Overview
The ZF 4644.026.177 6 WG 200(500/4) Powershift Transmission Assembly is a complete, factory-matched 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, clutch-less shifting under load. The SKU 4644.026.177 specifically denotes a 6-speed configuration with a 500/4 torque converter ratio, optimized for wheel loaders and graders. This complete unit replaces worn or failed transmissions, restoring original ZF performance and reliability.
Symptoms of Failure
When the ZF 4644.026.177 assembly begins to degrade, operators often notice distinct performance issues. Recognizing these signs early can prevent costly downtime.
- Erratic or delayed gear engagement: The transmission hesitates or slams into gear, particularly when shifting from forward to reverse. This indicates worn clutch packs or degraded valve body seals.
- Torque converter shudder under load: A persistent vibration or shudder during acceleration, especially in lower gears, suggests internal wear on the stator or turbine assembly.
- External oil leaks at the bell housing or PTO ports: Visible fluid drips or wet spots around the transmission casing, often accompanied by a burnt smell, point to failed shaft seals or gasket deterioration.
- Loss of power or slipping in higher gears: The engine revs without proportional vehicle speed increase, typically caused by worn planetary gear bearings or hydraulic pressure loss.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number / SKU | 4644.026.177 |
| Series | WG 200 |
| Configuration | 6 Forward / 4 Reverse |
| Torque Converter Ratio | 500/4 (2.0:1 stall) |
| Dry Weight (approx.) | 485 kg (1,069 lbs) |
| Housing Material | High-strength cast iron (GGG-40) |
| Overall Length (bell to tail) | 785 mm |
| OEM Reference | ZF 1321 301 004 |
| Max Input Torque | 1,200 Nm |
Compatibility
This complete assembly is engineered for the ZF WG 200 series powershift transmissions. It is a direct replacement for units originally installed in the following models and applications:
- ZF WG 180 – Upgraded replacement for 5-speed variants in compact loaders.
- ZF WG 200 – Primary fitment for wheel loaders (e.g., Liebherr L538, Volvo L60) and graders.
- ZF WG 210 – Compatible with high-torque versions used in mining trucks.
- ZF 6 WG 200 – Specific to 6-speed configurations with 500/4 torque converters.
Always verify the original transmission tag and vehicle OEM specifications before installation. This assembly does not include the external wiring harness or control module.
