Overview
The ZF 4644.026.406 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 clutch pack, planetary gear sets, and hydraulic control system into a single, ready-to-install package. As the core rotating assembly within the WG 200 series, it directly manages torque multiplication and gear ratio changes under load. The SKU 4644.026.406 specifically denotes a 6-speed configuration with a 555/5 ratio split, making it critical for wheel loaders and graders requiring precise inching control. This unit replaces the need to source individual clutch drums and shafts, reducing downtime during major overhauls.
Symptoms of Failure
When the ZF 4644.026.406 assembly begins to fail, operators often report delayed engagement when shifting from forward to reverse, a classic sign of worn clutch discs or seal leakage within the unit. Another common symptom is intermittent gear slippage under heavy load, particularly in 4th and 5th gears, which indicates degraded friction material or piston seal failure. You may also notice erratic shift quality or harsh engagement as the hydraulic control valves lose pressure due to internal wear. Finally, metallic debris in the transmission oil filter is a definitive indicator that the planetary gear sets or bearings inside this assembly are failing, requiring immediate replacement to avoid catastrophic damage to the 4644101249 TRANSMISSION HOUSING.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.026.406 |
| Series | WG 200 (6 WG 200) |
| Configuration | 6-Speed Powershift (555/5 Ratio) |
| Dry Weight | Approx. 185 kg (408 lbs) |
| Housing Material | High-Grade Cast Iron |
| Clutch Disc Material | Sintered Bronze / Steel |
| Max Input Torque | 1,200 Nm (885 lb-ft) |
| Overall Length | 620 mm |
| Flange Diameter | 200 mm (SAE 3) |
Compatibility
This complete assembly is engineered for the ZF WG 200 series, but it also shares core architecture with the WG 180 and WG 160 families. It is a direct fit for models requiring the 555/5 ratio split, including ZF 6 WG 200, 6 WG 180, and select 6 WG 160 variants used in loaders from 12 to 18 tons. When installing, ensure the 4644301402 TRANSMISSION HOUSING is inspected for cracks, as the assembly seats directly into it. The 4644301298 COVER PLATE must be torqued to spec to prevent oil bypass. Always replace the 0634306323 O-RING on the input shaft during installation to avoid pressure loss.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Alternate housing variant for WG 200 |
| 4644301298 | COVER PLATE | Seals the clutch access port |
| 0634306323 | O-RING | Seals input shaft against oil leaks |
| 0636305026 | SCREW PLUG | Closes hydraulic test ports |
| 4644301279 | SCREEN SHEET | Filters debris from lube oil circuit |
| 4644301088 | SEALING CAP | Protects output shaft splines |
| 4644298503 | REPAIR KIT | Contains gaskets and seals for rebuild |
| 4644309001 | OUTPUT FLANGE | Connects driveshaft to transmission |
| 4475280079 | SCREW PLUG | Seals drain/fill holes |
