Clutch pressure plate is an important component of the clutch, and its function plays a crucial role in vehicle driving safety. As one of the main parts of the clutch assembly, the clutch pressure plate transmits and cuts off the engine’s power transmission through a linkage mechanism according to the driver’s intention. It works in conjunction with the clutch disc to ensure smooth vehicle starting, seamless gear shifting, and prevention of engine overload.
Clutch pressure plate braking widely adopts a spring-loaded friction clutch (referred to as a friction clutch). The torque generated by the engine is transmitted to the driven disc through the frictional force between the flywheel, pressure plate, and the contact surface of the driven disc. When the driver depresses the clutch pedal, the large end of the diaphragm spring drives the pressure plate to move backward through the transmission of mechanical parts, separating the driven part from the driving part at this time.
Clutch pressure plate is equipped with friction plates, similar to the brake pads on wheels, which are made of wear-resistant asbestos and copper wires. The friction plates on the pressure plate also have a permissible minimum thickness. After long driving distances, the friction plates on the pressure plate need to be replaced. In the past, friction plates could be replaced with purchased spare parts, but now pre-assembled pressure plate sub-assemblies with friction plates are available, eliminating the need to replace friction plates separately—simply replace the clutch pressure plate. To reduce wear and tear on the clutch disc, there is a correct way to use the clutch pedal: avoid keeping the clutch pedal half-depressed. This places the clutch disc in a semi-engaged state, where the flywheel and pressure plate are in a frictional state. When the clutch pedal is fully depressed, the flywheel and clutch pressure plate are completely separated with no friction between them. When the clutch pedal is fully released, the flywheel and clutch pressure plate are fully engaged, where although there is some friction, it is essentially minimal. Therefore, the clutch pedal should not be kept in a half-depressed state.
How to inspect and repair the clutch pressure plate? The inspection methods and requirements for the clutch pressure plate are as follows:
- The flatness error of the clutch pressure plate working surface should not exceed 0.12mm, and the depth of grooves on it should not exceed 0.50mm. If too deep, it should be ground on a surface grinder, but the grinding thickness should not exceed 1mm. If the grinding thickness has reached the limit but a small amount of the surface remains unground, it can still be used as long as the unground area does not exceed 10% and is evenly distributed.
- After grinding, the pressure plate should undergo a balance test, with an unbalance error of no more than 50g·cm. If the error exceeds the limit, the drilling method can be used to drill holes in appropriate parts of the pressure plate to meet the balance requirement.
- For the middle pressure plate of a dual-disc clutch, the clearance between the transmission pin hole and the transmission pin should not exceed 1mm. The transmission pin can be reinstalled at a 90° rotation. Otherwise, it should be repaired or replaced.
- If the pressure plate shows severe aging, cracking, and the wear groove depth exceeds 0.50mm, it should be replaced with a new part.
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