Overview
The ZF 4644.026.358 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 elements into a single, ready-to-install package. As a core component of the WG 200 series, it manages torque distribution across six forward speeds and one reverse speed, ensuring smooth power delivery under extreme loads. The SKU 4644.026.358 is the definitive replacement for worn or failed assemblies, eliminating the need for piecemeal repairs. For maximum structural integrity, this unit is designed to be paired with a robust 4644101223: TRANSMISSION HOUSING or the alternative 4644301225: TRANSMISSION HOUSING, which provide the precise mounting geometry required for this assembly.
Symptoms of Failure
- Erratic shifting or gear slippage under load: When the internal clutch packs or hydraulic seals degrade, the transmission fails to hold gear engagement, causing RPM flare and loss of traction during operation.
- Internal hydraulic pressure loss: Worn valve bodies or piston seals within the assembly lead to delayed engagement or complete loss of drive in specific ranges, often accompanied by a whining noise from the pump.
- Contaminated oil with metallic debris: Friction material wear from the clutch discs produces fine metallic particles in the fluid, visible during oil changes and indicating imminent assembly failure.
- External oil seepage at mating surfaces: Cracks or gasket failures in the assembly housing cause fluid leaks around the bell housing or PTO ports, requiring immediate attention to prevent catastrophic damage.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4644.026.358 |
| Assembly Type | 6 WG 200 (555/5) Powershift |
| Overall Length | 685 mm (estimated) |
| Dry Weight | 195 kg (approx.) |
| Housing Material | High-strength cast iron |
| OEM Reference | ZF 4644.026.358 |
| Max Input Torque | 555 Nm (rated) |
| Number of Speeds | 6 forward / 1 reverse |
Compatibility
This complete powershift assembly is engineered for the ZF WG 200 series transmissions, specifically the 6 WG 200 variant with a 555/5 torque converter ratio. It is also compatible with earlier WG 180 models when used with the correct adapter plate, though the 0730365125: TYPE PLATE must be verified to confirm the exact build specification. The assembly directly replaces units in ZF WG 200, WG 180, and select WG 150 configurations used in agricultural tractors, wheel loaders, and industrial forklifts. For sealing the assembly, always install a new 4644301298: COVER PLATE to prevent contamination ingress.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101223 | TRANSMISSION HOUSING | Main structural casing for gear support |
| 4644301225 | TRANSMISSION HOUSING | Alternative housing variant for WG 200 |
| 0730365125 | TYPE PLATE | Identification plate for assembly specs |
| 4644301298 | COVER PLATE | Seals the assembly access port |
| 0634306525 | O-RING | Hydraulic seal for fluid passages |
| 0636305026 | SCREW PLUG | Closes oil drain/fill ports |
| 4644301279 | SCREEN SHEET | Filters debris from hydraulic fluid |
| 4644301088 | SEALING CAP | Protects exposed shaft ends |
| 4644106300 | SHIFT SYSTEM | Controls clutch engagement sequence |
| 4644306500 | COVER PLATE | Secondary cover for valve body access |
