1 CLUTCH 2C. OPERATING CONDITIONS Vehicles operating on shorter runs, city operations, off highway and operations in hilly terrains are obviously subjected to more number of clutch operations and thereby higher clutch wear. 3. PRELIMINARY INSPECTION OF CLUTCH Clutch needs replacement mainly on account of clutch slippage or imperfect engagement and disengagement. This may be due to worn out / damaged clutch parts. It is desirable to carry out the following preliminary checks before removal of the clutch for replacement of the parts. 3A. CLUTCH SLIPPAGE TEST Clutch slippage can be confirmed by any of the following twomethods : a) Drive the vehicle in 1st or 2nd gear at maximumspeed corresponding to that gear. With accelerator pedal fully pressed, apply brake graduallywith your left foot. If the engine stalls, it means that clutch does not slip. b) Drive loaded vehicle in 3rdgear on level ground and let the speed drop down to approximately 15 kmph / 9 mph. Now press accelerator pedal fully.With slipping clutch, the vehicle speed will not pick up and also clutch burning smell will be noticed. If this does not occur and vehicle picks up speed, it indicates that clutch does not slip. 3B. CLUTCH ENGAGEMENT AND DISENGAGEMENT TEST During the above test, when vehicle is in motion, depress clutch pedal fully without changing the accelerator pedal position. If the engine speed increases immediately,perfect clutchdisengagement is indicated.Further,release theclutchpedal suddenly. If the vehiclemoves forwardwith a little jerk, perfect clutch engagement is indicated. Caution This test should be carried out with utmost care because sudden release of the clutch might cause heavy jerk and damage to the clutch lining. 1. CONSTRUCTIONAL DETAILS Clutch is the mechanism interposed between engine and the gear box which enables engine power as well as torque of the engine to be transmitted at will to the gear box through friction drive. When clutch pedal is depressed the clutch is disengaged therefore motion and power flow from engine to gear box and hence to road wheels is disconnected. It is a single disc dry friction type clutch having 240 mm dia. clutch disc. Clutch pressure plate assembly is diaphragm spring type. Clutch release actuation is by clutch release bearing assembled with fork and guided on the drive shaft cover of the gear box. 2. FACTORS AFFECTING CLUTCH WEAR The clutch is designed to give maximum life under most severe conditions when handled carefully. However, while in operation, clutch lining is subjected to wear. Apart from this the extent of wear also depends on following. 2A. PROPER MAINTENANCE Maintenance of clutch includes adjustment of pedal stopper bolt, checking oil level and bleeding the system for defect free operation of clutch actuation mechanism and periodic lubrication. 2B. DRIVING Following driving conditions will affect the performance of the clutch. i. Clutch riding Using clutch pedal as a foot rest by keeping foot constantly on pedal while driving will cause partial clutch disengagement. It will result in slipping of the clutch disc and premature failure of the clutch. ii. Permitting the clutch to slip too long Half clutch driving and thereby permitting the clutch purposely to slip too long will have the same result as above. iii. Permitting the clutch to jerk Sudden clutch engagement at higher engine speed specially while moving out the stuck vehicle will cause severe instantaneous clutch loading, resulting in clutch slippage and burning of the lining locally. Starting the vehicle in first gear under such conditions will avoid such problem. Always start vehicle in first gear.
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