H-4WEH25E68/6HG24N9ETK4/B10D3

The H-4WEH25E68/6HG24N9ETK4/B10D3 valve is produced by Bosch Rexroth for the WEH Directional Spool Valves series. It is an electro-hydraulic directional unit intended to shift NG25 ports in hydraulic automation circuits. The electro-hydraulic actuation lets a small pilot signal move the spool so large flows can be directed with limited electrical power. A 24 V DC coil energizes the pilot stage, allowing direct connection to common machine control voltages. The nominal size NG25 provides passage dimensions suited to medium-flow industrial manifolds, while the ISO 4401-08-08-0-05 porting pattern matches standard sub-plate layouts. A maximum operating pressure of 350 bar at ports P, A, and B enables use in high-pressure power units. The spool identified by symbol E establishes the flow paths needed for typical cylinder control, and a hydraulic spool return re-centers the element when the pilot signal is removed. A Ø 1.0 mm throttle insert marked B10 limits pilot flow to stabilize shifting speed. Six mounting screw points secure the valve body firmly to the manifold to resist shock loads.

The valve accepts a pilot pressure up to 250 bar, giving ample margin above system transients while protecting the pilot stage. External port Y can be exposed to 210 bar in direct-current service so back-pressure does not hinder spool centering. Spring-centered operation needs at least 13 bar pilot pressure to override the centering force and initiate a shift. A secondary pressure limitation of 45 bar is specified for the d3 section to protect downstream components in regenerative circuits. Fluid cleanliness to ISO 4406 20/18/15 is required to maintain reliable spool movement and minimize wear; this limit keeps particle contamination from causing leakage or sticking. Installation uses M12 × 60 screws according to ISO 4762 so bolt stretch and clamping load meet industry practice. A surface coating up to 100 µm thick shields the housing from corrosion in humid plant environments, ensuring durability under long-term service.