A piston rod with a piston, against which a displaceable valve ring, a short, axially rigid striking pin, guided in a bush, and a pressure transformer piston are set, is immovably placed in one part of the supporting housing. A working tool is placed in the second part of the supporting housing in a tool bush protected on the outside by a lower sealing cover to prevent corrosion. A gas chamber is set up under the supporting housing, the pressure transformer piston and the striking pin. A pressure transformer cylinder and an equalizing chamber are formed between the piston rod and tfe pressure transformer piston. The striking pin is driven by a working fluid under pressure, which is distributed by a system of channels in the piston rod. The striking pin is driven onto the working tool in a striking action by high-pressure gas, which is pressurized in the gas chamber. The movement of the striking pin is controlled by a switching element, fitted in the piston rod, and a valve ring, pushed onto the piston rod surface. It is assisted by the pressure transformer, which eliminates pressure peaks of the working fluid.

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