Abstract: A device for and method of preventing accidents caused by jamming of a tool when working with hand-operated machine tools driving a rotating tool, especially hammer drills, is outfitted with an interrupter device for interrupting the action of the driving motor on the rotating tool depending on the operating state detected by a deflection sensor (1). The device includes a computer unit (R) in which a probability for an expected accident is determined from the sensor signals supplied by the deflection sensor (1), and in that the interrupter device (5, 6) can be activated when a preset accident probability is exceeded. In the method rotational movement values are determined from the measurement signals supplied by the deflection sensor (1), these rotational movement values are converted in a computer unit (R) by nonlinear logic operations to form accident probabilities and activating the interrupter device as soon as the estimated accident probability exceeds a preadjustable threshold value.

Abstract: A pot-shaped grinding wheel having a circular grinding region provided with a plurality of segment-like grinding members (5), a circular seat region (4) coaxial with an axially spaced from the grinding region (2), a transition region (3) extending between an inner contour of the grinding region (2) and an outer contour of the seat region (4) and tapering toward the outer contour of the seat region (4), and at least one bore (6) extending parallel to an axis of the grinding wheel and arranged in the grinding region (2) and at least one bore (7) likewise extending parallel to the grinding wheel axis and arranged in the transition region (3).

Abstract: A rotor for an electric motor, including a shaft (1), a lamination parcel (2) and a current distribution element (3), which are mounted on the shaft (1) coaxially therewith and for joint rotation therewith, and insulating sleeve members (4,5) coaxially mounted on the shaft (1) one behind another for insulatingly supporting, respectively, the lamination parcel (2) and the current distributions element (3) on the shaft (1).