Overview
The ZF 4644.026.227 6 WG 200(555/5) Powershift Transmission Assembly is a complete, fully assembled unit designed 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 4644.026.227 specifically denotes a 6-speed configuration with a 555/5 ratio set, engineered to handle high torque loads in construction, mining, and agricultural machinery. This complete unit replaces the need for individual sub-assembly procurement, ensuring direct OEM fitment and reducing downtime during major transmission overhauls.
Symptoms of Failure
When the ZF 4644.026.227 assembly begins to degrade, operators typically notice distinct performance issues. Recognizing these signs early can prevent catastrophic drivetrain damage.
- Erratic gear engagement and slipping under load: The most common symptom is a delay or harsh “clunk” when shifting between forward and reverse, often accompanied by the engine revving without proportional vehicle movement. This indicates worn clutch discs or degraded seals within the unit.
- Internal hydraulic pressure loss and overheating: A failing assembly often exhibits low line pressure, causing the transmission to run hotter than normal (exceeding 120°C). You may observe dark, burnt-smelling transmission fluid, signaling internal wear or pump cavitation.
- Torque converter shudder or vibration: If the torque converter lock-up clutch within the assembly fails, operators will feel a distinct vibration or “judder” during low-speed maneuvering, particularly when the converter is in the stall phase.
- External oil seepage from the bell housing or PTO ports: Visible fluid leaks around the main gasket surfaces or output shaft seals are a clear indicator that the assembly’s static seals have hardened or cracked, leading to gradual fluid loss.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number / SKU | 4644.026.227 |
| Assembly Type | Complete Powershift Unit (6 WG 200) |
| Number of Speeds | 6 Forward / 1 Reverse |
| Ratio Set | 555/5 (High Torque Variant) |
| Dry Weight (Approx.) | 385 kg (849 lbs) |
| Overall Length | 785 mm |
| Input Flange | SAE 3 (Standard) |
| Housing Material | High-Strength Cast Iron (GGG-40) |
| OEM Reference | ZF 4644.026.227 (Direct Replacement) |
Compatibility
This complete assembly is engineered primarily for the ZF WG 200 series, but its mounting pattern and hydraulic logic also allow direct fitment into select variants of the WG 180 and WG 150 series when using the correct adapter plate. It is specifically designed for machinery requiring the 555/5 ratio, such as wheel loaders and telehandlers. Always verify the bell housing pattern and PTO configuration against your existing unit before installation.
- ZF WG 200 Series: All 6-speed variants (standard duty and heavy duty).
- ZF WG 180 Series: Select models with SAE 3 input flanges (requires ratio verification).
- ZF WG 150 Series: Limited compatibility with specific OEM adapter kits (consult technical manual).
- Common Applications: Liebherr, Volvo, and Caterpillar wheel loaders (model years 2005-2015).
