| 摘要 |
PURPOSE:To eliminate power loss of a hydraulic pump, by providing such an arrangement that a pressure boost piston normally actuated under control pressure is actuated by the hydraulic pressure in a hydraulic pressure chamber connected to the discharge port of the hydraulic pump through a check valve, and the hydraulic pressure is relieved into a reservoir when the hydraulic pressure exceeds the braking pressure. CONSTITUTION:The discharge port of a pump 52 is connected through a check valve 54 to a power hydraulic chamber 55e in a regulator valve 55. The liquid pressure in the chamber 55e acts upon a small diameter pressure boost piton 55a while the hydraulic pressure in a master cylinder 12 acts upon a large diameter pressure boost piston 55b. A chamber 55g defined between both pressure boost pistons 55a, 55b and communicated with a reservoir 51 may be communicated with the power hydraulic pressure chamber 55e through a discharge valve 55d. Accordingly, upon operation of the master cylinder 12 a power hydraulic pressure is generated in the chamber 55e due to the operation of the pressure boost pistons 55a, 55b. With this generated hydraulic pressure a control piston 57f and an operating piston 58g are actuated. |
