4/3, 4/2 and 3/2 directional valve with fluidic actuation
Type WH 10, 16, 25 and 32
– Valves used to control the start, stop and direction of a fluid
– Hydraulic operation (WH)
– Porting pattern conforms o DIN 24 340 form A,ISO 4401 and
Function and configuration
Valves of type WH are directional spool valves with hydraulic
operation. They control the start, stop and direction of a flow.
1. Spring-centered 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 to tank from port X.
Structure chart of valve type WH25 with spring-centered.
Structure chart of valve
type WH25 with spring-centered
2. Hydraulic-centered 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.
Structure chart of valve type WH25 with
Switching time adjustment (see WEH) Flow area
when valve is in central position (see WEH)
Characteristic curve (see WEH)
Technical data (see hydraulic part of WEH
Performance limits (see WEH)
Additional device (stroke adjustment)
1. All control oil are external supply and external drain.
2. Control pressure in port X and port Y is not allowed to exceed
Connection dimensions and sub-plate
1. The same size of type WH and type WEH share same installation,
connection dimensions and sub-plate.
2. Regarding dimensions, only the height of type WH is different
from that of type WEH.
For type WH, there is a cover (height: 12mm) on top of the main
Also switching time adjusted can be topped with a height of 40mm.
Details see WEH.