Clutch: Testing and Inspection
DIAGNOSIS
CLUTCH MASTER CYLINDER
WHEN NOT OPERATING
As the piston is pushed to the right shown in the figure by the return spring force, no hydraulic pressure is generated in the chamber "a". The spring force also compresses the seal cup spring, opening the oil passage between the reservoir and the chamber "a".
WHEN OPERATING
Depressing the clutch pedal causes the piston to move to the left as shown in the image, thereby the piston return spring is compressed. Then the seal cup, by its own spring force, closes the oil passage between the reservoir and the chamber "a". Immediately after this closure, hydraulic pressure is generated in the chamber "a" and it is applied to the operating cylinder on the transmission.