Abstract: A steering drive system for a wheel side steered vehicle includes a coupling element couplable to output drives of the vehicle in order, when an amount of a superposition rotational speed of the coupling element is greater than zero, to provide at the output drives, which are driven at a basic rotational speed on the basis of a travel drive system of the vehicle, for steering the vehicle a superposition rotational speed which is to be superposed on the basic rotational speed. The system further includes at least one first electric machine whose rotational speed can be variably set or controlled, with a power summation and/or power branching unit, wherein a first connection of the power summation and/or power branching unit is coupled to a shaft which can be coupled, in particular via a defined transmission ratio, to a shaft of the travel drive system.