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 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 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 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 . <EOS>