Abstract: A power tool has a drive mechanism with an output shaft which performs an intermittent rotary motion. The output shaft drives, via an overrunning clutch, a tool drive shaft to drive a tool, which thus performs a quasi-continuous rotary motion that, as the load on the machine increases, transitions increasingly into a discontinuous rotary motion. The power tool can advantageously be used as a hand-held power tool for screwing, drilling, sawing, sanding, and the like, a high output torque with a low reaction torque being achievable as a result of the intermittent drive mechanism.

Abstract: In a drilling device, a holder is provided that is displaceable with respect to a foot in a feed direction. A drilling machine tool is carried by the holder. An electromotor provides a feed drive for driving the holder in the feed direction. The drilling machine tool and/or the holder are displaceable relative to the feed drive in an opposite direction to the feed direction by overcoming a counterforce. A switching element monitors the relative displacement and enables a signal to be derived for stopping the feed drive if a predetermined value of counterforce is exceeded. Motor current is limited to a predetermined maximum value during operation of the device.

Abstract: A safety device for a tool powered by an electric motor. It has a main switch, electronic controls, and a tachometer-generator. In order to provide a device for switching off a motor as a function of motor speed that is simple and economical and that will retain the same nominal switch-off value for the total life of the device, a relay is wired in parallel with the motor and controls the supply of power to the motor through a relay contact.

Abstract: A safety device for an electric power tool, especially a portable tool. It has a main switch, electronic controls, a tachometer-generator, and a relay. The relay electrically parallels the motor, acts on the supply of current to the motor through a relay contact, and is activated through the tachometer-generator and through a subsequent safety circuit. To provide a means of switching off the motor at excessively high speeds that will be inexpensive to manufacture and that will maintain a constant switch-off reference speed throughout its life, the safety circuit consists of a synchronization stage, an adjustable timer stage, a processing stage, an ignition amplifier, and an output section.