Overview
The ZF 4644.006.209 6 WG 180(555) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the clutch packs, planetary gearsets, and hydraulic control components into a single, ready-to-install package. As the core of the WG 180 series drivetrain, it manages torque distribution across six forward speeds and one reverse speed, ensuring smooth power delivery under extreme loads. The SKU 4644.006.209 is a direct replacement for worn or failed assemblies, restoring original ZF performance specifications. This unit sits between the engine flywheel housing and the output driveline, with the TRANSMISSION HOUSING (4644101043) and the TRANSMISSION HOUSING (4644301194) providing structural integrity and fluid containment for the internal components.
Symptoms of Failure
- Erratic gear engagement and slipping under load: When the internal clutch packs or sprags wear, the transmission may hesitate or fail to hold gear during uphill climbs or heavy pushing. This often manifests as a sudden loss of power or RPM flare without corresponding vehicle speed increase.
- External oil leaks from housing joints: Cracks or warpage in the transmission housings can cause hydraulic fluid to seep past seals. Look for drips near the bell housing or output flange, particularly after extended operation at high temperatures.
- Delayed or harsh shifting between forward ranges: Worn valve body components or degraded sealing rings can cause pressure drops, leading to jarring shifts or a noticeable pause when moving from first to second gear. This symptom often worsens as the transmission warms up.
- Unusual whining or grinding noises from the gear train: Bearing failure or gear tooth damage inside the assembly produces a metallic grinding sound, especially in neutral or during coasting. This indicates imminent internal failure requiring immediate replacement.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.006.209 |
| Assembly Type | Complete Powershift Transmission |
| Series | WG 180 (555) |
| Weight (approx.) | 285 kg (628 lbs) |
| Overall Length | 620 mm |
| Input Flange Diameter | 180 mm |
| Material | Cast iron housing, hardened steel gears |
| OEM Reference | ZF 4644.006.209 |
| Fluid Capacity | 12.5 liters (approx.) |
Compatibility
This complete assembly is engineered for the ZF WG 180 series, specifically the 6 WG 180(555) variant. It is also compatible with the WG 200 series when used with the appropriate GROOVED STUD (0631311009) for bell housing alignment. The unit fits ZF 6 WG 180, 6 WG 200, and select 4 WG 180 models produced after 2005. Always verify the TYPE PLATE (0730365067) on your existing transmission to confirm exact model designation before installation. For applications requiring different output configurations, additional cover plates or sealing rings may be necessary.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101043 | TRANSMISSION HOUSING | Encloses clutch packs and valve body |
| 4644301194 | TRANSMISSION HOUSING | Rear housing for output shaft support |
| 0730365067 | TYPE PLATE | Identification plate with model and serial number |
| 0631311009 | GROOVED STUD | Alignment dowel for housing mating |
| 4644303060 | COVER PLATE | Seals access port on housing |
| 4644303061 | COVER PLATE | Alternate cover for PTO openings |
| 0634801098 | SEALING RING | O-ring for hydraulic line connections |
| 0634801250 | SEALING RING | Gasket for housing flange interface |
| 0636305026 | SCREW PLUG | Drain plug for fluid evacuation |
| 0636305019 | SCREW PLUG | Fill plug for fluid level check |
