Safety-valve arrangement on a hydraulic working cylinder

摘要

Safety-valve arrangement for protecting a hydraulic working cylinder (10) against damage or destruction due to the piston (18) running into the cylinder cap (14) at the end of the useful working stroke. The valve arrangement has a valve block (32) arranged on the outside of the working cylinder (10) and having two non-return valves (34; 36) connected in series and blocking in opposite directions, the non-blocking inflow sides of which are each hydraulically connected to one of the pressure-medium connections to the working spaces (20; 22) of the working cylinder (10). A plunger element (48) guided in the working-stroke end area of the piston (18) and into the valve block (32) transmits the movement imparted to it by the piston (18) when approaching the end position to the valve element of the non-return valve (36), which closes off the outflow-side working space (22) to prevent transfer of pressure medium under working pressure. The two working spaces (20; 22) of the working cylinder (10) are hydraulically short-circuited by opening this valve element. In addition, a pressure-relief valve (42) is provided in the valve block (32). The pressure-relief valve (42) prevents inadmissibly high positive pressures from arising in the outflow-side working space (22) or in the lines connected to the latter. <IMAGE>