Clutch: Description and Operation

System Description

Delay Orifice Mechanism

Function
The delay orifice mechanism improves clutch operation by delaying the slave cylinder release speed when the clutch pedal is suddenly released. The delay orifice mechanism is built into the slave cylinder.





Operation
When the clutch pedal is pressed, the fluid pressure from the master cylinder moves the one-way valve in the direction shown in the illustration. The fluid flows through two passages: the orifice part and the filter part. It then flows out to the slave cylinder to release the pressure plate and clutch disc joint.





When the clutch pedal is released, the fluid pressure from the slave cylinder moves the one-way valve in the direction shown in the illustration. The one-way valve blocks the filter-part passage and delays the clutch release speed by returning the fluid to the master cylinder through only the orifice-part passage.





Self-Adjusting Clutch (SAC)

Function
On ordinary clutches, the clutch pedal load increases as the clutch disc wears. The self-adjusting clutch is designed so the clutch pedal load will not increase even when the clutch disc wears. This is done by automatically adjusting the fulcrum of the diaphragm spring in accordance with the wear of the clutch disc. The clutch pedal load stays consistent even when the clutch disc is worn.

Construction
The self-adjusting clutch consists of a pressure plate, a sensor spring, a diaphragm spring, an adjusting ring, three coil springs, a pressure plate cover, and a compensation spring. They are riveted together and must not be disassembled. If there is problem with any part of the pressure plate or clutch disc, they must be replaced as a set.





Operation
1. When the clutch disc wears slightly.
As the clutch begins to wear, the release load increases slightly. However, this does not affect the operation of the clutch because the release load does not exceed that of the sensor.





2. When the clutch disc wears considerably.
The sensor spring starts to deflect as the clutch disc is worn further and the release load exceeds that of the sensor.





The fulcrum then moves following the amount of sensor spring deflection. As this takes place, the fulcrum of the diaphragm spring is adjusted, keeping the release load consistent.