Timing Belts - Cross & Morse - #49

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cop Cat ref_09.indd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:7.00pt "Arial", sans-serif; } .font1 { font:9.00pt "Arial", sans-serif; } .font2 { font:5.00pt "Lucida Sans Unicode", sans-serif; } .font3 { font:7.00pt "Lucida Sans Unicode", sans-serif; } .font4 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font5 { font:10.00pt "Lucida Sans Unicode", sans-serif; } .font6 { font:8.00pt "Palatino Linotype", serif; } .font7 { font:9.00pt "Palatino Linotype", serif; } .font8 { font:11.00pt "Palatino Linotype", serif; } .font9 { font:12.00pt "Palatino Linotype", serif; } .font10 { font:17.00pt "Palatino Linotype", serif; } .font11 { font:25.00pt "Palatino Linotype", serif; } .font12 { font:4.00pt "Tahoma", sans-serif; } .font13 { font:7.00pt "Tahoma", sans-serif; } Timing Belt Trouble Shooting Guide When a timing belt drive is correctly designed and installed - with proper considération given to design factors for service conditions - premature failure should not occur. If problems are encountered the table below may help identify the cause and suitable corrective action. In addition to problems shown less apparent causes of drive failure may exist, such as excessive reverse bending, sub-minimum diameter idler, etc; and for complete assurance in determining cause of failure and correct remedy it is always advisable to consult a drive specialist. Causes of Premature Belt Failure Mode of Failure Probable Causes Corrective Action Abnormal wear of the belt: a) on the side of the tooth b) on the bottom of the tooth c) at the tooth root d) on the side of the belt Belt excessively taut Excessive overloading Incorrect contour or diameter of pulley Excessive installation tension Incorrect diameter of pulley Incorrect contour or diameter of pulley Misalignment or wrong setting of pulleys Oscillation of the axes and/or the bearings Flanges bent Reduce centre distance Use a wider belt Replace pulley after checking Reduce centre distance Replace pulley after checking Replace pulley after checking Correct the positioning of the pulleys Reinforce the bearing mountings Replace flanges Failure through traction or through laceration of the teeth, indicating corrosion of the tension member Diameter of pulley too small Excessive moisture Acid or caustic atmosphere Increase the diameter of the pulleys or use belts and pulleys of smaller pitch Eliminate the moisture Refer to factory for special belt Shearing of belt teeth Number of teeth in mesh less than six Excessive load Increase the pulley diameters or use belts and pulleys of smaller pitch Use a higher capacity bel Rupture of tension member Excessive load Diameter of pulley below minimum Use a higher capacity belt Increase the diameter of the pulleys Breaks or cracks in the top surface of the belt Exposure to excessively low temperatures (below - 25°C) Eliminate low temperature Softening of the top surface of the belt Exposure to excessively high temperatures (over + 100°C) or oil contamination Eliminate the high temperature or reduce the amount of oil present Apparent elongation of the belt Reduction of centre distance due to bearings not being firmly fixed Restore the initial centre distance and strengthen the bearings Belt overriding the flanges Faulty installation of the flanges Misalignment of pulleys Reinstall the flanges properly Align pulleys Excessive wear of pulley teeth Excessive overloading Belt excessively taut Pulley material insufficiently hard Use a higher capacity drive Reduce the centre distance Harden the pulley surface Drive excessively noisy Pulleys out of line Excessive installation tension Excessive load Diameter of pulley below minimum Air trapped in belt Align pulleys Reduce the centre distance Use a higher capacity drive Increase the diameter of the pulleys Change to Metric Series belt drive o L X 1^ 9 J en a CD 3 O CI) en 3 o r en CD o o 3 47 4 INDEX 4 BACK NEXT ►