System for steering steerable wheels of a trailer, comprising: - a hydraulic control circuit; - at least one hydraulic element for absorbing a movement of a vehicle pulling the trailer, which hydraulic absorbing element is connected for signal generation to the hydraulic control circuit, - at least one hydraulic operating element connected to the hydraulic control circuit and acting on a steerable wheel, and - means connected to the hydraulic control circuit for actively steering the steerable wheels, which active control means comprise a pump, wherein the hydraulic control circuit comprises at least one pressure-relief valve arranged between the at least one absorbing element and the at least one operating element and at least one non-return valve arranged between the pump of the active control means and the at least one operating element, wherein the at least one pressure-relief valve and the at least one non-return valve are integrated in a single valve unit, and wherein the at least one operating element acts in two directions and at least two integrated valve units connected in crosswise manner are incorporated in the hydraulic control circuit, characterized in that the at least one operating element has two chambers (15, 16) and a hydraulic conduit connecting the pump of the active control means to one of the chambers has a branch which is connected as control line to the integrated valve unit received in a conduit connecting the pump to the other chamber. - a hydraulic control circuit; - at least one hydraulic element for absorbing a movement of a vehicle pulling the trailer, which hydraulic absorbing element is connected for signal generation to the hydraulic control circuit, - at least one hydraulic operating element connected to the hydraulic control circuit and acting on a steerable wheel, and - means connected to the hydraulic control circuit for actively steering the steerable wheels, which active control means comprise a pump, wherein the hydraulic control circuit comprises at least one pressure-relief valve arranged between the at least one absorbing element and the at least one operating element and at least one non-return valve arranged between the pump of the active control means and the at least one operating element, wherein the at least one pressure-relief valve and the at least one non-return valve are integrated in a single valve unit, and wherein the at least one operating element acts in two directions and at least two integrated valve units connected in crosswise manner are incorporated in the hydraulic control circuit, characterized in that the at least one operating element has two chambers (15, 16) and a hydraulic conduit connecting the pump of the active control means to one of the chambers has a branch which is connected as control line to the integrated valve unit received in a conduit connecting the pump to the other chamber. wherein the hydraulic control circuit comprises at least one pressure-relief valve arranged between the at least one absorbing element and the at least one operating element and at least one non-return valve arranged between the pump of the active control means and the at least one operating element, wherein the at least one pressure-relief valve and the at least one non-return valve are integrated in a single valve unit, and wherein the at least one operating element acts in two directions and at least two integrated valve units connected in crosswise manner are incorporated in the hydraulic control circuit, characterized in that the at least one operating element has two chambers (15, 16) and a hydraulic conduit connecting the pump of the active control means to one of the chambers has a branch which is connected as control line to the integrated valve unit received in a conduit connecting the pump to the other chamber.