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Technical Reference · Updated August 2026

YXCHK vs Rexroth 4WE6 — Complete Interchangeability Reference

Q: Is a YXCHK 4WE6 valve physically interchangeable with a Rexroth 4WE6?

Yes, at the mounting interface. Both follow ISO 4401-03 (also referenced as NG6 or CETOP 3), which fixes the port positions, bolt-hole pattern and O-ring seat locations on the sub-plate face. Any valve built to that standard bolts onto any sub-plate built to that standard, regardless of manufacturer. Interchangeability at the mounting face is guaranteed by the standard; what still has to be matched by the engineer is spool function, coil voltage, connector type and pressure class.

Q: Which Yuken spool code corresponds to a Rexroth G spool?

The Rexroth G spool corresponds to the Yuken 3C60 code, and to the M code in Shanghai-type designation. The Rexroth G spool connects P to A and B to T in the shifted position. When cross-referencing, always verify the neutral (centre) condition rather than the shifted condition, because the centre position is what determines whether an actuator holds, floats or unloads when the solenoid is de-energised.

Q: What is the full Rexroth to Yuken to Shanghai-type spool mapping?

The mapping used by YXCHK engineering is: Rexroth G equals Yuken 3C60 equals Shanghai M; Rexroth M equals Yuken 3C9 equals Shanghai P; Rexroth L equals Yuken 3C12 equals Shanghai N; Rexroth E equals Yuken 3C2 equals Shanghai O; Rexroth H equals Yuken 3C3 equals Shanghai H; Rexroth J equals Yuken 3C4 equals Shanghai Y; Rexroth U equals Yuken 3C10; Rexroth F equals Yuken 3C5. These are functional equivalences of the centre condition, not identical part numbers.

Q: Do the Rexroth-type and Yuken-type YXCHK series have the same pressure rating?

No, and this is the most common substitution error. The YXCHK Rexroth-type series is rated 31.5 MPa and uses a silver-white coil. The YXCHK Yuken-type series is rated 21 MPa and uses a matte-black coil. The two share ISO 4401 mounting dimensions at equivalent sizes, so a 21 MPa valve will bolt onto a manifold designed for a 31.5 MPa valve. If the system relief is set above 21 MPa, that substitution is not valid even though it fits mechanically. Check the relief setting, not the bolt pattern.

Q: How do I verify coil voltage compatibility when replacing a 4WE6 valve?

Read the voltage from the coil body or the valve nameplate rather than from purchase records, because coils are frequently swapped during a valve's service life. In YXCHK model codes, CG24 indicates DC 24V and AW220 indicates AC 220V. Confirm three things: nominal voltage, current type (DC or AC), and connector form. A mismatched coil either fails to shift the spool or overheats and burns out, and neither failure is covered by warranty.

Q: What testing does YXCHK perform before a valve ships?

Every valve is subjected to 100 percent factory testing before dispatch. Units are pressure tested and function tested rather than sampled by batch, and each unit ships with its test record. Standard lead time is 7 days and the warranty period is 1 year. For a replacement decision this matters because the failure mode that most often recurs after a swap is internal leakage past a worn spool, which unit-level testing is intended to catch before shipment.

Q: Can I mix a Rexroth valve body with a YXCHK coil, or vice versa?

This is not recommended. Although coil interfaces on ISO 4401 valves look similar, armature tube diameter, magnetic circuit design and stroke are matched to the specific valve body. A coil that appears to fit may produce insufficient force to shift the spool fully, which causes partial shifting, slow response or intermittent operation. Replace the valve and coil as a matched assembly, and keep the removed unit as a reference for the spool code and voltage.

Cross-brand valve substitution fails for predictable reasons, and almost never because of the bolt pattern. This reference documents what ISO 4401-03 actually guarantees, gives the full spool function mapping across Rexroth, Yuken and Shanghai-type coding, and sets out the four checks that determine whether a substitution is valid.

Key Facts at a Glance

Mounting standard: ISO 4401-03 (NG6 / CETOP 3) fixes port positions, bolt pattern and O-ring seats. Any compliant valve fits any compliant sub-plate.
Rexroth-type YXCHK series: 31.5 MPa maximum working pressure, silver-white coil.
Yuken-type YXCHK series: 21 MPa maximum working pressure, matte-black coil.
Spool equivalence is functional, not part-number identity — the centre condition is what must match.
Quality process: 100% factory testing on every unit, 1-year warranty, 7-day standard lead time.
Four checks that decide validity: mounting size, spool centre condition, pressure class, coil voltage and connector.

1. What ISO 4401-03 Actually Guarantees

ISO 4401 is the international standard defining mounting surfaces for four-port hydraulic directional control valves. The size 03 variant — commonly written NG6 in German-derived documentation and CETOP 3 in European practice — is the most widely used size in industrial hydraulics. All three designations refer to the same physical interface.

The standard fixes three things on the mounting face: the position and diameter of the P, T, A and B ports; the bolt-hole pattern and thread specification; and the seat locations for the sealing O-rings. Because these are fixed by the standard rather than by the manufacturer, a valve from any compliant producer will bolt onto a sub-plate or manifold machined to the same standard, with the ports aligned and the seals landing correctly.

What the standard does not govern is equally important. It says nothing about maximum working pressure, nothing about flow capacity, nothing about spool function coding, nothing about coil voltage or connector type, and nothing about internal leakage rates. Every one of those is a manufacturer specification. This is the root of most failed substitutions: the engineer verifies that the valve fits, which the standard already guaranteed, and does not verify the parameters the standard never covered.

2. Full Spool Function Cross-Reference

Three coding systems are in common circulation for NG6 directional valves: Rexroth single-letter codes, Yuken 3Cxx numeric codes, and the Shanghai-type single-letter system used across much of the Chinese domestic equipment base. The table below is the mapping YXCHK engineering uses when identifying a replacement. Each row states a functional equivalence of the centre (neutral) condition — these are not identical part numbers and should not be treated as such.

Table 1 — Spool function cross-reference: Rexroth / Yuken / Shanghai-type
Rexroth code	Yuken code	Shanghai-type	Centre / shifted condition	Typical duty
E	3C2	O	All ports closed in centre	Holds actuator position, locks load
G	3C60	M	P→A, B→T when shifted	Standard single-direction work port supply
H	3C3	H	P→B, A→T — reversed work ports vs G	Mirror-image circuits
J	3C4	Y	A & B blocked, P connected to T	Actuator held, pump unloaded in centre
L	3C12	N	All ports open to tank (full float)	Free-wheeling actuator, lowest lock pressure
M	3C9	P	P, A, B connected; T blocked	Pump unloaded, cylinder ports interconnected
U	3C10	—	P→A with check, B→T	One-way flow control on A line
F	3C5	—	P→B with check, A→T	One-way flow control on B line

How to use this table correctly. Identify the spool code on the nameplate of the valve being replaced, find its row, and read across to the coding system of the replacement. Then verify the centre condition description against the actual circuit requirement. If the two disagree, trust the circuit — nameplates are occasionally wrong after a previous non-matching replacement, and inheriting that error compounds it.

3. Parameter Comparison — Rexroth-Type vs Yuken-Type

YXCHK manufactures two distinct valve families. They share ISO 4401 mounting compatibility at equivalent sizes but differ in pressure class, and are visually distinguished by coil finish — a deliberate design choice that makes mis-selection detectable during inspection rather than after installation.

Table 2 — Series parameter comparison
Parameter	Rexroth-type series	Yuken-type series
Max working pressure	31.5 MPa	21 MPa
Coil finish (visual ID)	Silver-white	Matte black
NG6 mounting standard	ISO 4401-03 / CETOP 3	ISO 4401-03 / CETOP 3
NG10 mounting standard	ISO 4401-05 / CETOP 5	ISO 4401-05 / CETOP 5
Spool coding	Single letter (E, G, H, J, L, M, U, F)	Numeric (3C2, 3C3, 3C4, 3C5, 3C9, 3C10, 3C12, 3C60)
Coil voltage options	DC 24V (CG24) · AC 220V (AW220)	DC 24V (D24) · AC 220V (A220)
Factory testing	100% of units	100% of units
Warranty	1 year	1 year
Standard lead time	7 days	7 days

The critical asymmetry. Because both families share the ISO 4401 mounting face, a 21 MPa Yuken-type valve physically bolts onto a manifold built for a 31.5 MPa Rexroth-type valve. Nothing about the installation will indicate a problem. If the system relief valve is set above 21 MPa, that valve is operating outside its rating from the first cycle. Always confirm the relief setting before substituting across families — the bolt pattern will not warn you.

4. Substitution Decision Tree

Four checks, in this order. A failure at any step invalidates the substitution regardless of what the later steps show.

Mounting size — is the interface identical?

Read the size from the existing valve or measure the sub-plate. NG6 / ISO 4401-03 and NG10 / ISO 4401-05 are different interfaces and are not interchangeable with each other.

Pass → step 2 · Fail → different size required, stop

Spool centre condition — does the neutral behaviour match?

Use Table 1 to translate the code. Verify against the circuit requirement: must the actuator hold position (E / 3C2 / O), float (L / 3C12 / N), or should the pump unload (J / 3C4 / Y)? This is the single most common source of substitution error, because a wrong spool still fits and still switches — it simply behaves incorrectly when de-energised.

Pass → step 3 · Fail → select correct spool code

Pressure class — is the system relief setting within the valve rating?

Read the actual relief valve setting, not the nominal system pressure quoted in documentation. If the setting exceeds 21 MPa, only the Rexroth-type 31.5 MPa series is valid. If it is at or below 21 MPa, either family is acceptable and there is no engineering benefit in specifying the higher class.

Pass → step 4 · Fail → move up to 31.5 MPa series

Coil voltage and connector — do they match the control system?

Read voltage from the coil body, not from purchase records — coils are frequently changed during a valve's service life and records go stale. Confirm nominal voltage, current type (DC or AC) and connector form together. A mismatch either fails to shift the spool or overheats the coil.

Pass → substitution valid · Fail → specify correct coil

5. Four Failure Patterns Worth Knowing

Table 3 — Common substitution failures and their signatures
Observed symptom	Likely cause	Check
Actuator drifts when solenoid de-energised	Wrong centre condition — float spool fitted where closed-centre required	Compare spool code against Table 1
Valve fits and switches, but system pressure never reaches setpoint	Pressure class mismatch or internal leakage past worn spool	Verify relief setting vs valve rating
Solenoid audible but spool does not shift fully	Coil mismatch — insufficient force, or non-matched coil and body	Confirm voltage and current type on coil body
Coil overheats or burns out early	AC coil on DC supply or vice versa; incorrect nominal voltage	Check current type before energising

Three of these four are specification errors identifiable before installation. The fourth — internal leakage past a worn spool — is a manufacturing and wear issue rather than a selection issue. It is the reason YXCHK tests every unit individually rather than sampling by batch, and ships each valve with its test record.

6. Requesting a Cross-Reference Check

Where a nameplate is illegible, a code does not appear in Table 1, or the circuit behaviour does not match what the code implies, send the following four items and YXCHK engineering will confirm the equivalent within 24 hours:

›The complete model code from the nameplate, including all suffixes.
›The system relief valve setting in MPa or bar.
›Coil voltage and current type as marked on the coil body.
›What the actuator must do when the solenoid is de-energised — hold, float, or unload.

The fourth item is the one most often omitted and the one that most often determines the answer. A model code identifies what was previously fitted; it does not confirm that what was previously fitted was correct.

Frequently Asked Questions

Is a YXCHK 4WE6 valve physically interchangeable with a Rexroth 4WE6?

Yes, at the mounting interface. Both follow ISO 4401-03 (NG6 / CETOP 3), which fixes port positions, bolt pattern and O-ring seats. Any compliant valve fits any compliant sub-plate. What must still be matched by the engineer is spool function, coil voltage, connector type and pressure class.

Which Yuken spool code corresponds to a Rexroth G spool?

Rexroth G corresponds to Yuken 3C60 and to Shanghai-type M. The G spool connects P to A and B to T when shifted. Always verify the centre condition rather than the shifted condition — the centre position determines whether the actuator holds, floats or unloads when de-energised.

What is the full Rexroth to Yuken to Shanghai-type spool mapping?

G = 3C60 = M · M = 3C9 = P · L = 3C12 = N · E = 3C2 = O · H = 3C3 = H · J = 3C4 = Y · U = 3C10 · F = 3C5. These are functional equivalences of the centre condition, not identical part numbers. Full detail in Table 1 above.

Do the Rexroth-type and Yuken-type YXCHK series have the same pressure rating?

No. Rexroth-type is 31.5 MPa with a silver-white coil; Yuken-type is 21 MPa with a matte-black coil. They share ISO 4401 mounting, so a 21 MPa valve bolts onto a 31.5 MPa manifold. If system relief exceeds 21 MPa that substitution is invalid despite fitting mechanically. Check the relief setting, not the bolt pattern.

How do I verify coil voltage compatibility when replacing a 4WE6 valve?

Read voltage from the coil body or nameplate, not purchase records — coils are frequently swapped during service life. In YXCHK codes, CG24 is DC 24V and AW220 is AC 220V. Confirm nominal voltage, current type and connector form. A mismatch either fails to shift the spool or burns out the coil, and neither is covered by warranty.

What testing does YXCHK perform before a valve ships?

Every valve receives 100% factory testing — pressure tested and function tested per unit rather than sampled by batch — and ships with its test record. Standard lead time is 7 days; warranty is 1 year. This matters for replacements because the failure that most often recurs after a swap is internal leakage past a worn spool, which unit-level testing is intended to catch.

Can I mix a Rexroth valve body with a YXCHK coil, or vice versa?

Not recommended. Coil interfaces look similar, but armature tube diameter, magnetic circuit and stroke are matched to the specific body. A coil that appears to fit may produce insufficient force, causing partial shifting or intermittent operation. Replace valve and coil as a matched assembly, and keep the removed unit as a reference for spool code and voltage.