constructional unit with the differential gear 22 provides the opportunity for compressing functions since the differential gear 22 and the switching stage or switching device 52 respectively can form one unit in addition it is possible in an especially simple manner to actuate the parking brake element by means of the actuator 64 by means of which the first switching element 54 is also actuated fig2 shows a schematic illustration of a second embodiment of a propulsion device 10 according to the present invention parts corresponding with those in fig1 are denoted by identical reference numerals the description below will center on the differences between the embodiments in this embodiment provision is made for planetary gear 38 of the planetary gear 38 which has a stationary gear ratio i 0 in an advantageous range of i 0 u2212 0 54 u2212 53 with wherein z a designates the number of teeth of the hollow gearwheel 40 and z b designates the number of teeth of the hollow gearwheel 40 in addition the respective planet gearwheel 46 is embodied as a double planet gearwheel so that the planet gearwheel 46 has two planet gearwheel elements 66 and 68 which are connected to one another in a torsion proof manner in this case z p1 designates the number of teeth of the planet gearwheel element 66 and z p2 number of teeth of the planet gearwheel element 68 the planet gearwheel element 66 is in engagement with the hollow gearwheel 40 and the planet gearwheel element 68 is in engagement with the hollow gearwheel 40 fig3 shows a schematic illustration of a third embodiment of a propulsion device 10 according to the present invention in this embodiment.