Master Cylinder, Brakes

The brake master cylinder contains a double hydraulic cylinder with primary and secondary hydraulic pistons and a brake master cylinder reservoir. When the anti-lock brake system (ABS) operates brake fluid pressure can cause undue wear to the primary cup of the secondary piston on conventional brake master cylinders. To prevent this condition, the relief port has been abolished in ABS-equipped brake master cylinders and a center valve port has been provided in the secondary piston.