Hydraulic Circuits and Valve Operation - Normal Braking: Overview

Fig. 12 Normal Braking -Hydraulic Control:

ISOLATION VALVES

Open to primary and secondary master cylinder fluid supply.

DECAY AND BUILD VALVES

Closed

The brake pedal is applied. The travel of the brake pedal closes primary, secondary and booster servo circuits from fluid supply at the fluid reservoir. Brake fluid from the primary and secondary circuits flows through the open isolation valves and applies the wheel brakes. Fluid from the booster servo circuit does not flow to the wheel brakes. The fluid flow is blocked by the closed build valves and check valves.
POWER ASSIST

The boost control valve shuttles between its three positions to provide power assisted braking.