Overview
The ZF 4644.152.233 is a critical OEM genuine component engineered specifically for the WG 158 Series transmission. This precision-machined part functions as a hydraulic control element within the valve body assembly, regulating oil flow to ensure smooth clutch engagement and disengagement during gear shifts. The SKU 4644.152.233 sits directly adjacent to the TRANSMISSION HOUSING and interfaces with the SHIFT SYSTEM to modulate pressure in the main circuit. As an OEM genuine part, it meets ZF’s exacting tolerances for bore clearance and surface hardness, making it indispensable for maintaining factory-specified shift quality in heavy-duty commercial vehicles.
Symptoms of Failure
- Delayed gear engagement when cold: A worn 4644.152.233 can cause sluggish forward or reverse engagement, especially after overnight downtime, as internal leakage reduces hydraulic pressure buildup.
- Erratic shift timing under load: When this part fatigues, operators may experience harsh or unpredictable upshifts while climbing grades, often accompanied by a momentary loss of power.
- Visible oil seepage around the valve body: Cracks or seal degradation in the 4644.152.233 allow transmission fluid to weep past the SCREW-IN SLEEVE, leaving drips on the bell housing or undercarriage.
- Neutral creep in drive: A failing unit may permit partial clutch pack application in neutral, causing the vehicle to inch forward at stoplights—a clear sign of internal pressure imbalance.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4644.152.233 |
| Material | Hardened alloy steel with nitrided surface |
| Length | 82.5 mm |
| Outer Diameter | 28.0 mm |
| Weight | 0.34 kg |
| Seal Type | PTFE lip seal (integrated) |
| Operating Pressure | 12–18 bar |
| Temperature Range | -40°C to +120°C |
| OEM Reference | ZF WG 158 Series |
Compatibility
This part is designed for the ZF WG 158 transmission series, but it also cross-fits several other ZF models that share the same valve body architecture. Compatible transmissions include the WG 158, WG 180, WG 200, and the earlier WG 150 series when used with the appropriate GEAR SHIFT HOUSING. Always verify the part number 4644.152.233 against your transmission’s serial plate before installation, as minor revisions exist for late-model WG 158 units with updated hydraulic circuits.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101190 | TRANSMISSION HOUSING | Encloses the gear train and valve body; provides structural rigidity |
| 4644159347 | SHIFT SYSTEM | Mechanical linkage that translates driver input to hydraulic valve movement |
| 4475280036 | SCREW-IN SLEEVE | Threaded bushing that retains the shift rail and prevents fluid bypass |
| 4644306511 | GEAR SHIFT HOUSING | Houses the shift forks and detent mechanism for gear selection |
| 4644306440 | PISTON | Hydraulic actuator that applies clutch packs under pressure |
| 0635470104 | ROLLER | Needle bearing that reduces friction in the shift rail assembly |
| 0730006344 | RING | Internal snap ring for securing piston in bore |
| 0730006345 | RING | External retaining ring for shift shaft |
| 0730006346 | RING | Backup ring for high-pressure seal |
| 0730006347 | RING | Spacer ring for clutch pack preload |
Frequently Asked Questions
Q: Can I install the 4644.152.233 without removing the transmission from the vehicle?
A: In most cases, yes—this part is accessible after dropping the transmission oil pan and removing the valve body cover. However, you must also inspect the TRANSMISSION HOUSING for wear at the bore where the part seats.
Q: How do I know if the 4644.152.233 is the correct revision for my WG 158?
A: Check the last three digits of your transmission serial number against ZF’s service bulletin. Units built after 2018 often require the updated 4644.152.233 with a hardened sealing lip.
Q: What torque should I use when reinstalling the SCREW-IN SLEEVE adjacent to this part?
A: ZF specifies 45 Nm for the sleeve retaining bolt. Over-torquing can distort the bore and cause premature failure of the 4644.152.233 seal.
📞 Need this part? Contact our ZF specialists:
Email: info@partszf.com |
Phone: +86 158 2286 3467 |
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