Vehicle brake apparatus

A brake apparatus for a vehicle having a brake pedal, comprising:

• a wheel brake cylinder adapted to be operatively mounted on a wheel for applying a braking force to the wheel;
• a pressure source for pressurizing brake fluid to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder;
• an auxiliary pressure source for pressurizing brake fluid in response to operation of the brake pedal to generate a hydraulic braking pressure and supply the hydraulic braking pressure to the wheel brake cylinder when the pressure source is non-operational;
• a mechanical valve operatively mounted between the wheel brake cylinder and the auxiliary pressure source, said mechanical valve including a first port and a second port;
• a first passage connected between the auxiliary pressure source and the first port of the mechanical valve;
• and
• a second passage connected between the second port of the mechanical valve and the wheel brake cylinder, said mechanical valve being selectively positionable in a first operating condition in which fluid flow is simultaneously permitted from the first port to the second port and from the second port to the first port, and a second operating condition in which fluid flow from the first port to the second port is permitted and fluid flow from the second port to the first port is prevented, said mechanical valve being positionable in said first and second operational conditions based on at least the pressure at said first port.