MANUAL CLUTCH

MANUAL CLUTCH

A clutch is required on a vehicle with a manually shifted transmission. The function of the cutch is to connect and disconnect from the transmission so that the driver can cornstarch the engine, shift the transmission into gear more easily, and allows the engine to run with the transmission in gear.

BASIC CLUTCH COMPONENTS AND OPERATION

The clutch is a mechanism that allows the driver to shift gears at different operating conditions. The operation requires connecting and disconnecting the engine from the power train. The clutch is, therefore, the unit that helps the driver to disconnect the engine from the power train when he pushes down the clutch pedal. As the driver slowly lifts his foot from the clutch pedal, the engine connects to the power train and the vehicle can move.

The clutch must engage gradually. It must not jump abruptly from no connection at all to a direct, solid connection. To move a vehicle the driver must speed up the engine to get enough power. The driver cannot in one moment bring the speed of the wheels up to the speed of the engine. 

Shifting gears in a moving car creates a similar situation; the wheels are not turning at the same speed as the engine. We require a mechanism that will allow the driver to gradually connect the engine to the power train so that the wheels can start to move slowly and gradually pick up speed, until finally the engine and the wheels are turning at the same rate and the clutch is solidly engaged.

The type of clutch used on most automobiles and light trucks is called a single

dry-disc clutch. The single dry-disc clutch comprises two driving members and one driven member. A strong spring or set of springs forces the two driving members together. This tightens their grip on the driven member and all will turn together as one unit.

The engine flywheel used as one of the driving members while the pressure plate is used as the other driving member. The face of the flywheel is machined very smooth where the driver member comes into contact. The pressure plate is a heavy ring of

Cast iron, smooth on one side. The pressure plate is fastened to the clutch cover, which is in turn bolted to the flywheel, so they all turn together as one member.

The driven plate is a flat disc of steel with friction material placed on each side. The disc is mounted onto splines on shaft going to the transmission named as transmission input shaft. The disc has a hole at the centre with internal splines, which allows the disc to slide on the input shaft. The pressure plate and the springs form what is known as the pressure plate assembly.

When the driver pushes down the clutch pedal, the pressure plate is forced to move away from the flywheel releasing the pressure from the clutch disc. At this instance the clutch disc will move away from the rotating flywheel. The engine no longer drives the clutch disc and the transmission input shaft, the clutch is in a disengaged position.

When the driver lifts his foot from the clutch pedal, a mechanism that allows the driver to actuate the pressure plate, the pressure plate assembly pushes the clutch disc against the flywheel. The disc is squeezed between the pressure plate and the flywheel forcing the cutch to turn with the flywheel and drive the transmission input shaft.