Patent ID: 7905317

Claim:
A superimposed steering system for a vehicle, comprising: a variable ratio gear unit including a first gear unit input shaft and a second gear unit input shaft and configured as a harmonic drive for superimposition of rotational angles which occur at the two gear unit input shafts onto a gear unit output shaft of the variable ratio gear unit, the gear unit output shaft adapted to act on an input shaft of a steering gear, the first gear unit input shaft operatively connected to a steering handle by a steering shaft and the second gear unit input shaft operatively connected to a servomotor, the first gear unit input shaft connected releasably to a radially flexible flexspline of the harmonic drive and penetrating an eccentric drive core of the harmonic drive, the eccentric drive core protruding into the radially flexible flexspline, the servomotor is supported on one of (a) another component, fixed to the vehicle, of the superimposed steering system and (b) the vehicle other than on a steering column, wherein the gear unit output shaft rotates relative to the first gear unit input shaft.