A rotary feedthrough for a compressed air supply system is provided between a stator and a rotor rotating relative to this stator. A compressed air channel disposed in the stator is connected to a compressed air line and leads into an annular chamber formed in the rotor, from which at least one working channel leading to a consumer proceeds. The stator is connected in the region of the rotary feedthrough to a control line. A moment of friction occurring in the region of the rotary feedthrough resulting in premature wear is reduced by providing a switchable non-return valve in the annular chamber. Blocking elements which extend within the annular chamber concentrically to the rotational axis of the rotor are moveable into an open position by an actuating element, which is displaced from the stator in the direction of the blocking elements.