Rexroth WE directional valves are between the hydraulic control system and electrical control system conversion elements, it utilizes the suction of both ends of the solenoids to achieve the movement of the spool in valve house, in order changing the on or off of the oil tunnels, which called direction control. There are 4/3 and 4/2 way valves, 4 means 4 main connection ports, 3 or 2 means 3 or 2 directional position.