Abstract: The invention relates to a drive unit for electric rail vehicles, wherein the hub (7) of a greater wheel (6) driven by an electric traction motor (1) via a pinion shaft (4) forms a hollow shaft stub which surrounds the shaft (9) of a wheel set with a defined play. By inserting a coupling (11) which is radially rigid but allows transverse and angular movements, the motor torque is transmitted to one of the wheels (10) of the wheel set. The axial mobility of the coupling (11) should not have any disturbing restoring forces or resilient forces. Therefore, the hub-side coupling half (11b) having a curved-teeth-shaped external toothing engages the wheel-side coupling half (11a) which is provided with a straight internal toothing. The wheel-side coupling half (11a) is detachably connected via coupling supports to the inside flank of a disk wheel (10) and the hub-side coupling half (11b) to the hub.