTlWbUPa5vt0ADR5QjJnU_1-U9Co_De0dBZwz_ZDmum6mdbGWYZned78Md58sYC81uM/s200/pict18.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.16</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;"> upstrokes, the rings tend to slide over the film of oil and so have less tendency to carry oil up into the combustion chamber.<span style="mso-spacerun: yes;"> </span></span></div><div style="text-align: justify;"> </div><br />
<div style="text-align: justify;"><span style="font-family: Arial;">During the </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">power stroke</span></i><i><span style="font-family: Arial;"> </span></i><span style="font-family: Arial;">(Figure 6.15(b)) combustion pressure forces down on the top of the ring and also against the back of the ring. This straightens the ring so that it has fill-face contact with the cylinder walls. This provides effective sealing.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Because of their twisting action, rings with a chamfer or counter-bore that act in the way described, are known as <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">torsional rings</span>. </i>Figure 6.16 shows how gas pressure from combustion gets behind the ring to force it against the cylinder wall and also downwards against the piston. <br />
Where shaped rings are used, the top of the ring is marked in some way so that it can be installed correctly (Figure 6.17). </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheZi2h0hHbrCAcf0iWXKHqrgPxBuUYArXMXL7DFASX5OWTRZhHDhR5Pn5WozFrYNqnAY_5iqaJ2a8bO6FgWJkfpvJXv0g1YPlFDM7zDVV8xXUFGD3b2bVdIhTWy_-HKiLFb4bGoTH_qrc/s1600/Fig+6.17.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="146" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheZi2h0hHbrCAcf0iWXKHqrgPxBuUYArXMXL7DFASX5OWTRZhHDhR5Pn5WozFrYNqnAY_5iqaJ2a8bO6FgWJkfpvJXv0g1YPlFDM7zDVV8xXUFGD3b2bVdIhTWy_-HKiLFb4bGoTH_qrc/s200/Fig+6.17.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.17</span></td></tr>
</tbody></table><div style="text-align: justify;"><br />
<b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Oil rings</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> </span></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Oil-control rings prevent excessive oil from working up past the piston into the combustion chambers. The oil that has to be controlled is thrown from the connecting-rod bearings and, in some cases, from an </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">oil <span style="mso-bidi-font-weight: bold;">jet</span></span></i><b><i><span style="font-family: Arial;">, </span></i></b><span style="font-family: Arial;">or from an <i>oil-spit hole </i>in the connecting rod (Figure 6.22). Generally, there is more oil than needed on the cylinder wall and the oil rings remove the surplus. They also help to provide a seal.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"><br />
</span><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-size: 12.0pt;">Types of oil rings</span></i></b><b><i><span style="font-size: 11.0pt;"> <br />
</span></i></b><span style="font-family: Arial;">The oil ring in Figure 6.13(b) is a one-piece ring that depends on its own tension to hold it</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQFhSKrIs02KdsG2zELLi6sN699K0k0L6osq745XWSeIwi164PH7FU1ldA-zqh1cyxAHDJABr12u242-XAsVEIPrCfQrSokScWsl2ykMgSR-l4Jrb6eFaIJbZcxj7BUb8QAkRuVXPmj20/s1600/Fig+6.18.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="165" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQFhSKrIs02KdsG2zELLi6sN699K0k0L6osq745XWSeIwi164PH7FU1ldA-zqh1cyxAHDJABr12u242-XAsVEIPrCfQrSokScWsl2ykMgSR-l4Jrb6eFaIJbZcxj7BUb8QAkRuVXPmj20/s200/Fig+6.18.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.18</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> against the cylinder walls. The slots in the ring, and the holes in the piston behind the ring, allow oil to return to the oil pan. This type of oil ring is usually used only in conjunction with another oil ring. </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> Most oil rings are <i>segmental </i>types with three or four segments, like the oil ring in Figure 6.18. This ring has two side rails and an expander, which also acts as a spacer for the rails.</span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> The side rails are usually of steel, with very little tension of their own. They depend on the expander to hold them against the cylinder walls. The expander is made of spring steel with a series of crimps which give it an outward spring force. </span><span style="font-size: 11.0pt;"><br style="mso-special-character: line-break;" /> </span><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb9NnmaO2crZm5USBnJ3fyCkdPODFrzVnA2phTibbw3XNmcLDzYw96yst9HdRR4XqsHRT3hyphenhyphenpZMKenbivPy2qxZIo8BYCWnZuqz4E3G_3ZfkgOk-qhd8fJPCeaXTIMjDrG7grOot9zpDU/s1600/Fig+6.19.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjb9NnmaO2crZm5USBnJ3fyCkdPODFrzVnA2phTibbw3XNmcLDzYw96yst9HdRR4XqsHRT3hyphenhyphenpZMKenbivPy2qxZIo8BYCWnZuqz4E3G_3ZfkgOk-qhd8fJPCeaXTIMjDrG7grOot9zpDU/s200/Fig+6.19.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig</span><span style="font-family: Arial;"> 6.19</span></td></tr>
</tbody></table><div class="MsoNormal" style="margin-left: 38.5pt; text-align: left; text-indent: -38.5pt;"><span style="color: #cc0000; font-family: Symbol;"><span>·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">This type of oil ring is very flexible and its open </span></i><i><span style="color: #cc0000; font-family: Georgia;">construction allows oil to pass </span></i><i><span style="color: #cc0000; font-family: Georgia;">through readily.</span></i></div><div class="MsoNormal" style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><i><span style="color: #cc0000; font-family: Georgia;"> <br style="mso-special-character: line-break;" /> </span></i><i><span style="color: #cc0000; font-family: Georgia;"> </span></i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><i><span style="color: #cc0000; font-size: 12.0pt;">Oil control</span></i></b><b><i><span style="font-size: 11.0pt;"> </span></i></b><br />
<b><i><span style="font-size: 11pt;"> </span></i></b><span style="font-family: Arial;">Under most circumstances, there is far more oil on the cylinder walls than is needed for lubrication, but the oil does several things: it lubricates, cools, cleans and seals. Most of the oil that is not needed for lubrication is scraped off the cylinder walls by the oil rings. </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPa6HanHzqT72dtopcXqHDPqJs98DPQHY2n1yW0qp6PNREwBLH3AU54wsM3IVYGLmk6o9OGzCtUEU3Lwbhu42o42Srfq5495ZlwzT0GGN4AEYmfguJ3iUowBnGXEXMm9EDyY0bO9-mdlE/s1600/pict26.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="120" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPa6HanHzqT72dtopcXqHDPqJs98DPQHY2n1yW0qp6PNREwBLH3AU54wsM3IVYGLmk6o9OGzCtUEU3Lwbhu42o42Srfq5495ZlwzT0GGN4AEYmfguJ3iUowBnGXEXMm9EDyY0bO9-mdlE/s200/pict26.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig </span><span style="font-family: Arial;">6.22</span></td></tr>
</tbody> </table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Figure 6.19 shows how oil can be controlled. As well as drain slots behind the oil ring, this piston has grooves which allow oil to pass down the sides. Oil scraped by the oil ring is returned to the oil pan through the spaces at the end of the piston-pin bosses and through the grooves provided in the sides of the piston. </span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div class="MsoNormal" style="text-align: right;"><span style="font-family: Arial;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See piston ring sets>>>>>>>>>>>>>>>>>>>>>>>>>>>></span></span></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-57757505719092550932011-06-16T00:18:00.000+05:002011-07-05T00:48:34.354+05:00Piston designs<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNya-0fV_l3j3jWQlHdWw-RNJWA99zK7XS89272OUIzWhMPIqJGdW30DShrR0WymzFPlEfKYVtkKF6eS70ERB7ypIanUECBWnh0pNHLXIiLDaGJhcn6GGl_VhZwwanF-XC9qI0sCzdoVA/s1600/Fig+6.10.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNya-0fV_l3j3jWQlHdWw-RNJWA99zK7XS89272OUIzWhMPIqJGdW30DShrR0WymzFPlEfKYVtkKF6eS70ERB7ypIanUECBWnh0pNHLXIiLDaGJhcn6GGl_VhZwwanF-XC9qI0sCzdoVA/s200/Fig+6.10.gif" width="200" /></a></td></tr>
<tr style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;">Fig 6.10</td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Pistons are designed with various shapes. The head of the piston can be flat, domed or hollow. The piston can have a short skirt, a full skirt, or the skirt can be cut away. <br />
The shape of the piston head is designed to suit the type of combustion chamber of the engine and to improve turbulence of the air as it is being compressed. The head of the piston can also be designed with recesses or depressions to provide clearance for the heads of the valves. <br />
Petrol engines use a slipper-type piston (Figure 6.10). Cutting away the skirt of the piston not only reduces the mass of the piston, but also provides clearance for the crankshaft balance weights when the piston is at BDC. This enables shorter connecting rods to be used, permitting a more compact engine design. On some engines, the balance weights are contoured to avoid interference between the weights and the pistons. </span></div><div></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Some pistons have a very narrow top land so that the top compression ring is close to the top of the piston. This reduces the size of the crevice between the piston and the cylinder wall, above the top piston ring. The crevice can collect traces of unburned fuel, which finds its way out of the exhaust so, reducing the crevice size reduces the hydrocarbon emissions from the engine.</span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston thrusts</span></u></b></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCfVmQg8SeKhFd8bxmTTSyhgA4KCZAcNMYMXVLkJxQDer7jVQBc_faMBvg5pr3l0hT_5ixxVnpEODn70IKAJ-GyH4gES2RUX59DTHid4VIitLBFM3AVl85WNfPC1VYcjK7KZjxU87kAJk/s1600/Fig6.11.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCfVmQg8SeKhFd8bxmTTSyhgA4KCZAcNMYMXVLkJxQDer7jVQBc_faMBvg5pr3l0hT_5ixxVnpEODn70IKAJ-GyH4gES2RUX59DTHid4VIitLBFM3AVl85WNfPC1VYcjK7KZjxU87kAJk/s200/Fig6.11.gif" width="132" /></a></td></tr>
<tr style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;">Fig 6.11</td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">During the power strokes, combustion pressures force the piston downwards. However, the piston does not bear evenly against the walls of the cylinder, but is thrust against the sides of the cylinder. This is caused by the angularity of the connecting rod (Figure 6.11). <br />
The combustion pressures force the piston downwards, and the connecting rod offers resistance, but it does this at an angle. The result is a side thrust of the piston against the cylinder wall, as shown. <br />
The piston also has a side thrust during the compression stroke, but this is on the opposite side of the cylinder. Also, this is a lesser thrust because the downward force from compression is much less than the downward force of combustion. <br />
The thrusts are sometimes referred to as the <i>major </i>and <i>minor </i>thrusts. Because the thrust during the power stroke (major thrust) is most important, this side of the engine is often referred to as the <i>thrust side </i>of the engine. It is necessary to know about the thrust side of an engine because the pistons in most engines have to be installed in a particular way. Pistons are often provided with a mark to show how they should be fitted in relation to the front of the engine.</span> <br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div class="MsoNormal" style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"></div><div class="MsoNormal" style="margin-left: 38.5pt; mso-list: l0 level1 lfo1; tab-stops: list 20.0pt; text-indent: -38.5pt;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">Thrusts occur on both the upstrokes and the down-strokes, but the major thrust is </span></i></div><div class="MsoNormal" style="margin-left: 38.5pt; text-indent: -38.5pt;"><i><span style="color: #cc0000; font-family: Georgia;">during the power</span></i><span style="color: #cc0000; font-family: Georgia;"><i> </i>stroke</span>. </div><i></i> <br />
<div class="MsoNormal" style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><i> </i></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv8ogm3whNMsFDR4E-fXg9O6_pko-amY5Jr0xgxRCOuP0wmmWYA82EOaoUDQ3OTL9vrY-HBqE8JPQO0rp6Px0Lv2YPnO8S2mZfHfdZtiIyZxOK4aWRswF0VmRXthsQVb6MUB77I7dsXL0/s1600/Fig+6.12.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv8ogm3whNMsFDR4E-fXg9O6_pko-amY5Jr0xgxRCOuP0wmmWYA82EOaoUDQ3OTL9vrY-HBqE8JPQO0rp6Px0Lv2YPnO8S2mZfHfdZtiIyZxOK4aWRswF0VmRXthsQVb6MUB77I7dsXL0/s200/Fig+6.12.gif" width="97" /></a></td></tr>
<tr style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;">Fig 6.12</td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Offset piston-pin bosses</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Pistons are often designed with the bosses for the piston pin slightly offset. With this design, the bosses are moved a little away (offset) from the centreline of the piston. This is towards the major thrust side (Figure 6.12). <br />
The offset, of about 1.50 mm, alters the angle of the connecting rod slightly and so transfers some of the force away from the thrust side of the piston. There is less tilt applied to the piston during the power stroke and so there is less chance of piston slap.</span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Offset pistons must be installed the correct way, otherwise the tilting action would be increased and this would cause pronounced piston knock. The front of the pistons will be marked for correct installation.</span><br />
<br />
<br />
<div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See piston rings>>>>>>>>>>>>>>>>>>>></span></span></span></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com1tag:blogger.com,1999:blog-761095749605083867.post-35275083861041641612011-06-15T04:45:00.002+05:002011-07-05T00:45:22.276+05:00Pistons, connecting rods and bearings<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjTtuqmgmB_wZbCx6NxWRhPIobVvqnP-YFI0Q99k1TrR17PvO5FIy7BvA2amkTfWiHv43G-wMiscn9G3oR_ab1WQneDhhDUl5vC2x3PGgVhrSdukP_sJ5iYkLrXUwPsN0XVkLuzRYQyVI/s1600/Fig+6.1.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjTtuqmgmB_wZbCx6NxWRhPIobVvqnP-YFI0Q99k1TrR17PvO5FIy7BvA2amkTfWiHv43G-wMiscn9G3oR_ab1WQneDhhDUl5vC2x3PGgVhrSdukP_sJ5iYkLrXUwPsN0XVkLuzRYQyVI/s200/Fig+6.1.gif" width="160" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.1</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Pistons are designed to resist high combustion temperatures and their piston rings have to seal against high combustion pressures. Connecting rods have to withstand high stresses as they transfer the reciprocating motion of the pistons to the cranks of the crankshaft. <br />
The piston, piston rings, piston pin, connecting rod and the bearing form the piston and connecting- rod assembly. The various parts are identified in Figure 6.1</span>.</div><div></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Pistons</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">Figure 6.2 shows a piston with its parts identified. This is a short-skirt piston with grooves for three piston rings. There are a number of variations in piston design, which include shape, mass, provision for expansion, and type of material. </span><br />
<span style="font-family: Arial;"> Pistons are made of cast iron or aluminium alloy. Aluminium alloy pistons are used in petrol and smaller diesel engines because they arc much lighter than cast iron pistons. However, aluminium has a greater rate of expansion than the cast iron cylinders in which most pistons operate. Because of this, aluminium alloy pistons are specially designed to control expansion. Some larger diesel engines, which operate at lower rpm than petrol engines, have cast iron pistons.</span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0kLkOPpvMysBYgQH2-SPceRuL4F7w-_JArE-PkfaG4zkGwE2kvmRsOj6aEocGjiDeRo5VHzu3Hq9_EZeXGUUa7WfKDjqJDLiZyS-Kpy1tQXz1Z2buLZsOCF1WDIUmBsNIfekdLTEdGHA/s1600/Fig+6.2.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0kLkOPpvMysBYgQH2-SPceRuL4F7w-_JArE-PkfaG4zkGwE2kvmRsOj6aEocGjiDeRo5VHzu3Hq9_EZeXGUUa7WfKDjqJDLiZyS-Kpy1tQXz1Z2buLZsOCF1WDIUmBsNIfekdLTEdGHA/s200/Fig+6.2.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.2</span></td></tr>
</tbody></table><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston clearance <br />
</span></u></b><span style="font-family: Arial;">A piston is slightly smaller in diameter than the cylinder in which it operates. This gives it a working clearance of about 0.02 mm to 0.05 mm. Figure 6.3 illustrates the clearance of a piston in its bore, but there are particular ways in which it is measured.</span> <br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">See Figures 7. </span></i><span style="color: #cc0000; font-family: Georgia;">7 </span><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">to 7.9 in the coming posts which </span></i><i><span style="color: #cc0000; font-family: Georgia;">show how piston clearance is measured.</span> <br />
</i><b><span style="font-family: "Helvetica, sans-serif"; font-size: 8pt;"></span></b><br />
<b><span style="font-family: "Helvetica, sans-serif"; font-size: 8pt;"> </span></b><span style="font-family: Arial;">If a piston has insufficient clearance, there will be no room for the piston to expand when it is hot and it will tend to seize on the<span style="color: #cc0000;"> </span>cylinder wall. This would cap score both the piston and the cylinder. If there is too much clearance, piston slap will occur, particularly when the engine is cold. Piston slap is caused by the sudden tilting of the piston in the cylinder as it starts down its power stroke. This is done with such force that it produces a distinct noise.<span style="color: #cc0000;"></span></span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1IARFY1yHOyF-TcmjPR9ptjJGEEZI421Z12qk_pMj1RPlfrWcrn-4f3HrNMckUz1u-IDYw8QdNblRDcoGxS1NZK_opWaMTKAswy6t7sHF1fczLQpzoL0arz4-F4NJbjvA1cqNqNxjoOI/s1600/Fig+6.3.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="163" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1IARFY1yHOyF-TcmjPR9ptjJGEEZI421Z12qk_pMj1RPlfrWcrn-4f3HrNMckUz1u-IDYw8QdNblRDcoGxS1NZK_opWaMTKAswy6t7sHF1fczLQpzoL0arz4-F4NJbjvA1cqNqNxjoOI/s200/Fig+6.3.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.3</span></td></tr>
</tbody></table><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;"> Piston slap can occur in older engines that have excessive piston clearance due to worn cylinders or worn or collapsed piston skirts.</span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston temperature</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">The piston is subjected to the full effects of combustion and so it has to be resistant to heat. Typical operating temperatures are shown in Figure 6.4. Under heavy operating conditions, these temperatures can become even higher. </span><br />
<span style="font-family: Arial;"> There is a big difference between the temperature of the head of the piston and the skirt of the piston. The heat causes expansion, and this is greatest at the top of the piston. For this reason, the lands at the top of the piston are given extra clearance. They could be as much as <i>0.75 </i>mm smaller in diameter than the skirt.</span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxOIabmfolUnxfZl2H5hU-_YZAETNEs4bX9mL8uSoEB9JTmWw90gYGW9VC1lZGg-xR0uMNWkOBhZ5VY_qRSWTeZ09lUPFrD8wPGIGk4P6RHpxjIV38t680lBToACeSee4UgAfX7O3ajZ4/s1600/Fig+6.4.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="122" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxOIabmfolUnxfZl2H5hU-_YZAETNEs4bX9mL8uSoEB9JTmWw90gYGW9VC1lZGg-xR0uMNWkOBhZ5VY_qRSWTeZ09lUPFrD8wPGIGk4P6RHpxjIV38t680lBToACeSee4UgAfX7O3ajZ4/s200/Fig+6.4.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.4</span></td></tr>
</tbody></table><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Control of piston temperature</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">There are several methods used to prevent pistons from expanding excessively. These include cam grinding, using steel struts, controlling the heat path, and oil cooling. All pistons have some means of controlling their temperature and some pistons have more than one.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibJ81TOrT_gWsmFgNBQQjCY3QzMwNCqKvguzmEJKBlIBRCKqK_Utj_t4A46CV03_SB-rUJK2AmopwqaUwHr8YOCdJQuHl3_2y3YkFQ3X-CH9O3sGFfGi74fVuT0az4g5EV-saNbYDggPk/s1600/Fig+6.5.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibJ81TOrT_gWsmFgNBQQjCY3QzMwNCqKvguzmEJKBlIBRCKqK_Utj_t4A46CV03_SB-rUJK2AmopwqaUwHr8YOCdJQuHl3_2y3YkFQ3X-CH9O3sGFfGi74fVuT0az4g5EV-saNbYDggPk/s200/Fig+6.5.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.5</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Cam-ground pistons</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">A piston that is cam-ground is slightly oval in shape. The shape is obtained by relieving some metal in the area of the piston-pin bosses (Figure <i>6.5). </i>This makes the diameter of the piston slightly smaller at the piston- pin bosses than at the thrust faces. This allows the piston to be fitted to the cylinder with minimum clearance at the thrust sides. The extra clearance provided at the bosses by cam grinding allows for piston expansion.</span> <br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div style="text-align: right;"></div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><br />
</div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><br />
</div><div style="margin-left: 38.5pt; text-align: justify; text-indent: -38.5pt;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">For an explanation of piston thrusts, see the coming post ‘Piston thrusts’.</span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">Cam-ground pistons get their name from the process by which pistons were finished to size. The machine uses a cam to move the piston backwards and forwards as it is being ground. When cam-ground pistons warm up, they become more round in shape, so the area of contact with the cylinder wall increases (Figure 6.6). Grinding generally refers to cast iron pistons, aluminium pistons can be turned, rather than ground.</span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsrL_aeWk0QHWKtpi5VShFDo5d3SSP63__Me4kGkFuPcRmhqD7DIyPQ-T6rzg8RAiqWoBBlQK-wWL13zAvHlCJZuK_6wXxXhyj1g4a8w-ne3tzCDsHiL9xqLUFpYqmHcLr4A37Xlqx98M/s1600/Fig+6.6.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="119" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsrL_aeWk0QHWKtpi5VShFDo5d3SSP63__Me4kGkFuPcRmhqD7DIyPQ-T6rzg8RAiqWoBBlQK-wWL13zAvHlCJZuK_6wXxXhyj1g4a8w-ne3tzCDsHiL9xqLUFpYqmHcLr4A37Xlqx98M/s200/Fig+6.6.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.6</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><br />
</span></u></b></div><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Steel-strut pistons</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Special alloy-steel struts are cast into the piston during manufacture. A strut is fitted to each side of thc piston (Figure 6.7). The steel from which the struts are made has a very low rate of expansion when it is heated. On the other hand, aluminium alloy has a fairly high rate of expansion. As the temperature of the piston increases, the aluminium alloy tries to expand, but it is restrained by the steel struts. This holds the piston at the thrust face to its specified size.</span></div><div style="text-align: justify;"></div><div class="separator" style="clear: both; text-align: center;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOXRVkL1U1yvagNR5xx2WqOffyW-hui3LW5qyMVrXuTBOUQ9xPQAwrli4VGXTRGs6O6HMxE3oSYhNa0K6nLEZGbqTBiSpBoOb4iZCV_NVCWjkNelXOgBqCZFML97gSRcZkcrquNEyFEh0/s1600/Fig+6.7.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="167" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOXRVkL1U1yvagNR5xx2WqOffyW-hui3LW5qyMVrXuTBOUQ9xPQAwrli4VGXTRGs6O6HMxE3oSYhNa0K6nLEZGbqTBiSpBoOb4iZCV_NVCWjkNelXOgBqCZFML97gSRcZkcrquNEyFEh0/s200/Fig+6.7.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.7</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"></span><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><br />
</span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Heat path in pistons</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;">As well as controlling piston expansion by struts, heat is kept away from the thrust faces of the piston as much as possible. This also reduces expansion. </span></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">One way of doing this is with horizontal slots in the thrust sides of the piston, either in or below the oil-ring groove (Figure 6.8). The slots are used to break the heat path between the head of the piston and the skirt at the thrust faces. The heat is directed to other parts of the piston, such as the piston-pin bosses, where there is more clearance and also more metal to absorb the heat. This reduces expansion at the thrust faces. </span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXhTr8e9wfTh3XlXwYgGOkbjSLcT2rw8JUfjDHE81Rjq6PUttjOOQE1ymk0rXJ1Daz3h5L3zJWj6fVkNJwNg4dFQ95A8NUwD7sE31qUJ_JGKla3krmYwhwKpNzgSquL09T-IY1Dbcp4c0/s1600/pict8.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="147" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXhTr8e9wfTh3XlXwYgGOkbjSLcT2rw8JUfjDHE81Rjq6PUttjOOQE1ymk0rXJ1Daz3h5L3zJWj6fVkNJwNg4dFQ95A8NUwD7sE31qUJ_JGKla3krmYwhwKpNzgSquL09T-IY1Dbcp4c0/s200/pict8.jpg" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.8</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b><br />
<b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Piston cooling jets</span></u></b></div><div style="text-align: justify;"></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Normal lubrication helps to cool the pistons and cylinder walls, but as well as this, some engines have</span><span style="font-family: Arial; font-size: 11pt;"> </span><span style="font-family: Arial;">cooling jets. These are small nozzles, or jets, which spray a jet of oil up into the piston. The oil strikes the piston head, absorbs heat and then drops back into the oil pan. The oil also lubricates the piston pin and cylinder walls. </span><br />
<span style="font-family: Arial;"> Figure 6.9 shows a cooling jet and its action. The jet is supplied with oil from the main oil gallery of the engine. It has a ball cheek valve that closes when the oil pressure in the gallery is low, or when the engine is stopped. At normal operating pressure, the ball valve is forced off its seat, so that the jet sprays oil into the piston. </span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9t0C7mrZW6dMt3neee1fdR3phGKUzpCACYST_fyNYGN0KejG0KfVF3eiL1vVo6gjtMT8Hj9kAYz6Bf2wsFAIRZXUbjccLz4tc15oYFiQoYd4ToIws8tun_oUA43vJt6GWCK52zjVnVB0/s1600/pict9.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="129" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9t0C7mrZW6dMt3neee1fdR3phGKUzpCACYST_fyNYGN0KejG0KfVF3eiL1vVo6gjtMT8Hj9kAYz6Bf2wsFAIRZXUbjccLz4tc15oYFiQoYd4ToIws8tun_oUA43vJt6GWCK52zjVnVB0/s200/pict9.jpg" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 6.9</span></td></tr>
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</div><div class="MsoNormal" style="text-align: center;"><span style="font-family: Arial;"> <span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Continued</span></span></span></div><div class="MsoNormal" style="text-align: right;"><span style="font-family: Arial;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See piston designs>>>>>>>>>>>>>>>>> </span></span></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-77360743189924938932011-06-14T04:32:00.000+05:002011-07-04T04:44:28.163+05:00Analyzing bearing failures<div dir="ltr" style="text-align: left;" trbidi="on"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2e7NcP8GwfYBPyYLP5l2EXLtlQpYNafUStGQDDhPISLK4uZ7jFSe5EKtl5_NmF6X5W3SWBdDE0_oG44UBn5TWeeowonNayBXIrpbt1-ExcoNlmIxSDdjcObWLX5CwaaJDT6WluGcwNIs/s1600/Fig+5.32%2528a%2529.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2e7NcP8GwfYBPyYLP5l2EXLtlQpYNafUStGQDDhPISLK4uZ7jFSe5EKtl5_NmF6X5W3SWBdDE0_oG44UBn5TWeeowonNayBXIrpbt1-ExcoNlmIxSDdjcObWLX5CwaaJDT6WluGcwNIs/s400/Fig+5.32%2528a%2529.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.32 (a-c)</span></td></tr>
</tbody></table><br />
<div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">Figure <i>5.32 </i>shows a number of ways in which engine bearings can fail. Generally, these apply to both main bearings and connecting-rod bearings, but some conditions are more likely to occur with connecting- rod bearings. <br />
When analyzing a bearing failure, consider the conditions under which the bearing operates and the loads that the bearing has to carry. This will help to find the cause of the problem. </span></div><div> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Lack of oil</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure 5.32(a). A bearing that is short of oil will overheat and bearing metal will be wiped off the steel back. If the bearing has no oil supply, almost all the bearing metal will melt. The steel back will then run directly on the journal and this will damage the journal. The crankshaft will have to be replaced, or the journals ground undersize. </span><br />
<span style="font-family: Arial;"> Lack of oil can be due to clogged oil lines, a defective oil pump, a faulty relief valve, or insufficient oil in the oil pan.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVySmpZFwM4cpGUlrznoUxq4Zsnz7hSNuOmLCHFlkfPW_MT8G_z3K4F09ncZ283ukssr89qBv0Uo34_Os-VwAMrVUDPaOI2QKLSqP4iiPFW8ePcMzKrvL9pL53_moVMPejKOW9IdqucY0/s1600/Fig+5.32%2528b%2529.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVySmpZFwM4cpGUlrznoUxq4Zsnz7hSNuOmLCHFlkfPW_MT8G_z3K4F09ncZ283ukssr89qBv0Uo34_Os-VwAMrVUDPaOI2QKLSqP4iiPFW8ePcMzKrvL9pL53_moVMPejKOW9IdqucY0/s400/Fig+5.32%2528b%2529.gif" width="400" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial,Helvetica,sans-serif;">Fig 5.32 (d-f)</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Fatigue failure</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure 5.32(b). Repeated application of loads on a bearing will fatigue the bearing metal so that it starts to crack. Small pieces break away from the steel back and small craters or holes form in the bearing. With continued use, more and more particles break away until a large surface of the steel back is exposed. <br />
The bearing is designed to resist fatigue under normal operating conditions, but there are conditions that could cause this problem. One condition is an out- of-round journal, which stresses the bearing with every crankshaft revolution. <br />
If the engine is <i>lugged, </i>the upper half of the connecting-rod bearing will be heavily loaded and could fatigue. High-speed operation could also cause fatigue, but this would be in the lower half of the bearing. </span><span style="font-size: 11.0pt;"></span></div><br />
<div style="text-align: justify;"> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">The terms </span></i><span style="color: #cc0000; font-family: Georgia;">lugged <i>and </i>lugging <i>refer to operating the engine at low speed at full throttle.</i></span><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Scratched by dirt</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure <i>5.32(c). </i>Some very small particles in the oil could become embedded in the bearing metal. Any larger particles will be carried around with the journal or bearing and will scratch the bearing surface. <br />
The cause could be poor cleaning during repairs, contaminants introduced with the oil, or a faulty oil filter.<span style="color: #cc0000;"></span></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Tapered journaL</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure 5.32(d). If a journal is tapered, one side of the bearing will carry most of the load. This side will overheat and lose its bearing metal. </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">This should not be confused with a failure from a bent connecting rod. With a tapered journal, both halves of the bearing will fail on the same side. With a bent connecting rod, the top half of the bearing will fail on one side and the bottom half will fail on the opposite side.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Radius ride</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure <i>5.32(e). </i>If the radius between the crankshaft journal and web is too large, the edge of the bearing will ride on the radius. There would be no clearance and metal could be wiped off the edge of the bearing. Also, the bearing could be cramped, causing poor seating, rapid fatigue and early failure. <br />
This problem could occur after a crankshaft has been ground if the edges of the journals have not been given the correct radius. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span><span style="font-size: 11.0pt;"></span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Poor seating</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Refer to Figure 5.32(f). Poor seating of a bearing in its bore will cause high spots where there is not enough bearing clearance. This will show up as bright sections where the bearing is worn. <br />
Poor seating not only reduces bearing clearance and causes wear, but it leaves air space between the back of the bearing shell and its bore. This interferes with heat transfer from the bearing to its cap or to the crankcase. </span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;"><span>Continued</span></span></div><div style="text-align: right;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See pistons, connecting rods and bearings</span></span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-71447124614799685272011-06-13T03:49:00.000+05:002011-07-04T04:32:17.059+05:00Main bearings Service<div dir="ltr" style="text-align: left;" trbidi="on"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6KpuM6dWk-rZTzVh2dg81UO75fXtfm4OyST8fT3zwJEeRj5FLa-iyQqGdMdzfq5-cErzKoJ-YASgztJN4mVi1CQUDK_ubOu0jccCLGL4vOUYuC5a7O0EkxiHEVEIu62YaOv6hUbKPAtc/s1600/pict20.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="105" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6KpuM6dWk-rZTzVh2dg81UO75fXtfm4OyST8fT3zwJEeRj5FLa-iyQqGdMdzfq5-cErzKoJ-YASgztJN4mVi1CQUDK_ubOu0jccCLGL4vOUYuC5a7O0EkxiHEVEIu62YaOv6hUbKPAtc/s200/pict20.jpg" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 5.22 measuring journal size</span></td><td class="tr-caption" style="text-align: center;"><br />
</td><td class="tr-caption" style="text-align: center;"><br />
</td><td class="tr-caption" style="text-align: center;"><br />
</td><td class="tr-caption" style="text-align: center;"><br />
</td><td class="tr-caption" style="text-align: center;"><br />
</td></tr>
</tbody></table><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if !mso]><img src="http://img2.blogblog.com/img/video_object.png" style="background-color: #b2b2b2; " class="BLOGGER-object-element tr_noresize tr_placeholder" id="ieooui" data-original-id="ieooui" /> <style>
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</style> <![endif]--> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt;"></span></u></b><b><span style="font-family: "Helvetica\, sans-serif"; font-size: 17.0pt;"> </span></b><span style="font-family: Arial;">With an engine dismantled, the main bearings can be checked visually for wear or damage as outlined below (see later section Analyzing bearing failures’). The crankshaft-to-bearing clearance can be checked by measurement or with Plastigage. </span><br />
<span style="font-family: Arial;"> Figure 5.22 shows how the clearance is found by measuring the crankshaft journal with a micrometer and the bearing with a dial gauge. Readings are taken at four different places on the shall, and four measurements are made of the bearing. The dial gauge reading can he checked with the micrometer to determine the bearing clearance.</span></div><div> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5xiUYd8b2GzO-ssR4Rq7WAOY0FmuRGCvX7IJQ0VtpJ5UJvJ-vjqgr2rgJ4NO7Tj0Jm0P57jfMjGtfc05r4VMuFv4NEYUZDf-1y-2O5AeQOi4Y5K-bqNjNrZINt8nZV9pU0y9Av9MF4m0/s1600/pict21.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="101" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5xiUYd8b2GzO-ssR4Rq7WAOY0FmuRGCvX7IJQ0VtpJ5UJvJ-vjqgr2rgJ4NO7Tj0Jm0P57jfMjGtfc05r4VMuFv4NEYUZDf-1y-2O5AeQOi4Y5K-bqNjNrZINt8nZV9pU0y9Av9MF4m0/s200/pict21.jpg" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 5.22</span></td><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;"></span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><br />
<b><u><span style="color: #006600; font-family: Arial; font-size: 12pt;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Using Plastigage</span></u></b></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The use of Plastigage to check a bearing clearance is shown in Figure 5.23. The procedure is: <br />
I. Wipe the journal and bearing clean of oil. <br />
2. Place a strip of Plastigage in the centre of the bearing. <br />
3. Replace and tighten the bearing cap and do not turn the crankshaft. <span style="background-color: cyan; font-size: x-small;">Measuring bearing dia.</span><br />
4. Remove the cap and, with the scale provided, measure the flattened Plastigage at its widest point this is the bearing clearance.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-size: 11.0pt;">For more information on Plastigage, refer to the section ‘Checking connecting-rod bearings’ in later</span></i><span style="font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><i><span style="color: #cc0000; font-size: 11.0pt;">posts.</span></i><span style="font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="font-size: small;"><i><span style="color: #cc0000;"></span></i></span><span style="font-family: Arial;"></span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcRf-csplVou3hDnCz6ZxWm3gVDkdrig7X0WTmcv_Lfg5tbBWWgAPBwy9F_kHBkB5iE6fZm5DmyBBLEfWQLnnFA4S32kJOjzToL1YEVD8UeBrvAjpsY8cAYY7yf4xLhpbVGFrS2vnLWPo/s1600/pict24.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="131" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcRf-csplVou3hDnCz6ZxWm3gVDkdrig7X0WTmcv_Lfg5tbBWWgAPBwy9F_kHBkB5iE6fZm5DmyBBLEfWQLnnFA4S32kJOjzToL1YEVD8UeBrvAjpsY8cAYY7yf4xLhpbVGFrS2vnLWPo/s200/pict24.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.23</span></td></tr>
</tbody></table><div style="text-align: justify;"><i><span style="color: #cc0000; font-size: 11.0pt;"> </span></i><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt; mso-fareast-font-family: Calibri;"> </span></i></b></div><div style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Conditions during measurement</span></i></b><i><span style="font-size: 11.0pt;"> <br />
</span></i><span style="font-family: Arial;">If the engine is removed from the vehicle and upside down, then the crankshaft will rest in the bearings that are in the crankcase. The clearance will be between the journals and the halves of the bearings in the caps. This is where the Plastigage is used to take the measurements. <br />
However, if the engine is installed in the vehicle, the crankshaft will rest in the bearings in the caps. Therefore, it must be held upwards to obtain the clearance and to prevent incorrect measurement. <br />
One way of supporting the crankshaft is to place a small jack under the web of the crankshaft, next to the bearing being measured. Another method is to remove the bearing from the bearing caps on each side of the bearing that is to be measured and insert soft packing pieces. The cap bolts are then tightened to lift and support the crankshaft.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Checking crankshaft end-play</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> </span></b></div><div> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVBDrx5xmhYnwx072kI810hWJt_aZ0guoic7mXQO4TqlrZbnE9LXDiDavc39nhBwdATH-XUT2oBXHsDEhuJe7QVsLPIKZ9kAGjJY9s8HhxdUaRW1GhJtsah2ZrPjNr_No2Pt3k4DNiONg/s1600/pict23.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVBDrx5xmhYnwx072kI810hWJt_aZ0guoic7mXQO4TqlrZbnE9LXDiDavc39nhBwdATH-XUT2oBXHsDEhuJe7QVsLPIKZ9kAGjJY9s8HhxdUaRW1GhJtsah2ZrPjNr_No2Pt3k4DNiONg/s200/pict23.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.24</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Crankshaft end-play will become excessive if the end- thrust bearings are worn. This can produce engine noise in the form of a noticeable sharp irregular knock. <br />
Check the end-play by forcing the crankshaft endwise as far as it will go with a pry bar and then measuring the clearance at the end-thrust bearing with a feeler gauge (Figure 5.24). Consult the engine manufacturer’s manual for allowable end-play. </span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Replacing crankshaft rear oil seal</span></u></b></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwVm0ZJ1UFZXMNabv_XWtfgzYoRrWuU4eel1sLKmkMbowz3Z7IiJD5QP4Y0EjDVgvCAUFrFFXUX7Gld46k3hRg0Pkm9_vsghXhoEBUVPhsDcRw6kCzJnuAVL3NMiMYPH253a7df2N96Ho/s1600/pict25.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwVm0ZJ1UFZXMNabv_XWtfgzYoRrWuU4eel1sLKmkMbowz3Z7IiJD5QP4Y0EjDVgvCAUFrFFXUX7Gld46k3hRg0Pkm9_vsghXhoEBUVPhsDcRw6kCzJnuAVL3NMiMYPH253a7df2N96Ho/s200/pict25.jpg" width="138" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.25</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">An oil seal is fitted at the rear main bearing to prevent oil leakage (Figure 5.25). When main-bearing service is being performed, or whenever leaking is noticed at the rear main bearing, the oil seal must be replaced. </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The procedure for replacement varies with different constructions. On some engines using a split oil seal, the crankshaft must be removed and a special oil-seal installer used to insert the new seal in the cylinder block. <br />
On engines with seals of the type shown in Figures <i>5.25 </i>and 5.26, it is not necessary to remove the crankshaft. However, components have to be removed from the rear of the engine to gain access to the oil seal. These include the transmission, clutch and the flywheel. For an automatic transmission vehicle, the components would be the automatic transmission, the torque converter and its drive plate. <br />
The rear oil seal in Figure 5.26 is a lip-type seal that fits into a housing. The housing is then bolted to the block.</span><span style="font-size: 11.0pt;"> <br style="mso-special-character: line-break;" /> </span><br style="mso-special-character: line-break;" /><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOGuHZtuparvwTuKtjrnCIuEnZ10SoSOFjH5_mJXI1nKIcW8gEz-W_e-xKcrB3Fz2jIkGn0fie5WcQs67FDOiLcsSrUcASkyA3-PkU_Tcg5pzMf6b8A5Qp1fRMTEY3eT8ue0PKEVuQxB0/s1600/pict27.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="130" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOGuHZtuparvwTuKtjrnCIuEnZ10SoSOFjH5_mJXI1nKIcW8gEz-W_e-xKcrB3Fz2jIkGn0fie5WcQs67FDOiLcsSrUcASkyA3-PkU_Tcg5pzMf6b8A5Qp1fRMTEY3eT8ue0PKEVuQxB0/s200/pict27.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.26</span></td></tr>
</tbody></table><div class="MsoNormal" style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div class="MsoNormal" style="margin-left: .25in; mso-list: l0 level1 lfo1; tab-stops: list .25in; text-indent: -.25in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-size: 11.0pt;">The illustration shows a drive plate for the torque converter of an automatic</span> <span style="font-size: x-small;"><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">transmission</span></span></i></div><i><span style="color: #cc0000; font-size: 11.0pt;"></span></i><div class="MsoNormal" style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="font-size: small;"><i><span style="color: #cc0000;"></span></i></span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Replacing main bearings</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">In most cases where main bearings are being replaced, the engine will have been removed from the vehicle and completely dismantled. <br />
Bearings are installed as follows: <br />
1. Wipe the bearing bores and the bearing caps clean.</span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqsk5_XzqJh3070ezw5FuSaxz5140xqhOpIRpg41k6LoEYbhr0hPaJBTFnktHCRvepuA-m5a_54oYLa__Iwo1vCpj-d08LN_XcYfjeM4Cr5TRAt1Sr3O8JStOutFgLaBpfhVsjQD3SA38/s1600/pict26.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqsk5_XzqJh3070ezw5FuSaxz5140xqhOpIRpg41k6LoEYbhr0hPaJBTFnktHCRvepuA-m5a_54oYLa__Iwo1vCpj-d08LN_XcYfjeM4Cr5TRAt1Sr3O8JStOutFgLaBpfhVsjQD3SA38/s200/pict26.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.27</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">2. Coat the upper halves of the bearing with engine oil and slide each bearing into its correct bore in the crankcase (Figure 5.27). <br />
3. Make sure that each bearing is properly seated in its bore and that the tang of the bearing fits into the notch in the bore. <br />
4. Oil the crankshaft and install it in the bearings in the crankcase. </span><br />
<span style="font-family: Arial;"> 5. Fit the lower halves of the bearings in their caps, making sure that they seat properly. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">6. Install the caps in their original positions. A number will be marked on each cap, or there will be some other identifying mark (Figure 5.28). The front of the cap must also be identified. <br />
7. Tap the caps into place with a soft-faced hammer and tighten the bolts to the correct torque. <br />
8. During tightening, rotate the crankshaft to make sure that it is not binding. The sides of the caps can be tapped lightly with a soft-faced hammer to assist with cap alignment. <br />
Where the thrusts are separate from the bearing (Figure <i>5.29), </i>the bearing is installed in its bore. The thrusts are then installed in their grooves in the crankcase web beside the bearing.</span> <br />
<span style="mso-spacerun: yes;"> </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtNIw77yK6eUG6WjJ5u4ed4bpH76W-WFCgrswPvl2ucp1nMVF106aJM01ru0vkGaKY1AvunvAqLYdeYq9qS-uIhgkN2dCh2cMyoCF6TaV5T5WprTutdaGDRlxEbNZn1_zzsgNTj2pAnb8/s1600/pict30.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtNIw77yK6eUG6WjJ5u4ed4bpH76W-WFCgrswPvl2ucp1nMVF106aJM01ru0vkGaKY1AvunvAqLYdeYq9qS-uIhgkN2dCh2cMyoCF6TaV5T5WprTutdaGDRlxEbNZn1_zzsgNTj2pAnb8/s200/pict30.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.28</span></td></tr>
</tbody></table><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="font-size: small;"><span style="color: #cc0000; font-family: Symbol;"><span>·<span style="-moz-font-feature-settings: normal; -moz-font-language-override: normal; font-family: "Times New Roman"; font-size-adjust: none; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal;"> </span></span></span><i><span style="color: #cc0000;">All </span></i><span style="color: #cc0000;">main </span><i><span style="color: #cc0000;">bearings are not the same, some are </span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">grooved </span></i><i><span style="color: #cc0000;">and one </span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">could have </span><span style="color: #cc0000;">thrust </span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">faces. </span></i></span><span style="color: #cc0000;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Tightening bearing cap bolts</span></i></b><i><span style="font-size: 11.0pt;"> <br />
</span></i><span style="font-family: Arial;">There are a number of designs of main-bearing caps where the cap bolts have to be tightened in a specified sequence. Figure 5.30 shows a sequence for main bearings that have a beam-type cap. The bearing caps are joined together to provide rigidity. The cap bolts must be tightened progressively in the right sequence as well as to the correct torque. <br />
Figure 5.31 shows another crankshaft and bearing assembly. This has four bolts for each bearing cap and</span><span style="font-size: 11.0pt;"> </span><span style="font-family: Arial;">a bearing cap bridge, or beam, that fits over the bearing caps. The cap bolts secure the bridge as well as the bearing caps. The sequence for tightening the bolts is shown. This starts with the two inner bolts of one bearing. It follows a spiral pattern, with the inner bolts being tightened before the outer ones. <br style="mso-special-character: line-break;" /> </span><br style="mso-special-character: line-break;" /><span style="font-family: Arial;"> </span></div><div style="text-align: justify;"> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiTYJsg_gyx1yA-O8bYOWS25_DgRK6ZsWL1ANeL3vCLGvWmfIbfA-VqXDR7M3O_N2hgDKqRp7uLQg6pzcwUXEjRSVYBMGWtkVhmVb4cHN3TEI090V34cycIwDbiWUIGd0nbvzjN9strBA/s1600/pict29.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="157" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiTYJsg_gyx1yA-O8bYOWS25_DgRK6ZsWL1ANeL3vCLGvWmfIbfA-VqXDR7M3O_N2hgDKqRp7uLQg6pzcwUXEjRSVYBMGWtkVhmVb4cHN3TEI090V34cycIwDbiWUIGd0nbvzjN9strBA/s200/pict29.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.29</span></td></tr>
</tbody></table><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><span style="font-size: small;"><i><span style="color: #cc0000;">All </span></i><span style="color: #cc0000;"><i><span style="font-family: Georgia,"Times New Roman",serif;">main</span></i> </span><i><span style="color: #cc0000;">bearings are not the same, some are </span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">grooved </span></i><i><span style="color: #cc0000;">and one </span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">could have </span><span style="color: #cc0000;">thrust</span></i><span style="color: #cc0000;"></span><i><span style="color: #cc0000;"><span> </span></span></i><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">faces. </span></i></span><span style="color: #cc0000;"></span> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="color: #cc0000;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><br />
<br />
<div style="text-align: justify;"><span style="font-family: Arial;">In some engines, the main-bearing inserts can be removed and replaced with the engine in the vehicle. This is done without removing the crankshaft from the engine. This would only be done if the crankshaft journals were not worn or scored. <br />
The method involves slackening off all the main- bearing cap bolts one or two turns so that clearance is obtained between the journals and the upper halves of the bearings. <br />
Starting at one end of the crankshaft, remove the main-bearing cap. The upper bearing insert can then be pushed around the crankshaft journal using a piece of thin, soft metal. The insert</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfA8G1Cr9VrUuO8ZKyvSZID0skKetIfK23ccK-2U9czow4FbBi36LtLQ6fIYWdqWuGGXOkhK2u0tIA44o6pCSjvvlv_CInYCvUX5V1tLXqswP0yeA5Yo4MZvKWtSksI53AJEihLFpKn-g/s1600/pict31.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" height="131" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfA8G1Cr9VrUuO8ZKyvSZID0skKetIfK23ccK-2U9czow4FbBi36LtLQ6fIYWdqWuGGXOkhK2u0tIA44o6pCSjvvlv_CInYCvUX5V1tLXqswP0yeA5Yo4MZvKWtSksI53AJEihLFpKn-g/s200/pict31.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.30</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;"> is pushed on the opposite side to its locating tang. <br />
A new bearing is installed and the bearing cap is replaced to support the crankshaft before proceeding to the next bearing. <br />
When bearings are replaced in this manner, it is essential that every care be taken in regard to cleanliness. Unfortunately, it is not possible to see how the new bearing is located in the housing once it has been installed, so that every care must be taken during assembly. </span><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> <span style="font-family: Arial;"></span></div><div style="text-align: justify;"> </div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-size: x-small;"><span style="font-family: Georgia,"Times New Roman",serif;"><span>·<span style="-moz-font-feature-settings: normal; -moz-font-language-override: normal; font-size-adjust: none; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal;"> </span></span></span><i style="font-family: Georgia,"Times New Roman",serif;">The preferred method of installing main bearings is with the engine completely dismantled and the crankshaft removed.</i></span><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ1GIUQlneNJVPKw8yCU2HvVxMHRFgqG_9NEHg1ya86lV1Wo9ztOmIxqqFLSOiGGzPtt49Xfciaiypgz9p_ZNKWxyYmqNrLu3Ye-oz5OghcRUhqS7kOwW-RxR_0LbSAx1oBG-7alhryF8/s1600/pict32.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="174" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ1GIUQlneNJVPKw8yCU2HvVxMHRFgqG_9NEHg1ya86lV1Wo9ztOmIxqqFLSOiGGzPtt49Xfciaiypgz9p_ZNKWxyYmqNrLu3Ye-oz5OghcRUhqS7kOwW-RxR_0LbSAx1oBG-7alhryF8/s200/pict32.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.31</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Bearing oil-leak test</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Main bearings and connecting-rod bearings can be checked with a bearing leak tester. The oil pan has to be removed so that the amount of oil passing the bearings can be seen. <br />
The tester is basically a pressure container of oil that is connected by a hose to the oil gallery of the engine. It uses compressed air to supply the stationary engine with oil at normal oil pressure. <br />
A normal bearing will leak between about twenty to <i>150 </i>drops of oil per minute. A bearing will leak more if it is worn or has excessive clearance. Less than twenty drops could mean a restricted passage or blocked oil-way. <br />
If oil passages in the crankshaft and bearing happen to be in line, then more oil than normal will pass through the bearing. This could give the impression that the bearing has excessive clearance.</span> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </div><div style="text-align: justify;"> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><i><span style="color: #cc0000; font-family: Georgia;">If this happen; the crankshaft should be turned to move the oil holes away from each </span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><i><span style="color: #cc0000; font-family: Georgia;">other.</span></i></div><div style="text-align: justify;"><br />
</div><div style="text-align: center;"><span style="color: #cc0000; font-family: Georgia;"><span style="color: black;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Continued</span></span></span></span></div><div style="text-align: right;"><span style="color: #cc0000; font-family: Georgia;"><span style="color: black;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See Analyzing bearing failures>>>>>>> </span></span></span></span></div><div style="text-align: justify;"><span style="color: #cc0000; font-family: Georgia;"><span style="color: black;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;"> </span></span></span></span><i><span style="color: #cc0000; font-family: Georgia;"> </span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"> </div><div style="margin-left: 0.25in; text-align: justify; text-indent: -0.25in;"><i><span style="color: #cc0000; font-family: Georgia;"></span></i><span style="color: #cc0000; font-family: Georgia;"></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-56548476678184038152011-06-12T03:37:00.000+05:002011-07-04T03:49:12.577+05:00Servicing crankshaft<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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</style> <![endif]--> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;"></span></u></b></div><div> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">With the crankshaft in the cylinder block, the clearance of the main bearings can be checked and the condition of the crankshaft journals can be checked visually. However, to actually measure the main-bearing journals, the crankshaft has to be removed from the engine. To enable this to be done, the engine must be removed from the vehicle and dismantled. <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitc5tsVla-cK_Aesb69s9pjTYfS9P0a9eBIBloUxvO73y53h7eZYdORIN9WFuqxIhH4dDxcQ2IeQANF9Zn9S4u43lGHY8M-5L80aFndbd-B-vNuoCfClQO8cxhYkdoQDpicc-LEGhfhRY/s1600/pict16.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="134" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitc5tsVla-cK_Aesb69s9pjTYfS9P0a9eBIBloUxvO73y53h7eZYdORIN9WFuqxIhH4dDxcQ2IeQANF9Zn9S4u43lGHY8M-5L80aFndbd-B-vNuoCfClQO8cxhYkdoQDpicc-LEGhfhRY/s200/pict16.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.18</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Measuring crankshaft journals</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Measure the journals with an outside micrometer as shown in Figure 5.18. Check for both taper and out-of- round. When checking taper, measure each end of the</span><span style="font-family: Arial; font-size: 11.0pt;"> </span><span style="font-family: Arial;">journal. When checking out-of-round, take measurements at </span><span style="font-family: Arial; font-size: 8.0pt;"><span style="font-size: small;">900</span>. </span><span style="font-family: Arial;">There are four places where measurements have to be taken. These are shown in Figure 5.19. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Typical specifications for a crankshaft and bearings are set out in Table. This shows the type of service data provided in workshop manuals, although specifications will vary for different engines. </span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieETCWfoknxgxiw8KobmozvJFD3_5u4JUuozdk8EPmBgAoO5yjHBunQTApV8EA5Kl7PwKvIbPDp8ji7k3L_6_AhEu9KXefstBmRk0sKV8XNhvb1YcbrnAlBs0ElsHkg_JK7oS2Cj2H1OU/s1600/pict18.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="72" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieETCWfoknxgxiw8KobmozvJFD3_5u4JUuozdk8EPmBgAoO5yjHBunQTApV8EA5Kl7PwKvIbPDp8ji7k3L_6_AhEu9KXefstBmRk0sKV8XNhvb1YcbrnAlBs0ElsHkg_JK7oS2Cj2H1OU/s200/pict18.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.19</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">The crankshaft will have to be replaced or the journals ground if taper or out-of-round exceeds specifications, or if the journals are rough, scratched or damaged in any way. The journals can be ground undersize and suitable undersize bearings fitted.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: medium none; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;"> <td colspan="2" style="padding: 0in 5.4pt 0in 5.4pt;"> <div align="center" style="text-align: center;"><b><span style="font-family: Arial;">Crankshaft and bearing specifications</span></b></div></td> </tr>
<tr style="mso-yfti-irow: 1;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <b><span style="font-family: Arial; font-size: 8.0pt;"> CRANKSHAFT ITEM </span></b><span style="font-family: Arial;"></span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <b><span style="font-family: Arial; font-size: 8.0pt;">SPECIFICATIONS </span></b><span style="font-family: Arial;"></span><br />
</td> </tr>
<tr style="mso-yfti-irow: 2;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Crankshaft runout at centre </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.06 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 3;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="background: lime; font-family: Arial; mso-highlight: lime;"><span style="background-color: #f4cccc;">Main-journal diameter</span> </span><br />
</td> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">49.95—50.00 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 4;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Main-journal out-of-round </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.04 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 5;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="background: lime; font-family: Arial; mso-highlight: lime;"><span style="background-color: #f4cccc;">Crankpin diameter</span> </span><br />
</td> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">44.95—45.00 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 6;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Crank-pin taper and out-of-round </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.04 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 7;"> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">Main-bearing clearance </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="background: lime; font-family: Arial; mso-highlight: lime;"><span style="background-color: #f4cccc;">0.030—0.050 mm</span> </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 8;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Crankshaft end-play </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.10—0.30 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 9;"> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">Connecting-rod bearing clearance </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="background: lime; font-family: Arial; mso-highlight: lime;"><span style="background-color: #f4cccc;">0.02—0.06 mm</span> </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 10;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Connecting-rod big-end side </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <div class="MsoNormal"><br />
</div></td> </tr>
<tr style="mso-yfti-irow: 11;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">clearance </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.10—0.35 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 12;"> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">Bearing under-sizes </span><br />
</td> <td style="background-color: #f4cccc; padding: 0in 5.4pt;"> <span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto; font-family: Arial;">0.25. 0.50, 0.75 mm </span><br />
</td> </tr>
<tr style="mso-yfti-irow: 13; mso-yfti-lastrow: yes;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">Flywheel run-out </span><br />
</td> <td style="padding: 0in 5.4pt 0in 5.4pt;"> <span style="font-family: Arial;">0.20 mm </span><br />
</td> </tr>
</tbody></table><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEia4tvNReSCjFkeU94bZbJicO10J4WH6S4Ujk4OZF0XM_sWaFCIo6WL45a0lyFrMGpjhY_R5m141FeREL9qsl5zVjNPE48G68ArdwcG2CodviSJ7zq5oaX6tkxLmmuXIGpW6049Ry5XfX4/s1600/pict19.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="99" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEia4tvNReSCjFkeU94bZbJicO10J4WH6S4Ujk4OZF0XM_sWaFCIo6WL45a0lyFrMGpjhY_R5m141FeREL9qsl5zVjNPE48G68ArdwcG2CodviSJ7zq5oaX6tkxLmmuXIGpW6049Ry5XfX4/s200/pict19.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.20</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Grinding crankshaft journals</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">A special crankshaft grinder is used to grind crankshaft journals (Figure 5.20). The grinder is fitted with chucks at each end which support the ends of the crankshaft. During grinding, the shaft is rotated and the grinding wheel of the machine is used to accurately grind each journal. This is done to a specified size to suit undersize bearings. </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">When the main bearing journals are being ground, the crankshaft is aligned with the machine but, when grinding the crank-pin journals, the crankshaft has to he offset in the grinder. This enables the crank-pin being ground to be rotated about its own axis.</span> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Cleaning crankshafts</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">When a crankshaft is removed from the engine, it should be cleaned in a suitable solvent, particularly the oil passages. To prevent rusting, the journals should be oiled immediately after they have been cleaned. <br />
A crankshaft that has been ground needs to be cleaned properly to remove abrasive and metal particles that are the result of grinding. </span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Crankshaft alignment</span></u></b><span style="font-family: Tahoma;"></span></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsA5xtfTqTgU9ZxHKODI4KvSWisrXnI98ph6k7u1jlCPMcan-G4ZyRmwVfOoEWHJsfuTGJTHUrMFPyxfCC1A7Lq2pOd77A04xAj2DxuNuWTEV3diZcwtmo-TkcdTPjVKJZU2lLIvSuz5k/s1600/pict22.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="101" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsA5xtfTqTgU9ZxHKODI4KvSWisrXnI98ph6k7u1jlCPMcan-G4ZyRmwVfOoEWHJsfuTGJTHUrMFPyxfCC1A7Lq2pOd77A04xAj2DxuNuWTEV3diZcwtmo-TkcdTPjVKJZU2lLIvSuz5k/s200/pict22.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.21</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">To check for alignment, the crankshaft is mounted between centres or in V-blocks on a large hat surface. A dial gauge on a surface block is set up on the journal of the centre bearing. The crankshaft is rotated slowly to measure the run-out (Figure 5.21). A bent crankshaft will have to be discarded, although a slightly bent shaft can sometimes be ground to provide accurate alignment.</span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div class="MsoNormal" style="text-align: right;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See main bearings service>>>>>>>>>>> </span></span><span style="font-size: 11.0pt;"> </span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-24252307306810395742011-06-11T03:22:00.000+05:002011-07-04T03:35:50.911+05:00Cylinders boring<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic5-GHKhZNVodEy5kw2eJNTyh8GyjKWO3XuzBD6L6f6pEJGB-qhvNgggFAbRYpw_-MO0YFPyIAU05jApewyoaW3ZT_owOmGEtQUHpUVIe6ZThZ9A8U85a2h34m3uv8H1xZWurmCuI5xrE/s1600/pict13.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEic5-GHKhZNVodEy5kw2eJNTyh8GyjKWO3XuzBD6L6f6pEJGB-qhvNgggFAbRYpw_-MO0YFPyIAU05jApewyoaW3ZT_owOmGEtQUHpUVIe6ZThZ9A8U85a2h34m3uv8H1xZWurmCuI5xrE/s200/pict13.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.14</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">With the cutter set to make the desired cut, the spindle is brought down to the top of the cylinder block and the machine is started. The boring bar with the cutter will feed itself slowly down the cylinder, cutting as it goes (Figure <i>5.14). </i>When it reaches the bottom of the cylinder, cutting will stop. <br />
During the cut, the </span><i style="mso-bidi-font-style: normal;"><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">cats paws</span></i><span style="font-family: Arial;"> are extended against the cylinder to support the end of the bar and keep it cutting true.</span></div><div> </div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div class="MsoNormal" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12.0pt;">Honing after boring</span></i></b><b><i><span style="font-family: "Helvetica\, sans-serif"; font-size: 11.0pt;"> <br />
</span></i></b><span style="font-family: Arial,Helvetica,sans-serif;">The cylinders are bored slightly under-size to allow for honing. The cutter of the boring bar leaves a series of fine ridges in the new bore that are not a suitable surface for piston rings. Honing after boring finishes the cylinder to size and gives it a cross-hatch pattern.</span></div><div style="text-align: justify;"> </div><div class="MsoNormal" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18.0pt; mso-fareast-font-family: Calibri;">Servicing cylinder sleeves</span></u></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">The three types of sleeves used in engines are </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">dry sleeves</span></i><i><span style="font-family: Arial;">, </span></i><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">dry flanged sleeves</span></i><i><span style="font-family: Arial;"> </span></i><span style="font-family: Arial;">and </span><i><span style="color: #cc0000; font-family: Georgia; mso-bidi-font-family: Arial;">wet sleeves</span></i><i><span style="font-family: Arial;">. </span></i><span style="font-family: Arial;">Each has a different method of installation. <br />
Sleeves must be installed correctly; otherwise the cylinder bores will be distorted. This can reduce piston clearance and cause scoring of the piston and cylinder. Also, the piston rings will not follow the distorted bore, and this will cause blowby and oil burning. <br />
The way in which the different sleeves are installed is covered briefly under the headings that follow.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIk7Z6iVlRcLjAHwjgttO7uwUjRsWDkby6XiRt4WvCfcUjjsXvizd0pQsGRszQlqZHa-x519qZOQykEJCR71obct1602bVHmwjxGK0sd4m7NHxIPqFXjcoEMueGOmT9ppKWBDzU8UwpOc/s1600/pict14.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIk7Z6iVlRcLjAHwjgttO7uwUjRsWDkby6XiRt4WvCfcUjjsXvizd0pQsGRszQlqZHa-x519qZOQykEJCR71obct1602bVHmwjxGK0sd4m7NHxIPqFXjcoEMueGOmT9ppKWBDzU8UwpOc/s200/pict14.jpg" width="165" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.15</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Installing dry sleeves</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Dry repair sleeves are used to recondition badly worn or damaged cylinders that cannot be re-bored without removing excess metal. The cylinder is bored to suit the outside diameter of the sleeve which is pressed into the block (Figure <i>5.15). </i>After installation, the inside of the sleeve is finished to standard size.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">The brief procedure for installing a sleeve is as follows: <br />
I. Bore the cylinder to the outside diameter of the sleeve — provide for a 0.08 to 0.10 mm press fit. <br />
2. Measure the length of the bore and cut the sleeve so that it is about 3 mm longer. <br />
3. Shrink the sleeve with dry ice to ease installation and press it into place. Then finish the top of the sleeve flush with the top of the block. <br />
4. Bore the sleeve slightly smaller than the final diameter and hone it to size.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Installing flanged dry sleeves</span></u></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">Dry replacement sleeves have a flange that holds them in place. They do not fit as tightly in the cylinder block as dry repair sleeves. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">1. Clean the bore in the block and check for distortion. Clean the counter-bore at the top of the block and check for size. The bore should be measured at several places. <br />
2. Wash the outer surface of the sleeve with solvent to remove any dirt or protective coating. <br />
3. Install the sleeve in the cylinder. If it is the correct fit, it should be possible to press the sleeve two- thirds of the way in with hand pressure. <br />
4. Press the sleeve the rest of the way into the block, and check the distance that it protrudes above the top of the block. A general rule is for the flange to protrude 0.02 to 0.12 mm above the top of the block. <br />
<span style="mso-bidi-font-style: italic;">5</span></span><i><span style="font-family: Arial; font-size: 11.0pt;">. </span></i><span style="font-family: Arial;">Compare the protrusion of adjacent sleeves. There should be no more than 0.02 mm difference.</span> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </div><div style="text-align: justify;"> </div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol;"><span style="mso-list: Ignore;">·<span style="font: 7.0pt "Times New Roman";"> </span></span></span><span style="font-size: small;"><i><span style="color: #cc0000;">If there is too much protrusion the cylinder-head gasket will not he able to seal properly</span></i><i><span>.</span></i></span><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Arial;"></span></u></b></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;">Installing wet sleeves</span></u></b></div><div style="text-align: justify;"> </div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5mUiuGb9xB9oKrRH2sWi01dvYs8eoa2rYn0VtrhoWvuxiqxrZsJW-MtxFGfrQk-w8Xo8stODYTk8rxoW2oZKoNOvkpXsIXp62sx8y1F0JxScjKK7AH4OLS78vIcEoYUv8IRcGyZJZWmE/s1600/pict15.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="103" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5mUiuGb9xB9oKrRH2sWi01dvYs8eoa2rYn0VtrhoWvuxiqxrZsJW-MtxFGfrQk-w8Xo8stODYTk8rxoW2oZKoNOvkpXsIXp62sx8y1F0JxScjKK7AH4OLS78vIcEoYUv8IRcGyZJZWmE/s200/pict15.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.16</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Because a wet sleeve is in contact with the engine coolant, its fit and scaling in the cylinder block are important. All rust and scale must be removed from the block counter-bore and the sealing-ring area. The new sleeve should be washed in solvent before it is installed. <br />
Some brief points about installation are: <br />
I. Try the sleeve in the block bore before installing the sealing rings — it should fit freely without binding. <br />
2. Check the protrusion above the block. Hold-down clamps can be used to keep the sleeve seated (Figure <i>5.16). <br />
</i>3. Remove the sleeve from the block and install the sealing rings. Lubricate the sealing rings with lubricating oil or grease. </span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><span style="font-family: Arial;">4. Install the sleeve in the bore so that it seats against <span style="mso-bidi-font-weight: bold;">the counter bore<b>. </b></span>A sleeve driver is used, or a piece of wood is placed over the sleeve, and the sleeve is tapped into place with a hammer. <br />
When the sleeve has been installed, the piston (without rings) should be inserted and moved the full length of the sleeve to check for distortion. The piston should have the same clearance and slide freely for the full length of the bore.</span></div><div style="text-align: justify;"> </div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt; mso-fareast-font-family: Calibri;"><br />
</span></u></b></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3YvtgPKQ95ps8W734Fz0dIIc7PBWBshrfImdzU3PH47LU1PvqLiCUF8eqTrFyV8J9B75KUUR52LdvyJ6ZhFifM8lc469l44i4Ze0MAl5FCS_vxJ_5Vkpxqvnt5mYdT4wdtGmbnlJA3eQ/s1600/pict17.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="125" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3YvtgPKQ95ps8W734Fz0dIIc7PBWBshrfImdzU3PH47LU1PvqLiCUF8eqTrFyV8J9B75KUUR52LdvyJ6ZhFifM8lc469l44i4Ze0MAl5FCS_vxJ_5Vkpxqvnt5mYdT4wdtGmbnlJA3eQ/s200/pict17.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Figure 5.17</span></td></tr>
</tbody></table><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Removing cylinder sleeves</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">If a thin dry sleeve has to be removed, then it could be bored out. The boring bar is mounted a little to the side of the cylinder so that it cuts away the side of the sleeve, but not the block. This relieves the interference fit between the sleeve and the cylinder block so that the sleeve can be removed. <br />
Replaceable dry sleeves and wet sleeves can be removed and installed with a sleeve puller (Figure 5.17). Wet sleeves arc easier to remove than dry sleeves.</span></div><div style="text-align: justify;"><br />
</div><div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">See Crankshaft service>>>>>>>>>>>>>>></span></span></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-11630361038066665932011-06-10T02:23:00.001+05:002011-07-04T03:22:34.225+05:00Cylinders re-boring<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"><span style="font-family: Arial;">In engine-reconditioning workshops, large boring machines are used to re-bore engine cylinders. The block is set up on the bed of’ the machine with the boring bar mounted above. <br />
In a general workshop, a portable boring bar might be used. This is mounted on top of the cylinder block. The method of setting up and boring cylinders with this type of boring bar will be briefly described.</span></div><div style="text-align: justify;"><br />
</div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx9Okn52xJUVqMV1MiBm1Q9fhY-V2GL4yw_M8li67FdXfLUQxrojgVoA0Z8nrXITFi-dV4T89yTtvZ-6cuvDxxEl3IuBl6faIM9pGIP-Ccf9nFULleViMlREge66nkA_dYx6XImlNhOwA/s1600/pict10.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx9Okn52xJUVqMV1MiBm1Q9fhY-V2GL4yw_M8li67FdXfLUQxrojgVoA0Z8nrXITFi-dV4T89yTtvZ-6cuvDxxEl3IuBl6faIM9pGIP-Ccf9nFULleViMlREge66nkA_dYx6XImlNhOwA/s200/pict10.jpg" width="167" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Arial;">Fig 5.11</span></span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Portable boring bar </span></u></b></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">A portable boring bar consists of a base that is clamped to the top of the cylinder block, a spindle which can move up and down the cylinder, a rotating boring bar with a cutter, and an electric motor that drives the boring bar. <br />
It can be set up on the top of the cylinder block to bore one cylinder at a time (Figure 5.11). <br />
When accurately set up on the cylinder block, the boring bar and its cutter feed slowly down the cylinder boring it oversize. It stops automatically when the cutter reaches the bottom of the cylinder.</span><span style="font-size: 11pt;"> </span></div><div style="text-align: justify;"><span style="font-size: 11pt;"> </span><span style="background-color: #cfe2f3; font-size: x-small;"><span style="font-family: Arial,Helvetica,sans-serif;">5.11 Portable boring bar parts labeled</span></span></div><div style="text-align: justify;"><span style="font-size: x-small;"><b style="font-family: Arial,Helvetica,sans-serif;"> </b><span style="background-color: white; font-family: Arial,Helvetica,sans-serif;"><span style="background-color: #f4cccc;">1 diamond Lap for toot sharpening, 2 adjuster for cats paws.</span> </span></span></div><div style="background-color: white; text-align: justify;"><span style="background-color: #ea9999; font-size: x-small;"><span style="font-family: Arial,Helvetica,sans-serif;"> <span style="background-color: #f4cccc;">3 spindle, 4 handle for raising and Lowering the spindle, </span></span></span></div><div style="background-color: white; text-align: justify;"><span style="background-color: #ea9999; font-size: x-small;"><span style="font-family: Arial,Helvetica,sans-serif;"> <span style="background-color: white;"><span style="background-color: #f4cccc;">5 adjustable stop for spindle travel, 6 driving shaft from</span> </span></span></span></div><div style="background-color: white; text-align: justify;"><span style="background-color: #ea9999; font-size: x-small;"><span style="font-family: Arial,Helvetica,sans-serif;"> <span style="background-color: #f4cccc;">motor, 7 clamp to cylinder block</span></span></span></div><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Setting up a boring ba</span></u></b><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma;">r</span></u></b></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The following points provide an appreciation of the method of using a portable boring bar and the need for accuracy.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div class="MsoNormal" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Checking bore size</span></i></b><i><span style="font-size: 11pt;"> <br />
</span></i><span style="font-family: Arial;">Check all the bores and decide which one has the most wear. Use the size of this cylinder to determine the oversize to which all the cylinders will be bored.</span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Oversize of cylinders</span></i></b><i><span style="font-size: 11pt;"> <br />
</span></i><span style="font-family: Arial;">The bores are machined to a definite size, for example, <br />
<i><span style="color: #cc0000;">74.25 </span></i><span style="color: #cc0000;">mm</span>. This would be for a<span style="color: #cc0000;"> 74 mm</span> bore being bored <i><span style="color: #cc0000;">0.25 </span></i><span style="color: #cc0000;">mm</span> oversize. If the worst cylinder will clean up to this size, then so will the others. Work on the worst cylinder first. <br />
Oversize pistons are used and these are slightly smaller than the bore because they have an allowance for clearance. <br />
Typical specifications for a cylinder and oversize pistons are shown in the following Table.</span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"> </span></div><table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: medium none; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr> <td colspan="2" style="padding: 0in 5.4pt;"><div style="text-align: center;"><span style="font-family: Arial; font-size: 9pt;">Table Cylinder and piston specifications </span></div></td> </tr>
<tr style="mso-yfti-irow: 1;"> <td style="padding: 0in 5.4pt 0in 5.4pt;"><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="font-family: Arial; font-size: 9pt;">ITEM </span></div></td> <td style="padding: 0in 5.4pt 0in 5.4pt;"><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="font-family: Arial; font-size: 9pt;">SPECIFICATION </span></div></td> </tr>
<tr style="mso-yfti-irow: 2; mso-yfti-lastrow: yes;"> <td style="padding: 0in 5.4pt 0in 5.4pt;" valign="top"><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="background: none repeat scroll 0% 0% lime; font-family: Arial;"><span style="background-color: #f4cccc;">Cylinder bore (standard)</span> </span></div><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="font-family: Arial;">Cylinder-bore out-of-round<span style="background: none repeat scroll 0% 0% silver;"> </span></span></div><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="font-family: Arial;">(service limit) <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">Cylinder-bore taper (service limit)</span> <br />
Cylinder-to-piston clearance <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">Piston diameter (standard)</span> <br />
Piston diameter (0.25 mm oversize) <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">Piston diameter (0.50 mm oversize)</span> </span></div></td> <td style="padding: 0in 5.4pt 0in 5.4pt;" valign="top"><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="background: none repeat scroll 0% 0% rgb(244, 204, 204); font-family: Arial;">74.00—74.02 mm</span><span style="font-family: Arial;"><span style="background-color: #ea9999;"> </span><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="mso-element-anchor-horizontal: page; mso-element-anchor-vertical: paragraph; mso-element-frame-hspace: 9.0pt; mso-element-left: center; mso-element-top: 15.2pt; mso-element-wrap: around; mso-element: frame; mso-height-rule: exactly;"><span style="font-family: Arial;">0.10 mm <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">0.10 mm</span> <br />
0.02—0.05 mm <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">73.97—73.99 mm</span> <br />
74.22—74.23 mm <br />
<span style="background: none repeat scroll 0% 0% rgb(244, 204, 204);">74.47—74.48 mm</span> </span></div></td> </tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="margin-left: -5pt; text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;"> </span></i></b></div><div class="MsoNormal" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Accurate measurements</span></i></b><span style="font-family: Georgia;"> </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">An inside micrometer is used to measure the cylinder bore and an outside micrometer is used to measure the piston. Check the outside micrometer with its setting bar and adjust it if necessary. Then use the outside micrometer to check the inside micrometer.</span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">The inside and outside micrometers must read the<b> </b>same.</span></i></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiS1XWGeIIkYTzmoteKg-ioghGe_OAjlDuoDT0WbYXfFUxF2ykrWaDAJJSuRkPjGA3ya1qIAKFkwzKvv4ooB20SoqxHVbd283BTYDGxwf1wKA2RZZmYDyuc1tpuO7LFKlBDtZoBN_lxCSs/s1600/pict12.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiS1XWGeIIkYTzmoteKg-ioghGe_OAjlDuoDT0WbYXfFUxF2ykrWaDAJJSuRkPjGA3ya1qIAKFkwzKvv4ooB20SoqxHVbd283BTYDGxwf1wKA2RZZmYDyuc1tpuO7LFKlBDtZoBN_lxCSs/s200/pict12.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.12</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Arial;"><span style="text-decoration: none;"><br />
</span></span></u></b></div><div class="MsoNormal" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">Mounting the boring ba</span></i></b><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 12pt;">r</span></i></b></div><div style="text-align: justify;"><span style="font-family: Arial;">The surface of the block and the base of the boring bar must be clean before the boring bar is mounted on the block. </span></div><div style="text-align: justify;"><span style="font-family: Arial;"> The boring bar is correctly positioned so that it bores concentric with the original bore. This is done with expanding lingers, called </span><i><span style="color: #cc0000; font-family: Georgia;">cats paws</span></i><i><span style="font-family: Arial;">, </span></i><span style="font-family: Arial;">on the lower end of the spindle (Figure 5.12<i>). </i>When the </span><i><span style="color: #cc0000; font-family: Georgia;">cats paws</span></i><span style="font-family: Arial;"> are expanded against the cylinder, they centre the spindle in the bore (Figure 5.12<i>). </i></span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;"><i> </i>Once accurately centered, the base of the machine is clamped to the top of the cylinder block. It remains clamped in position until boring of the cylinder is completed.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1ZS5qv6eAPys1-FXOhZ5u3tERgVAd9FqHY1FJnuB6U2haZjHEYAiqpVq6oIAJweF3TXPWJF2gYKcU-cA9xU2BZlqFXO1MKWHW2mkdIal3AnSgjfDkKzrXTARQEaniZUdeelL4qJ_vljA/s1600/pict11.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="145" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1ZS5qv6eAPys1-FXOhZ5u3tERgVAd9FqHY1FJnuB6U2haZjHEYAiqpVq6oIAJweF3TXPWJF2gYKcU-cA9xU2BZlqFXO1MKWHW2mkdIal3AnSgjfDkKzrXTARQEaniZUdeelL4qJ_vljA/s200/pict11.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.13</span></td></tr>
</tbody></table><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The cutter, that does the boring, rotates in a carrier at the bottom of the spindle. The cutter is adjusted for depth of cut in a special micrometer (Figure <i>5.13). </i>This has to be an accurate setting because it determines the finished size of the bore. The cutter is set slightly undersize to allow for a final finish by honing. <br />
The micrometer for setting the cutter has a scale that is twice that of a standard micrometer. This compensates for the fact that metal is removed from each side of the cylinder by the cutter</span>.<br />
<br />
<div style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Continued </span></span></div><div style="text-align: right;"><span style="font-family: "Courier New",Courier,monospace; font-size: x-small;">See cylinders boring</span>>>>>>>>>>>>>>>></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-9233201338331191382011-06-09T02:05:00.000+05:002011-07-04T03:21:16.280+05:00Hones and cylinders honing<div dir="ltr" style="text-align: left;" trbidi="on"><div></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">Cylinders with limited wear, or with any of the conditions previously outlined, can usually be restored by honing. This does not apply to badly worn or damaged cylinders which will have to be reconditioned by re-boring or sleeving. <br />
Honing is an abrasive process which leaves small scratches on the surface of the cylinder bore. The depth of the scratches is determined by the grit size of the abrasive method being used. Oil is trapped in the scratches and provides lubrication during running-in and normal engine operation. <br />
The cylinders of aluminium cylinder blocks can be restored by honing but, for some engines, the manufacturers do not recommend re-boring. </span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW_9UkGQF8PjHDfH-KztOsToBQDPjKT6SlYYK3D-cQaqBpcBLdpSLPxS326_JlRyNld_2hXlI2i2ZFydft7I51HEGpBSpCIh75CCYrz3D3wRLh-N3rhxt4S3IWyXu2vwbrXozYB4V3EIU/s1600/Fig+5.7.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW_9UkGQF8PjHDfH-KztOsToBQDPjKT6SlYYK3D-cQaqBpcBLdpSLPxS326_JlRyNld_2hXlI2i2ZFydft7I51HEGpBSpCIh75CCYrz3D3wRLh-N3rhxt4S3IWyXu2vwbrXozYB4V3EIU/s200/Fig+5.7.gif" width="182" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.7</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Cylinders in good condition are not usually honed before fitting new piston rings. Generally, the surface of the cylinders is suitable for replacement rings without any treatment. However, if the cylinders are glazed, they are usually given a light hone. <br />
There are two types of cylinder hones. One has rigid stones and the other has a large number of small beads of abrasive arranged in the form of a brush. Hone stones are made of aluminium oxide or silicon carbide, both are very hard abrasives. <br />
Before using a hone, all exposed parts, such as the crankshaft, should be covered with oil-soaked rags that will hold dust and particles of abrasive. The cylinders should he cleaned carefully after honing, as any abrasive material left behind will damage the engine.</span><span style="font-size: 11pt;"> <br />
</span><span style="font-family: Arial;">Hones are driven by a portable electric drill. This rotates the hone while the operator moves it up and down in the cylinder bore to produce a cross-hatch pattern on the cylinder wall (Figure <i>5.7).</i></span><i><span style="font-size: 11pt;"> </span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">When using a hone, the vertical movement must suit the speed of the drill to produce the correct angle in the pattern.</span></i></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Rigid hone</span></u></b></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-knQDwl7N8WND7pZluALtBm7YyccBpKtPnH1ogIa7nJwSe9hbgaRODExyT7v27-v9Q3b0TP6XWh0NsK3i4z1jvLFA8g_U4WMCMBEkahhVTQvzrmdIlK8yEqwM_Ydb1ZDMZyPkoVueFOE/s1600/pict9.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-knQDwl7N8WND7pZluALtBm7YyccBpKtPnH1ogIa7nJwSe9hbgaRODExyT7v27-v9Q3b0TP6XWh0NsK3i4z1jvLFA8g_U4WMCMBEkahhVTQvzrmdIlK8yEqwM_Ydb1ZDMZyPkoVueFOE/s200/pict9.jpg" width="200" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Arial;">Fig 5.8</span></span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial; font-size: 10pt;"><span style="font-size: small;">A rigid cylinder hone has four stones, or blades, each mounted in a carrier (Figure 5.8)<i>. </i>The carriers can be expanded by a knurled nut at the top of the hone to bring the stones against the walls of the cylinder.</span> </span><span style="font-family: Arial;"><br />
</span></div><div style="text-align: justify;"><span style="font-family: Arial;">The hone is used as follows: </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">1. Place the hone in the cylinder and expand the stones against the unworn part of the cylinder. <br />
2. Shake the hone to make sure that all the stones contact the cylinder wall. <br />
3. If the hone shakes, remove it and pack behind the low stones to get rid of the shake. <br />
4. Operate the hone for about two strokes, and again try the hone for shake. Check it in another bore and. if satisfactory, proceed to hone. Lubricate the stones during use. <br />
<i>5. </i>Use a slow drill speed and adjust the up-and-down movement so that the desired cross-hatch pattern is obtained. If the vertical movement is too slow or too short, the angle of the pattern will be too flat.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"><span style="text-decoration: none;"><br />
</span></span></u></b></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_oYRjeFFrv9NQCQvrQkJ1lL7SaIrOClOC5IWAPJbYPGDVUELTn-lcnEjfyGxnJ1vpJZRECcpsmJcbA3Im-BMTCNxwC6lK6EskmS3C9x9J4w8r7-YexJwIRONjumKH2bNmyvewGVewVgs/s1600/pict8.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_oYRjeFFrv9NQCQvrQkJ1lL7SaIrOClOC5IWAPJbYPGDVUELTn-lcnEjfyGxnJ1vpJZRECcpsmJcbA3Im-BMTCNxwC6lK6EskmS3C9x9J4w8r7-YexJwIRONjumKH2bNmyvewGVewVgs/s200/pict8.jpg" width="189" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><span style="font-family: Arial;">Figure 5.9</span></span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Brush-type hone</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">This type of hone consists of a central shaft with a cylindrical brush head. Small abrasive beads are attached to the ends of nylon filaments to form the head of the brush (Figure 5.9)<i>. </i>The hones are made in a number of sizes with different abrasives. Each hone</span> <span style="font-family: Arial;">size is suitable for a range of cylinder sizes.</span> </div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Arial;"><span style="text-decoration: none;"></span></span></u></b></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">The hone is simple in design and use, requiring no adjustment. Through centrifugal action, the hone is self-centering and self-aligning in the cylinder bore. <br />
The hone is driven by an electric drill and operated up and down the cylinder to produce the desired crosshatch pattern.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Plateau honing</span></u></b></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWRbniLccD5VCoaAEoTd9H-mHwmhKkjUFxl_hg6PrvQFlz2myHDWpYueMd404j06-vqfVvhh7IjHGwcJFUSUn1umzlQpGtwqJEusMAdapuPJYfI4sAaNefYcjqBqzK8uhSgB6hi3-Z92M/s1600/Fig+5.10.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWRbniLccD5VCoaAEoTd9H-mHwmhKkjUFxl_hg6PrvQFlz2myHDWpYueMd404j06-vqfVvhh7IjHGwcJFUSUn1umzlQpGtwqJEusMAdapuPJYfI4sAaNefYcjqBqzK8uhSgB6hi3-Z92M/s200/Fig+5.10.gif" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 5.10 (a & b)</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Both rigid and brush-type honing methods described above produce sharp peaks when viewed under close magnification (Figure <i>5. </i>10(a)). These can create problems with some low-ring wall tension rings. Plateau honing takes the sharp tops off the peaks to provide a plateau-like finish (Figure <i>5.10(b)). </i>A rigid hone with nylon filaments is used.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Cleaning cylinders after honing</span></u></b></div><div></div><div style="text-align: justify;"><span style="font-family: Arial;">When cylinders are honed or deglazed, the bores must be thoroughly cleaned before the engine is reassembled. Unless this is done, abrasive will remain in the engine and will cause rapid wear of rings, cylinder walls and bearings. </span><br />
<span style="font-family: Arial;"> A recommended cleaning method is: </span><br />
<span style="font-family: Arial;"> I. Clean the bores with detergent and water and a stiff brush. </span><br />
<span style="font-family: Arial;"> 2. Rinse with clean water and dry with a clean cloth. </span><br />
<span style="font-family: Arial;"> 3. Wipe the bores with a clean cloth that has been dipped in engine oil.</span><span style="font-size: 11pt;"> </span><br />
<span style="font-size: 11pt;"></span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">If the engine has not been dismantled, the crankshaft must be suitably covered before honing and bore cleaning.</span></i></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><br />
</div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><br />
</div><div style="color: black; font-family: "Courier New",Courier,monospace; margin-left: 0in; text-align: center; text-indent: 0in;"><span style="font-size: x-small;">Continued</span></div><div style="margin-left: 0in; text-align: right; text-indent: 0in;"><span style="color: black; font-size: x-small;"><span style="font-family: Georgia;"><span style="font-family: "Courier New",Courier,monospace;">See cylinders re-boring>>>>>>>>>>>>>></span></span></span><i><span style="color: #cc0000; font-family: Georgia;"> </span></i></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-9454503167319843472011-06-08T01:38:00.000+05:002011-07-04T03:20:47.520+05:00Cylinders measurements<div dir="ltr" style="text-align: left;" trbidi="on"><div></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO0ZvjFuXgctZ3u2P-foDmEUN6kxp9TdoAWoUNDLYbS6TAsyl1xOxUvNMpDf8wqCkjYFBA9tNvZNWzQk4zt_YFvNQsF0y0IGmXkQX4MF_OV77X-ETfqYAv9CquSs-baOW0JVraPiMpYgo/s1600/Fig+5.3.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO0ZvjFuXgctZ3u2P-foDmEUN6kxp9TdoAWoUNDLYbS6TAsyl1xOxUvNMpDf8wqCkjYFBA9tNvZNWzQk4zt_YFvNQsF0y0IGmXkQX4MF_OV77X-ETfqYAv9CquSs-baOW0JVraPiMpYgo/s200/Fig+5.3.gif" width="150" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 5.3</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;">An inside micrometer can be used to measure the size of a cylinder, but the most accurate way of determining wear is with a <i>cylinder-bore gauge </i>(Figure 5.3). This consists of a dial gauge with a guide to locate it in the cylinder. As the gauge is moved up and down the cylinder, the pointer of the gauge will show any variations in the size of the bore. <br />
<b> </b>Cylinders are measured in the following way: <br />
I. Before measuring cylinder wear, wipe the cylinder clean and examine it for scores and visible wear. <br />
2. Place the cylinder-bore gauge across the cylinder, just below the unworn ring ridge. <br />
3. Turn the bezel to set the dial gauge to zero. <br />
4. Move the gauge slowly up and down the cylinder to measure <i>taper. </i>The pointer will move on the scale. <br />
<i>5. </i>Turn the cylinder-bore gauge 900<b> </b>in the cylinder to measure out-of-round.</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg73_Sl8YruavWkhOMAuFShvSDej6X9wVfjEcjAb8nkL2O6-5aRs7LvPY0zg0FOF_WjWFIh4X4ZsDQLSuDD7BMKCK7UGnjL3QzFD53mFX_aA8gTMOfxr7r1LaI6XOOYshBJJegZ8QhxXOc/s1600/Fig+5.4.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg73_Sl8YruavWkhOMAuFShvSDej6X9wVfjEcjAb8nkL2O6-5aRs7LvPY0zg0FOF_WjWFIh4X4ZsDQLSuDD7BMKCK7UGnjL3QzFD53mFX_aA8gTMOfxr7r1LaI6XOOYshBJJegZ8QhxXOc/s200/Fig+5.4.gif" width="157" /></a></td></tr>
<tr style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.4</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">Measurements</span></i></b></div><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">Figure 5.4</span><i><span style="font-family: Arial; font-size: 11pt;"> </span></i><span style="font-family: Arial;">shows where the cylinder is checked. Readings should be taken at A—A and also at B—B. They should be taken at both the top and bottom of the cylinder. These measurements will allow the wear of the cylinder to be determined as follows:</span> <br />
<span style="font-family: Arial;">Out-of-round = difference between A—A and B—B <br />
Taper = difference between A—A measured at the top of the cylinder and A—A measured at the bottom of the cylinder</span> <br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">The taper is checked at A—A because this is the thrust part of the cylinder. It will have more wear than B—B. </span></i></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Condition of cylinders </span></u></b><span style="font-family: Tahoma;"></span></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0_BpqP0dlf33iMi26Fhcsf6ilgYgTgk5zuZJrjSqSGDrAutcduFKBxHekUXiAYDHgJqEsy_6IwHyP8-Yib-LIjdB6Vul_C6jIw2311Y2Gu3aHIfJLbzHncyCADfPCfpptLM-4vHRdGh4/s1600/Fig+5.5.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0_BpqP0dlf33iMi26Fhcsf6ilgYgTgk5zuZJrjSqSGDrAutcduFKBxHekUXiAYDHgJqEsy_6IwHyP8-Yib-LIjdB6Vul_C6jIw2311Y2Gu3aHIfJLbzHncyCADfPCfpptLM-4vHRdGh4/s200/Fig+5.5.gif" width="141" /></a></td></tr>
<tr style="background-color: cyan;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.5</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">The parts of a cylinder that normally wear are shown in Figure </span><i style="font-family: Arial,Helvetica,sans-serif;">5.5. </i><span style="font-family: Arial,Helvetica,sans-serif;">Wear is caused by the piston rings rubbing on the cylinder walls. Very little wear is actually caused by the piston. Ring wear leaves ridges in the cylinder at the top and bottom limits of ring travel.</span><span style="font-size: 11pt;"><span style="font-family: Arial,Helvetica,sans-serif;"> </span><br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 0in; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">The piston rings naturally expand against the cylinder wall, but they are also forced outward by gas pressure.</span></i><span style="color: #993300; font-family: Georgia;"></span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">The types of wear that can be found in the cylinders when an engine is dismantled are</span> <b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">bore <span style="font-size: small;">distortion</span></span></i></b><span style="font-size: small;"><i><span style="color: #cc0000;">, </span></i><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">waviness</span></i></b><i><span style="color: #cc0000;">, </span></i><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">scuffing</span></i></b></span><i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial,Helvetica,sans-serif;">and</span> <b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";">scoring</span></i></b><b><i><span style="font-family: "Helvetica, sans-serif";"> </span></i></b><span style="font-family: Arial,Helvetica,sans-serif;">(Figure 5.6</span><i style="font-family: Arial,Helvetica,sans-serif;"><span style="font-size: 11pt;">). </span></i><span style="font-family: Arial,Helvetica,sans-serif;">These conditions are described in the following paragraphs. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> The top of the cylinder suffers the greatest wear, and this leaves a definite ring ridge in a worn cylinder. The lower ring ridge is not as noticeable because less wear occurs at the bottom of a cylinder. The bottom of the cylinder below the ring travel is almost unworn.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol; font-size: 11pt;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">Cylinder wear is also illustrated in Figure 4. 9 in the previous posts. </span></i><i><span style="font-family: "Helvetica, sans-serif"; font-size: 11pt;"><br style="mso-special-character: line-break;" /> </span></i><br />
<i><span style="font-family: "Helvetica, sans-serif"; font-size: 11pt;"> </span></i></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Bore distortion</span></i></b></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">This can be caused by uneven distribution of coolant around the cylinders, or by incorrect tightening of the cylinder-head studs. Bore distortion can sometimes be identified by obvious discoloration of the cylinders, but this is not always the case. </span><br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioHoS_znk7bdGJezA6dSRK4BDb-W15_FVzbe9mOJgZM9dl8kc2ghhIbe5nHB-wtxtiSwhV1fxi7lm20AaxPECyM-r_Ud3iDXKgO3j-pIIlvulbUmziA3cA5BIXNGhIvyMl9m8YlwrF26Y/s1600/Fig+5.6.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="130" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioHoS_znk7bdGJezA6dSRK4BDb-W15_FVzbe9mOJgZM9dl8kc2ghhIbe5nHB-wtxtiSwhV1fxi7lm20AaxPECyM-r_Ud3iDXKgO3j-pIIlvulbUmziA3cA5BIXNGhIvyMl9m8YlwrF26Y/s400/Fig+5.6.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial;">Fig 5.6</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Waviness</span></i></b><i><span style="font-size: 11pt;"> </span></i><br />
<i><span style="font-size: 11pt;"> </span></i><span style="font-family: Arial,Helvetica,sans-serif;">This is a series of parallel lines or low ridges running around the bore. Waviness can be at any part of the bore but is mainly found in the top regions of ring travel. Waviness is a condition that is hard to measure, but it can be seen and can be felt by lightly running the finger vertically in the bore.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Scuffing</span></i></b><b><i><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></i></b><span style="font-family: Arial,Helvetica,sans-serif;">This is evident from small areas of the cylinder wall that have discoloration and minute raised areas in which particles of the piston ring have cold-welded themselves to the cylinder walls.</span></div><div style="text-align: justify;"></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">Scuffing can be the result of localised hot spots in the cylinder water-jackets. This could be caused by deposits that allow small areas of the cylinder wall to reach high temperatures. It could also be the result of continued operation of the engine with loss of coolant. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> Incorrect type or grade of oil could create problems. High temperatures will break down the lubricating-oil film and allow metal-to-metal contact between the piston rings and the cylinder wall. </span><br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif"; font-size: 12pt;">Scoring</span></i></b></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">This can be an advanced stage of</span> <i><span style="color: #cc0000; font-family: Georgia;">scuffing</span>, </i><span style="font-family: Arial,Helvetica,sans-serif;">in which piston ring particles have scratched the cylinder surface. Broken rings or abrasives can also cause bore scoring. Provided scoring is not deep, honing the cylinder can be used to correct it.</span><b><i><span style="color: #cc0000; font-family: "Helvetica, sans-serif";"></span></i></b></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">With scuffing and scoring, the piston will also be similarly affected.</span></i></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><br />
</div><div class="NormalLatinArial" style="color: black; font-family: "Courier New",Courier,monospace; margin-left: 0.5in; text-align: center; text-indent: -0.5in;"><span style="font-size: x-small;">Continued </span></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: right; text-indent: -0.5in;"><i><span style="color: #cc0000; font-family: Georgia;"> </span></i><span style="font-size: x-small;"><span style="color: black; font-family: Georgia;"><span style="font-family: "Courier New",Courier,monospace;">See hones and cylinders honing>>>>>>>></span></span></span><i><span style="color: #cc0000; font-family: Georgia;"><br />
</span></i></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-2367864491262441962011-06-07T01:02:00.000+05:002011-07-04T03:20:19.678+05:00Cylinder block, crankshaft and bearing service<div dir="ltr" style="text-align: left;" trbidi="on"><div></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">The engine is usually removed from the vehicle for any major service work on the cylinder block and crankshaft, although some jobs can be done with the engine in the vehicle. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> As well as dismantling and reassembling procedures, service items include checking the cylinder bores for wear, reconditioning the cylinders by honing or boring, renewing cylinder sleeves, checking crankshaft journals for wear, and checking and replacing crankshaft bearings. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> Some information on engine reconditioning will be included in upcoming posts. While major items are often handled by engine-reconditioning workshops, a general appreciation of these procedures is needed by all automotive technicians. </span><br />
<br style="mso-special-character: line-break;" /></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitqtiqEcZZCgjHqY1OaxqkT8_OWLCQ57ejlPlQJIqRaS3ace6yaLGUPm-_uUOr8wW9eMIzF1OqjgG20_PolIboVwwuh0qZ78eqwKI0ETku2IRiySFj9x9_4qcbzjn1zGXif7b-ABvpN68/s1600/Fig+5.1.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="204" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitqtiqEcZZCgjHqY1OaxqkT8_OWLCQ57ejlPlQJIqRaS3ace6yaLGUPm-_uUOr8wW9eMIzF1OqjgG20_PolIboVwwuh0qZ78eqwKI0ETku2IRiySFj9x9_4qcbzjn1zGXif7b-ABvpN68/s320/Fig+5.1.gif" width="320" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 5.1</span></td></tr>
</tbody></table><div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Servicing cylinder blocks</span></u></b><b><span style="font-family: Arial; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial;">After the various components have been dismantled from the cylinder block, it should be cleaned and inspected. The block can be steam-cleaned, pressure- cleaned with water, or cleaned in a cleaning tank. Alternatively, solvent can be applied by spray gun or brush and jetted off with water. All old gaskets and sealing material must be removed from the machined surfaces. <br />
For a thorough cleaning, the plugs that blank off oil passages should be removed and the passages blown through with compressed air. The passages must be free of sludge or deposits that could have been loosened during cleaning. </span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif;">A general check of the cylinder block should be carried out, as shown in Figure </span><i style="font-family: Arial,Helvetica,sans-serif;">5.1. </i><span style="font-family: Arial,Helvetica,sans-serif;">Checks include machined surfaces, threaded holes, and core plugs. The cylinders are checked for cracks, scores and</span><span style="font-size: 11pt;"><span style="font-family: Arial,Helvetica,sans-serif;"> wear. </span><br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="margin: 5pt 0in 0.0001pt; text-align: justify; text-indent: 0in;"><span style="color: #cc0000; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">Minute cracks will show up f the suspected area of the block is checked with one of the crack-detection methods. </span></i><span style="color: #cc0000; font-family: Georgia;"></span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">Machined surfaces</span></i><i><span style="font-size: 11pt;"> </span></i></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEh_kCfSINGL5moIVBv-RRgztxPCnna0LLKpb9bqcUtjTBbQAMrAls6F5lLNcQr7fTWCvgkQ19b60XMG96xUFNNl0C-lVw_0lt6KVJDNUGHw0_q6ngsITe9gooNaEa4g0Ea4rsbyKdLCg/s1600/Fig+5.2.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEh_kCfSINGL5moIVBv-RRgztxPCnna0LLKpb9bqcUtjTBbQAMrAls6F5lLNcQr7fTWCvgkQ19b60XMG96xUFNNl0C-lVw_0lt6KVJDNUGHw0_q6ngsITe9gooNaEa4g0Ea4rsbyKdLCg/s320/Fig+5.2.gif" width="320" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 5.2</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Machined surfaces should be inspected for burrs, nicks and scratches. Minor damage can be carefully removed with a fine file or an oil stone. <br />
The top of the cylinder block can be checked for flatness by using a straightedge and feeler gauge (Figure <i>5.2). </i>This is done in a similar manner to that previously described for the cylinder head (Chapter 3). The surface can be machined to restore the flatness if necessary, but only a limited amount of metal (for example, 0.25 mm) should be removed.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #cc0000; font-family: Georgia;">For more information on bolts and threads see upcoming "General engine service."</span></i></div><div style="text-align: justify;"></div><br />
<div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><b><i><span style="color: #cc0000; font-family: Georgia; font-size: 11pt;">Expansion or core plugs</span></i></b><b><i><span style="font-family: Georgia; font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial,Helvetica,sans-serif;">Expansion plugs in the cylinder block should be replaced if they show any evidence of leaking. Most plugs can be removed by drilling or punching a hole in the centre, and then levering them out with a punch or small pry bar. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> To install a new plug, scrape any rust from the recess in the block, coat the recess with a suitable sealing compound and place the new plug in the recess, convex side out. Tap the centre of the plug to make sure it is seated, then use a flat-ended punch and a hammer to drive against the centre of the plug and expand it into the recess. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> Cup-shaped plugs are treated in a similar way, except that it is not necessary to expand them after they have been tapped into the recess in the cylinder block.</span></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div class="NormalLatinArial" style="text-align: justify;"></div><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Checking and measurement of cylinders for service</span></u></b><b><span style="font-family: Tahoma; font-size: 17pt;"> </span></b><br />
<div align="left" class="NormalLatinArial" style="text-align: left;"><br />
</div><div style="text-align: justify;"><span style="font-family: Arial;">The cylinders do not wear uniformly, but wear tapered and out-of-round. They must be measured accurately to find the amount of wear and to determine what reconditioning is needed. </span></div><span style="font-size: small;"><span style="font-family: Arial;">If the wear is not excessive, new piston rings and bearings can be fitted and this will provide a satisfactory repair. However, if the cylinders have worn beyond a certain limit, new rings will not be sufficient and the cylinders will have to be reconditioned. </span></span><br />
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<div style="font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: small;"><span style="font-size: x-small;">Continued </span></span></div><div style="font-family: "Courier New",Courier,monospace; text-align: right;"><span style="font-size: small;"><span style="font-size: x-small;">See measuring cylinders>>>>>>>>>>>>>> </span></span></div><br />
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</div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-88058184936620442642011-06-06T00:10:00.001+05:002011-07-04T01:35:18.926+05:00Balance for power impulses<div dir="ltr" style="text-align: left;" trbidi="on"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWsh7msylInGI5lZHx84Jg4XvQYj1cvyw2bu3M8e4EsvA0Pt0Xd44Q5fna78D2G6OXT64zR7u3zqFc3ZtDBt0_WS4ABD9roLm3WS1aTbaaiMiT8vbiyZg8CcUh1jV2AZiYaW5Mju2Mb_o/s1600/pict22.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="84" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWsh7msylInGI5lZHx84Jg4XvQYj1cvyw2bu3M8e4EsvA0Pt0Xd44Q5fna78D2G6OXT64zR7u3zqFc3ZtDBt0_WS4ABD9roLm3WS1aTbaaiMiT8vbiyZg8CcUh1jV2AZiYaW5Mju2Mb_o/s320/pict22.jpg" width="320" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.24</span></td></tr>
</tbody></table><br />
<div class="MsoNormal" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;">The power impulses from the engine cylinders tend to make the crankshaft speed up and slow down. This causes a twisting vibration, referred to as</span> <i><span style="color: #993300; font-family: Georgia;">torsional vibration</span>. <br />
</i><span style="font-family: Arial;">Figure 4.24 shows the power strokes in four- cylinder, six-cylinder and eight-cylinder engines. Power is delivered from the top of a stroke as a</span> <i><span style="color: #993300; font-family: Georgia;">power impulse</span> </i><span style="font-family: Arial;">and the impulses are transmitted to the crankshaft.</span> <br />
<span style="font-family: Arial;">The crankshaft vibrates because each impulse causes it to accelerate a little, followed by a deceleration as the impulse is reduced. The power strokes on six-cylinder and eight-cylinder engines overlap, and this smoothens out the impulses but increases their frequency.</span> </div><div></div><div class="MsoNormal" style="text-align: justify;"><i style="color: purple;"><span style="font-family: Arial,Helvetica,sans-serif;">Power impulses in 4-cylinder, 6-cylinder and 8-cylinder engines, each circle shows the two complete revolutions of crankshaft(720 degrees)</span></i></div><div style="text-align: justify;"></div><div class="MsoNormal" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">The power impulses produce torsional vibration in the crankshaft. </span></i></div><div style="text-align: justify;"></div><div style="margin-top: 10pt; text-align: justify;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNI_tkAp-KW5ETuZhbB82-etxsJ4kUT43MwWYp0HaG8wAh15X6ZX6odlvwGPSqsNJP2d26zb4TY6zTn7_X4iUVtqVYU7l8f8I6GssVY59pesD7FSGCGeIn8k2I3UojZWi5WTKf54Snh1A/s1600/pict23.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNI_tkAp-KW5ETuZhbB82-etxsJ4kUT43MwWYp0HaG8wAh15X6ZX6odlvwGPSqsNJP2d26zb4TY6zTn7_X4iUVtqVYU7l8f8I6GssVY59pesD7FSGCGeIn8k2I3UojZWi5WTKf54Snh1A/s320/pict23.jpg" width="164" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.25</span></td></tr>
</tbody></table><b style="mso-bidi-font-weight: normal;"><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Flywheels</span></i></b><i> <br />
</i><span style="font-family: Arial;">The flywheel helps to reduce this type of vibration because it tries to keep the crankshaft rotating at a constant speed. The flywheel absorbs energy as the crankshaft tends to speed up, and gives back energy as the crankshaft tends to slow down. <br />
A normal flywheel is a single piece of solid cast iron, but some flywheels have two parts and are designed to absorb torsional vibrations. This design is known as a</span> <i><span style="color: #993300; font-family: Georgia;">dual-mass</span> </i><span style="font-family: Arial;">flywheel (Figure <i>4.25). </i>The front part of the flywheel is connected to the crankshaft and the rear part is connected to it through springs. <br />
When a power impulse tries to speed up the front part of the flywheel, the rear part lags behind. This tends to cancel out the force of the impulse. The opposite effect occurs when the impulse ceases, the inertia of the rear part of the flywheel tends to keep it turning.</span> </div><div style="text-align: justify;"></div><div style="margin: 10pt 0in 0.0001pt 0.5in; text-align: justify; text-indent: -0.5in;"><span style="font-size: x-small;"><span style="color: #993300; font-family: Symbol;">·<span style="-moz-font-feature-settings: normal; -moz-font-language-override: normal; font-family: "Times New Roman"; font-size-adjust: none; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal;"> </span></span><span style="font-size: small;"><i><span style="color: #993300; font-family: Georgia;">The principle of operation f a dual-mass flywheel is similar to that of a vibration damper.</span></i></span></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><div class="separator" style="clear: both; text-align: center;"></div><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Torque converters</span></i></b><i><span style="font-size: 11pt;"> <br />
</span></i><span style="font-family: Arial;">A torque converter used with an automatic transmission acts in the same way as a flywheel. It can he considered as being a flywheel filled with fluid. The torque converter and the fluid that it contains provide the mass needed. Also, because torque is transmitted through the fluid at lower speeds, less vibration is transferred through to the drive line.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><div class="separator" style="clear: both; text-align: center;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8B9JJH7GMv23EQEEfVZBHcDWkPLtB1ekkFNDDs7x4ks5g5Ixij_8eLtfNpOG3OS-GQaNXx5h9TbYHbQoJwkBGYpFNULXkU5mFJm8PZRCapu2DySwbv0ZsPJvisAuCV84SPdnPBs36BoY/s1600/Fig+4.26.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8B9JJH7GMv23EQEEfVZBHcDWkPLtB1ekkFNDDs7x4ks5g5Ixij_8eLtfNpOG3OS-GQaNXx5h9TbYHbQoJwkBGYpFNULXkU5mFJm8PZRCapu2DySwbv0ZsPJvisAuCV84SPdnPBs36BoY/s200/Fig+4.26.gif" width="199" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.26</span></td></tr>
</tbody></table><b style="mso-bidi-font-weight: normal;"><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Vibration dampers</span></i></b><i><span style="font-size: 11pt;"> <br />
</span></i><span style="font-family: Arial;">A vibration damper is fitted to the front of the crankshaft. This is usually part of the crankshaft pulley (Figure 4.26). The damper consists of two main parts: <br />
a hub that mounts on the front of the crankshaft, and an inertia ring (a small flywheel) that is attached to the hub by a bonded-rubber insert. The rubber allows the inertia ring to move a little in relation to the hub. Dual- type dampers have two inertia rings. <br />
The inertia ring dampens out crankshaft vibrations in the following way: When the crankshaft tends to speed up, the inertia ring tends to lag behind to oppose the force producing the vibration. When the crankshaft tends to slow down, the inertia ring tries to keep it moving. In this way, the action of the inertia ring on its rubber mounting helps to dampen out crankshaft vibrations. <br />
Inertia is the tendency of a body to resist changes in motion. For example, a flywheel does not suddenly start to rotate as a force applied, nor does it suddenly stop if the force is removed.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> <br style="mso-special-character: line-break;" /> </span></div><div style="text-align: justify;"></div><div style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">In simple terms, inertia is a form of laziness.</span></i><br />
<br />
<div style="color: black; font-family: "Courier New",Courier,monospace; text-align: center;"><span style="font-size: x-small;">Continued </span></div><div style="text-align: right;"><span style="font-size: x-small;"><i style="color: black;"><span style="font-family: Georgia;"> </span></i></span><span style="color: #993300; font-family: Georgia;"><span style="font-size: x-small;"><span style="color: black; font-family: "Courier New",Courier,monospace;">See Balancing of reciprocating parts</span></span> </span><i><span style="font-size: 11pt;"> </span></i></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-83560825351715051942011-06-05T00:40:00.000+05:002011-07-04T03:19:49.342+05:00Balance of reciprocating parts<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"></div><div style="text-align: justify;"><span style="font-family: Arial;">The reciprocating parts of the engine are the piston assembly and the upper part of the connecting rod. Each time a piston reaches TDC or BDC it has to stop and change its direction. Each time this occurs an inertia force is produced which tries to keep the piston moving and this tries to move the engine up or down. <br />
To reduce the effects of inertia forces, all the pistons and associated parts are of equal weight.</span><span style="font-size: 11pt;"> <br style="mso-special-character: line-break;" /> </span></div><div></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1onQE6xJXRD1Hd_rfY8dWLg9wH4pT6ivzXGzlmstrm9CMvKFGQWOQjLD1LvSik9WLYgN2dJ5RDIA7p_8mvALzQq1xUeUNpu2qW9PqthP9IWQXqP0t7KXNSlxKZccyAcYDv9lkls94Gpk/s1600/pict25.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1onQE6xJXRD1Hd_rfY8dWLg9wH4pT6ivzXGzlmstrm9CMvKFGQWOQjLD1LvSik9WLYgN2dJ5RDIA7p_8mvALzQq1xUeUNpu2qW9PqthP9IWQXqP0t7KXNSlxKZccyAcYDv9lkls94Gpk/s200/pict25.jpg" width="173" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.27</span></td></tr>
</tbody></table><br />
<div style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Reducing resonance</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Everything has a natural frequency at which it will vibrate if caused to do so. The engine vibrations are related to speed so, at various times, the engine will be producing vibrations at the same frequency as the natural frequency of some other part. When this occurs, the part will commence to vibrate. This is known as </span><i style="mso-bidi-font-style: normal;"><span style="color: #993300; font-family: Georgia;">resonance</span></i><span style="font-family: Arial;">. <br />
To prevent vibrations from being transmitted to the body and becoming noticeable, insulators are used. These include rubber mountings for the engine and sub-frame, and insulation and sound-deadening materials applied to body panels.</span><i><span style="font-size: 11pt;"><br />
</span></i><span style="font-family: Arial;">Engine mountings are designed to be flexible at idle, and more rigid at higher speeds. Figure 4.27 shows a liquid-filled engine mounting. The rubber molding is hollow and contains liquid. It has two chambers connected by an orifice. When lightly loaded, liquid can pass between the chambers through the hole, but when heavily loaded or subjected to large vibrations, the liquid has a dampening effect. <br />
Another method of reducing vibrations is with a dynamic damper (Figure 4.28). This is a rubber- mounted weight attached by a metal bracket to the sub-frame. Its function is to absorb vibrations and prevent resonance noise being transferred to the interior of the vehicle. This damper is designed to come into operation in the <i style="color: purple;">2000</i> engine rpm range.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYZGTpKaDRmgPozsEDdZMGyK0C_pfWu4cHpyb47n1zV0O7K_MQsL_9tk50nUgkrZ92rBIBmE_9dHClpKS9MCcm_mWvNjDtUYn4i8ooPFWm5W8xLgdJnehHWGYqecSk3Cb8gFe1NvsQEw4/s1600/pict26.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="94" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYZGTpKaDRmgPozsEDdZMGyK0C_pfWu4cHpyb47n1zV0O7K_MQsL_9tk50nUgkrZ92rBIBmE_9dHClpKS9MCcm_mWvNjDtUYn4i8ooPFWm5W8xLgdJnehHWGYqecSk3Cb8gFe1NvsQEw4/s200/pict26.jpg" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.28</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;"> The damper action depends on the inertia of the weight. If a vibration causes the damper to move, the inertia of the weight causes it to lag behind and oppose movement. In this way, the weight absorbs energy and acts as a dampening device. Vibration dampers act by temporarily absorbing energy and then releasing it.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="separator" style="clear: both; text-align: center;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5s39h2-WwX6-YQ0pX09w8e2UuvpEGk8oMWW7I_sTb-lZ67K8zIDOWCtxCN3aGdd5o9IuPsSh3NaIOQYKvkIFLvASw7sicFL6k1QEYBKb7fIKVN2c9OgSF4bHivi0xTP7TMoeL0gy1RR0/s1600/Fig+4.29.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="141" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5s39h2-WwX6-YQ0pX09w8e2UuvpEGk8oMWW7I_sTb-lZ67K8zIDOWCtxCN3aGdd5o9IuPsSh3NaIOQYKvkIFLvASw7sicFL6k1QEYBKb7fIKVN2c9OgSF4bHivi0xTP7TMoeL0gy1RR0/s200/Fig+4.29.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.29</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="text-align: justify;"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Balance shafts</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-family: Arial,Helvetica,sans-serif;">Balance shafts are used in some engines to reduce vibration. Some engines have a single balance shaft, while others have two balance shafts. Balance shafts are mounted in bearings in the crankcase, parallel to the crankshaft, and are driven by a chain or gears. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> Figure 4.29 is one example, where a single balance shaft is driven by gears from the crankshaft at crankshaft speed. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> The purpose of balance shafts is to reduce the up- and-down vibrations of the engine by producing their own inertia forces. The shaft is designed to counter the forces at both TDC and BDC. Balance shafts can be driven at engine speed, but they are often driven at twice engine speed to increase their effect. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif;"> Figure 4.30 shows how two balance shafts are used. Both shafts are driven at twice the engine speed. The chain rotates the left balance shaft in the same direction as the crankshaft, while the right shaft rotates in the opposite direction via an idler sprocket and gear.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; font-family: Arial,Helvetica,sans-serif; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCwcAtINtaNvLy-Xy2tCnFfmCxtTLAZnBg-HwFdsPsk5Ou_98QxWONQVlN1jICIY9EYpcqmEKr3mM4DctxzwLK0fYS0yPMHtTHsxyf0jBwasmrssvtTPlwzE4orgpEnRIMAyF1-uQZsSw/s1600/Fig+4.30.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="160" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCwcAtINtaNvLy-Xy2tCnFfmCxtTLAZnBg-HwFdsPsk5Ou_98QxWONQVlN1jICIY9EYpcqmEKr3mM4DctxzwLK0fYS0yPMHtTHsxyf0jBwasmrssvtTPlwzE4orgpEnRIMAyF1-uQZsSw/s200/Fig+4.30.gif" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;">Fig 4.30</span></td></tr>
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</div><div class="NormalLatinArial" style="text-align: center;"><br />
</div><div class="NormalLatinArial" style="text-align: center;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: x-small;"><span style="font-family: "Courier New",Courier,monospace;">Continued</span></span><br />
<div class="NormalLatinArial" style="text-align: right;"><span style="font-family: Arial,Helvetica,sans-serif;"><span style="font-family: "Courier New",Courier,monospace; font-size: x-small;">See Cylinder block, crankshaft and bearing service </span> </span></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-64149041265342548952011-06-04T07:53:00.003+05:002011-07-04T00:10:39.698+05:00Cylinder block and crankcase design<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"><style>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
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<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan;"><span style="font-family: Arial,Helvetica,sans-serif;">Fig 4.21</span></span></td></tr>
</tbody></table><span style="font-size: 11pt;"><span style="font-size: small;"><span style="font-family: Arial,Helvetica,sans-serif;">There are a number of variations in crankcase design. As previously indicated, some cylinder blocks have a skirt, but others do not have a skirt below the crankshaft’s centre-line. The skirt also has a bearing on the design of the oil pan and the main bearing caps. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> Most of the variations are designed to produce a stiffer engine structure. These designs also allow the use of lighter materials or thinner sections. Having a more rigid cylinder block assembly also helps to reduce engine vibrations. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> The two-part engine block assembly shown previously in Figure </span><i style="font-family: Arial,Helvetica,sans-serif;">4.5 </i><span style="font-family: Arial,Helvetica,sans-serif;">is made of aluminium alloy and is in two parts. The parts are split along the crankshaft centre-line. There arc no main bearing caps. The</span> <i><span style="color: #cc0000; font-family: Georgia,"Times New Roman",serif;">cylinder block</span> </i><span style="font-family: Arial,Helvetica,sans-serif;">carries the upper halves of the bearings in the normal way and the </span><i style="font-family: Arial,Helvetica,sans-serif;">block base </i><span style="font-family: Arial,Helvetica,sans-serif;">carries the lower halves of the bearings. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> This arrangement provides a stiff crankcase and well supported bearings. As well, there is a cast aluminium alloy oil pan fitted to the underside of the block base and this adds to the rigidity of the engine.</span> </span><br />
</span><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Main bearing caps</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial,Helvetica,sans-serif; font-size: small;">The main bearing caps of many engines are secured by two bolts as shown previously in Figure 4. 17. However, they can also be secured by four or more bolts and Figure 4.21 is one example.</span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIfFdl5eDVtIQQIUvVeL8ISxlUk_-BVn5fx5_H13Qmbm3SW1kRRebNMXSViE2CSAm4Rai1zNEn1fJD6NROh_tHMBqJJVc8N6yLr2iOz483sZQCqk1yCSDkFHd1015-doXNYFSBC5A5r9M/s1600/pict21.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIfFdl5eDVtIQQIUvVeL8ISxlUk_-BVn5fx5_H13Qmbm3SW1kRRebNMXSViE2CSAm4Rai1zNEn1fJD6NROh_tHMBqJJVc8N6yLr2iOz483sZQCqk1yCSDkFHd1015-doXNYFSBC5A5r9M/s200/pict21.jpg" width="186" /></a></td></tr>
<tr style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;"><span style="font-family: Arial,Helvetica,sans-serif;">Fig 4.22</span></td></tr>
</tbody></table><span style="font-family: Arial,Helvetica,sans-serif; font-size: small;"> This cylinder block for a V-6 engine has a skirt that extends below the crankshaft. The main bearings have the usual two bolts at the top of each cap, but they also have side bolts. The side bolts pass through the skirt of the crankcase from the outside and are threaded into the main bearing caps. This increases the rigidity of the bearing caps. </span><span style="font-family: Arial,Helvetica,sans-serif; font-size: small;"><br />
</span><span style="font-size: small;"><b style="font-family: Georgia,"Times New Roman",serif;"><i><span style="color: #993300;">In-line engine</span></i></b><i style="font-family: Arial,Helvetica,sans-serif;"> <br />
</i></span><span style="font-family: Arial,Helvetica,sans-serif; font-size: small;">Figure 4.22 shows part of a cylinder block and crankshaft assembly for an in-line engine. This cylinder block does not have a skirt. Each of the main bearing caps is secured by four bolts -- two through the top of the cap and one on each side. There is also a support brace on top of the bearing caps that is held down by the cap bolts. </span><br />
<span style="font-family: Arial,Helvetica,sans-serif; font-size: small;"> The oil pan that is bolted to the underside of the cylinder block is of cast aluminium alloy. The side bolts pass through the sides of the oil pan and are threaded into the sides of the bearing caps. The engine block, main bearing caps, support brace and oil pan are all bolted together to form a rigid assembly.</span></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div class="MsoNormal" style="margin-bottom: 10pt; text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Engine vibration and balance</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> <br />
</span></b><span style="font-size: small;"><span style="font-family: Arial;">There are four main causes of vibration in an engine. Engine designers have to consider these and arrange </span><span style="font-family: Arial;">for them to be balanced or reduced in some way. Briefly, the causes of vibration are as follows:</span></span> <br />
<span style="font-size: small;"><span style="font-family: Arial;">1</span>. </span><i><span style="font-size: small;"><span style="color: #993300; font-family: Georgia;">Rotating parts</span></span>. </i><span style="font-size: small;"><span style="font-family: Arial;">Centrifugal force acts on all parts that rotate. Parts such as the crankshaft, flywheel and clutch must be balanced.</span></span> <span style="font-family: Arial;"><o:p></o:p></span></div><div style="margin-bottom: 10pt; text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial;">2</span>. </span><i><span style="font-size: small;"><span style="color: #993300; font-family: Georgia;">Power impulses</span></span>. </i><span style="font-size: small;"><span style="font-family: Arial;">The pistons deliver power to the crankshaft as impulses and this causes a type of rotary </span><span style="font-family: Arial;">vibration in the crankshaft.</span></span> <br />
<br />
</div><div style="margin: 10pt 0in; text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial;">3</span>. </span><i><span style="font-size: small;"><span style="color: #993300; font-family: Georgia;">Reciprocating parts</span></span>. </i><span style="font-size: small;"><span style="font-family: Arial;">The pistons, in particular, produce an inertia force at the top and bottom of their strokes. This causes up-and-down vibrations in an engine.</span></span> <br />
<br />
</div><div style="text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial;">4</span><span style="font-family: "Times New Roman";">. </span></span><i><span style="font-size: small;"><span style="color: #993300; font-family: Georgia;">Resonance</span></span><span style="font-family: "Times New Roman"; font-size: 10pt;">. </span></i><span style="font-size: small;"><span style="font-family: Arial;">Vibrations can be transmitted between parts and amplified, even though the parts may not be directly connected.</span></span><br />
<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9SUYPiineWsss2yCjy1hfA4zhaiSITvqumagPIoxNCbA3zHtt4Tl013AWCB2ga7S-e7u-QvAgw0EKT9xEOJa6Q92WBhyE9A4VRGENctiJY_jHFaxNLECQgBIFRBXIRwDQUKT_Eew3x3Q/s1600/Fig+4.23.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="83" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9SUYPiineWsss2yCjy1hfA4zhaiSITvqumagPIoxNCbA3zHtt4Tl013AWCB2ga7S-e7u-QvAgw0EKT9xEOJa6Q92WBhyE9A4VRGENctiJY_jHFaxNLECQgBIFRBXIRwDQUKT_Eew3x3Q/s200/Fig+4.23.gif" width="200" /></a></td></tr>
<tr style="font-family: Arial,Helvetica,sans-serif;"><td class="tr-caption" style="text-align: center;">Fig 4.23 (a,b and c)</td></tr>
</tbody></table><div class="MsoNormal"><b style="mso-bidi-font-weight: normal;"><u><span style="color: #006600; font-family: Tahoma; font-size: 12.0pt;">Balancing rotating parts</span></u></b><b><span style="font-family: "Helvetica\, sans-serif";"> <br />
</span></b><span style="font-size: small;"><span style="font-family: Arial;">Figure 4.23 shows, simply, how rotating parts such as a crankshaft are affected by centrifugal force. <br />
Figure 4.23(a) shows a section through a shaft that is in balance. Centrifugal force will act on the shaft when it rotates but, because it has no heavy spots, there will be no noticeable effect. <br />
Figure 4.23(b) has a mass added to the shaft and so an unbalanced condition has been created. Centrifugal force will pull the mass outwards as the shaft rotates. Centrifugal force will increase rapidly as the speed of rotation is increased. This is the effect produced by the crank-pins of a crankshaft.</span></span> </div><span style="font-size: small;"> </span><div class="MsoNormal"><span style="font-size: small;"><span style="font-family: Arial;">Figure 4.23(c) has a balance mass added. This is equal to, and directly opposite, the other mass. The centrifugal force from both masses will now balance and will not be noticeable. This is the effect achieved by having balance weights on a crankshaft.</span></span></div><br />
<br />
<div style="text-align: center;"><span style="font-size: small;"><span style="font-family: Arial;"><span style="font-family: "Courier New",Courier,monospace;">Continued</span> </span></span></div><div style="text-align: right;"><span style="font-family: "Courier New",Courier,monospace; font-size: small;">See Balancing of power impulses</span><span style="font-family: "Times New Roman"; font-size: 10pt;"> </span></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-53277379765093900792011-06-03T04:52:00.003+05:002011-06-22T04:24:49.516+05:00Crankshaft bearings<div dir="ltr" style="text-align: left;" trbidi="on"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdysO6ffnA8Ok4hmL-7SWjvWkB1VkJKX0-ypsxMqHhL45Hr0KRcctTlhOJwQxxHwXPTjaHX2oVA2vTrgmQstJACvPKFVjITwUAQBwgtaESpLEMnwbeFq-ROen3fdCDlrJ638ZtvsbONl8/s1600/pict15.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdysO6ffnA8Ok4hmL-7SWjvWkB1VkJKX0-ypsxMqHhL45Hr0KRcctTlhOJwQxxHwXPTjaHX2oVA2vTrgmQstJACvPKFVjITwUAQBwgtaESpLEMnwbeFq-ROen3fdCDlrJ638ZtvsbONl8/s320/pict15.jpg" width="280" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.16</span></td></tr>
</tbody></table><div style="text-align: justify;"><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> </span></b><span style="font-family: Arial;">Figure 4.16 shows a crankshaft and its related parts, including the crankshaft bearings. There are two sets of these: the</span> <i><span style="color: #993300; font-family: Georgia;">main bearings</span></i><i><span style="font-size: 11pt;">, </span></i><span style="font-family: Arial;">which support the crankshaft in the crankcase, and the</span> <i><span style="color: #993300; font-family: Georgia;">connecting-rod hearings</span></i><i><span style="font-family: Arial;">, </span></i><span style="font-family: Arial;">which are located between the connecting rod and the crank-pin journal.</span> </div><div style="text-align: justify;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: small;">Figure 4.16 Crankshaft for a four-cylinder diesel engine and its associated parts <b><br />
</b>1—3 piston rings, 4 piston, 5 piston pin, 6 circlip, 7 bush, B bearing, 9 connecting rod, 10 flywheel, 11 retainer, 12 pilot bearing, 13 pulley bolt, 14 crankshaft pulley, 15 oil deflector, 16 wave washer, 17 friction gear, 18 crankshaft gear, 19 crankshaft, 20 thrust bearing. 21 main bearing, 22 main-bearing cap, 23 rear oil seal, 24 gasket, 25 retainer</span><span style="font-family: Arial;"> </span></div><div style="text-align: justify;"><span style="font-family: Arial;">The crankshaft main bearings and the connecting- rod bearings are of the split-sleeve type, which means that they are in two halves. They cannot be used on their own and must be inserted into a housing of some kind that has been accurately machined to suit them. <br />
With main bearings, the upper half of the bearing fits into a machined section of a crankcase web, and the lower half is carried in the bearing cap, which bolts onto the crankcase web (Figure 4.17). <br />
With connecting-rod bearings, the upper half of the bearing is carried in the big end of the connecting rod, and the lower half is carried in the connecting-rod cap.</span> </div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><span style="font-family: Arial;">One of the main bearings is provided with thrust faces to accept end movement of the crankshaft. Thrust faces are either built into the bearings or provided as separate segments. These are faced with bearing material and located at each side of one of the main bearings (see illustrations in the upcoming posts).</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFu3CP8_3HgzdgNy0ZoXW4DlQgSV5nwCG94-R7JxWhS1IKKI4i-LSYz6IOof6F4CjFqXZ4KJ4lyI9aPBpO1ChkjOpKzd5LsbvMoplaH_MDkYB6JDlnpv9E9aAuaNxfaTdchbIoTSj-lgE/s1600/pict16.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFu3CP8_3HgzdgNy0ZoXW4DlQgSV5nwCG94-R7JxWhS1IKKI4i-LSYz6IOof6F4CjFqXZ4KJ4lyI9aPBpO1ChkjOpKzd5LsbvMoplaH_MDkYB6JDlnpv9E9aAuaNxfaTdchbIoTSj-lgE/s320/pict16.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.17</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div class="MsoNormal" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Precision-insert bearings</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b></div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">The precision inserts used for crankshaft bearings consist of a steel back to which a thin layer of bearing material is bonded. In some bearings, more than one layer of bearing material is used. Replacement bearings are accurately finished to size and are installed directly into their housings without any fitting or adjustment</span>. </div><div class="MsoNormal" style="text-align: justify;"><span style="font-family: Arial;">A bearing insert is shown in Figure 4.18, with its web parts identified. An oil hole is located in the centre of the bearing. For a main bearing, the oil hole lines up with an oil drilling in the crankcase web, and for a connecting-rod bearing, the oil hole lines up with a hole in the crank-pin journal.</span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 0px; margin-right: 0px; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMh-Cexl-2XOSKDNOyTuwf6L8Bw-IYJtlYOst9kUbLuwrleCbSrEXtA-q-0tP7FXDuoVCxywLmdCKySpedR0ixIysdHztBiYrAdYBnVvlqKORZpS5Pa19dGCvzRn1f0OtDhjnPxhKA2OI/s1600/pict17.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMh-Cexl-2XOSKDNOyTuwf6L8Bw-IYJtlYOst9kUbLuwrleCbSrEXtA-q-0tP7FXDuoVCxywLmdCKySpedR0ixIysdHztBiYrAdYBnVvlqKORZpS5Pa19dGCvzRn1f0OtDhjnPxhKA2OI/s320/pict17.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.18</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Some main bearings have an annular oil groove as shown, others are plain. The bearing insert is prevented from rotating by a locating tang that fits into a slot in the bearing housing or cap.</span><span style="font-size: 11pt;"> </span></div><div class="MsoNormal" style="text-align: justify;"><span style="font-size: 11pt;"> <br />
</span></div><div class="MsoNormal" style="margin-left: 15pt; text-align: justify; text-indent: -15pt;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">Crankshaft and connecting rod bearings are usually referred to as </span></i><span style="font-family: Georgia;">inserts</span><i><span style="color: #993300; font-family: Georgia;">, but they are also called </span></i><span style="font-family: Georgia;">slippers<i><span style="color: #993300;"> or</span></i></span><i><span style="font-size: 11pt;"> </span></i><span style="font-family: Georgia;">shells</span><span style="font-size: 11pt;">.</span></div><div class="MsoNormal" style="text-align: justify;"><br />
</div><div style="margin-bottom: 12pt; text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Bearing requirements</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Apart from reducing friction and wear, crankshaft bearings have a number of different requirements, as noted under the headings that follow.</span><span style="font-size: 11pt;"> <br />
</span><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Load-carrying capacity</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">The bearing must be of sufficient size to carry the loads imposed on it. It must also be made of a suitable material so that it will sustain the loads under various conditions of engine operation. <br />
The bearing material must be hard enough to resist wear. At the same time, it must be relatively soft so that it does not damage or wear the shaft on which it operates. A very hard bearing could seize on its shaft if it was heavily loaded. </span><b><i><span style="font-size: 11pt;"><br />
<br />
</span></i></b></div><div style="margin-bottom: 12pt; text-align: justify;"><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Fatigue resistance</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">Crankshaft bearings are subjected to varying loads and are repeatedly stressed. The bearing material must be able to resist this without failure from fatigue. Where unusual conditions exist, or after a long period of service, fatigue failure can occur. <br />
Fatigue occurs when a piece of metal is repeatedly stressed, causing it to flex or bend. The continual bending tends to harden the metal, which ultimately breaks. This is called</span><span style="font-size: 11pt;"> </span><i><span style="color: #993300; font-family: Georgia;">a fatigue failure</span></i><i><span style="font-size: 11pt;">. <br />
</span></i></div><div style="margin: 0in 0in 12pt 20pt; text-align: justify; text-indent: -20pt;"><span style="color: #993300; font-family: Symbol; font-size: 11pt;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">The everyday meaning of fatigue is tiredness and this, simply, also applies to metal fatigue. <br />
<br />
</span></i></div><div style="text-align: justify;"><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Embeddability</span></i></b><i><span style="font-size: 11pt;"> <br />
</span></i><span style="font-family: Arial;">This term refers to the ability of a bearing to permit small foreign particles to become embedded in it. This is a way in which the bearing can protect itself. <br />
Precision-insert bearings, with their thin layers of alloy material, have very little embeddability and depend on good filtration and a flow of oil to flush away any dust particles that might reach the bearing.</span><span style="font-size: 11pt;"> </span><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Conformability</span></i></b><b><i><span style="font-size: 11pt;"><br />
</span></i></b><span style="font-family: Arial;">This refers to the ability of a bearing to conform to small variations in shaft alignment and journal shape. </span></div><div style="text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial;">If a bearing material has high conformability, it will cold-flow slightly to relieve the load on local areas that are heavily loaded. This is very limited for precision-insert bearings</span></span><span style="font-family: "Times New Roman"; font-size: 11pt;"><span style="font-size: small;">. </span></span></div><div style="text-align: justify;"><span style="font-family: "Times New Roman"; font-size: 11pt;"> </span><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Corrosion resistance</span><span style="font-family: "Times New Roman"; font-size: 11pt;"> </span></i></b></div><div style="text-align: justify;"><b><i><span style="font-family: "Times New Roman"; font-size: 11pt;"> </span></i></b><span style="font-size: small;"><span style="font-family: Arial;">Bearing materials must be resistant to corrosion because some of the by-products of combustion can form corrosive substances. These could affect the bearing material. </span></span></div><div style="text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial;"> This is one of the reasons why crankcases are provided with positive ventilation. The clean air being circulated through the crankcase removes corrosive gases.</span></span></div><div style="text-align: justify;"><br />
</div><br />
<div style="text-align: justify;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYYTh1at7HCljue1sVVNeiS_I6BpsIfUZVNjDBfjaNpnVsHLXXHrRvvCfCizJpjYAXhwTiedDG4V7uyaB797Qg4uo3vYPTKjbjmQq-SNW2TNl-LUCkCyYoHghWVImmYQOYzhfJ0QV1xyU/s1600/pict18.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Bearing materials</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">Insert bearings have a steel back and arc lined with alloys which include copper, lead, tin, aluminium, antimony and cadmium. There are many combinations. These alloys generally have limited <i><span style="color: #990000; font-family: Georgia,"Times New Roman",serif;">conformability</span> </i>and </span><i><span style="color: #993300; font-family: Georgia;">embeddability</span></i><i><span style="font-family: Arial;">, </span></i><span style="font-family: Arial;">and depend on finely ground journals and a good flow of oil to wash away any foreign particles that might reach the bearing. <br />
Engine bearings are overlay-type bearings. A typical bearing of this type has a thin, flexible steel back, with a 0.05 mm layer of alloy and another layer of 0.02 mm of softer material. Some bearings have an extra overlay of thin plating. </span><b><span style="font-family: "Helvetica, sans-serif";"><br />
</span></b><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Bearing clearances</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">A working clearance is provided between the bearing and the crankshaft journal (Figure 4. 1 9). </span></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYYTh1at7HCljue1sVVNeiS_I6BpsIfUZVNjDBfjaNpnVsHLXXHrRvvCfCizJpjYAXhwTiedDG4V7uyaB797Qg4uo3vYPTKjbjmQq-SNW2TNl-LUCkCyYoHghWVImmYQOYzhfJ0QV1xyU/s1600/pict18.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYYTh1at7HCljue1sVVNeiS_I6BpsIfUZVNjDBfjaNpnVsHLXXHrRvvCfCizJpjYAXhwTiedDG4V7uyaB797Qg4uo3vYPTKjbjmQq-SNW2TNl-LUCkCyYoHghWVImmYQOYzhfJ0QV1xyU/s320/pict18.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.19</span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">This varies <br />
with the type of bearing material, but 0.02 mm to 0.08 mm is a typical specification.</span><br />
<span style="font-family: Arial;"> Too little clearance will not allow adequate lubrication and will cause, rapid wear, bearing failure </span><span style="font-family: Arial;">and shaft damage on the design of the oil pan and the main bearing. Too much clearance can cause loss of oil and low oil pressure. Also, there will be a lot of oil thrown from the bearings and onto the cylinder walls. The piston rings will find this hard to control, and oil will find its way up past the piston into the combustion chamber where it will burn to form carbon and cause other problems.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8DfH2Mdy12r1C8lNmZrNPDeceXaiTrN0B6mkrK9OpuNoDxFD6SmiMfBsboBtUSMgwp0MiE13TM5Hd3faPo2GTdyuwLhALaon7QOHIZCXoCiNvUXB4DwdO93zgTvCWVLDZlrPOSlOxMj4/s1600/pict19.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8DfH2Mdy12r1C8lNmZrNPDeceXaiTrN0B6mkrK9OpuNoDxFD6SmiMfBsboBtUSMgwp0MiE13TM5Hd3faPo2GTdyuwLhALaon7QOHIZCXoCiNvUXB4DwdO93zgTvCWVLDZlrPOSlOxMj4/s320/pict19.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.20</span></td></tr>
</tbody></table><div class="NormalLatinArial" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Bearing Lubrication</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-size: small;"><span style="font-family: Arial,Helvetica,sans-serif;">Engine bearings must be given adequate lubrication. The lubricant reduces friction, removes heat and reduces noise. </span><br style="font-family: Arial,Helvetica,sans-serif;" /> <span style="font-family: Arial,Helvetica,sans-serif;"> The flow of lubricant to the crankshaft and bearings is shown in Figure 4.20. Oil from the oil pan is circulated by the oil pump at the front of the crankcase. It passes through the oil filter, along the main oil gallery and then down through drillings in the crankcase webs to the main bearings. </span></span><br />
<span style="font-size: small;"> <span style="font-family: Arial,Helvetica,sans-serif;"> The connecting-rod bearings are lubricated from the main bearings through holes drilled in the crankshaft webs. Oil thrown from the connecting-rod bearings helps to lubricate the pistons, the cylinder walls and other engine parts.</span></span></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="font-family: Arial,Helvetica,sans-serif; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: x-small;">See </span><span style="color: black; font-family: Arial,Helvetica,sans-serif; font-size: x-small;">Cylinder block and crankcase design>>>>>>></span><span style="font-family: "Times New Roman"; font-size: 11pt;"> </span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0Islamabad, Pakistan33.718151 73.06054700000004233.639677 72.938652500000046 33.796625 73.182441500000039tag:blogger.com,1999:blog-761095749605083867.post-3705224524569259492011-06-02T04:18:00.002+05:002011-06-22T04:25:19.409+05:00Balance wieghts (for crankshafts)<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdCfj2NkwgCttY31JUwNj8Oixitb5orVBRqgsXR-yo1FTGotJB5v3GF59RrzPkph0iaXn3odHLq363yK9u9Xu1yHEijUGqQC4ggBjSdElpgpSgit3cLBHu5sNYMkzFM22XFI1qT7jnzVI/s1600/pict10.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="116" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdCfj2NkwgCttY31JUwNj8Oixitb5orVBRqgsXR-yo1FTGotJB5v3GF59RrzPkph0iaXn3odHLq363yK9u9Xu1yHEijUGqQC4ggBjSdElpgpSgit3cLBHu5sNYMkzFM22XFI1qT7jnzVI/s200/pict10.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.12 (a)</span></td></tr>
</tbody></table><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;"></span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> </span></b><span style="font-family: Arial;">In automotive engines, which operate at high speeds, centrifugal force is produced by the rotating crank-pins. In a four-cylinder crankshaft, balance weights are placed on the crankshaft opposite the crank-pins. Centrifugal force also acts on the balance weights, but in an opposite direction to that on the crank-pins. The forces tend to cancel out, so that vibration is reduced. </span><br />
<span style="font-family: Arial;"> A four-cylinder in-line engine operating at low speeds would need very little balance, because No. 1 cylinder is balanced by No. 2 cylinder, and No. 3 is balanced by No. 4. However, for a shaft operating at high speeds, separate balance weights are used for each crank-pin. This contains the forces within the parts of the crankshaft in which they are</span> <span style="font-family: Arial;">produced</span>. </div><div></div><div style="text-align: justify;"><br />
</div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgy263De66GzdsNR1Bv9QBiezhbP24q7e6Ks0UgkcXq9xDUX_kCVmVYNwyzXXtmKW5n1CQeoONn97kJusjYkF_H-7Z2pykLefN9bbU5lzhFu9d2B7LF5QIgnNnQVH2pFMZOAZf_nop4oHo/s1600/pict11.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgy263De66GzdsNR1Bv9QBiezhbP24q7e6Ks0UgkcXq9xDUX_kCVmVYNwyzXXtmKW5n1CQeoONn97kJusjYkF_H-7Z2pykLefN9bbU5lzhFu9d2B7LF5QIgnNnQVH2pFMZOAZf_nop4oHo/s200/pict11.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.12 (b)</span></td></tr>
</tbody></table><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Crankshaft designs</span></u></b><b><span style="font-family: "Helvetica, sans-serif";"> <br />
</span></b><span style="font-family: Arial;">The crankshafts of six-cylinder engines require more complex balance weights, and V-type engines have balance weights arranged differently again. Figure 4.12(a) shows a crankshaft for a V-6 engine which has its cylinders arranged at an angle of 90<b><sup>˚</sup>. </b>Also shown are its camshaft and balance shaft. <br />
Many V-type engines have the connecting rods of opposite cylinders connected side by side to a common journal but, in this engine, each connecting rod has its own journal. The crank-pin journals for opposite cylinders are on the same throw of the crankshaft, but they are offset at an angle of 30° to each other (Figure 4.12(b) This is done so that firing order of the cylinders can be evenly spaced exactly at each 120° of crankshaft rotation. <br />
Some crankshafts are solid, but others have hollow crank-pins. This reduces their mass and so reduces the effects of centrifugal force. This helps with shaft balance.</span> <br />
<br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 15pt; text-align: justify; text-indent: -15pt;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">Hollow crank-pins do not affect the strength of the shaft because, in ass for mass, a hollow shaft has greater strength than a solid one.</span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgubRMPpQFeVc-qHAULwk2yyZdyhu2TkxON5zugFqDSJoaugTtgwFVl-WNyr0ImgvwmZ9eP4syvQ5Anc7w69Zpf-VBfXQLwJHxeH8i6SI3_aLCfUex558LInNw5y2iCEmNt_wB3PrhXsBM/s1600/pict12.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgubRMPpQFeVc-qHAULwk2yyZdyhu2TkxON5zugFqDSJoaugTtgwFVl-WNyr0ImgvwmZ9eP4syvQ5Anc7w69Zpf-VBfXQLwJHxeH8i6SI3_aLCfUex558LInNw5y2iCEmNt_wB3PrhXsBM/s200/pict12.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.13 </span></td></tr>
</tbody></table><div style="text-align: justify;"><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Journal overlap</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">A rigid crankshaft that will resist twisting and bending needs large journal diameters and thick webs. These two requirements have been combined in a design feature known</span> <i><span style="color: #993300; font-family: Georgia;">as journal overlap</span>. <br />
</i><span style="font-family: Arial;">With this design, the crank-pins overlap the main journals as shown in Figure 4.13. This makes the crankshaft more rigid. If necessary, the web thickness can be decreased to reduce the overall length of the shaft while maintaining rigidity. Compare Figure 4.13 with Figure 4.14 which has no overlap.</span><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;"></span></i></b></div><div style="text-align: justify;"></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq5b-M_cvhgRhyMaJqYtkdV98ow4P6I1BBCw_JLN2LiY6mHor9HzjRfc4M2aF7v6ZkJOwm334mVK_uJqlajml4GMJb4kW05smWqBpKsmr7GYfZ1uclKAy0nq7wpSQQVEELkAtwxNRLBfI/s1600/pict14.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="157" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq5b-M_cvhgRhyMaJqYtkdV98ow4P6I1BBCw_JLN2LiY6mHor9HzjRfc4M2aF7v6ZkJOwm334mVK_uJqlajml4GMJb4kW05smWqBpKsmr7GYfZ1uclKAy0nq7wpSQQVEELkAtwxNRLBfI/s200/pict14.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.14 </span></td></tr>
</tbody></table><div style="text-align: justify;"><b><i><span style="color: #993300; font-family: Georgia; font-size: 12pt;">Crankshaft fillets</span></i></b><b><i><span style="font-size: 11pt;"> <br />
</span></i></b><span style="font-family: Arial;">A radius, or fillet, is formed between the edges of the journal and the webs of the crankshaft. These fillets, although small, are quite important because they provide a gradual change in the thickness of the section (Figure 4.14). </span></div><div style="text-align: justify;"></div><div style="margin-bottom: 12pt; text-align: justify;"><span style="font-family: Arial;">With no fillet, this section of the crankshaft will be subjected to a</span> <i><span style="color: #993300; font-family: Georgia;">stress rise</span></i><span style="color: #993300; font-family: Arial;">,</span><i> </i><span style="font-family: Arial;">which means that it will carry a greater load (and greater stress) than the section next to it. Stress could cause fatigue and a crack could start at this point.</span> <br />
<br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 15pt; text-align: justify; text-indent: -15pt;"><span style="color: #993300; font-family: Symbol; font-size: 11pt;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;"> A crankshaft that is badly ground during reconditioning could fail because of badly shaped fillets.</span></i><i><span style="font-size: 11pt;"> <br />
<br />
</span></i></div><div style="text-align: justify;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC6AN10XQtMSJYkphfwnkJH6vQs1c5QbGR9gLDROzvlykcx_uYFPdaJrOM-W99Lp_JHSE-qd0XCWnIfodBwZO0nvAdJyU6-cPQE9SBMceOGPc8k1H1PJKLCATfvpeb1FmA0TBwAls23hw/s1600/pict13.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="106" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC6AN10XQtMSJYkphfwnkJH6vQs1c5QbGR9gLDROzvlykcx_uYFPdaJrOM-W99Lp_JHSE-qd0XCWnIfodBwZO0nvAdJyU6-cPQE9SBMceOGPc8k1H1PJKLCATfvpeb1FmA0TBwAls23hw/s200/pict13.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.15 </span></td></tr>
</tbody></table><div style="text-align: justify;"><span style="font-family: Arial;">Figure 4.15 shows a journal with rolled fillets. This design feature is used to reduce local stress points between the journals and the webs. The crankshaft also has journal overlap, so it would not be subjected to the stress rise of a crankshaft without overlap. </span></div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;"><br />
</div><div style="text-align: center;"><span style="font-family: Arial;">Continued</span></div><div style="text-align: right;"><span style="font-family: Arial;">See c</span><span style="font-family: Arial;"></span><span style="font-family: Arial;">rankshaft bearings>>>>>>>>>>>>>></span></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0tag:blogger.com,1999:blog-761095749605083867.post-73848467313688774872011-06-01T03:42:00.033+05:002011-06-22T04:27:45.802+05:00Cylinder surface-finish & Crankshafts<div dir="ltr" style="text-align: left;" trbidi="on"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeXwbmCf5TPZAsRZ0RRf_33iyL0jvr2LmMkpRkMtPpcceuFInPc1RPPxtVMj-hW3AuIG4I77J54RQXbE_7DJh6wkP8_qgPI3Vv2AZNxkeKffxHHlrEMQWVToGzEhgJm132LgdkCaW7400/s1600/pict7.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="161" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeXwbmCf5TPZAsRZ0RRf_33iyL0jvr2LmMkpRkMtPpcceuFInPc1RPPxtVMj-hW3AuIG4I77J54RQXbE_7DJh6wkP8_qgPI3Vv2AZNxkeKffxHHlrEMQWVToGzEhgJm132LgdkCaW7400/s200/pict7.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.8</span></td></tr>
</tbody></table><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;"></span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"><span id="goog_1204729289"></span><span id="goog_1204729290"></span> </span></b><span style="font-size: small;"><span style="font-family: Arial,Helvetica,sans-serif;">The surface of the cylinder consists of fine scratches that form a cross-hatch pattern (Figure 4.8). This finish is produced with a hone that uses abrasive stones. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> Cylinder walls must be smooth enough to enable the piston rings to seal and for the pistons to operate without friction. At the same time, they must have a surface that is able to retain a film of oil. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> If the surface of the cylinder (the cylinder wall) is too smooth, oil will be wiped from the cylinder by the piston rings. Oil can also be ‘pumped’ upwards by the pistons and rings into the combustion chamber where it will burn. This will produce smoke and carbon. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> The ideal finish for a cylinder is a series of plateaus, or very small flat surfaces between the fine grooves that are left after honing. The grooves in the surface retain oil. </span><br style="font-family: Arial,Helvetica,sans-serif;" /><span style="font-family: Arial,Helvetica,sans-serif;"> A surface with sharp peaks and grooves will also retain oil, but the peaks will have to wear away to allow the piston rings to ‘bed in’ before a satisfactory working surface is obtained. During this time, there could be some </span><i style="font-family: Arial,Helvetica,sans-serif;"><span style="color: #993300;">blowby</span> </i><span style="font-family: Arial,Helvetica,sans-serif;">and the engine could use oil. </span></span><br />
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</div><div></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><i><span style="color: #993300; font-family: Georgia;">• The term </span></i><span style="font-family: Arial,Helvetica,sans-serif;">blowby</span><i><span style="color: #993300; font-family: Georgia;"> refers to combustion gases that escape past the piston rings.</span></i></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 12pt;">Cylinder wear </span></u></b></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifssshO7lX809MsdU2k8xSQ_7D8X0JchreOibkjEGiRV1qkIQXPeSNFsKCGdPTT76Dnqtughr2R5oaz_iMxTNhZMY1vmukUWlJCr4ydMtSQ-7-Zpubo0hAodI99yfKHthJENZQ8AZg4XU/s1600/pict27.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifssshO7lX809MsdU2k8xSQ_7D8X0JchreOibkjEGiRV1qkIQXPeSNFsKCGdPTT76Dnqtughr2R5oaz_iMxTNhZMY1vmukUWlJCr4ydMtSQ-7-Zpubo0hAodI99yfKHthJENZQ8AZg4XU/s200/pict27.jpg" width="157" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.9</span></td></tr>
</tbody></table><span style="font-size: small;">Figure 4.9 shows, how an engine cylinder wears (the wear is shown exaggerated). Most wear takes place at the top of the cylinder and so the cylinder becomes tapered. The maximum wear is at the top, just below the ring ridge. This is where combustion pressure and temperature are greatest. As the piston moves down the cylinder on the power stroke, the pressure and temperature both decrease so that less wear takes place. <br />
The cylinder also tends to wear oval-shaped. This is due to the side thrust of the piston as it moves down the cylinder on the power stroke. The side thrust is caused by the angle of the connecting rod </span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;"><span style="font-size: small;"><br />
Another possible cause of wear, with carburettor engines, is the washing action of the fuel. If the air and fuel are not correctly mixed, small droplets of fuel tend to wash the oil film from the cylinder walls. This does not occur with EFI engines.</span></div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="font-family: Arial,Helvetica,sans-serif; text-align: justify;"><br />
</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="text-align: justify;"><span style="font-size: small;"><span style="font-family: Arial,Helvetica,sans-serif;">Worn cylinders can be reconditioned to a certain extent by honing, but badly worn cylinders have to be </span><i style="font-family: Arial,Helvetica,sans-serif;"><span style="color: #993300;">re-bored</span>. </i><span style="font-family: Arial,Helvetica,sans-serif;">The worn cylinder shown could be bored oversize to the diameter A, or bored out to diameter B and a dry sleeve fitted. </span></span><br />
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</div><div style="text-align: justify;"></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><span style="color: #993300; font-family: Symbol;">·<span style="font: 7pt "Times New Roman";"> </span></span><i><span style="color: #993300; font-family: Georgia;">The ring ridges at the top and bottom of the cylinder are caused by the limits of the</span></i></div><div class="NormalLatinArial" style="margin-left: 0.5in; text-align: justify; text-indent: -0.5in;"><i><span style="color: #993300; font-family: Georgia;"> piston-ring travel.</span></i></div><div style="text-align: justify;"></div><div style="text-align: justify;"><b><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;"><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbY1YwOrHwm3MVCohhYpet7sW2f3KyQSeCK7jku5lnQXhwhj9ci2Mmbpyww5emp1VaskHUGFsbINLdQQe9be_p_6bRNFzRyvu3kcb6B_YqibbKUKt5QKtFavCQ9PgYLOrztNeDqoJ4Fm0/s1600/pict28.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="104" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbY1YwOrHwm3MVCohhYpet7sW2f3KyQSeCK7jku5lnQXhwhj9ci2Mmbpyww5emp1VaskHUGFsbINLdQQe9be_p_6bRNFzRyvu3kcb6B_YqibbKUKt5QKtFavCQ9PgYLOrztNeDqoJ4Fm0/s320/pict28.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.10</span></td></tr>
</tbody></table><b><u><span style="color: #006600; font-family: Tahoma; font-size: 18pt;">Crankshafts</span></u></b><b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> </span></b><br />
<b><span style="font-family: "Helvetica, sans-serif"; font-size: 17pt;"> </span></b><span style="font-family: Arial;">Figure 4.10 shows a basic crankshaft with its parts named. This is for a four-cylinder engine, so it has four cranks. Each crank, also called a throw, consists of a crank web and a journal (crank-pin) that has a finely- finished surface for the connecting-rod bearing. This crankshaft is supported in the crankcase by three main bearings and so is referred to as a</span> <i><span style="color: #993300; font-family: Georgia;">three-bearing</span> </i><span style="font-family: Arial,Helvetica,sans-serif;">crankshaft</span>. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCMH8cPh43huO7eyFG-83zE4-Ght6jPELzL5ufInUG6HC1QSbZQ0ocazC9U_orctBN6zC1kAKjDuO3jPjBUCqEqNgoEsJyHyBToppadyLD22Fbk-AwzuAgaMTLXSR7PqKXFu4UV61PPKA/s1600/pict8.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="168" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCMH8cPh43huO7eyFG-83zE4-Ght6jPELzL5ufInUG6HC1QSbZQ0ocazC9U_orctBN6zC1kAKjDuO3jPjBUCqEqNgoEsJyHyBToppadyLD22Fbk-AwzuAgaMTLXSR7PqKXFu4UV61PPKA/s320/pict8.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: cyan; font-family: Arial,Helvetica,sans-serif;">Fig 4.11</span></td></tr>
</tbody></table><span style="font-family: Arial,Helvetica,sans-serif;">The type of crankshaft normally used is shown in Figure 4.11. This is a five-bearing crankshaft, with a main bearing located between each crank. It also has</span> <span style="font-family: Arial;">balance weights. The extra main bearings reduce shaft distortion, and the balance weights reduce vibration. </span><br />
<span style="font-family: Arial;"> Crankshafts are a one-piece casting or forging of heat-treated alloy steel with high mechanical strength. The crankshaft must be strong enough to take the downward thrusts of the pistons during the power strokes without distortion, as well as being well balanced to offset the effects of the cranks.</span><br />
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</div><div style="font-family: Arial,Helvetica,sans-serif; margin-bottom: 0.0001pt;"><span style="font-size: small;"><span style="color: purple;">Parts label Figure 4.11 Crankshaft for a four-cylinder engine</span><b style="color: purple;"> <br />
</b><span style="color: purple;">1—5 main-bearing journals, 6—9 crank-pin </span><br style="color: purple;" /><span style="color: purple;"> journals, 10—12 balance weights, 13 mounting flange for flywheel or drive plate.</span></span><br />
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<div style="color: black; text-align: center;"><span style="font-size: x-small;">Continued</span></div><div style="color: black; text-align: right;"><span style="font-size: x-small;">See balance weights (for crankshafts)>>> </span></div><span style="font-size: small;"> </span></div></div></div>Pirmudassirhttp://www.blogger.com/profile/09237118055071602721noreply@blogger.com0