There is a closed cavity in the lower base of the solenoid valve. There are through holes at different positions. Each hole leads to a different oil pipe. There is a valve in the middle of the cavity and two electromagnets on both sides. Which side of the magnet coil is energized? Which way will it be attracted? By controlling the movement of the valve body to block or leak out different oil drain holes, and the oil inlet hole is normally open, the hydraulic oil will enter different oil drain pipes, and then through the oil pressure Pushing the oil-rigid piston, the piston drives the piston rod, and the piston rod drives the mechanical device.