WH WEH 3WH 3WEH 4WH 4WEH Internally Pilot Operated Externally Pilot Operated 3/2 , 4/2 , 4/3 Hydraulic Directional Valves

Valves of type WEH are directional spool valves with electrohydraulic actuation. The control the start, stop and direction of a flow.

These directional valves basically consist of the main valve with housing (1), main control spool (2), one or two return springs (3.1) and (3.2), as well as pilot valve (4) with one or two solenoids "a" (5.1) and/or "b"(5.2).

Main control spool (2) in the main valve is held in the zero or initial position by springs or through pressurization. In the depressurized condition, the two spring chambers (6) and (8) are pressureless connected to the tank via pilot valve (4). The pilot valve is supplied with pilot oil via pilot line (7). The supply can be provided internally or externally (externally via port X).

When the pilot valve is operated, e.g. solenoid "a", pilot spool (10) is pushed to the left and spring chamber (8) is therefore pressurized to pilot pressure. Spring chamber (6) remains pressureless.

The pilot pressure acts on the left side of main control spool (2) and shifts the latter against spring (3.1). In the main valve, port P is consequently connected to B and A to T.

When the solenoid is de-energized, pilot spool (10) returns to its starting position (except for impulse spool). Spring chamber (8) is unloaded to the tank.

The pilot oil is drained internally (via channel T) or externally (via channel Y).

An optional manual override (9) allows pilot spool (10) to be moved without energization of the solenoid.