Abstract: In a drilling device, a tool mounted in the device can be selectively switched from right-hand rotation to left-hand rotation. The tool can be connected to an output shaft on which two conical gear wheels are mounted in spaced relation so that they can be rotated in opposite directions around the output shaft. The teeth on the conical gear wheels face one another and are in meshed engagement with gear teeth on a drive shaft. A coupling part is slidably displaceably mounted on the output shaft and can be engaged with one or the other of the conical gear wheels. The coupling part is secured on the output shaft so that as it is rotated by one or the other conical gear wheels, in turn, it rotates the output shaft in the desired direction.

Abstract: In a hammer drill, a striking mechanism supplied percussive force to a tool. The striking mechanism includes a free piston slidably displaceable in a reciprocating manner within a guide cylinder. Balls mounted in the guide cylinder are spring biased into a recess in the free piston for securing the piston in a locked position so that it cannot deliver percussive force to the tool. The balls are spring biased by a ring encircling the cylinder with a spring pressing the ring in the axial direction of the cylinder against the balls.

Abstract: A hammer drill includes a unit for supplying impact force to a tool inserted into the hammer drill and a unit for supplying rotational forces to the tool. A first drive motor drives the impact force unit and a second drive motor drives the rotational force unit. The motors can be operated independently of one another. A first drive train interconnects the first drive motor to the impact force unit and a second drive train interconnects the second drive motor and the rotational force unit. A coupling device interconnects the first and second drive trains so that at least one of the impact force unit the rotational force unit can be selectively driven by both the first and second motors.

Abstract: A tool chuck for securing a tool bit in a drilling and cutting device includes a guide tube into which the tool bit is inserted and an adjusting sleeve displaceable relative to the guide tube. The guide tube has spaced first and second apertures with the first apertures holding locking members and the second apertures holding entrainment strips. The adjusting sleeve has alternating first and second pockets in its inside surface for receiving the locking members and the entrainment strips. With a tool bit having slots for both the locking members and the entrainment strip, both the locking members and entrainment strips can be displaced radially inwardly by the adjusting sleeve. If the tool bit has only slots for the locking members, the locking action can be effected with the entrainment strips maintained radially outwardly from the tool bit.