Abstract: A drive unit is described for switching circuit breakers on and off, in particular disconnecting switches and/or grounding switches of medium-voltage switchgear. The drive unit includes a reversible d.c. motor and a switching device containing two separately drivable and interlocked reversing switches, one assigned to each direction of rotation of the d.c. motor, their contacts performing the current reversal on the windings of the d.c. motor as required to reverse the direction of rotation. The drive unit further includes power contactors whose contacts have the required switching capacity for load switching. The all-or-nothing relays and safety switches are implemented by uniform low-power relays representing the direction of rotation, each having at least two electrically isolated relay contacts connected in parallel and also having an equalizing capacitor connected in parallel to each. Such drive units are used in connection with switchgear for power transmission and distribution.