Abstract: A system for the elimination of consequences of angular clearances in driving gears, especially in machine tool driving gears consisting of a dynamic electromagnetically operated brake and of a power unit for exciting said brake. The brake has a rotor coupled without play with a spindle and constituted by the rotor of an asynchronous motor. The brake also has an exciter with double push-pull windings connected with a power unit. The power unit consists of a hand-adjusted direction current source supplying the main excitation winding, and a section generating a current which supplies the other excitation winding. The current supplying the additional excitation winding 10 is proportional to the current absorbed by the driving motor and to the current supplying the main excitation winding.