Overview
The ZF 4644.026.402 6 WG 200 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. This assembly integrates the clutch packs, planetary gear sets, and hydraulic control system into a single drop-in replacement. The SKU 4644.026.402 sits at the core of the drivetrain, converting engine torque into precise, multi-speed power for wheel loaders, graders, and industrial vehicles. It is engineered to withstand extreme cyclic loads and is a direct OEM-specification unit for the WG 200 series.
Symptoms of Failure
- Erratic gear engagement or slipping under load: When the internal clutch discs or seals degrade, the transmission fails to hold torque, causing the machine to lurch or lose power during operation.
- Hydraulic oil leaks from the bell housing or sump: Worn O-rings or housing cracks allow pressurized ATF to escape, leading to low fluid levels and eventual transmission overheating.
- Delayed or harsh shifting between forward and reverse: A failing valve body or worn piston seals within the assembly cause pressure drops, resulting in jarring shifts or a significant pause before gear engagement.
- Unusual whining or grinding noises from the transmission center: Bearing failure or gear tooth damage inside the 4644.026.402 produces metallic sounds that intensify with speed.
Technical Specifications
| Specification | Value |
|---|---|
| OEM Part Number | 4644.026.402 |
| Series | WG 200 (6-speed powershift) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length | 720 mm |
| Overall Width | 510 mm |
| Overall Height | 580 mm |
| Housing Material | High-strength cast iron |
| Max Input Torque | 1,200 Nm |
| Fluid Capacity | 22 liters (ATF Dexron III) |
Compatibility
This complete assembly is engineered for the ZF WG 200 series powershift transmissions. It is directly compatible with models including the WG 180, WG 200, and WG 210, commonly found in articulated dump trucks, wheel loaders, and graders from manufacturers such as Volvo, Case, and JCB. The 4644.026.402 replaces earlier WG 200 variants and is not backward-compatible with the WG 120 or WG 150 series without significant modification.
When installing this unit, always inspect the TRANSMISSION HOUSING (4644101249) and the TRANSMISSION HOUSING (4644301402) for cracks or wear. The COVER PLATE (4644301298) must be torqued to spec, and a fresh O-RING (0634306323) is required to prevent fluid bypass at the main joint.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Secondary housing for clutch pack |
| 4644301298 | COVER PLATE | Seals the valve body access port |
| 0634306323 | O-RING | Hydraulic seal between housings |
| 0636305026 | SCREW PLUG | Drain/fill port closure |
| 4644301279 | SCREEN SHEET | Filter mesh for oil pickup |
| 4644301088 | SEALING CAP | Protects hydraulic ports during storage |
| 4644109046 | PARKING BRAKE | Spring-applied, hydraulically released brake |
| 0501216078 | BRAKE | Service brake disc assembly |
| 0501298641 | SEAL KIT | Complete gasket and O-ring set for rebuild |
