Overview
The ZF 4644.036.066 6 WG 201 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. This assembly integrates the main gear cluster, clutch packs, and hydraulic control components into a single ready-to-install package. As a core element of the WG 201 series, it manages torque distribution across six forward speeds, enabling smooth power shifts under load. The SKU 4644.036.066 replaces worn or failed assemblies in graders, loaders, and dump trucks, restoring full driveline efficiency. This unit works in concert with the TRANSMISSION HOUSING and the TRANSMISSION HOUSING to contain lubrication and support rotating elements.
Symptoms of Failure
- Erratic gear engagement under load: When the 4644.036.066 assembly wears, operators report delayed or harsh shifts, especially when transitioning from forward to reverse. This often indicates worn clutch discs or degraded sealing rings within the unit.
- Internal hydraulic pressure loss: A failing assembly may cause gradual pressure drops in the control circuit, leading to slipping in higher gears. Technicians frequently trace this to fatigued O-rings or scored valve bores inside the assembly.
- Metallic debris in transmission fluid: Advanced wear generates fine metal particles from gear teeth or bearing surfaces. If you find glitter-like contamination during oil changes, the 4644.036.066 assembly likely requires immediate replacement to prevent cascading damage to the THREADED BUSH and adjacent components.
- Audible whining or grinding from the bell housing: Noise that intensifies with engine RPM suggests bearing fatigue inside the assembly. This symptom often precedes complete seizure if left unaddressed.
Technical Specifications
| Parameter | Value |
|---|---|
| Assembly Weight | 185 kg (408 lbs) |
| Overall Length | 620 mm |
| Overall Width | 480 mm |
| Overall Height | 510 mm |
| Housing Material | Cast Iron (GGG-40) |
| OEM Reference | ZF 4644.036.066 |
| Gear Ratio Range | 6.12:1 to 0.78:1 (6 forward speeds) |
| Max Input Torque | 1,200 Nm |
| Fluid Capacity (Assembly) | 14.5 liters |
Compatibility
This complete assembly is engineered for the ZF WG 201 transmission series. It directly fits WG 201 models used in Volvo G-Series graders, Case 821/921 wheel loaders, and Terex TA30 articulated trucks. The 4644.036.066 also serves as a direct replacement for earlier WG 180 and WG 200 series units when paired with the correct SCREW PLUG kit for port adaption. Verify your transmission tag (e.g., 6 WG 201) before ordering to ensure proper spline count and clutch pack configuration.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101160 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301323 | TRANSMISSION HOUSING | Secondary housing for clutch pack section |
| 4644301189 | THREADED BUSH | Wear-resistant insert for shift fork pivot |
| 4475280043 | SCREW PLUG | Seals hydraulic test ports |
| 0634306198 | O-RING | Prevents fluid leakage at housing joints |
| 0730365067 | TYPE PLATE | Identification tag for transmission model |
| 4644301161 | COVER PLATE | Encloses valve body access area |
| 0636100621 | HEXAGON SCREW | Fastens housing halves together |
| 0631610020 | SET SCREW | Locks adjustment collars in place |
| 0501218540 | BREATHER | Equalizes internal air pressure |
