Overview
The ZF 4644.026.354 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 components into a single, ready-to-install package. As a core element of the WG 200 series, it manages torque distribution across six forward speeds and one reverse, ensuring smooth power delivery under extreme loads. The SKU 4644.026.354 identifies this as a fully assembled unit, eliminating the need for piecemeal rebuilds. For proper mounting, this assembly mates with the 4644101131: TRANSMISSION HOUSING and the 4644301228: TRANSMISSION HOUSING to form the complete gearbox casing. Identification is verified via the 0730365067: TYPE PLATE, which must be secured with the 0631311009: GROOVED STUD.
Symptoms of Failure
When the ZF 4644.026.354 assembly begins to degrade, operators often notice specific performance issues. Delayed or harsh engagement between forward and reverse gears is a primary indicator, often caused by worn clutch discs or degraded seals within the unit. Another common symptom is intermittent gear slipping under load, particularly when climbing grades or hauling heavy payloads, which points to hydraulic pressure loss or internal wear. Contaminated transmission fluid with metallic particles is a clear sign of internal component fatigue, often accompanied by a burnt odor. Finally, erratic shift patterns or failure to shift into higher gears can occur as the valve body and piston assemblies lose calibration. These failure modes often necessitate a complete assembly replacement rather than individual part swaps.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4644.026.354 |
| Assembly Type | Complete Powershift Unit (6 WG 200) |
| Gear Configuration | 6 Forward / 1 Reverse (555/5 ratio set) |
| Housing Material | High-Strength Cast Iron |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length (approx.) | 720 mm |
| OEM Reference | ZF WG 200 Series |
| Max Input Torque | 555 Nm (estimated) |
Compatibility
This assembly is engineered for the ZF WG 200 series of powershift transmissions, commonly deployed in wheel loaders, telehandlers, and industrial tractors. While the 4644.026.354 is specifically calibrated for the WG 200(555/5) variant, its core architecture is shared with the WG 180 and WG 210 series. It is not directly interchangeable with older WG 150 or WG 120 units without significant modification. The assembly is designed to work with the 4644301298: COVER PLATE for sealing and the 0634306525: O-RING for hydraulic circuit integrity. Additional sealing is provided by the 0636305026: SCREW PLUG, while the 4475280078: ADAPTER ensures proper pump mounting. Ventilation is handled by the 0501316470: BREATHER, and internal filtration relies on the 4644301279: SCREEN SHEET.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101131 | TRANSMISSION HOUSING | Main structural casing for gear cluster |
| 4644301228 | TRANSMISSION HOUSING | Secondary housing for clutch pack section |
| 0730365067 | TYPE PLATE | Identification and serial number plate |
| 0631311009 | GROOVED STUD | Fastener for type plate attachment |
| 4644301298 | COVER PLATE | Seals the rear access port |
| 0634306525 | O-RING | Hydraulic seal for cover plate |
| 0636305026 | SCREW PLUG | Closes oil drain or test ports |
| 4475280078 | ADAPTER | Mounts hydraulic pump to transmission |
| 0501316470 | BREATHER | Equalizes internal pressure |
| 4644301279 | SCREEN SHEET | Filters debris from oil sump |
