Vacuum Booster

Pedal pressure is amplified by the vacuum booster. The engine is an air pump with suction on the intake side. The low pressure in the intake manifold is applied to a rubber diaphragm on the vacuum side of the chamber (red speckled area) which then pulls the piston rod in when the brakes are applied to supply a power assist. The piston rod is connected to the brake pedal. A good check on booster operation is to apply light pressure to the pedal when the engine is cranking, the pedal should drop a little when the engine fires up.


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