Written by the Hydraulic & Engineering Services workshop team, Strood, Kent. Reviewed against the Bosch Rexroth data sheet RE 23178 (WE 6 directional valves). Last updated 13 August 2026.
TL;DR: A Rexroth 4WE6 part number is read left to right in blocks. “4WE6” tells you it is a 4 way, size 6 (NG6 / CETOP 3) solenoid operated directional spool valve. The next letter is the spool symbol, which sets how oil flows in the neutral position (E is closed centre, H is tandem, J is float, G is open centre). “6X” is the design series. After the slash come the actuation and electrical details: the voltage (G24 is 24V DC, W230 is 230V AC), the manual override (N9 is a concealed pushbutton) and the electrical connection (K4 is an individual connection without a plug). So 4WE6E6X/EG24N9K4 is a size 6, closed centre, series 6X valve with a 24V DC solenoid, concealed override and DIN connection. The R9xxxxxxx code you often see is the Rexroth material (order) number, which is the stock reference for one exact build. Hydraulic & Engineering Services (HESL) stocks and identifies directional control valves ex-stock at its Strood trade counter. Send us the code or a photo and we will match it.
How do you read a Rexroth 4WE6 part number?
A Rexroth directional valve type code looks intimidating, but it is simply a string of blocks read from left to right, and each block answers one question about the valve. Once you know what each block means you can read almost any 4WE6 code off the body without a catalogue.
Take the most common code on the shelf, 4WE6E6X/EG24N9K4, and split it up.
| Block | What it means | In this example |
|---|---|---|
| 4 | Number of main ports (4 way: P, T, A, B) | 4 way |
| W | Directional spool valve (from the German Wegeventil) | Directional valve |
| E | Solenoid (electrically) operated | Solenoid operated |
| 6 | Nominal size NG6, which is CETOP 3 / ISO 4401-03 | Size 6 |
| E | Spool symbol (flow pattern in neutral) | Closed centre |
| 6X | Design series (60 to 69, the current generation) | Series 6X |
| /E | Actuation detail (wet-pin on/off solenoid) | Standard wet-pin |
| G24 | Solenoid voltage (G is DC, W is AC) | 24V DC |
| N9 | Manual override type | Concealed pushbutton |
| K4 | Electrical connection | Individual connection, no plug |
Read as a sentence, that code is a 4 way, size 6, closed centre, current series solenoid valve running on 24 volts DC, with a hidden hand override and a DIN style electrical connection. Everything a buyer needs is in those characters.
What does 4WE6 mean?
The first four characters are the family, and they are the part most people already half recognise.
The 4 is the number of main working ports: P (pump), T (tank), A and B (the two service ports that feed the actuator). A valve written as 3WE6 uses only three ports and is a 3/2 valve.
The W stands for directional spool valve. Rexroth uses the German abbreviation, so the letter never changes on this family.
The E means the valve is operated electrically, by a solenoid. If you see 4WEH6 instead, the H tells you the valve is pilot (hydraulically) operated, which is how Rexroth handles higher flows than a direct solenoid can shift.
The 6 is the nominal size, NG6. That is the same interface as CETOP 3 and ISO 4401-03, so a 4WE6 bolts onto any CETOP 3 subplate. If you are unsure how the size relates to flow, our guide to CETOP valve sizes explains why the number sets the maximum flow rather than the valve function. A size 6 valve passes up to around 80 litres per minute and is rated to 350 bar on the P, A and B ports, with a lower limit on the tank line.
Rexroth 4WE6 spool symbols explained
The single letter after the size is the most important choice in the whole code, because it decides what the valve does when it sits in the middle (neutral) position with no solenoid energised. Pick the wrong spool and the circuit will not hold a load, or the pump will not unload, however good the valve is.
| Spool code | Common name | Flow in neutral | Typical use |
|---|---|---|---|
| E | Closed centre | All ports blocked (P, A, B, T) | Holding a load or position, multiple actuators |
| H | Tandem centre | P to T open, A and B blocked | Unloading the pump to save energy while holding the load |
| J | Float centre | A and B open to T, P blocked | Hydraulic motors and cylinders that must free-wheel |
| G | Open centre | All ports interconnected | Simple low-pressure circuits, stacking several valves |
| C | Special | P open to A and B, T blocked | Regenerative and dual-pressure circuits |
These are the everyday spools. Rexroth publishes more than twenty symbols in total for the WE 6 range, including variants where the spool is offset to one side or has a defined overlap, so always match the exact letter on your valve. As a working rule: choose E to hold a load, H to unload the pump, and J for a motor. If a leaking or sticking spool is the actual problem rather than the spec, that is a repair rather than a re-order, and our hydraulic repairs team can strip and test the valve.
What does 6X mean in a 4WE6 code?
The 6X is the design or component series. It groups the valve into the 60 to 69 generation, which is the current standard build. Rexroth uses the series to signal a set of installation dimensions and internal features that stay consistent within that band, so a 5X (an older 50 to 59 series valve) and a 6X share the same mounting pattern and are generally a straight swap, while the newer series carries the latest sealing and coil design. When you replace like for like, a 6X is the safe default to specify unless a machine builder has called out something specific.
Decoding the part after the slash: voltage, override and connector
Everything after the slash describes how the valve is actuated and wired, and this is where two valves with identical hydraulics can differ.
Voltage is the block most people need. The letter tells you the current type and the number tells you the voltage. G means DC and W means AC, so G24 is 24V DC, G12 is 12V DC, W110 is 110V AC and W230 is 230V AC. Fitting a 24V coil to a 230V supply, or the reverse, is the single most common ordering mistake, so confirm the control voltage before you buy.
The manual override lets you shift the spool by hand for setup or in a power failure. N9 is a concealed pushbutton behind a protective cap, which is the standard fit. A code with no override is a solenoid-only build.
The electrical connection is the last common block. K4 is an individual connection to a DIN 43650 (Form A) plug, and the plug itself is usually ordered separately. Other codes cover LED plugs, flying leads or deutsch style connectors.
What do the R9xxxxxxx numbers mean?
Alongside the descriptive type code, every Rexroth valve also carries a material number that looks like R900561278 or R978017734. This is not a second specification. It is the order or stock number, the equivalent of a SKU, and each one maps to exactly one complete build of the valve.
That matters for two reasons. First, if you quote the R9 number, a supplier can pull the precise valve with no ambiguity, because the material number already contains every option baked into one reference. Second, if you only have the R9 number and not the type code, the supplier can still cross-reference it back to the full 4WE6 specification. Both directions work, which is why it is worth reading both numbers off the valve or the old delivery note before you enquire. If the label has worn off, a clear photo of the valve and its coil is usually enough for us to identify it.
4WE6 vs 4WE10: are they interchangeable?
No. The size number is not cosmetic. A 4WE6 is an NG6 (CETOP 3) valve with a 31 by 40.5 mm bolt pattern and a flow limit around 80 litres per minute. A 4WE10 is an NG10 (CETOP 5) valve with a larger 54 by 46 mm bolt pattern and a flow limit around 120 litres per minute. They will not bolt onto each other’s subplates and the ports do not line up, so you cannot swap one for the other without changing the manifold. If a circuit needs more flow than an NG6 can pass, the answer is to move up to NG10, not to force a size 6 valve to work beyond its rating.
When to repair, replace or re-specify a 4WE6
Reading the code correctly usually points to one of three actions. If the valve is simply worn or the coil has burned out, a like-for-like replacement using the same type code or R9 number is the quickest fix. If the valve sticks intermittently, the cause is very often contamination rather than the valve itself, and cleaning or repair with a system flush is the better call. If the machine has always run hot or held a load poorly, the spool symbol may have been wrong from the start, and re-specifying to a better-suited spool is worth the small extra cost. Our engineers can advise on all three, and for a system-level rethink the hydraulic design team can review the circuit rather than just swapping the part.
Where to buy or identify a Rexroth 4WE6 valve
Hydraulic & Engineering Services carries directional control valves, flow and pressure controls, pumps and motors on an ex-stock basis at its Strood trade counter, backed by next-day supply from the major manufacturers. If you have a code you cannot read, a valve with no label, or you are not sure which spool you need, send us the details and we will identify it and confirm availability. Visit the trade counter or send us your valve code.
Frequently asked questions
What does 4WE6 stand for?
4WE6 means a 4 way (four main ports), solenoid operated directional spool valve of nominal size 6 (NG6), which is the CETOP 3 / ISO 4401-03 mounting interface. The W is the German abbreviation for a directional valve and the E means it is electrically operated.
What is the spool symbol in a Rexroth valve code?
The spool symbol is the letter immediately after the size number, for example the E in 4WE6E6X. It defines how oil flows when the valve is in its neutral position. E is closed centre (all ports blocked), H is tandem centre (pump unloads to tank), J is float centre (service ports open to tank) and G is open centre (all ports connected).
What voltage is G24 on a Rexroth valve?
G24 means a 24 volt DC solenoid. In Rexroth codes the letter shows the current type, where G is DC and W is AC, and the number is the nominal voltage. So G12 is 12V DC, W110 is 110V AC and W230 is 230V AC.
What is the difference between the type code and the R9 number?
The type code (such as 4WE6E6X/EG24N9K4) is a descriptive string that spells out every option. The R9 number (such as R900561278) is the material or order number, a single stock reference that maps to one exact build. Either can be used to order or to cross-reference the valve.
Is a 4WE6 the same as a 4WE10?
No. A 4WE6 is size NG6 (CETOP 3) with a flow limit around 80 litres per minute, and a 4WE10 is the larger NG10 (CETOP 5) with a limit around 120 litres per minute. They have different bolt patterns and port layouts and are not interchangeable.
What does 6X mean in 4WE6?
6X is the design series, meaning the 60 to 69 generation, which is the current standard build. It sets a consistent group of mounting dimensions and internal features, and it is the default series to specify for a like-for-like replacement.