A solenoid valve is an electrically activated valve typically used to control the flow or direction of air or liquid in fluid power systems. Solenoid valve are used in both pneumatic and hydraulic fluid power systems, and most often in either poppet or spool configurations.
A hydraulic solenoid valve is a solenoid controlled directional valve used in a hydraulic system for opening, closing or changing the direction of flow of the liquid. The valve operates with a solenoid, which is an electric coil wound around a ferromagnetic core at its center.
The valve consists of various chambers also called ports. The solenoid is used for sliding the spool within the valve, opening or closing the ports. The spool is the cylindrical component which serves the function of the valve by either blocking or allowing the flow of liquid through these ports, depending upon its position.
Hydraulic solenoid valves are widely used in industries like manufacturing, aerospace, construction and many others that require hydraulic systems. Figure 1 is an example of a hydraulic solenoid valve.