| 摘要 |
PURPOSE:To provide a good brake feeling without causing a delay in the return movement of a power piston by providing a valve mechanism that allows a free passage of the fluid which is fed into and drained from a stabilizer chamber and a pressure modulating chamber. CONSTITUTION:A second valve mechanism 30 opens and closes between passages 29, 31. The valve body 36 is interlocked with a key member 20 in an air- tight manner, and closes between the passages 29, 31 by seating on the valve seat 38 by means of a spring 37 under inoperative conditions where the key member 20 is located at the advancing end relative to the valve body 7. When a power piston 3 returns, the key member 20 is shifted to the returning end relative to the valve body 7 to allow the second valve mechanism to communicate between the passages 29, 31, and since the pressure fluid in a stabilizer chamber 5 and the pressure fluid in a pressure modulating chamber 6 that is connected to the stabilizer chamber 5 with a large flow passage area are expeditiously drained, there is no delay in the retreating movement of the power piston 3. |
