<p>A pressure compensation valve (6) holds the pressure of the lower flow side of the variable throttle (8) of the changeover valve (2) by a specific pressure higher than pressure of the pilot line (13). A regulating mechanism (15,16) holds the pump delivery pressure higher by a specific pressure than the pressure of the pilot line. A positioning member is provided to which operating oil is fed after pressure compensation by the pressure compensation valve (6). Communicating outlets (30,31) of the changeover valve connect on the outflow side of the pressure compensation valve. A check valve (32) only permits flow from the side of the pressure compensation valve to the side of the first communicating outlet (30). A further such valve (33) functions identically but to the side of the second communicating outlet (31).</p>
