The task of pressure reducing valves in a hydraulic circuit is to maintain a rather constant outlet pressure despite a higher and changing inlet pressure. They are used when an hydraulic circuit with a higher pressure level (primary side) is to supply another circuit with a lower pressure level (secondary side), without affecting the higher pressure in the primary circuit. These valves are intended for the supply of control circuits with low flow requirements. There is a design related leakage flow which has to be led pressureless via port R to the tank. A reversal of the direction of flow is possible up to approx. 30% of Qmax . A by-pass check valve has to be provided for higher reversed flow. These pressure reducing valves feature a override compensation i.e. acting like a pressure limiting valve, if the pressure on the secondary side exceeds the set pressure e.g. due to external forces.