Overview
The ZF 4644.026.300 6 WG 200 (555/5) Powershift Transmission Assembly is a complete, factory-grade replacement unit designed for heavy-duty off-highway applications. This assembly integrates the torque converter, planetary gear sets, and hydraulic control system into a single, ready-to-install package. As the core of the WG 200 series, it manages power distribution from the engine to the driveline, enabling smooth, clutchless gear changes under full load. The SKU 4644.026.300 specifically denotes a 6-speed forward, 1-reverse configuration with a 555/5 gear ratio spread, optimized for loaders, graders, and material handlers. This unit replaces worn or failed assemblies to restore original machine performance and reduce downtime.
Symptoms of Failure
When the ZF 4644.026.300 assembly begins to degrade, operators often notice distinct operational issues. Below are the most common failure indicators:
- Delayed or harsh gear engagement: A noticeable lag or “clunk” when shifting from neutral to forward or reverse, indicating worn clutch packs or low hydraulic pressure.
- Transmission oil overheating: Persistent high temperature readings on the dash gauge, often caused by internal leakage or a failing torque converter stator.
- Intermittent gear slipping under load: The machine loses power or revs up without corresponding speed increase when climbing grades or pushing heavy material, pointing to worn friction discs.
- External oil seepage from the main housing: Visible fluid leaks around the bell housing or output flange, typically from degraded shaft seals or gasket failure.
Technical Specifications
| Parameter | Specification |
|---|---|
| Assembly Type | Complete Powershift Transmission (6WG200) |
| OEM Part Number | 4644.026.300 |
| Gear Configuration | 6 Forward / 1 Reverse (555/5 Ratio Spread) |
| Dry Weight (approx.) | 385 kg (849 lbs) |
| Overall Length | 720 mm |
| Input Torque Capacity | 555 Nm (max) |
| Housing Material | High-strength cast iron |
| Hydraulic Control | Modulating pressure, wet clutch pack |
Compatibility
This complete assembly is engineered for the ZF WG 200 series transmission family. It is a direct fit for the following models and their variants:
- ZF WG 200 (6WG200) – Primary application for this SKU.
- ZF WG 180 (6WG180) – Shares the same bell housing pattern and hydraulic interface, though gear ratios differ.
- ZF WG 150 (6WG150) – Compatible with adapter kits for certain loader models.
- ZF Ergopower 200 – Some crossover applications in older telehandlers.
Always verify the original transmission tag and machine model before installation. This unit replaces all previous revisions of the 4644.026.xxx series.
