• A check valve is the simplest type of directional control valve used in hydraulic systems.Check valves allows flow of fluid in one direction and blocks in opposite direction.

Application of check valve

• Meter in circuit, meter out circuit, sequencing circuit, loading and unloading circuits etc.

• Figure shows a meter-in circuit with control of extend stroke.

• The inlet flow into the cylinder is controlled using a flow-control valve. In the return stroke, however, the fluid can bypass the needle valve and flow through the check valve and hence the return speed is not controlled.

• This implies that the extending speed of the cylinder is controlled whereas the retracing speed is not.