Abstract: A hydropunch comprises a cylinder, with one end thereof facing the working surface of a die intended for positioning thereon a workpiece to be treated. Accommodated inside the cylinder and forming an above-the-ram chamber and a below-the-ram chamber is a ram which is actuated by means of a suitable actuator mounted on that end of the cylinder which is opposite to the aforementioned end thereof, the ram being connected with a system for returning the ram to its original position. In addition, the hydropunch includes a compressed gas receiver communicating with the above-the-ram chamber of the cylinder, and a cover adapted for closing both the cylinder and receiver. In accordance with the invention, the system for returning the ram to its original position comprises a closed chamber communicating with the below-the-ram chamber of the cylinder, and a value intended for communicating the above-the-ram chamber with the atmosphere.

Abstract: The herein disclosed mechanism comprises a compressed gas receiver, a shaft with a striker movable therein, and control and working cylinders arranged in series one after the other, whose pistons are interconnected by means of a rod. According to the present invention, said working cylinder is mounted in the receiver and defines a circular space between the end of the receiver and the end of the shaft. In so doing, said circular space communicates with the receiver space while the piston of said working cylinder is mounted for movement relative to the rod to permit pressure from the receiver to pass and drive the striker for a working stroke.