Overview
This ZF 4644.026.251 6 WG 200(400/3) Powershift Transmission Assembly is a complete, ready-to-install unit engineered for heavy-duty industrial applications. As a core component of the WG 200 series, this assembly integrates the torque converter, planetary gear sets, and hydraulic control system into a single, sealed housing. The SKU 4644.026.251 specifically denotes a 6-speed configuration with a 400/3 torque converter ratio, designed to deliver precise power modulation and smooth gear shifts under extreme loads. This unit replaces worn or failed transmissions in wheel loaders, forklifts, and material handlers, restoring original OEM performance and reducing downtime.
Symptoms of Failure
When the ZF 4644.026.251 assembly begins to degrade, operators will notice distinct operational issues. The most common failure symptoms include:
- Delayed or harsh engagement: A noticeable lag when shifting from neutral to forward or reverse, often accompanied by a jarring clunk, indicating worn clutch packs or hydraulic pressure loss.
- Transmission oil overheating: Persistent high temperature readings on the dash gauge, even under normal load, suggesting internal seal failure or torque converter slippage.
- Intermittent gear slipping under load: The transmission momentarily loses drive power when climbing or pushing, a classic sign of worn planetary gears or damaged valve body components.
- External oil seepage from bell housing: Visible drips or wetness around the input shaft area, pointing to a failed front pump seal or converter hub wear.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.026.251 |
| Assembly Type | Complete Powershift Unit |
| Speed Configuration | 6 Forward / 3 Reverse |
| Torque Converter Ratio | 400/3 (2.83:1 stall) |
| Dry Weight | Approx. 285 kg (628 lbs) |
| Overall Length | 620 mm |
| Housing Material | High-strength cast iron |
| OEM Reference | ZF 4644.026.251 / WG 200 |
| Fluid Capacity | 18.5 liters (ZF EcoFluid M-1) |
Compatibility
This complete unit is specifically designed for the ZF WG 200 series powershift transmissions. It is a direct replacement for models utilizing the 6 WG 200(400/3) configuration. While the WG 200 series shares many internal components with the WG 180 and WG 210 families, the 4644.026.251 assembly is calibrated for the 400/3 torque converter and will not function correctly in a WG 180 chassis without significant modifications. Compatible vehicle applications include:
- ZF WG 200 (all sub-variants with 6-speed and 400/3 converter)
- ZF WG 180 (only with adapter kit, not direct fit)
- ZF WG 210 (only with adapter kit, not direct fit)
- Select models of ZF 6 WG 200 series used in 15-20 ton wheel loaders
Always verify your existing transmission tag or vehicle VIN before ordering. The 4644.026.251 is not backward-compatible with older 4-speed WG series units.
