Overview
This OEM genuine ZF 4644.014.008 component is a critical hydraulic control element specifically engineered for the WG 158 Series transmission. It regulates oil flow within the valve body assembly, ensuring precise clutch engagement and disengagement during gear changes. The SKU 4644.014.008 is manufactured to ZF’s exacting tolerances, providing consistent pressure modulation that directly impacts shift quality and transmission longevity. When installed alongside the TRANSMISSION HOUSING, this part forms a sealed hydraulic circuit that prevents cross-contamination between lubrication and control circuits.
Symptoms of Failure
When the 4644.014.008 begins to wear, operators typically notice delayed gear engagement when shifting from neutral to drive or reverse. A second common failure symptom is intermittent transmission slipping under load, particularly during uphill climbs or when towing heavy equipment. Technicians often report erratic shift patterns where the transmission hunts between gears or fails to hold a selected ratio. Finally, external hydraulic fluid seepage around the valve body mating surface indicates the seal integrity of this part has been compromised, requiring immediate replacement to avoid pressure loss.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.014.008 |
| Material | Hardened alloy steel with corrosion-resistant coating |
| Weight | 0.42 kg (0.93 lbs) |
| Length | 78 mm |
| Width | 32 mm |
| Height | 28 mm |
| Operating Pressure Range | 8–18 bar (116–261 psi) |
| Temperature Range | -40°C to +120°C |
| OEM Reference | ZF 4644.014.008 (Genuine) |
Compatibility
This genuine ZF 4644.014.008 is designed primarily for the WG 158 Series transmission family. It is also compatible with the WG 180 and WG 200 series transmissions produced after 2012, provided the valve body configuration matches. The part integrates directly with the SHIFT SYSTEM and mounts securely within the GEAR SHIFT HOUSING. For applications requiring additional sealing, the SCREW-IN SLEEVE should be inspected and replaced concurrently to maintain proper hydraulic circuit integrity.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101190 | TRANSMISSION HOUSING | Encloses and protects internal gear train and hydraulic components |
| 4644159347 | SHIFT SYSTEM | Mechanical linkage that translates driver input to valve body commands |
| 4475280036 | SCREW-IN SLEEVE | Threaded adapter for hydraulic line connections to the valve body |
| 4644306511 | GEAR SHIFT HOUSING | Houses shift forks and selector mechanisms for gear engagement |
| 4644306440 | PISTON | Hydraulic actuator that applies clutch pack pressure |
| 0635470104 | ROLLER | Reduces friction in shift rail movement |
| 0730006344 | RING | Seals hydraulic passages between valve body sections |
| 0730006345 | RING | Secondary sealing element for high-pressure circuits |
| 0730006346 | RING | Backup ring for O-ring groove reinforcement |
| 0730006347 | RING | Wiper ring preventing debris ingress into valve body |
Frequently Asked Questions
Q: How do I know if the 4644.014.008 needs replacement?
A: Perform a pressure test at the valve body test port. If readings fluctuate more than 2 bar during steady-state operation, or if you observe visible fluid weeping around the part’s mounting flange, replacement is necessary.
Q: Can this part be installed without removing the transmission?
A: Yes, the 4644.014.008 is accessible after removing the transmission oil pan and valve body cover. However, the SHIFT SYSTEM must be temporarily disconnected to access the retaining bolts.
Q: Is this part interchangeable with aftermarket alternatives?
A: We strongly recommend using only OEM genuine ZF parts. Aftermarket copies often use inferior steel alloys that wear prematurely, leading to the exact failure symptoms described above within 10,000 operating hours.
📞 Need this part? Contact our ZF specialists:
Email: info@partszf.com |
Phone: +86 158 2286 3467 |
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