Power Brake Unit

Fig. 1 Exploded View Of AC-Delco Tandem Diaphragm Booster:

Fig. 2 Exploded View Of Power Head Assembly. AC-Delco Tandem Diaphragm Booster:

DESCRIPTION
This unit utilizes a vacuum power chamber, consisting of a front and rear shell, housing divider, front and rear diaphragm, plate assemblies, hydraulic pushrod and a diaphragm return spring, Fig. 1 and 2 .

OPERATION
In normal operating mode, with service brakes in released position, the booster operates with vacuum on both sides of its diaphragms. When brakes are applied, air at atmospheric pressure is admitted to one side of each diaphragm to provide power assist. When the service brake is released, atmospheric air is shut off from one side of each diaphragm. The air is then drawn from the booster through the vacuum check valve to the vacuum source.