Abstract: A hammer drill or chipping hammer includes a housing, a striking mechanism movably displaceably mounted within the housing, and a handle spring supported on the housing. To absorb vibrations generated during operation of the drill or hammer, piston-like weighted members are slidably mounted in the housing for movement parallel to the axial direction of the striking mechanism. The weighted members are supported by springs. Each weighted member is located within a separate cylinder and divides the cylinder into separate spaces. The spaces in the cylinders are interconnected by a fluid medium communicating between them for effecting balanced operation of the weighted members.

Abstract: A weighting circuit operates to process a torque signal which may be produced by a strain gauge located within the handle of a drilling machine. The circuit includes a first sensor device for receiving the torque signal, and an integrator which integrates the torque signal when the amplitude of the torque signal exceeds a certain level as determined by the first sensor device. The output of the integrator is applied to a second sensor device which operates to switch off the machine when a predetermined integration value produced by the integrator is exceeded. The torque signal thus can be evaluated very thoroughly with the present circuit, so that improved control over the response of a drilling machine during blocking, jamming or twisting conditions, can be obtained.

Abstract: In a friction clutch a first disc-shaped driving member and a second disc-shaped driving member are held in frictional contact by a spring so that the driving members rotate coaxially, each driving member has a facing surface directed toward the other. Rolling members are positioned between the facing surfaces and seat in opposed indentations when the driving members rotate as a unit. When a predetermined torque is exceeded, the biasing action of the spring is overcome and the driving members move away from one another in the axial direction. During such axial displacement, the rolling members move out of at least the indentations in one of the driving members and aid in the separation of the driving members.