A solenoid directional valve is a core control component in hydraulic and pneumatic systems. It changes the direction of fluid flow to control the start, stop, and reversal of actuators such as hydraulic cylinders and motors. Its working principle is based on electromagnetism: when the solenoid coil is energized, it generates a magnetic field that attracts the iron core or push rod, moving the spool inside the body to open or close flow paths.

When de-energized, a return spring pushes the spool back to its initial position, enabling direction switching. By energizing different coils, two-position, three-position, and other configurations can be achieved to meet complex automation requirements. These valves are widely used in construction machinery (excavators, loaders), industrial equipment, and agricultural machinery.