Abstract: The apparatus has a drive hub with a fixing pin and driving flange. A cross slide carrying a tool is displaceably guided in the flange. Displacement takes place by a guidance roller, which fits into a guidance groove of a planetary web of a planetary gear constructed as a cam plate. Together with a further similar planetary gear, the first planetary gear forms a planetary power split transmission, on which is superimposed the rotary movement of an annular motor. As a result of the rotary movement of the cam plate with the guidance groove the displacement of the cross slide is brought about. Using an envelope drive, the rotary movement of the motor is transferred to a tachoalternator with a pulse generator. The pulses of the pulse generator are processed in a processor, which controls the motor and therefore the displacement movement of the cross slide.