Overview
The ZF 4644.026.385 6 WG 200 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. 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 and one reverse, enabling smooth power shifts under load. The SKU 4644.026.385 is a direct OEM replacement, ensuring precise fitment within the transmission housing. When paired with a robust TRANSMISSION HOUSING, this assembly forms the backbone of your drivetrain, delivering reliable performance in demanding applications like mining loaders and construction dozers.
Symptoms of Failure
When the ZF 4644.026.385 assembly begins to fail, operators typically notice these specific issues:
- Erratic gear engagement or slipping under load: Worn clutch discs or damaged seals inside the assembly cause the transmission to hesitate or lose torque during shifting, especially on inclines.
- Internal hydraulic pressure loss: Cracks in the valve body or piston bores lead to low line pressure, resulting in delayed shifts and overheating.
- Metallic debris in the oil pan: Bearing or gear wear generates fine metal particles, which can clog the SCREEN SHEET and accelerate damage to other components.
- External oil seepage at the main case joint: A failing gasket or warped housing face allows fluid to escape, often requiring replacement of the O-RING and a new COVER PLATE to restore sealing integrity.
Technical Specifications
| Specification | Value |
|---|---|
| OEM Part Number | 4644.026.385 |
| Assembly Type | Complete Powershift Unit (6 WG 200) |
| Dry Weight | ~185 kg (408 lbs) |
| Overall Length | 720 mm |
| Overall Width | 410 mm |
| Overall Height | 480 mm |
| Housing Material | High-tensile cast iron (GGG-40) |
| Max Input Torque | 2,000 Nm |
| OEM Reference | ZF 6 WG 200 Series |
Compatibility
This complete assembly is engineered for the ZF WG 200 series, including models such as the WG180, WG200, and WG210. It is commonly found in articulated dump trucks, wheel loaders, and telehandlers from manufacturers like Volvo, Liebherr, and JCB. For proper installation, ensure the mating TRANSMISSION HOUSING is free of cracks and that all hydraulic passages are clean. The unit also integrates with the OIL PIPE for lubrication flow and requires a fresh O-RING at the input flange to prevent leaks.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural case for gear and shaft support |
| 4644301402 | TRANSMISSION HOUSING | Alternative housing variant for WG200 series |
| 4644301298 | COVER PLATE | Seals the rear access opening of the assembly |
| 0634306323 | O-RING | Provides leak-proof seal between housing and cover |
| 0636305026 | SCREW PLUG | Closes hydraulic test ports in the valve body |
| 4644301279 | SCREEN SHEET | Filters debris from the oil return circuit |
| 4644301088 | SEALING CAP | Protects unused hydraulic ports from contamination |
| 4644298503 | REPAIR KIT | Contains gaskets, seals, and O-rings for overhaul |
| 4475280079 | SCREW PLUG | Magnetic plug for ferrous debris collection |
| 4644121150 | OIL PIPE | Routes pressurized oil to clutch packs |
