Abstract: A device for driving a screwdriver spindle has a claw clutch and an over-detent clutch. The two clutches are arranged coaxially to each other and have coupling parts which are displaceable in an axial direction. Upon a first response of the over-detent clutch, the claw clutch is disengaged, a correspondingly axially displaceable coupling part of the claw clutch is then locked in a disengaged position by a disengageable safety which is simply a radially elastically expandable clamping sleeve which is connected to the claw-clutch and has a detent projection which protrudes radially inward. The screwdriver spindle on which the clamping sleeve is arranged has two circumferential grooves for engagement of the detent projection, the axial center-to-center distance of which is greater than the coupling stroke of the claw clutch.

Abstract: A device for the fine adjustment of the cutting depth of a surface milling cutter, where a cutter holder supporting a drive and a cutting head is displaceable with respect to a foot plate along guide columns which extend vertically to the foot plate and are supported therein. The cutter holder is fixable in a first, rough vertical distance position (cutting depth) by means of at least one locking element, with a threaded spindle, which is preferably adjustable parallel to the guide columns. The cutter holder has a stop face, which cooperates with a bit stop, fastened to be adjustable in height on the foot plate, so that a fine height adjustment is possible when the locking element(s) is (are) released.

Abstract: A cordless electrical tool has a housing forming a pair of battery mounts, an electrical motor in the housing, respective batteries removably carried in the mounts, and circuitry connecting the batteries in series with each other and across the motor. A cutoff switch is connected in series between the batteries and the motor and can open to electrically disconnect the motor from the batteries. Respective control circuits detect the charge levels of the batteries and open the cutoff switch when the respective charge level drops below a predetermined threshold. Respective light-emitting diodes are provided to indicate which of the batteries is below its permissible charge.

Abstract: A power tool has a housing, a blade support reciprocal in the housing, a blade carried on the support for joint reciprocation therewith and projecting from the housing at a work area, and a drive in the housing for reciprocating the support and blade. A bulb generally fixedly mounted in the housing adjacent the support, elastically compressible from a large volume to a small volume, and having an outlet is operatively engageable with an actuator formation between the blade support and the bulb so as to compress the bulb each time the support reciprocates and thereby emit a gust of air from the bulb outlet. A nozzle or conduit is mounted on the outlet and open at the work area for directing the gusts of air at the area and thereby blowing chips and dust created by the blade from the area with each reciprocation of the blade.

Abstract: A damping element for damping three-dimensional and torsional oscillations, in particular in hand tools, is proposed. The damping element includes an approximately bell-shaped rubber spring element defining a cavity which is filled with a damping fluid. The cavity is closed off at its open end with a rubber diaphragm. Within the cavity there is mounted at least one partition which defines overflow conduits or passages, and additional partitions at an angle to the partition defining the overflow conduits. The partition defining the overflow conduits is rigidly joined to a fastening sleeve situated in the rubber spring at the end thereof opposite to its open end.

Abstract: An electric motor has a ferrous core extending along, rotatable about, and centered on an axis. This core is formed with axial slots and has opposite end edges centered on the axis. A winding extends along the slots of the core and has opposite axial ends extending axially beyond the core. A fan on the core circulates air axially over the core and winding. Respective deflector cages on the winding ends each include an inner ring, an outer ring fitted over the respective end edge of the core, and a plurality of ribs extending axially and radially between the rings and projecting generally axially from the respective winding end. The ribs are spaced apart on the respective winding end such that the winding end is exposed between the ribs. Thus on rotation of the rotor, particles blown by the fan are deflected by the ribs before they engage the winding ends.

Abstract: A portable chain saw wherein the motor drives a hub which is coaxial with a cylindrical portion of the shaft for one sprocket wheel of the chain. A coil spring is wound around the hub and the cylindrical portion to normally transmit torque from the hub to the shaft and to brake the shaft in response to its disengagement from the hub as a result of pivoting of a guard for one hand of the operator. The guard is pivoted by the one hand when the chain saw wobbles or performs other undesirable movements. The coil spring, the hub and the cylindrical portion together constitute a so-called wrap spring clutch wherein the spring rotates with the hub until arrested by a pin-shaped decoupling element which is movable radially of the hub by a second spring in response to pivoting of the guard.

Abstract: A portable electric grinder wherein the grinding wheel is held against rotation relative to the spindle by two annular clamping rings. The spindle has a motor-driven hollow outer shaft and an inner shaft which is installed in the outer shaft and can be held against rotation with the outer shaft by a manually depressible arresting member. One of the clamping rings rotates with the hollow shaft and the other clamping ring mates with the inner shaft. When the inner shaft is held against rotation and the motor is started for a short interval of time, the hollow shaft rotates the one clamping ring which rotates the grinding wheel and the other clamping ring by friction so that the grip of the clamping rings upon the grinding wheel is loosened and the grinding wheel can be fully separated from the spindle by completing the unscrewing of the other clamping ring from the inner shaft. The motor drives the hollow shaft through the medium of a step-down transmission.

Abstract: A hammer drill has clamping jaws which are provided, in addition to clamping surfaces for radial clamping a cylindrical tool shaft, also with additional axially extending guiding surfaces for axially non-rotatably holding and guiding of the tool shaft, and the tool shaft is provided with guiding grooves associated with the clamping jaws.

Abstract: A damping element for damping three-dimensional and torsional oscillations, in particular in hand tools, is proposed. The damping element includes an approximately bell-shaped rubber spring element defining a cavity which is filled with a damping fluid. The cavity is closed off at its open end with a rubber diaphragm. Within the cavity there is mounted at least one partition which defines overflow conduits or passages, and additional partitions at an angle to the partition defining the overflow conduits. The partition defining the overflow conduits is rigidly joined to a fastening sleeve situated in the rubber spring at the end thereof opposite to its open end.

Abstract: An overload protection arrangement for an electric motor, especially of a hand-held power tool, includes an electronic speed of rotation control arrangement which is, in turn, controlled by an overload circuitry which includes a positive temperature coefficient resistor situated in the winding of the electric motor and incorporated in a voltage divider. The output of the PTC-resistor is amplified by an amplifier and, when the temperature of the winding increases above an acceptable level, the maximum current which can be drawn by the electric motor is reduced to a level at which the winding cannot burn out even if the rotor of the electric motor is blocked. If the rotor can rotate freely, the speed of rotation thereof even at the reduced power input will be sufficient to assure rapid cooling of the device powered by the electric motor. A time-delay member consisting of a capacitor and a resistor is arranged in parallel with the operational amplifier.

Abstract: A hedge cutting arrangement has a cutting device, a drive motor for driving the cutting device, a coupling arranged between the cutting device and the drive motor, two handles for two-hand operation, and two switching devices including actuating members, wherein the coupling is connected with both actuating members so that even when only one of the actuating members moves to its switching off position, the cutting device disconnects from the drive motor.

Abstract: A switch includes an actuating element movable against a biasing force from a rest into a working position. The element is engageable with a member movable under a force of a predetermined magnitude applied thereto between a first position corresponding to the rest position of the element and a second position in which it displaces the element into the working position. The member is provided with a spring for urging the member against the applied force into the first position so as to release the actuating element. The member tends to prematurely move into the first position in response to a slight decrease of the applied force to a lever below the predetermined magnitude. The switch is further provided with an arrangement for preventing the premature movement of the member into the first position until after the applied force decreases below the above-mentioned level.

Abstract: A hammer drill has a housing and a spindle mounted on the housing for rotating and reciprocating longitudinal movement. The spindle has a leading end provided with an end portion extending outward through a hole in the housing, facing a wall to be drilled. The housing is provided with a motor rotating the spindle and a member which subjects the spindle, when the latter rotates, to reciprocating longitudinal movement.