The clutch disc consists of a hub mounted on the spline of the clutch shaft and a support plate, to which the friction linings are riveted with rivets. The rivets connect the hub to the backing plate.
The friction linings are made of special materials, characterized by a high coefficient of friction, resistance to abrasion, resistance to high temperatures (the heat is generated by friction) and resistance to significant pressures. They are usually asbestos-based materials with many additives to strengthen and improve thermal conductivity.
Clutch plates are often equipped with torsional vibration dampers. Their task is to protect the drive system against vibrations caused by sudden changes in torque.
Torsional vibration dampers are additional springs with specific characteristics, positioned circumferentially between the support plate and the hub. In the event of a sudden load, e.g.. the spring hubs yield to cushion the impulse and transfer it to the support plate. The friction inserts are usually additional damping elements, located between the support plate and the hub, which obstruct the relative movements of these elements.
There may be several or a dozen of compression springs. They are small diameter cylindrical coil springs or one, large diameter central spring, called the plate.
The pressure plate is usually made of cast iron. It rotates with the handwheel, however, it is also capable of being slid along the axis of the clutch when disengaging it. This is ensured by a special arrangement of spring connectors or special lugs in the shield that cooperate with the grooves in the flywheel..
The release levers transmit the axial movement of the release bearing to the pressure plate. The levers come in various shapes and are made of castings, forgings or stampings of sheet steel.