a transmission with variable mechanical prestress including a pinion driven by an electric motor , a driven gearwheel with its bearings in a housing , and an electromagnetic actuator for applying a prestress force which is controllable in dependence on an instantaneous load to be handled by the transmission . the electric motor with the pinion is supported so that it can be tilted relative to the housing . owing to a tilting movement of the electric motor caused by the actuator , the pinion is pressed against the gearwheel with a certain prestress force in a radial direction . the transmission is free from play , while the virtual play arising from friction and hysteresis is strongly reduced , and the positioning accuracy is enhanced as a result .