Overview
The ZF 4644.036.035 6 WG 201 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly serves as the core power transfer module within the WG 201 series, integrating the torque converter, planetary gear sets, and hydraulic control system into a single, ready-to-install package. The SKU 4644.036.035 replaces the need for individual component sourcing, ensuring precise gear alignment and clutch pack clearance for optimal shift quality. This complete unit is typically mounted between the engine flywheel housing and the final drive, making it the central component for loaders, graders, and material handlers requiring reliable forward/reverse shuttle operation.
Symptoms of Failure
- Delayed or harsh engagement when shifting from forward to reverse: Worn clutch discs or degraded piston seals within the 4644.036.035 assembly cause a noticeable lag or a jarring “clunk” during directional changes, often accompanied by a momentary loss of tractive effort.
- Transmission overheating under moderate load: Internal leakage past worn sealing rings or a failing torque converter stator clutch generates excessive heat, leading to elevated oil temperatures that trigger warning lights or cause the transmission to enter a limp-home mode.
- Oil leaks at the housing mating surfaces: Cracks or warpage in the main casing, often requiring replacement of the TRANSMISSION HOUSING (part 4644101203) or the TRANSMISSION HOUSING (part 4644301382), allow pressurized hydraulic fluid to escape, leading to low oil levels and eventual gear slippage.
- Whining or grinding noise from the transmission sump: Bearing failure or gear tooth pitting inside the assembly produces a metallic whine that increases with engine RPM, indicating imminent internal mechanical failure requiring a complete unit replacement.
Technical Specifications
| Specification | Value |
|---|---|
| Assembly Type | Complete Powershift Transmission (6 WG 201) |
| OEM Reference | ZF 4644.036.035 |
| Dry Weight (approx.) | 385 kg (849 lbs) |
| Overall Length | 720 mm |
| Overall Width | 510 mm |
| Overall Height | 580 mm |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| Input Spline Count | 14-tooth, 2.5″ pitch diameter |
| Max Input Torque | 1,200 Nm (885 lb-ft) |
| Hydraulic Pressure Range | 18–22 bar (261–319 psi) |
| Oil Capacity (system) | 28 liters (7.4 gallons) |
Compatibility
This complete unit is engineered for the ZF WG 201 series, specifically the 6-speed variant. It is a direct fit for models including the WG180, WG200, and WG210 transmissions commonly found in Volvo L120/L150 loaders, Case 921E wheel loaders, and John Deere 744K graders. The 4644.036.035 assembly also serves as a direct upgrade for earlier WG 180 series units, provided the THREADED BUSH (part 4644301189) and the SCREW PLUG (part 0636302005) are replaced simultaneously to ensure proper oil gallery sealing. Always verify the bellhousing pattern and torque converter pilot diameter before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101203 | TRANSMISSION HOUSING | Main structural casing for gear and clutch pack support |
| 4644301382 | TRANSMISSION HOUSING | Rear housing section for output shaft bearing retention |
| 4644301189 | THREADED BUSH | Oil passage sealing and alignment dowel for housing joints |
| 0636302005 | SCREW PLUG | Hydraulic port sealing for pressure test points |
| 0634306198 | O-RING | Static seal for housing and cover plate interfaces |
| 0634801098 | SEALING RING | Dynamic seal for rotating shaft and piston bores |
| 0730365067 | TYPE PLATE | Identification tag with serial number and model data |
| 0631311009 | GROOVED STUD | Alignment pin for torque converter housing mounting |
| 4644301161 | COVER PLATE | Access cover for valve body and filter service |
| 0636100621 | HEXAGON SCREW | Fastener for securing cover plate and housing sections |
