Hydraulic brake system having servo pressure generator activated by movement of braking device due to torque transmitted from rotor to brake pad

摘要

A hydraulically operated brake system having a servo pressure generating device activated by a torque transmitted from a disc rotor to a braking device with a brake cylinder during activation of the braking device by an operator-controlled master cylinder, to generate a servo pressure which is applied to the brake cylinder through a pressure control valve when the servo pressure is higher than the master cylinder pressure. The pressure control valve inhibits a flow of the fluid from the braking device toward the servo pressure generating device when the servo pressure is lower than the master cylinder pressure. A by-pass passage is provided for connecting the braking device and the servo pressure generating device while by-passing the pressure control valve, and a shut-off valve is provided in the by-pass passage. The shut-off valve is open when the master cylinder pressure is lower than a predetermined level, and closed when the master cylinder pressure exceeds the predetermined level.