Abstract: A locking device for use in motor-vehicle steering systems, the locking device having a blocking mechanism by which a pitman arm shaft can be locked, a steering wheel of the motor vehicle can be prevented from rotating and vehicle wheels of the motor vehicle can be prevented from being turned or steered. The blocking mechanism includes two end positions, one of which is unlocked and one of which is locked, and is electromechanically operable. An electromagnet causes concentric external gear teeth of the pitman arm shaft to mesh with internal gear teeth of an axially movable and radially non-rotatable locking ring so that the pitman arm shaft is not rotatable in the locked state.