| 摘要 |
PURPOSE:To surely lower hydraulic pressure in a primary delay pressure chamber by forming a path which is in parallel with a path provided with a variable orifice and connects the primary delay pressure chamber to an upper working oil chamber, and interposing a check valve opened toward the upper working oil chamber side in that path. CONSTITUTION:In extension stroke in which a piston 2 moves toward an upper working oil chamber A, working oil in the upper working oil chamber A flows into a lower working oil chamber B while deflecting the inner surface of a relief valve 10 downward to produce a damping force in extension direction. Also a hydraulic pressure generated in the upper working oil chamber A is led into a primary delay pressure chamber R through a variable orifice 15c, etc., in a control valve 15 to push down a push member 11. Further, in retraction stroke, when a hydraulic pressure in the upper working oil chamber A lowers and a difference in pressure is produced between the upper working oil chamber A and the primary delay pressure chamber R, a check valve 36 is opened immediately. Then the amount of working oil flowed into the primary delay pressure chamber R in the extension stroke is returned back to the upper working oil chamber A to equalize the hydraulic pressures in both chambers R and A with each other. |
