As a rule, hydrodynamic transmissions are used in motor vehicles as continuously variable gearboxes. As in the case of a torque converter, the driving factor is the liquid that swirls between the blades of the rotors. The converter has a fixed rotor-shaped element, the so-called. the steering wheel (in addition to the driving pump and driven turbine). The steering wheel makes it possible to increase the value of the transmitted torque, according to the instantaneous load.
In cars, the torque converter ratio is insufficient. Therefore, usually the torque converter is combined with a multi-speed mechanical gearbox, in which individual gears are switched on by means of an additional automatic control system. Such an assembly is called a hydromechanical gearbox.