Brake Proportioning/Combination Valve: Description and Operation

The brake master cylinder fluid control valve regulates the hydraulic pressure in the rear hydraulic circuit. It is located on the brake master cylinder and is screwed into the rear most outlet port. When the brake pedal is applied, the full brake pressure passes through the brake master cylinder fluid control valve to the rear hydraulic circuit until the valve's split point is reached Above its split point, the brake master cylinder fluid control valve begins to reduce the hydraulic pressure at the rear brakes, creating a balanced braking condition between the front and rear wheels to minimize rear wheel lockup during hard braking.