Overview
The ZF 4644.026.383 6 WG 200 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 components into a single ready-to-install package. As the core of the WG 200 series, it manages torque distribution across six forward speeds, ensuring smooth power delivery under extreme loads. The SKU 4644.026.383 is a direct OEM replacement, eliminating the need for piecemeal rebuilding. This complete unit sits between the engine bellhousing and the final drive, converting rotational force into usable traction for wheel loaders, graders, and industrial tractors.
Symptoms of Failure
- Delayed or harsh gear engagement: When the internal clutch packs wear, operators experience a noticeable lag or a jarring shift when moving from neutral to forward or reverse. This often indicates internal seal degradation within the 4644.026.383 assembly.
- Low hydraulic pressure and erratic shifting: A failing unit will cause the transmission to hunt between gears or refuse to shift under load. This is frequently traced to worn valve bodies or piston rings inside the complete assembly.
- External oil leaks at the housing joint: Pressurized ATF escaping from the main case seam is a clear sign of gasket failure. This often requires replacing the 0634306323: O-RING and inspecting the 4644101249: TRANSMISSION HOUSING for cracks.
- Metallic grinding noise during operation: Contaminated fluid or failed bearings produce a distinct whine or grind, especially in lower gears. This symptom demands immediate replacement of the complete unit to avoid catastrophic failure.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4644.026.383 |
| Assembly Type | Complete Powershift Unit |
| Series | WG 200 |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length | 720 mm |
| Overall Width | 480 mm |
| Overall Height | 560 mm |
| Housing Material | High-Strength Cast Iron |
| Seal Material | Nitrile Rubber (NBR) |
| Max Input Torque | 1,200 Nm |
| Fluid Capacity | 22 Liters |
Compatibility
This complete assembly is engineered for the ZF WG 200 series transmissions. It is a direct fit for models including the WG 180, WG 200, and WG 210, which are commonly found in Volvo L120, L150, and Caterpillar 950 wheel loaders. The 4644.026.383 unit also integrates with earlier WG 160 variants when paired with the correct 4644301402: TRANSMISSION HOUSING and 4644301298: COVER PLATE. Always verify your transmission serial number against the OEM parts list before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear and shaft support |
| 4644301402 | TRANSMISSION HOUSING | Secondary housing for clutch pack enclosure |
| 4644301298 | COVER PLATE | Seals the valve body access port |
| 0634306323 | O-RING | Prevents fluid leaks at housing joints |
| 0636305026 | SCREW PLUG | Seals drain and test ports |
| 4644301279 | SCREEN SHEET | Filters debris from hydraulic fluid |
| 4644301088 | SEALING CAP | Protects exposed shaft splines during storage |
| 4644109044 | PARKING BRAKE | Spring-applied, hydraulically released brake unit |
| 0501211070 | BRAKE | Service brake disc pack for wheel ends |
| 0501317036 | PISTON | Hydraulic actuator for clutch engagement |
