Overview
The ZF 4656.056.139 is a precision-engineered OEM genuine component designed specifically for the WG 160 Series transmission. This part functions as a critical sealing and alignment element within the hydraulic control unit, ensuring consistent oil pressure regulation and smooth gear engagement. The SKU 4656.056.139 is manufactured to ZF’s exacting tolerances, making it a direct replacement for worn units in heavy-duty commercial vehicle transmissions. It sits adjacent to the main valve body assembly, where it interfaces with the TRANSMISSION HOUSING to maintain structural integrity under high torque loads.
Symptoms of Failure
- Delayed gear engagement or slipping — When the 4656.056.139 wears, hydraulic pressure drops, causing hesitation when shifting from neutral to drive or reverse.
- External oil seepage near the valve body — A degraded seal allows transmission fluid to escape, often visible as drips under the bell housing area.
- Erratic shift timing — The part’s failure disrupts pilot pressure signals, leading to harsh or unpredictable upshifts and downshifts.
- Overheating transmission fluid — Internal leakage caused by a worn 4656.056.139 forces the pump to work harder, raising operating temperatures beyond normal ranges.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4656.056.139 |
| OEM Reference | ZF WG 160 Series |
| Material | Hardened alloy steel with nitrile sealing surface |
| Weight | 0.42 kg (0.93 lbs) |
| Outer Diameter | 38.5 mm |
| Inner Diameter | 18.2 mm |
| Height | 14.7 mm |
Compatibility
This genuine ZF part is primarily engineered for the WG 160 transmission series. It is also compatible with the WG 180 and WG 200 models that share the same hydraulic control architecture. The 4656.056.139 works in conjunction with the HOUS.FRONT SECT and the HOUSING REAR PART to form a sealed pressure chamber. For complete assembly, it is often replaced alongside the HOUSING REAR SECTION to prevent recurring leaks.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4656101057 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4656201075 | HOUS.FRONT SECT | Front section of the housing assembly |
| 4656201078 | HOUSING REAR PART | Rear housing segment for output shaft |
| 4656298050 | HOUSING REAR SECTION | Additional rear cover for hydraulic circuits |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for housing mating |
| 4656301148 | FIXING PLATE | Retains valve body components |
| 0636100817 | CAP SCREW | Fastener for housing sections |
| 4656301016 | SCREEN SHEET | Fine mesh filter for oil return |
| 4656301017 | SCREEN SHEET | Coarse mesh pre-filter |
| 0636100803 | CAP SCREW | Bolt for valve body attachment |
Frequently Asked Questions
Q: Can the 4656.056.139 be reused after removal?
A: No. This is a single-use sealing component. Once compressed during installation, its sealing properties are permanently altered. Always install a new OEM genuine part to avoid immediate leakage.
Q: How do I know if my WG 160 needs this part replaced?
A: If you observe fluid weeping from the valve body area or experience soft shifts that worsen as the transmission warms up, the 4656.056.139 is likely compromised. A pressure test showing below-spec pilot pressure confirms the diagnosis.
Q: Is this part interchangeable with aftermarket versions?
A: While aftermarket copies exist, only the OEM genuine 4656.056.139 guarantees the exact Shore hardness and dimensional tolerance required for WG 160 series reliability. Non-OEM parts often cause erratic shift patterns within 10,000 km.
📞 Need this part? Contact our ZF specialists:
Email: info@partszf.com |
Phone: +86 158 2286 3467 |
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