GM 1620210 Power Brake Booster Assembly (Hydraulic) (Service)

An assistor, power brake booster, has been included on all models since and can utilize vacuum from the manifold of the engine. When there is fault in the booster, enough vacuum is reserved to help with two or three brake application, additional pressure is then required in the hydraulic brake system. Different kinds of power brake boosters consist of Delco-Moraine and Bendix, and both works on the same mechanism. In case brakes are released and in the same time the engine is on, vacuum is present on the both sides of the power piston, simultaneously, the air filters enters and is stopped in the air valve. When the driver applies the brake, pressing the brake pedal, the push rod gets translated, which leads to the admission of atmospheric air and consequent forward stroke of the power piston that redistributes the oil in the hydraulic master cylinder and at the same time feeds back to the driver. Namely, the power piston remains in that position once the desired level of braking force has been developed; the brake pedal pressure will alter it. Letting go of the pedal pressure opens the air valve and it comes into contact with the power piston, thus sealing the admission of atmospheric air, and also resets the power piston to its original position which then releases the hydraulic pressure. In case of vacuum failure, the brake pedal is useable for emergency braking, which demands higher pressure much as standard brake system. This involves the examination of hoses and the air filter of the power brake unit The dismantling of a power brake unit can be best done, with power brake special tools while it is more advisable to replace power brake unit than overhaul it, after a fault has been discovered.

Inside the car, disconnect the power brake push rod from the brake pedal without forcing it to the side.