Overview
The ZF 4644.026.403 6 WG 200(555/5) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the main gear cluster, clutch packs, and hydraulic control system into a single, ready-to-install package. As a core component of the WG 200 series, it manages torque distribution across six forward and three reverse speeds. The SKU 4644.026.403 replaces the need for individual sub-assembly rebuilds, ensuring precise gear engagement under high load conditions. When paired with a robust TRANSMISSION HOUSING (part 4644101249), this unit provides the structural integrity required for demanding construction and agricultural machinery.
Symptoms of Failure
- Delayed or harsh gear engagement: When the internal clutch packs or spool valves wear, operators experience a noticeable lag or jarring shift between forward and reverse ranges.
- Intermittent loss of drive under load: A failing assembly may cause the transmission to momentarily slip or lose power when climbing grades or pushing heavy material, often accompanied by erratic hydraulic pressure readings.
- Contaminated or burnt transmission fluid: Internal wear generates metallic debris or friction material that darkens the oil and produces a distinct burnt odor, indicating imminent failure of the clutch discs.
- External oil seepage at mating surfaces: Worn seals or gaskets allow fluid to escape around the bell housing or PTO cover, leading to low oil levels and eventual overheating.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.026.403 |
| Assembly Type | Complete Powershift Transmission Unit |
| Series | WG 200 (6 WG 200/555/5) |
| Weight (approx.) | 185 kg (408 lbs) |
| Housing Material | High-strength cast iron |
| Input Torque Capacity | 555 Nm (410 lb-ft) |
| Number of Speeds | 6 Forward / 3 Reverse |
| Fluid Capacity | 12.5 liters (3.3 gallons) |
| Mounting Interface | SAE 3 bell housing pattern |
Compatibility
This assembly is engineered specifically for the ZF WG 200 series, including the WG180, WG200, and WG210 variants found in telehandlers, wheel loaders, and industrial tractors. It directly replaces the 6 WG 200(555/5) configuration. For proper installation, ensure the TRANSMISSION HOUSING (part 4644301402) is inspected for cracks, and that the COVER PLATE (part 4644301298) is torqued to factory specifications. Always install a new O-RING (part 0634306323) at the input shaft to prevent fluid bypass. This unit is not compatible with the older WG 120 series without adapter modifications.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Alternative housing variant for WG200 |
| 4644301298 | COVER PLATE | Seals the clutch access port |
| 0634306323 | O-RING | Prevents fluid leaks at shaft joints |
| 0636305026 | SCREW PLUG | Seals hydraulic test ports |
| 4644301279 | SCREEN SHEET | Filters debris from oil sump |
| 4644301088 | SEALING CAP | Protects unused PTO openings |
| 4644109046 | PARKING BRAKE | Spring-applied brake for stationary hold |
| 0501216078 | BRAKE | Service brake for dynamic stopping |
| 0501298641 | SEAL KIT | Complete gasket and o-ring set for rebuild |
