Abstract: To create an additional steering angle for a vehicle, an actuator having a microprocessor-controlled electric motor functioning as the drive and a gear driven by said electric motor, is used to apply to the wheels the additional steering angle at the vehicle axle. The gear is a known constant-pitch planetary rolling-contact threaded-spindle gear (constant-pitch PRCTS gear) (12), consisting of a spindle rod (16), a spindle nut (14) surrounding the former, and a number of interposed rollers or rolling elements (18) with a groove profile (19) matching the thread (17) of the spindle rod (16). The rollers or rolling elements (18) are run on a number of guide rings (20) and interposed bearings (20), and placed at a fixed predetermined distance relative to the spindle nut (14) and to one another. The spindle rod (16) concurrently functions as the axis of the electric motor and is placed inside an electric motor rotor (9′).