Abstract: An electric motor has a switching device, a driving circuit connectable to a voltage supply through the switching device and having a drive shaft, a mechanically acting braking device for braking the drive shaft when disconnecting the electric motor from the voltage supply, a rotor serving to generate torque and acted upon by a mechanical braking force when switching off the voltage supply, at least one radially displaceable part which applies the braking force and is magnetizable and acted upon by an electromagnetic releasing force which is directed opposite to the braking force and is greater than the braking force, and a stator having an axial slit which is overlapped by the part, and at least one shorted turn arranged in an area of the slit.

Abstract: A handheld machine tool, for example a circular saw, has a disk-shaped tool which is driven in rotation in a housing which holds a drive motor and a tool shaft carrying the tool. The tool can be clamped between a clamping nut, a clamping screw, and two supporting flanges. One supporting flange can be rotated easily relative to the tool shaft without use of auxiliary tools and is supported with an extensive friction at the tool. This supporting flange can be dependably clamped or loosened without tools. The machine tool further has an adjusting device which is coupled with that supporting flange to displace the latter axially toward the tool when that supporting shaft is rotated relative to the tool shaft due to rotational driving. The adjusting device therefore clamps the tool with an increasing force and tries to displace that supporting flange axially away from the tool automatically when the tool is stopped and accordingly reduces the clamping force.

Abstract: The hand-held machine tool has a tool holder (20) provided with a receptacle (19) into which a shaft portion (15) of a tool (16) is axially insertable. The tool holder (20) has a longitudinal axis (11) and includes a guide device (18) for axially guiding the tool (16); a device (23) for rotary slaving of the tool (16); a retaining device (28) for axially securing the tool (16) and a locking member (34) for locking the retaining device (28) in an open configuration for insertion or removal of the tool (16). The retaining device (28) is located in front of the guide device in an insertion direction of the tool (16) in the tool holder (16). The retaining device (28) is provided with an opening (31) for passage of the tool (16) through it.

Abstract: A series-wound motor, wherein, for braking purposes, the polarity of the armature of the motor is reversed for the opposite direction of rotation. The current supply for the motor is maintained until the armature comes substantially to a standstill and subsequently, the current supply to the motor is interrupted. The braking time is controlled in dependence upon operating parameters. For example, the braking time can be controlled by a predetermined time constant for the interruption of the current supply. To prevent running in the opposite direction, a reversal preventing device can be provided.

Abstract: A hand-held power tool, particularly hand-operated angle grinder has a device housing having a motor housing receiving an electric drive, a gear head arranged at one end of the motor housing and having a projecting drive spindle for a tool, and a handle arranged at another end of the motor housing and having a switch strip for switching the electric drive on and off, at least one of the handle and the gear head forming a rotatable housing part and being rotatable relative to the motor housing around a longitudinal axis of the motor housing. A manually actuated positioning device fixes the rotatable housing part in at least two different rotational positions, while the motor housing being provided with a central bearing neck, the rotatable housing part being provided with a rotating cross which is received on the bearing neck so as to be rotatable and secured against axial displacement, the positioning device being formed to cause a positive-locking engagement between the motor housing and the rotating cross.

Abstract: A motor-driven hand-held machine tool with spindle brake, in particular an angle grinder (1), has a device for clamping a disk-shaped tool (33, 83) at a work spindle (7, 67) between an inner flange (29, 79) and an outer flange (31, 81) which has a central bore hole (39, 84) overlapping the work spindle (7, 67) with play. The outer flange (31, 81) can be screwed on a fastening thread (37, 85) against the working rotational direction of the work spindle (7, 67). The hand-held machine tool is designed in such a way that the clamping pressure on the tool (63, 83) between the inner and outer flange (29, 31, 79, 81) can be increased when the work spindle (7, 67) is braked and the tool (33, 83) continues to rotate because of the inertia resulting from the braking so that the tool (33, 63) cannot be loosened from the work spindle (7, 67) unintentionally when the latter is braked.

Abstract: The armature (1) for high-speed electric motors force-ventilated in air containing abrasive dust, in particular in electric tools including right angle grinders, has windings which are laid in slots (7) of an armature laminate stack (5), and are held down in the slots (7) by elongated, elastic slot seals (15), and forth winding overhangs (9, 11) on the end faces of the armature. To increase the strength of the armature winding, the resistance to cooling air containing abrasive dust, and to improve the cooling, the slot seals (15) project over the slots (7), follow the contour of the winding overhangs (9, 11), in particular along surface lines, in the armature longitudinal direction, extend up to the end faces of the armature (1), and their ends are secured there by a ring (19) or cord winding (17).

Abstract: A power hand tool has a gear box casing having an opening, at least one high speed shaft extending through the opening, sealing member for sealing the gear box casing against lubricant leakage. The sealing member includes a sealing washer which does not rotate and sits tightly on the shaft and which radially touches a circumference of the opening. The sealing washer is composed of an elastic material which can absorb and release lubricant.

Abstract: A device for axially clamping a disc-shaped tool on a flange of a driven spindle with a threaded end, includes a clamping nut, a clamping disc supported on the clamping nut for biasing the disc against the flange and connected with the clamping nut for joint rotation therewith and axial displacement relative thereto, and supporting bodies arranged between the clamping nut and the clamping disc. An actuating member is located between the clamping nut and the clamping disc, and rolling bodies are displaceable along guide paths defined by guide tracks of the supporting bodies and guide track means of the actuating member for radially loading the supporting bodies. An insert member is supported between the clamping nut and the clamping disc and includes a plurality of stops projecting into the guide paths.

Abstract: To provide sufficient magnetization to the field of a series motor when the series motor is to be operated in dynamic braking mode, with a dissipating resistor or short circuit element (4) connected across the armature (5), a circuit connection is established between one of the main terminals of the motor through the series field to supply a minimum magnetization current, at least when the motor operates under dynamic braking conditions, typically a few to up to 15% of no-load current of the motor. This is sufficient magnetization so that, even in larger motors where remanent magnetism of the field structure is insufficient, reliable dynamic braking can be ensured. A switch (S; S.sub.1, S.sub.2) selectively connects the motor armature for motor drive or running operation and dynamic braking operation.

Abstract: The clamping device for portable grinding machines is part of the clamping nut, which can be screwed on the threaded spindle portion of the drive spindle (10) at its free end for tightening a grinding disk. The clamping nut carries a non-rotatable and axially displaceable clamping disk. Both contain annular surfaces (25, 26) which complement one another approximately so as to form a ball groove, and balls serving to support the clamping disk can roll along these annular surfaces. The clamping disk and clamping nut are coupled via coaxial longitudinal pins which simultaneously form ball stops. A ring with a ball groove sits axially between the clamping disk (21) and the clamping nut, and radial pins projecting into the ball track press against the balls via springs. The annular surface of the clamping disk contains ball cut-out portions, the balls penetrating into the ball cut-out portions when the actuating member is rotated accompanied by axial relieving of the clamping disk (FIG. 1).

Abstract: A clamp device for clamping a disc tool to a driven spindle and comprising a clamp nut, a clamp disc, and an arrangement for connecting the clamp disc to the clamp nut and which arrangement includes a ring having an inner track in which a plurality of rolling members are displaceable and are spring biased against respective stops projecting from at least one of the clamp nut and the clamp disc, and which is rotatable against a spring force to release the clamp disc from the clamp nut.

Abstract: A device for releasable mounting of a disk-shaped tool on a working spindle, comprises two flange members arranged to abut against the tool, supporting elements arranged to support one of the flange members against its axial displacement on the working spindle, wherein the supporting elements are releasable so as to unload the one flange member from a clamping pressure and formed as rolling bodies, arranged between the working spindle and the one flange member and displaceable transversely to their supporting direction into a deviating space.

Abstract: A safety claw clutch wherein the adjacent end faces of driving and driven rotary clutch elements have alternating claws and recesses and the driven clutch element is biased axially against the driving clutch element by a spring. The bottom surfaces in the recesses of the clutch elements make a first acute angle with a plane which is normal to the common axis of the clutch elements and the front surfaces of claws of the driving clutch element (and hence the rear surfaces of claws of the driven clutch element) make with such plane a second acute angle which is larger than the first acute angle. The top surfaces of the claws are parallel to the respective bottom surfaces.