Overview
The ZF 4644.004.190 4 WG 180(555) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. 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 180 series, it replaces the need for piecemeal repairs by providing a fully assembled drop-in solution. The SKU 4644.004.190 is specifically engineered to handle high torque loads in wheel loaders, dozers, and material handlers, ensuring seamless power transfer from the engine to the driveline.
Symptoms of Failure
- Delayed or harsh engagement: When the transmission hesitates before moving or slams into gear, internal clutch pack wear or hydraulic pressure loss is often the cause. This is a common “ZF powershift transmission slipping” issue.
- Torque converter overheating: If the transmission fluid temperature spikes during normal operation, the internal stator or turbine components may be failing, leading to “transmission overheating under load” scenarios.
- Metallic debris in the oil pan: Finding metal shavings or clutch material during an oil change indicates advanced wear of the planetary gears or friction discs, a classic sign of “internal transmission failure” in WG 180 units.
- Loss of power in forward or reverse: A sudden inability to move in one direction while the other works fine points to a failed directional clutch pack or a broken seal within the assembly.
Technical Specifications
| Specification | Value |
|---|---|
| OEM Part Number | 4644.004.190 |
| Assembly Type | Complete Powershift Unit (4 WG 180) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Housing Material | High-strength cast iron |
| Overall Length | 720 mm |
| Overall Width | 480 mm |
| Overall Height | 560 mm |
| Fluid Capacity | 12.5 liters (approximate) |
Compatibility
This assembly is primarily designed for the ZF WG 180 transmission series, commonly found in Volvo L120, L150, and L180 wheel loaders, as well as certain Caterpillar and Case models that utilize ZF drivetrains. It is also compatible with the WG 200 series in specific applications where the bellhousing and output flange match. For exact fitment verification, always cross-reference the OEM serial number with the 4644.004.190 SKU. The unit is not backward-compatible with older WG 160 or WG 120 series without significant adapter modifications.
Installation Notes
When replacing this assembly, inspect the TRANSMISSION HOUSING (4644101249) and the TRANSMISSION HOUSING (4644301402) for cracks or warping, as these support the entire unit. The COVER PLATE (4644301298) must be torqued to spec to prevent fluid loss. Always replace the O-RING (0634306323) between the housing and the cover plate to guarantee a leak-free seal.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Secondary housing for clutch packs |
| 4644301298 | COVER PLATE | Seals the transmission housing |
| 0634306323 | O-RING | Prevents fluid leaks at joints |
| 0636305026 | SCREW PLUG | Seals drain/fill ports |
| 4644301279 | SCREEN SHEET | Filters debris from hydraulic fluid |
| 4644301088 | SEALING CAP | Protects exposed ports during storage |
| 4644159347 | SHIFT SYSTEM | Controls clutch engagement sequence |
| 4475280036 | SCREW-IN SLEEVE | Provides threaded connection for sensors |
| 4644306511 | GEAR SHIFT HOUSING | Encloses shift mechanism |
