The task of pressure reducing valves in a hydraulic circuit is to maintaina rather constant outlet pressure despite a higher and changing inletpressure. They are used when an hydraulic circuit with a higher pressurelevel (primary side) is to supply another circuit with a lower pressure level(secondary side), without affecting the higher pressure in the primarycircuit. These valves are either directly controlled (type ADM) or hydraulically piloted (type VDM). There is a design related leakage flow which has to be led pressurelessvia port L to the tank. A reversal of the direction of flow is possible up toapprox. 50% of Qmax . A by-pass checkvalve has to be provided for higher reversed flow. The pressure reducing valves type ADM feature a override compensation i.e. acting like a pressure limiting valve, if the pressure on the secondary side exceeds the set pressuree.g. due to external forces.