Anti-lock system for vehicles

摘要

Herein disclosed is a vehicular anti-lock system of the type, in which a valve mechanism is disposed in a main passage which connects a master cylinder and a brake system such that its opening and closing operations are controlled by the movement of a control piston having its one end subjected to the pressure of the brake system. A fail-safe piston is made movable in a cylinder and has its one end engaging with the valve seat member of the valve mechanism and its other end connected with a liquid pressure source which is independent of the master cylinder. The control piston is made movable in the fail-safe piston and has its other end facing a control chamber. Between the liquid pressure source and the control chamber, there is connected a first valve which is adapted to be closed in response to a brake releasing signal. Between the control chamber and a reservoir, there is connected a second valve which is adapted to be opened in response to the brake releasing signal. A bypass passage is disposed in parallel with the valve mechanism and is adapted to be closed when the fail-safe piston is caused to bring the valve seat member into engagement with the wall of the valve chamber by the pressure of the liquid pressure source.