Overview
The ZF 4644.026.072 6 WG 200(555/5) Powershift Transmission Assembly is a complete, factory-grade unit designed for heavy-duty off-highway applications. As a fully assembled drop-in replacement, this assembly integrates the torque converter, clutch packs, and planetary gear sets into a single, pre-tested module. It sits at the core of the ZF WG 200 series, managing power distribution from the engine to the driveline under high-stress conditions. The SKU 4644.026.072 specifically denotes the 6-speed configuration with a 555/5 gear ratio split, ensuring precise load handling for wheel loaders, graders, and material handlers. This unit eliminates the need for piecemeal repairs, offering a direct exchange for worn or failed transmissions.
Symptoms of Failure
When the ZF 4644.026.072 assembly begins to degrade, operators typically notice these distinct failure modes:
- Delayed or harsh gear engagement: A noticeable lag when shifting from neutral to forward or reverse, often accompanied by a jarring clunk. This indicates worn clutch discs or degraded hydraulic pressure within the valve body.
- Torque converter shudder under load: A vibration or shaking sensation when the machine is under heavy load, such as during digging or climbing. This points to failing stator bearings or a damaged lock-up clutch.
- External oil seepage at the PTO housing: Persistent fluid leaks around the power take-off (PTO) mounting flange or the main case split line, often caused by degraded O-rings or a cracked housing from thermal stress.
- Intermittent loss of drive in higher gears: The machine may suddenly lose power in 4th, 5th, or 6th gear while lower gears remain functional, a classic sign of a failing planetary gear carrier or a seized one-way clutch.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 4644.026.072 |
| Assembly Type | Complete Powershift Unit (6 WG 200) |
| Gear Configuration | 6 Forward / 3 Reverse (555/5 Ratio Set) |
| Dry Weight (Approx.) | 385 kg (849 lbs) |
| Overall Length | 720 mm |
| Overall Width | 510 mm |
| Overall Height | 480 mm |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| OEM Reference | ZF 4644.026.072 (Direct OE Replacement) |
| Fluid Capacity | 14.5 Liters (ZF TE-ML 03 Spec) |
Compatibility
This 4644.026.072 assembly is engineered specifically for the ZF WG 200 transmission series. It is a direct fit for the following models and their sub-variants:
- ZF WG 200 (all 6-speed configurations with 555/5 ratio)
- ZF WG 180 (retrofit applications requiring upgraded torque capacity)
- ZF WG 150 (only when used with the 555/5 gear set adapter kit)
- ZF 6 WG 200 (original equipment on Volvo L120, Caterpillar 950, and Komatsu WA380 wheel loaders)
Note: Always verify the bell housing pattern and PTO flange orientation before installation. This unit replaces older 4644.026.070 and 4644.026.071 revisions without modification.
