Clutch Operation
The clutch disc is a disc coated in a high friction material capable of remaining fixed even under very high shear forces. The Clutch engages with the high-friction surfaces comprising the flywheel & pressure plate. This system enables the engine to transmit its power hence transmission.
The clutch centre has a spline pattern that meshes with splines on the power input shaft of the transmission system.
The clutch forces against the flywheel as the clutch engages. This friction link transmits power from the crankshaft to the transmission shaft.
Dis-engaging the clutch pulls on the heavy-duty release springs isolating the pressure plate so that the disc is no longer forced against the flywheel.
The pressure plate is asembled from heavy-duty release springs, a metal pressure ring forming a high friction surface to interact with the clutch disc, a thrust ring (or thrust fingers) for the release bearing, and release levers.
As the clutch dis-engages; the clamping force is removed so the clutch disc spins with the flywheel and no power is transmitted.
Clutch failure often occurs when one or more of the high friction surface materials wears out on the disc. Even when the pressure plate is engaged and a clamping force is applied, there is no longer sufficient friction to transmit power without the clutch slipping. Normally the clutch disc and pressure plate are replaced. Replacing a Vehicle Clutch is a major operation and it is sometimes advisable to replace a number of items, often supplied as a Vehicle clutch kit:-
- clutch disc
- pressure plate
- release bearing
- pilot bearing - bushing (when required)
- internal slave cylinder (if required)