Brakes and Traction Control: Description and Operation

These units are self contained vacuum hydraulic power braking units. They are the vacuum suspended type which use engine intake manifold vacuum and atmospheric pressure for their power, eliminating the need for a vacuum reservoir. A mechanically operated control valve, integral with the vacuum power diaphragms, controls degree of brake application or release depending on amount of foot pressure applied to valve operating rod through the brake pedal linkage.

The control valve is a single poppet type valve with the atmospheric port and a vacuum port. The vacuum port seal is a part of the valve body attached to the diaphragm assembly. The atmospheric port is a part of the valve plunger which moves within the valve housing and vacuum power diaphragm assembly.

These units require no maintenance and must be replaced as a complete assembly.