Directional valves with fluidic operation, type WHWH valves are fluidic operated directional spool valves. They are used for the control of flow direction.1. Spring-centred valve: The main spool (2) is kept in the centre position by the return springs (3). If external control fluid enters main valve (1) from port X then enters left spring chamber (5) via cover (4), the main spool is pushed into the switching position. The oil of right spring chamber returns to tank from port Y. When the control fluid is cancelled, the main spool returns to centre position under the action of right spring force. And if the control fluid enters from port Y, then the main spring moves to left to switching direction and the oil of left spring chamber returns lo tank from port X.2. Hydraulic-centred valve: Pressure fluid acts on both sides of main spool (2) and main spool (2) is fixed by a locating sleeve. If one side of the main spool is unloaded, then it moves under pressure at opposite side to switch direction. If the control fluid enters left chamber of main valve from port X, the main spool moves right, the fluid of right chamber returns to tank from port Y; and if the control fluid enters right chamber from port Y, the main spool moves left, the fluid of left chamber returns to tank from port X. Internal leakage oil directly returns to tank from port L.Switching time adjustment (see WEH)Flow area when valve is in central position (see WEH)Characteristic curve (see WEH)Performance limits (see WEH)Technical data (see hydraulic part of WEH technical data)Additional device (stroke adjustment) (see WEH)WH.pdf