| 摘要 |
PURPOSE:To obtain normal contracting operation, by providing the No.1 bypass oil passage with a normally-opened pilot valve, which is closed only when the pressure oil is supplied, together with providing the No.2 bypass oil passage with a non-return valve. CONSTITUTION:A piston-rod-side oil chamber 5b is connected to a non-return valve 11 via the No.1 bypass oil passage 14. At the same time, the chamber 5b is connected to the suction side of a pump 8 via the No.2 bypass oil passage. The No.1 bypass oil passage 14 is provided with a pilot valve 17, which is normally open and is closed only when the pressure oil is supplied, while the No.2 bypass oil passage 15 is provided with a non-return valve 18. With this contrivance, the oil in a hydraulic cylinder 5 can completely be discharged when the hydraulic cylinder 5 is operated toward the discharge side. Therefore, normal contracting operation of the hydraulic cylinder can be ensured.
|
