Overview
The ZF 4644.026.366 6 WG 200(555/5) Powershift Transmission Assembly | Complete Unit is a fully assembled drop-in solution for heavy-duty off-highway machinery. This complete unit integrates the clutch packs, planetary gear sets, and hydraulic control system into a single, pre-tested assembly. Designed for the WG 200 Series, the SKU 4644.026.366 serves as the core power transfer module, replacing the need to piece together individual internal components. It sits directly between the engine bell housing and the final drive, managing torque distribution across six forward speeds and one reverse. For optimal sealing during installation, pair this assembly with a new 0634306323: O-RING to prevent fluid bypass at the main housing interface.
Symptoms of Failure
- Delayed or harsh engagement when shifting from neutral to forward: Worn clutch discs inside the assembly cause hesitation or a jarring lurch, indicating the unit requires replacement.
- Progressive loss of hydraulic pressure and erratic shifting: Internal seal degradation leads to pressure drops, causing the transmission to slip under load or fail to hold gear selection.
- Visible fluid leakage at the bell housing or output flange area: Cracks in the main casing or failed gaskets allow transmission oil to escape, often accompanied by a burnt smell from overheated fluid.
- Unusual grinding or whining noise during operation: Bearing wear or gear tooth damage within the complete unit produces metallic sounds that worsen with engine RPM.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number / SKU | 4644.026.366 |
| Assembly Type | Complete Powershift Unit (6 WG 200) |
| OEM Reference | 555/5 |
| Weight (approx.) | 185 kg (408 lbs) |
| Housing Material | High-strength cast iron |
| Overall Length | 620 mm |
| Input Spline Count | 14-tooth |
| Output Flange Type | SAE C (compatible with 4644309001: OUTPUT FLANGE) |
Compatibility
This complete unit is engineered for the ZF WG 200 Series powershift transmissions, specifically the 6 WG 200 variant with a 555/5 ratio configuration. It is also backward-compatible with earlier WG 180 models when used with the correct adapter components, such as the 4644101249: TRANSMISSION HOUSING or the 4644301402: TRANSMISSION HOUSING. The unit fits common applications including ZF-built telehandlers, wheel loaders, and industrial tractors. Always verify the bell housing pattern and output shaft configuration before ordering. For installations requiring a sealed top cover, use the 4644301298: COVER PLATE to protect internal components from debris ingress.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear support |
| 4644301402 | TRANSMISSION HOUSING | Alternate housing variant for WG 200 |
| 4644301298 | COVER PLATE | Seals the top access port |
| 0634306323 | O-RING | Prevents fluid leaks at joints |
| 0636305026 | SCREW PLUG | Closes drain/fill ports |
| 4644301279 | SCREEN SHEET | Filters debris from hydraulic oil |
| 4644301088 | SEALING CAP | Protects unused ports |
| 4644298503 | REPAIR KIT | Contains seals and gaskets for overhaul |
| 4644309001 | OUTPUT FLANGE | Connects to driveshaft |
| 4475280079 | SCREW PLUG | High-torque port plug |
