| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a suitable hydraulic cylinder for a power tool in hand or the like. SOLUTION: A helical compression spring 26 is inserted in the rod side oil chamber of a hydraulic cylinder 3, and a hydraulic piston 21 is held at a head side initial position. A passage 21a for a communication of the rod side with the head side is formed in the hydraulic piston 21, and a helical compression spring 23 and a poppet type check valve 24 are inserted in the passage 21a. The check valve 24 is constantly in an opening position, and closed while compressing the helical compression spring 23 when a hydraulic pressure is applied on the head side of the hydraulic piston 21. When the hydraulic pressure is applied the check valve 24 is closed, the hydraulic piston 21 is driven to advance, and the oil of the rod side is discharged into a pipe passage 22. When the hydraulic pressure of the head side is released, the check valve 24 is opened, the oil of the head side flows the rod side, and the hydraulic piston 21 is pushed by the helical compression spring 26 to return at the initial position.</p> |
