Abstract: A rotational speed superimposing device for a vehicle steering system has an input shaft with an output shaft, which is oriented toward the input shaft in the axial direction thereof, and has a supporting arrangement, which positions the input shaft and the output shaft so that they are at least, in part, rotationally mounted. An auxiliary drive provided with a rotor, which is connected in a rotationally fixed manner to a wave generator, such as an oval disk on whose periphery an external toothed flexible ring is directly or indirectly mounted, this external toothing engaging in an internal gear at least at two opposite peripheral points. The supporting arrangement is fixed to the vehicle body. The output shaft is connected in a rotationally fixed manner to the internal gear, and the input shaft is connected in a rotationally fixed manner to the external toothed flexible ring. The input shaft and the output shaft are mounted so they freely rotate independently of one another.