Vehicle Systems
Hydraulic System Operation
38
Brake System
Master Cylinder
Master Cylinder And Wheel Cylinder
(1) Master cylinder reservoir. (2) Master cylinder.
(3) Wheel cylinder.
Brake fluid from remote reservoir (1) to replenish
master cylinder (2).
The master cylinder has a piston which pushes
brake liquid into the brake lines. The reservoir,
located on the cowl, is connected to inlet of master
cylinder. The supply lines keep master cylinder (2)
filled so no air enters the system. Reservoir (1)
supplies brake liquid to the system.
When the brake pedal is first pushed, the piston
moves into the master cylinder and push brake
liquid through outlet into the brake lines. When
floating piston seats on seal, the liquid that is
pushed by piston goes around cup seal, out through
loading piston and outlet. This action continues until
the liquid pressure in piston bore reaches the
pressure that opens relief valve. The liquid, being
pushed by piston, now returns to reservoir(1). Cup
seal, seals and the liquid inside piston is pushed
through piston and outlet.
The liquid pushed through outlet goes through the
brake lines to wheel cylinders (3).
Check valve in the master cylinder keeps a small
amount of pressure in the brake lines and wheel
cylinders (3) when the pedal is released. This small
amount of pressure helps the wheel cylinder piston
cup seal seat, which keeps air out of the brake
system.
