Abstract: A circular saw includes a clutch assembly to surround the rotating blade shaft of the saw. The blade shaft is rotated by a shaft having a gear at one end. The clutch assembly includes a clutch gear to engage with the rotating pinion. The clutch gear is held to the blade shaft by a shaft washer that has a frictional material laminated to one end. The shaft washer is pressed to the clutch gear by spring washers.

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: A door opener wich can be used for closed-circuit current operation as well s for working current operation, includes a door latch and a trimmer which can be moved for blocking and releasing the door latch, an armature which can be displaced for blocking or releasing the trimmer, an electromagnet for displacing the armature, whereby the armature can be moved between three consecutive armature positions, namely a first armature position, a second armature position, and a third armature position. The armature positions alternately provide a locking and releasing of the door latch. The door opener also includes a stop element, which can be displaced for delimiting the displacement path of the armature between a first stop position and a second stop position such that the first or third armature position is blocked.

Abstract: The blade holder includes a mounting portion for attachment to the reciprocating plunger of a power saw. The blade holder also includes an integral exposed portion provided with a slot for receiving a substantial portion of the shank of the blade. The slot is dimensioned with respect to the blade shank such that an edge of the blade shank projects from the slot. The exposed portion of the blade holder includes an external surface in opposed relationship with the slot. A resiliently biased wedging washer engages the exposed edge of the blade and the external surface for holding the blade in place.

Abstract: An electric door opener with a trimmer actuatable by an armature and a mat coil. The trimmer is adjustably positioned for the release or locking of a door opener latch. The door opener is useable as an electric no-load current door opener and as an operating current door opener because a selector device is provided to switch the armature-trimmer system between no-load current movement positions and operating current movement position.

Abstract: In the first embodiment, the distal end of a reciprocating plunger of a power saw includes a longitudinally extending cavity receiving a block-like wedge member. A planar wall of the cavity and a planar face of the wedge member are arranged for substantial coextensive engagement with respective opposed faces of the saw blade. A spring in the cavity engages the wedge member for urging the same outwardly of the cavity. A pin extends through the wedge and has its opposite ends received in slots in opposed walls of the plunger. These slots are inclined with respect to the longitudinal axis of the plunger and cooperate with the pin to form a cam to urge the planar surfaces into clamping engagement with the blade under the influence of the spring. The blade may be released by forcing the wedge inwardly of the cavity under finger pressure. In a second embodiment, a similar block-like wedge member cooperates with a U-shaped member mounted on the plunger.

Abstract: An automatic shaft lock for use in power tools with one end that carries implements such as screwdriver heads, drill bits and the like, permits use of the tool manually, i.e., without power. The locking mechanism allows rotation of the shaft by the motor but locks rotation of the shaft when torque is applied at the implement end or to the housing so as to allow manual use of the tool. In the preferred embodiment, a locking ring is concentric with an end of the spindle that is connected to the implement and also with an end of the output shaft driven by the motor. A wedging pin wedges against the locking ring to prohibit rotation of the spindle and the output shaft except when the spindle is driven by the output shaft which, when driven in either direction, traps the pin in a non-wedging position.