Abstract: A single fluid power operated piston connected to a tool operating arm pivoted intermediate its opposite ends, undergoes movement through a predetermined stroke between limit positions to alternately perform punching and shearing operations at spaced stations along a common support bed of a metal working machine. The tool operating arm is held in one of its limit positions by the piston device under control of a selector valve while a foot pedal operated valve is displaced against a spring bias by the operator to effect powered displacement of the piston device to the other limit position in order to effect either a punching or shearing operation depending on the position of the selector valve. A shearing operation may also be performed through a second shear arm pivotally connected to the frame and actuated by the piston device.