| 摘要 |
PURPOSE:To prevent slipping-off of the sealing member on the outer periphery of a valve opening piston by forming the stopper part for restricting the transfer of a valve opening piston on a pressure receiving piston and restricting when one system is broken. CONSTITUTION:A pressure receiving piston 9 is operated by the hydraulic pressure which operates between an input hydraulic chamber 18 and an output hydraulic chamber and the force of a spring 12, and a valve 23 is urged by the piston 9, then the output hydraulic pressure is controlled. A valve opening piston 11 is driven by the oil pressure of the other system, when one system is broken, and the valve 23 is put into inoperative state. As the inside shoulder part 14 of the pressure receiving piston 9 operates as stopper at this time, the valve opening piston 11 can be prevented from making a movement to the extent more than required. Therefore, slipping-off of a sealing member 33 can be prevented, and the whole apparatus can be miniaturized. |
