Power Brake Booster
The power brake booster assembly mounts on the engine side of the dash panel. It is externally connected to the brake pedal by an input push rod extending out the rear of the booster. See Fig 1 . The master cylinder is bolted to the front of the power brake booster assembly. A vacuum check valve is mounted on the power brake booster body. A vacuum line connects the booster (check valve) to the intake manifold. The purpose of the power brake booster is to reduce the amount of force required by the driver (foot-pedal pressure) to obtain the required hydraulic pressure in the brake system to stop the vehicle. This vehicle utilizes a Bosch power brake booster to accomplish this task in all brake applications. The power brake booster is vacuum operated. The vacuum is supplied from the intake manifold on the engine through the vacuum hoses and power brake booster check valve. See Fig 1 . As the brake pedal is pressed, the power brake booster's input rod moves forward. This opens and closes valves in the power brake booster, creating a vacuum on one side of the diaphragm and allowing atmospheric pressure to enter on the other. This difference in pressure forces the output rod of the power brake booster out against the primary piston of the master cylinder. As the pistons in the master cylinder move forward, this creates the hydraulic pressure in the brake system.