Abstract: Disclosed herein is a device for introducing beating or pulsed movements into tube walls within a pressure vessel, wherein a first ram imparting the beating pulse to the tube wall passes through the pressure vessel wall and is guided into a pressurized first annular space which is acted upon by a second ram, which is guided in a further tubular chamber. Such a device is intended to provide a solution by which the wear of the ram that acts on the tube wall is compensated over as long a time as possible and effective sealing with respect to the surroundings is ensured.