Bosch Rexroth 4WEH Pilot-Operated Directional Spool Valve

Overview

The Bosch Rexroth 4WEH is a pilot-operated directional spool valve with electro-hydraulic actuation, designed for flows that are too large for a direct solenoid valve. It is part of the Rexroth WEH and WH family described in data sheet RE 24751, covering sizes 10, 16, 25 and 32 in component series 4X, 6X and 7X. A small solenoid pilot valve shifts the main spool hydraulically, so the valve controls start, stop and direction of flows up to 1100 l/min at operating pressures up to 350 bar. The hydraulic version WH is actuated by an external pilot signal instead of a solenoid pilot.

Seven Star LLC supplies the Bosch Rexroth 4WEH and related WH valves to plant maintenance teams, hydraulic contractors and OEM packagers in the Sultanate of Oman and the GCC. High-flow directional valves of this type control large cylinders and hydraulic motors on presses, steel and aluminium plant machinery, marine and offshore equipment and heavy material handling systems, so exact replacement matters when production depends on them. Our team in Muscat provides engineering support, helping decode the type designation, including size, spool symbol, pilot oil routing, voltage and options, before supply.

Operating Principle

The Bosch Rexroth 4WEH consists of a main valve with housing, main control spool and return springs, and a pilot control valve, normally a size 6 solenoid valve, mounted on top. When a pilot solenoid is energised, the pilot spool directs pilot oil into one spring chamber of the main valve. The pressure on that end face moves the main control spool into the switching position and connects the required working ports. The opposite spring chamber is unloaded to tank through the pilot valve. When the solenoid is switched off, the pilot spool returns to its initial position, the spring chamber is unloaded and the springs return the main spool to zero or its initial position.

Pilot oil can be taken internally from channel P or supplied externally through port X, and the pilot return can be internal or external through port Y. The data sheet lists minimum pilot pressures for each configuration, for example 12 bar for a spring-centred 3-position size 10 valve with external pilot supply, and a maximum pilot pressure of 250 bar for most sizes. Besides spring centering, pressure centering and hydraulic end positions are available. This arrangement lets the Bosch Rexroth 4WEH use a small solenoid to control a very large flow with low electrical power and predictable switching behaviour.

Engineering Design of the Bosch Rexroth 4WEH

The Bosch Rexroth 4WEH is designed for subplate mounting with porting patterns according to ISO 4401 and NFPA T3.5.1 R2, namely ISO 4401-05-05-0-05 (NFPA D05), ISO 4401-07-07-0-05 (D07), ISO 4401-08-08-0-05 (D08) and ISO 4401-10-09-0-05 (D10) across the size range. It is available as a 4/3-, 4/2- or 3/2-way valve, with wet-pin DC or AC solenoids on the pilot stage and electrical connection as individual or central connection. Weight ranges from about 6.4 kg for a size 10 valve with one solenoid to 41 kg for a size 32 valve with two solenoids.

Options listed for the Bosch Rexroth 4WEH include manual override, switching time adjustment (S and S2 sandwich plates), a pressure reducing valve D3 for the pilot supply, a preload valve in channel P of the main valve, and stroke setting or spool position monitoring. The H-4WEH high-pressure version is rated at 350 bar at ports P, A and B, while the standard W.H version is rated at 280 bar. With internal pilot return the tank port is limited to 210 bar with DC solenoids and 160 bar with AC solenoids, which must be checked when the valve replaces an older unit.

Key Features

The Bosch Rexroth 4WEH combines high flow with flexible configuration, as summarised below.

• Sizes 10, 16, 25 and 32 handle flows up to 1100 l/min, depending on size and spool symbol.
• Maximum operating pressure is 350 bar at ports P, A and B in the H-version and 280 bar in the standard version.
• Actuation is electro-hydraulic (WEH) or purely hydraulic (WH), with internal or external pilot control.
• The 4/3-, 4/2- and 3/2-way versions are offered with many spool symbols for different circuit functions.
• Spring centering, pressure centering, spring end position or hydraulic end position can be selected.
• Porting of the Bosch Rexroth 4WEH follows ISO 4401 and NFPA T3.5.1 R2, so the valve fits standard subplates and manifolds.
• Switching time adjustment, stroke setting, preload valve and pilot pressure reducing valve are available as options.
• The pilot stage uses wet-pin DC or AC solenoids with individual or central electrical connection.

Industrial Applications

In Oman and the wider Gulf, the Bosch Rexroth 4WEH is typically used on press lines and forging equipment, aluminium and steel plant machinery in Sohar, large hydraulic power units for gates, bridges and dam structures, marine steering and deck machinery, offshore crane and winch systems, and test rigs that need to switch high flows quickly. On the Bosch Rexroth 4WEH, the optional switching time adjustment is useful on heavy cylinders where a gentle start and stop prevents pressure shocks and protects pipework, and the pressure-centred versions suit machines that need a defined spool position with large flow forces.

Seven Star LLC supplies the Bosch Rexroth 4WEH with other Rexroth hydraulic components, such as the Bosch Rexroth A10VSO axial piston variable pump, the Rexroth DB10G2-5X/50 pressure relief valve and the Bosch Rexroth R928006678 hydraulic filter element. The data sheet specifies a maximum contamination level of class 20/18/15 to ISO 4406 (c), so we often supply valves and filter elements together for customers in Muscat, Sohar, Duqm and Salalah.

Technical Specifications

Bosch Rexroth 4WEH and WH data below are taken from data sheet RE 24751 (edition 2018-12); performance limits per spool symbol are given in the data sheet curves.

How to Order

To order the Bosch Rexroth 4WEH, send Seven Star LLC the complete type code from the valve nameplate, or the size, spool symbol, pilot oil configuration, voltage and options you require. Our hydraulics team in Muscat will confirm the variant against the manufacturer data, share the technical datasheet for download and issue a formal quotation. Seven Star LLC supplies Rexroth valves to customers in Oman and the GCC with engineering support.