| 摘要 |
A light-weight and compact hand actuated hydraulic tool (20) for the setting of fasteners (172) having a sleeve (174) and stem (170) is disclosed. The tool comprises a housing (22, 222), sleeve engaging nose piece (44, 244) connected to a piston (43, 243) which is slidable in the housing (22, 222), a fluid reservoir (34, 234), handoperated pump lines, and a drawbolt (52, 252) which has stem gripping jaws (60, 260) connected thereto. The stem (170) of a fastener (172) is gripped by the jaws (60, 260), and the sleeve (174) of the fastener (172) is engaged by the nose piece (44, 244). In an initial stage, a pump plunger (58, 258) compresses liquid in first and second chambers (102, 106 and 302, 306) into a piston chamber (116, 316), which affects movement of the housing (22, 222) and drawbolt (52, 252) in relation to the piston (43, 243), pulling the stem (170) in relation to the sleeve (174). As the pulling force increases, and thus the necessary hand pumping force, pressure in the piston chamber (116, 316) opens a valve (124, 129 and 348), allowing fluid in the first chamber (102, 302) to return to the reservoir (34) so that only the second plunger chamber (106, 306) is used to compress the liquid into the piston pressure chamber (116, 316), lessening the force necessary to actuate the pump lever (88, 288). In one arrangement, a pilot piston (332) that opens the valve (348) includes an internal relief valve (338) that allows liquid in the piston chamber (316) to return to the reservoir (34) in response to predetermined maximum piston chamber pressure or in response to manual pressure. |
