US Patent 7251980 Hydraulically powered gripping tool

A hydraulic operated tool includes a body (B), a pair of jaws (21) mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage workpiece (W) between the jaws. A ram assembly (2) is disposed in the body and is operatively associated with the jaws. Spring structure (1) causes the ram assembly to move thereby causing the jaws to initially engage the workpiece with a first force. A pump assembly (7) exerts fluid on the ram assembly to move the ram assembly further, causing the jaws to exert a second force, greater than the first force, on the workpiece.