Abstract: A motor driven by a pressurized fluid medium for operating an impact tool in a linear direction adapted for metal stamping and high velocity milling comprising a housing and a piston unit. The latter comprises a drive piston, a piston rod and a tool. In addition, the motor includes a kinetic energy absorbing device comprising a hydraulic fluid chamber and a retard piston which is rigidly connected to said piston unit and arranged to reciprocate in said fluid chamber. The retard piston retards the piston unit at the end of the strokes only and is freely passed by hydraulic fluid during the working stroke. Cup-shaped means are provided to restrict said by-pass flow of hydraulic fluid at the end of the strokes and thereby protect the motor from excessive stresses during no-load conditions.

Abstract: A pneumatic impact device comprising a housing, a drive piston and a piston rod. At the forward end of the piston rod there is attached a tool intended for metal working like punching, cropping or forging. The housing contains a drive chamber, an air charge chamber, a reverse chamber and a retard chamber. The piston rod is provided with two forward-facing, annular shoulders one of which constitutes a reverse piston for working in the reverse chamber and the other a retard piston for working in the retard chamber. For being protected from impact strains, the drive piston is longitudinally displaceable relative to the piston rod. During the working strokes, the drive piston cooperates with a backwardly facing shoulder on the piston rod, but just before the latter reaches the point where the tool hits the billet to be worked, the drive piston is stopped in the drive chamber and is thereby separated from the piston rod shoulder.