Abstract: The drilling device includes a telescopable Kellybar (16) with an outer tube (17) and at least one telescope tube (18). A tool (22) is mounted to the lower end of the telescope tube (18). In order to supply pressure medium to the drilling tool (22), the telescope tube (18) includes an inner tube (25) which is connected to a pressure line (33) via a rotating head (30). In order to secure the stator of the rotating head against rotation, a rotation protecting means (36) is provided which projects into the outer tube (17). Without exchanging the drilling mast, the drilling device can be used for drill hole depths greater than the length of the drilling mast (10); nevertheless, it can be used with pressure fluid as flushing agent or driving agent for a tool.

Abstract: A pneumatic hammer is provided which includes a working piston (16) movable in a working cylinder (22) and defining therewith front and rear cylinder working chambers (23, 24, respectively). The working piston (16) impacts upon an anvil (15) to drive a drill bit (12) through utilizing a source of compressed air. An adjusting mechanism (37) adjusts the length of the return stroke of the working piston (16) in dependence upon the supply pressure of the compressed air.

Abstract: A pneumatic hammer is provided with an adjusting piston (37) dependent on the supply pressure, which adjusts the stroke length of the working piston (16). Thereby, the same pneumatic hammer may be operated both at low and high supply pressures. With high supply pressures, either the early ending of the acceleration phase or the early start of the compression phase or the shortening of the working cylinder shortens the stroke length. Thereby, the pneumatic hammer performs impacts with a substantially constant single-impact energy, regardless of the supply pressure. High supply pressures increase the impact frequency. This results in a considerably improved efficiency at a high drill capacity, a reduced wear and a reduced risk of ruptures of the components of the hammer.