| 摘要 |
A light-weight and compact hand actuated hydraulic tool for the setting of fasteners having a sleeve and stem is disclosed. The tool comprises a housing, sleeve engaging nose piece connected to a piston which is slidable in the housing, a fluid reservoir, hand-operated pump lines, and a drawbolt which has stem gripping jaws connected thereto. The stem of a fastener is gripped by the jaws, and the sleeve of the fastener is engaged by the nose piece. In an initial stage, a pump plunger compresses liquid in first and second chambers into a piston chamber, which affects movement of the housing and drawbolt in relation to the piston, pulling the stem in relation to the sleeve. As the pulling force increases, and thus the necessary hand pumping force, pressure in the piston chamber opens a valve, allowing fluid in the first chamber to return to the reservoir so that only the second plunger chamber is used to compress the liquid into the piston pressure chamber, lessening the force necessary to actuate the pump lever. In one arrangement, a pilot piston that opens the valve includes an internal relief valve that allows liquid in the piston chamber to return to the reservoir in response to predetermined maximum piston chamber pressure or in response to manual pressure.
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