Proportioning Valve Description

The proportioning/differential valve is used on vehicles equipped with the Antilock Brake System (ABS). Outlet pressure is controlled to the rear brakes after a predetermined rear input pressure has been reached. This allows for smooth braking action and reduces the chances of rear wheel lockup during normal braking.
The proportional/differential valve has a bypass feature which insures full system pressure to the rear brakes in the event of a front brake system failure. In case of a rear brake system failure, full system pressure is delivered to the front brake system.