Abstract: A power hammer drill includes a tool holder and an air cushion striking mechanism for driving a tool and including a striker, a reciprocating piston for displacing the striker, and an axially displaceable guide tube for guiding the piston. A device for holding the striker in a forward position thereof adjacent to the tool holder in an idling condition of the hammer drill is provided in the hammer drill. The device has a guide element fixed in the drill housing for guiding the guide tube. The guide tube has a control opening for venting the air cushion and which remains in open or closed condition dependent on axial position of the guide tube.