Manual braking system with hydraulic brake booster

This invention relates to vehicle braking systems and more particularly, to an improved manual-braking mode. A hydraulic pressure intensifier for operating a vehicle braking system under conditions that are not conducive to the proper operation of a power assist for the braking system. The hydraulic pressure intensifier has an intensifier inlet fluidly connected to a master cylinder and an intensifier outlet fluidly connected to a wheel cylinder. A bypass valve has an input and output fluidly connected to the intensifier inlet and the intensifier outlet, respectively. With normal power assisted braking operation, the bypass valve is open and the master cylinder is fluidly connected to the wheel cylinder via the bypass valve. In a manual or nonpower assisted braking operation, the bypass valve is closed; and the hydraulic pressure intensifier is fluidly connected between the master cylinder and the wheel cylinder. Thus, with the bypass valve closed, a fluid pressure from the master cylinder that is applied to the inlet of the intensifier cylinder is multiplied to a greater fluid pressure at the outlet of the intensifier cylinder and applied to the wheel cylinder.