Direct-acting solenoid valve, the coil is energized, and the electromagnetic force lifts the valve stem and the main spool. The auxiliary valve port and the main spool are opened, and the main spool in the solenoid valve is completely lifted. The pressure in the upper cavity behind the valve quickly disappears and the medium circulates.
Pilot solenoid valve, coil energized. First, the electromagnetic force lifts the valve stem and the pilot port opens. The pressure in the upper cavity of the solenoid valve is released through the pilot hole, and the main spool is opened for circulation under the action of pressure difference.