| 摘要 |
An arrangement for controlling the admission of a hydraulic fluid to respective wheel brake actuating cylinders either from an auxiliary pressure source or from a master cylinder includes a pressure limiting valve and a hydraulically operatable switching valve including a valve body movable only when the auxiliary pressure source is fully operational from a first position in which it connects the master cylinder with the actuating cylinders to a second position in which it connects the auxiliary pressure source with the actuating cylinders and the master cylinder with the pressure limiting valve. The limiting pressure of the pressure limiting valve is adjusted in dependence on the brake pedal travel. The respective master cylinder piston carries a deflectable seal which permits fluid to flow past it in one direction but not in the opposite direction. The pressure at which the switching valve member moves into its second position has a predetermined level, preferably 1 to 2 bar gauge. Check valves which open toward the actuating cylinders when the pressure acting on the switching valve member exceeds the switching pressure by a predetermined amount are interposed in bypass conduits circumventing the switching valve. |
