Clutch: stepping on the pedal, clutch master pump high pressure brake fluid, oil chamber from the inlet of input, in the relay piston yesterday master cylinder piston in the left, on the one hand promote the master cylinder piston to drive the push rod to produce thrust to the left and right, of the on the other hand pushed to relay the piston moves to the right, open the valve assembly, the compressed air through the channel into the booster cylinder piston to the left.