Overview
The ZF 4644.151.238 is a precision-engineered OEM genuine component designed specifically for the WG 158 series transmission. This part functions as a critical hydraulic control element within the valve body assembly, regulating oil flow to ensure smooth clutch engagement and gear shifts. As an original ZF part, SKU 4644.151.238 guarantees exact fitment and factory-specified tolerances, eliminating the guesswork associated with aftermarket alternatives. It sits directly adjacent to the TRANSMISSION HOUSING and interfaces with the SHIFT SYSTEM to modulate pressure during directional changes.
Symptoms of Failure
When the 4644.151.238 begins to wear, operators often notice delayed engagement when shifting from neutral to drive or reverse. A second common symptom is erratic gear slipping under moderate load, particularly during uphill climbs. Third, internal hydraulic leaks may develop, leading to low transmission fluid levels without visible external drips. Finally, harsh or jarring shifts between first and second gear frequently point to degradation of this specific valve component. Addressing these issues promptly with the OEM part prevents cascading damage to the GEAR SHIFT HOUSING.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4644.151.238 |
| Material | Hardened steel with anti-corrosion coating |
| Weight | 0.85 kg (1.87 lbs) |
| Length | 142 mm |
| Diameter | 38 mm |
| OEM Reference | ZF WG 158 Series |
| Operating Pressure | 12–18 bar |
Compatibility
This genuine ZF part is primarily designed for the WG 158 transmission series, but it also fits select models in the WG 180 and WG 200 families due to shared hydraulic architecture. It is commonly used in municipal buses, medium-duty trucks, and construction loaders. For proper installation, ensure the SCREW-IN SLEEVE is torqued to factory specifications to prevent fluid bypass. Always verify your transmission serial number against ZF’s compatibility chart before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101190 | TRANSMISSION HOUSING | Encloses and supports all internal transmission components |
| 4644159347 | SHIFT SYSTEM | Manages gear selection and hydraulic routing |
| 4475280036 | SCREW-IN SLEEVE | Secures hydraulic lines and prevents pressure loss |
| 4644306511 | GEAR SHIFT HOUSING | Houses shift forks and selector mechanisms |
| 4644306440 | PISTON | Converts hydraulic pressure into mechanical force |
| 0635470104 | ROLLER | Reduces friction in shift rail movement |
| 0730006344 | RING | Seals hydraulic circuits against leakage |
| 0730006345 | RING | Provides secondary sealing for high-pressure zones |
| 0730006346 | RING | Prevents cross-contamination between fluid channels |
| 0730006347 | RING | Maintains consistent pressure during temperature changes |
Frequently Asked Questions
Q: Can I use the 4644.151.238 in a WG 200 transmission?
A: Yes, this part is cross-compatible with WG 200 series transmissions that share the same valve body configuration, though we recommend verifying your specific model year.
Q: What tools are needed to replace this part?
A: Standard socket set, torque wrench, and a seal pick are required. You will also need to remove the GEAR SHIFT HOUSING for access.
Q: How often should this component be inspected?
A: During every major transmission overhaul (typically every 200,000 miles or 5,000 operating hours), the 4644.151.238 should be checked for scoring or wear.
📞 Need this part? Contact our ZF specialists:
Email: info@partszf.com |
Phone: +86 158 2286 3467 |
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