1) The driving members consist of a flywheel mounted on the engine crankshaft. The fly wheel is bolted to a cover which carries a pressure plate or driving disc, pressure springs and releasing levers. Thus the entire assembly of the flywheel and the cover rotate all the times. The clutch housing and the cover provided with openings dissipate the heat generated by the friction during the clutch operation.
2 ) The driven membersconsists of a disc or plate, called the clutch plate. It is free to slide lengthwise on the splines of the clutch shaft. It carries friction materials on both of its surface. When it is griped between the flywheel and the pressure plate, it rotates the clutch shaft through the splines.
3) The operating membersconsist of a foot pedal, linkage, release or throw-out bearing, release levers and the springs necessary to insure the proper operating of the clutch.
Single plate clutch:
It is the most common type of clutch used in motor vehicles. Basically, it consists of only one clutch plate, mounted on the splines of the clutch shaft. The fly wheel is mounted on the engine crankshaft and rotates with it. The pressure plate is bolted to the flywheel through clutch springs and is free to slide on the clutch shaft when the clutch pedal is operated. When the clutch is engaged the clutch plate is gripped between the flywheel and the pressure plate. The friction linings are on both the sides of the clutch plate. Due to the friction between the flywheel, clutch plate and pressure plate, the clutch plate revolves with the flywheel. As the clutch plate revolves, the clutch shaft also revolves.
Clutch shaft is connected to the transmission. Thus the engine power is transmitted to the crankshaft to the clutch shaft.
When the clutch pedal is pressed, the pressure plate moves back against the force of the springs and the clutch plate becomes free between the flywheel and the pressure plate. Thus, the flywheel remains rotating as long as the engine is running and the clutch shaft speed reduces slowly and finally it stops rotating. As soon as the clutch pedal is pressed, the clutch is said to be disengaged, otherwise it remains engaged due to the spring forces.
Multiplate clutch consists of a number of clutch plates, instead of only one clutch plate as in the case of single plate clutch. As the number of clutch plates are increased, the friction surface also increase. The increased number of friction surfaces obviously increases the capacity of the clutch to transmit torque. The plates are alternately fitted to the engine shaft and the gear box shaft. They are firmly pressed by strong coil spring and assembled in a drum. Each of the alternate plate slides in grooves on the flywheel and the other slides on splines on the pressure plate. Thus, each alternate plate has inner and outer splines.
The multiple clutch works in the same way as the single plate clutch, by operating the clutch pedal. The multiplate clutches are used in heavy commercial vehicles, racing cars and motor cycles for transmitting high torque.
The multiple clutches may be dry or wet. When the clutch is operated in an oil bath, it is called a wet clutch. When the clutch is operated dry, it is called dry clutch. The wet clutch are generally used in conjunction with, or as a part of the automatic transmission.