Overview
The ZF 4644.159.255 SHIFT SYSTEM is a precision-engineered OEM genuine component designed exclusively for the WG 201 Series transmission. This critical assembly governs the hydraulic selection of forward and reverse gears, ensuring smooth engagement and disengagement under heavy-duty operating conditions. Positioned within the valve body and directly interfacing with the main control module, the shift system translates driver commands into precise clutch pack actuation. The SKU 4644.159.255 is manufactured to ZF’s original tolerances, guaranteeing a direct fit and long service life without the risk of aftermarket variability.
Symptoms of Failure
- Delayed or harsh gear engagement: When the shift system wears, operators often experience a noticeable lag or a jarring “clunk” when shifting from neutral to drive or reverse. This is a common long-tail search query for “ZF WG201 hard shifting fix.”
- Intermittent gear slipping under load: A failing shift system may cause the transmission to momentarily lose power delivery, especially during uphill climbs or heavy hauling. This symptom is frequently searched as “WG201 transmission slipping under load causes.”
- Hydraulic fluid contamination: Internal wear of the shift system can generate metallic debris, which circulates through the oil. This often leads to “ZF transmission oil dark and metallic” complaints and can damage adjacent components like the TRANSMISSION HOUSING (4644101172).
- No shift response in cold conditions: A worn shift system may fail to build adequate pilot pressure when the transmission fluid is cold, resulting in a “no-move” condition until the oil warms up.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number (SKU) | 4644.159.255 |
| OEM Reference | ZF 4644.159.255 |
| Material | Hardened steel with corrosion-resistant coating |
| Weight | 1.2 kg (2.65 lbs) |
| Dimensions (L x W x H) | 210 mm x 85 mm x 45 mm |
| Operating Pressure | 12–18 bar |
| Sealing Elements | Includes O-RING (0634306198) and SEALING RING (0634801098) |
| Mounting Hardware | Requires HEXAGON SCREW (0636100621) |
| Identification | Includes TYPE PLATE (0730365067) |
Compatibility
This shift system is engineered for the ZF WG 201 Series, which encompasses the WG180, WG200, and WG210 models. It is also backward-compatible with select earlier WG transmissions that share the same valve body architecture. For proper installation, ensure the mating TRANSMISSION HOUSING (4644301390) is free of cracks and that the THREADED BUSH (4644301189) is torqued to specification. Always replace the SCREW PLUG (0636302005) during service to prevent pressure loss.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101172 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301390 | TRANSMISSION HOUSING | Alternate housing variant for WG201 |
| 4644301189 | THREADED BUSH | Guides shift rod through housing |
| 0636302005 | SCREW PLUG | Seals hydraulic test ports |
| 0634306198 | O-RING | Prevents fluid leakage at joints |
| 0634801098 | SEALING RING | Static seal for valve body interfaces |
| 0730365067 | TYPE PLATE | Identification label for transmission model |
| 0631311009 | GROOVED STUD | Alignment pin for shift system mounting |
| 4644301161 | COVER PLATE | Protects shift mechanism from debris |
| 0636100621 | HEXAGON SCREW | Fastener for shift system retention |
ZF 4644.159.255 SHIFT SYSTEM – Shift System RFQ Support
PartsZF supports ZF 4644.159.255 SHIFT SYSTEM RFQs by checking the part number, related documentation, and buyer-supplied transmission context before quotation.
Part-Number Summary
Use ZF number 4644.159.255 when sending your RFQ. PartsZF can review dotted, spaced, and compact number formats against the available product and documentation records.
Application Context
- Illustration section: SHIFT SYSTEM
Cross Reference Support
If you have an OEM number, old supplier number, or visible marking, include it with your RFQ so PartsZF can compare it with the available records.
Specification Snapshot
| ZF part number | 4644.159.255 |
|---|---|
| Normalized SKU | 4644159255 |
| Part name | SHIFT SYSTEM |
| Product category | shift system |
| RFQ support | Part-number lookup and documentation review |
| Media support | Product photo or diagram review when available |
Image and Documentation Notes
Current product media status: fallback. Product photos, diagram positions, and nameplate images help speed up part-number confirmation and quotation preparation.
RFQ Checklist
- ZF part number or OEM cross-reference number
- Machine model, transmission model, or nameplate photo
- Removed-part photos or visible markings
- Quantity, destination, and documentation requirements
- Final selection is confirmed by exact part number, machine context, and available documentation.
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