These valves are used for controlling flow rate of the hydraulic circuit and eventually controlling speed of the actuator precisely.These valves are pressure compensating type (QF) and flow compensating type with integral check valve (QDFT). The former consists of valve body, pressure compensator; the latter includes valve body, thin blade type restrictor and restrictor, pressure compensator and a check valve. These valves can maintain a constant flow rate independent of the system pressure (load). Also blade restrictor may reduce sensitivity of throttled flow against oil viscosity QDEF type valve with an integral check valve allows a controlled flow and reverse free flow.

QDFT - B * * - Y₁