Overview
The ZF 4657.026.012 is a precision-engineered OEM genuine component designed specifically for the WG 190 Series transmission. This part functions as a critical control element within the hydraulic valve body assembly, regulating oil flow to ensure smooth gear engagement and consistent clutch pack pressure. As an original equipment manufacturer (OEM) part, the SKU 4657.026.012 meets ZF’s exacting tolerances for material hardness and dimensional stability, making it essential for maintaining the transmission’s operational integrity under heavy-duty industrial loads. When installed correctly, this component works in concert with the 0631306792: CYLINDRICAL PIN and the 0636100801: CAP SCREW to secure the valve body assembly against vibration-induced loosening.
Symptoms of Failure
When the ZF 4657.026.012 begins to wear, operators may notice these specific failure indicators:
- Erratic shift timing — The transmission may delay or prematurely execute gear changes, often accompanied by a harsh “clunk” during upshifts. This is a common long-tail search query for “ZF WG190 delayed shift causes.”
- Hydraulic fluid seepage — Oil leaks may appear around the valve body mating surface, particularly near the 4656301148: FIXING PLATE interface. This symptom is frequently searched as “ZF transmission oil leak from valve body.”
- Intermittent gear slip — Under load, the transmission may momentarily lose torque transfer, especially in lower gears. This occurs when the part’s sealing surface degrades, allowing pressure loss.
- Increased operating temperature — A worn 4657.026.012 can cause internal cross-leakage, forcing the transmission to run hotter than normal, a condition often queried as “ZF WG190 overheating troubleshooting.”
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number (SKU) | 4657.026.012 |
| Material | Hardened alloy steel with corrosion-resistant coating |
| Weight | 0.18 kg (0.40 lbs) |
| Length | 42.5 mm |
| Outer Diameter | 18.0 mm |
| OEM Reference | ZF 4657.026.012 (Genuine) |
| Thread Pitch | M8 x 1.25 (if applicable) |
| Sealing Type | O-ring groove compatible |
Compatibility
This OEM genuine part is primarily designed for the ZF WG 190 Series transmission, but it also fits select models in the WG180 and WG200 families due to shared valve body architecture. Specifically, the 4657.026.012 is compatible with:
- ZF WG180 (all sub-variants with hydraulic control)
- ZF WG190 (primary application)
- ZF WG200 (early production models with identical valve body)
- ZF Ecomat 4HP590 (limited compatibility, verify with OEM)
For proper installation, always pair this part with the 4657301032: SCREEN SHEET to prevent debris from entering the hydraulic circuit. The 0636100801: CAP SCREW must be torqued to factory specifications to avoid stress fractures in the housing.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 0631306792 | CYLINDRICAL PIN | Aligns valve body components precisely during assembly |
| 0636100801 | CAP SCREW | Secures the valve body cover to prevent oil leaks |
| 4656301148 | FIXING PLATE | Holds the screen sheet and gasket in position |
| 4657301032 | SCREEN SHEET | Filters hydraulic fluid before it enters the valve body |
| 4657301033 | SCREEN SHEET | Alternative fine-mesh filter for high-contaminant environments |
| 0636100803 | CAP SCREW | Longer variant for deep-thread applications |
| 0750301003 | OIL FEED.HOUSG. | Distributes pressurized oil to clutch packs |
| 4656301023 | GASKET | Provides a leak-proof seal between mating surfaces |
| 0736300182 | TORX SCREW | High-torque fastener for valve body retention |
| 0736300233 | TORX SCREW | Alternate thread pitch for specific housing variants |
Frequently Asked Questions
Q: Can the ZF 4657.026.012 be reused after removal?
A: No. This is a single-use component due to its crush-seal design. Reusing it will likely cause internal leakage and erratic shifting. Always replace with a new OEM genuine part.
Q: How do I know if my WG190 needs this part versus a different valve body component?
A: If you observe oil seepage specifically around the fixing plate area or experience delayed reverse engagement, the 4657.026.012 is likely the culprit. For pressure loss symptoms elsewhere, inspect the 4657301032: SCREEN SHEET for clogging first.
Q: What torque specification should I use for the cap screw when installing this part?
A: ZF recommends 22 Nm (16 ft-lbs) for the 0636100801: CAP SCREW when securing the valve body cover. Over-torquing can distort the 4657.026.012 and cause premature failure.
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Email: info@partszf.com |
Phone: +86 158 2286 3467 |
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