Operation of the Clutch
Applying the Clutch Brake
The purpose of the clutch brake is to stop the transmission gears from rotating in order to engage the transmission gears quickly in making an initial start. To apply the clutch brake, put the transmission in neutral and press the clutch pedal to the floor.
Notice: Never apply the clutch brake while the vehicle is moving. The clutch pedal should never be pressed down fully before putting the transmission in neutral. Considerable heat will be generated, which will be detrimental to the friction discs, release bearings, and transmission front bearings.
Applying the clutch brake with the transmission still in gear puts a reverse load on the gear. At the same time, it will have the effect of trying to stop or decelerate the vehicle with the clutch brake. Rapid wear of friction discs will take place, necessitating frequent replacement.
Vehicle Overload, or Overloading the Clutch
Notice: Overloading will not only result in damage to the clutch, but also to the entire powertrain.
Clutches are designed for specific vehicle applications and loads. These limitations should not be exceeded.
Riding the Clutch Pedal
Riding the clutch pedal is destructive to the clutch. Partial clutch engagement permits slippage, and generates excessive heat. Riding the clutch pedal will also put a constant thrust load on the release bearing, which can thin out the lubricant. Release bearing failures can be attributed to this type of misuse.
Holding the Vehicle on an Incline With a Slipping Clutch
A slipping clutch accumulates heat faster than it can be dissipated, resulting in early clutch failures. Never use the clutch to hold a vehicle on a hill.
Coasting With the Clutch Released (pedal down) and the Transmission in Gear
Warning: Do not allow the vehicle to coast with the clutch released (pedal down) and the transmission in gear. If the clutch facing is thrown off the disc, flying debris could cause injury to persons in the vehicle.
If the transmission remains in a low gear and the vehicle gains speed, as may occur on a downgrade, the input shaft and clutch driven disc will turn at speeds that are higher than normal. This occurs because the rear wheels and the driveline become the input for the transmission, and a higher-than-normal speed for a given transmission gear translates to a higher rpm value for the clutch driven disc.
Clutch driven discs are designed to allow for some amount of excess rotational speed, but the facing has a limited burst strength. If the clutch driven disc rpm increases too much, the clutch facing can be thrown off the disc(s).
Engaging the Clutch While Coasting
Engaging the clutch while coasting can result in tremendous shock loads and possible damage to the clutch as well as to the entire drivetrain.
Report Erratic Clutch Operation Promptly
Reporting erratic clutch operation as soon as possible will give maintenance personnel a chance to inspect the clutch components.
Caution: Operating the vehicle with incorrect clutch pedal free-travel could result in clutch damage. See Group 25 of the S2 Chassis Workshop Manual for free-pedal adjustment procedures and specifications.
On mechanical clutch linkages, free-pedal travel should be included and commented on daily in the driver's report, since clutch free-pedal travel is the best guide to the condition of the clutch and the release mechanism.