Abstract: In an electropneumatic drill or chipping hammer with an air cushion transmitting driving force of an exciter piston to a percussion piston, a clutch is provided to interengage a drive motor with the exciter piston. The clutch can be selectively engaged by an axially displacing holding sleeve which positions a tool on the front end of the drill or hammer.

Abstract: A hammer drill includes a tubular guide member for transmitting rotational movement to a tool and an anvil axially displaceably supported in the tubular guide member for imparting impacting force to the tool. An impacting mechanism within a cylindrical guide member is aligned with a tubular guide member for transmitting impacting force to the anvil. A tool holder is mounted on the front part of the tubular guide member and has a radially adjustable tool holding zone. The radial adjustment is effected by radially displaceable jaws cooperating with the conically shaped section of the tool holder. When the shank of a tool is inserted into the holder, by axially adjusting the conically shaped section, the jaws can be displaced inwardly into holding contact with the tool shank. For improved concentricity, the cylindrical guide member and the tubular guide member are formed as an axially extending unit.

Abstract: In a tool holder for securing a tool in a hammer drill in a form-locking manner, locking elements are radially displaceably mounted in a guide member. An adjustment ring is threaded onto the guide member and by rotating the adjustment ring relative to the guide member, the locking elements can be adjustably tightened or loosened. The locking elements seat in closed end recesses in the shank of the tool to be secured. The adjustment ring can be locked in different rotational positions by an interlocking tooth arrangement. Teeth are provided on the adjustment ring and on a fixing sleeve axially slidably positioned on the guide member. The fixing sleeve can be moved axially between a position for locking the adjustment ring and another position permitting the adjustment ring to be rotated relative to the guide member.