Operating Principle

Torque is transmitted from the engine to the transmission through the clutch. It works exclusively by friction, which can be visualized as follows: two contact surfaces are pressed firmly against a third and hold it so tightly that it is forced to rotate together with the two. The purpose of the design is that this connection can be disengaged at any time; otherwise, these two parts could just as well be bolted together. Let us name them: the flywheel and the pressure plate, loaded by spring force, are rigidly connected to the engine. The driven plate is clamped between them and is rigidly engaged by splines with the transmission input shaft.

The next important function is performed by the release bearing: when the clutch pedal is depressed, it is pressed against the pressure plate by the clutch actuating mechanism (see next section) and overcomes the force of the pressure plate spring. The driven plate is thereby released from its clamped position and can rotate freely between the pressure plate and the flywheel. Torque transmission between the engine and the transmission is interrupted.

When the clutch pedal is released again, the diaphragm spring of the pressure plate presses the driven plate against the flywheel again, instantly stopping its free rotation. All three components are again rigidly connected. Engine torque can be transmitted to the drivetrain.