US Patent 7100373 Hydraulic tool

A hydraulic tool is provided with a spool valve 24 for changing the flow of a working fluid pressurized by a hydraulic power generating mechanism in a hydraulic circuit. The spool valve 24 is slidable in directions perpendicular to a piston rod 18. A cylindrical grip handle 34 to be operated by the operator's hand is extended parallel to the piston rod 18 on the outer surface of the main casing 5 so as to be turnable about its own axis. The spool valve 24 and the grip handle 34 are interlocked by a cam mechanism including members 29, 30 and 21. The spool valve 24 is moved axially by turning the grip handle 34 to control the flow direction of the working fluid.