Overview
The ZF 4644.026.280 6 WG 200(555/5) Powershift Transmission Assembly is a complete, fully assembled unit engineered for heavy-duty off-highway applications. As a core component of the WG 200 Series, this assembly integrates the torque converter, clutch packs, and planetary gear sets into a single, ready-to-install package. The SKU 4644.026.280 specifically designates the 6-speed version with a 555/5 gear ratio configuration, optimized for loaders, graders, and material handlers requiring precise power modulation under high torque loads. This unit replaces the need for individual sub-assembly procurement, reducing downtime during major overhauls.
Symptoms of Failure
When the ZF 4644.026.280 assembly begins to degrade, operators typically encounter these distinct failure modes:
- Delayed or harsh engagement when shifting from neutral to forward or reverse, often accompanied by a loud clunk. This indicates worn clutch pack friction discs or degraded sealing rings within the hydraulic control system.
- Intermittent gear slipping under load, particularly on inclines or during bucket breakout operations. This suggests internal pressure loss from worn pump gears or valve body bore scoring.
- External oil seepage at the bell housing or output flange, commonly caused by hardened lip seals or cracked housing due to thermal cycling. Visible drips on the undercarriage are a primary indicator.
- Erratic shifting patterns where the transmission hunts between gears or fails to hold a selected gear. This points to a failing speed sensor or degraded solenoid pack in the electro-hydraulic module.
Technical Specifications
| Parameter | Value |
|---|---|
| Assembly Weight (Dry) | 385 kg (849 lbs) |
| Overall Length | 785 mm |
| Input Torque Capacity | 555 Nm (409 lb-ft) |
| Number of Speeds | 6 Forward / 3 Reverse |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| OEM Reference | ZF 4644.026.280 |
| Fluid Capacity | 18.5 Liters (4.9 Gallons) |
| Mounting Pattern | SAE 3 Bell Housing |
Compatibility
This complete unit is specifically designed for the ZF WG 200 Series transmission family. It is a direct fit for the following models:
- ZF WG 200 (555/5) – Primary application for this SKU.
- ZF WG 180 – Compatible with adapter plate modifications for lower torque applications.
- ZF WG 210 – Shares the same hydraulic control architecture and gear train layout.
- ZF 6 WG 200 – Earlier generation units with mechanical shift valves (requires ECU reflash for electro-hydraulic versions).
Always verify the serial number on your existing transmission tag before ordering. This assembly is not backward compatible with the WG 160 or WG 250 series without significant driveline modifications.
