| 摘要 |
PURPOSE:To shorten an operating stroke by interposing an on-off valve, which opens when a hydraulic pressure in an output hydraulic pressure chamber is less than the specified value, between a boost chamber, being partitioned off between a master cylinder body and a booster cylinder, and a reservoir after installing it at the outside of a booster piston. CONSTITUTION:In a hydraulic booster B having a booster piston 15, adjoining its back to an output hydraulic pressure chamber 14 and being slidably fitted in a booster cylinder 13 to be concentrically to the rear end of a cylinder body 1 of a master cylinder, and a valve piston 16 being fitted in this booster piston 15 free of slide motion while connected to an operating member 40, a front end of the booster piston 15 is formed into a larger diameter than the rear end of a master piston 6, and a boost chamber 32 is partitioned off in space between the cylinder body 1 of the master cylinder M and the booster cylinder 13 of the hydraulic booster B. Then, an on-off valve 58 to be opened according to a fact that the hydraulic pressure in the output hydraulic chamber 14 becomes less than the specified value is installed between this boost chamber 32 and a reservoir R2, and this valve 58 is installed at the outside of the booster piston 15. |
