Overview
The ZF 4644.026.367 6 WG 200(555/5) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the main drive housing, clutch packs, and hydraulic control system into a single drop-in replacement for WG 200 series transmissions. The SKU 4644.026.367 specifically denotes a 6-speed forward, 1-reverse configuration with a 555/5 ratio set, commonly used in wheel loaders, graders, and industrial tractors. This assembly sits as the central power transfer module between the engine and the driveline, managing torque distribution through electro-hydraulic modulation. When replacing this unit, ensure the 4644101249: TRANSMISSION HOUSING and 4644301402: TRANSMISSION HOUSING are inspected for cracks or wear, as they form the structural backbone of the assembly.
Symptoms of Failure
- Erratic gear engagement or delayed shifting: When the internal clutch piston seals degrade, hydraulic pressure drops, causing hesitation between forward and reverse shifts. This is often accompanied by a “flare” in RPM before engagement.
- Torque converter shudder under load: A worn stator or damaged lock-up clutch within the assembly produces a vibration that intensifies during low-speed, high-torque maneuvers like loading or grading.
- External oil seepage at the bell housing joint: The main gasket between the transmission housing and the converter housing can fail, leaving wet spots on the underside. This is frequently misdiagnosed as a rear main seal leak.
- Metallic debris in the hydraulic filter: Shedding from planetary gear sets or bearing races generates fine steel particles, which accelerate wear on the 0634306323: O-RING and valve body spools.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.026.367 |
| Series | WG 200 (6 WG 200) |
| Configuration | 6 Forward / 1 Reverse (555/5 ratio) |
| Dry Weight | Approx. 385 kg (849 lbs) |
| Overall Length | 720 mm |
| Input Flange | SAE 3 (10-spline) |
| Output Flange | SAE C (14-spline) |
| Housing Material | High-strength cast iron (GGG-40) |
| Max Input Torque | 1,200 Nm (885 lb-ft) |
| Hydraulic Pressure Range | 18–22 bar (261–319 psi) |
Compatibility
This complete assembly is engineered for the ZF WG 200 series, including the WG 180, WG 200, and WG 210 variants. It directly replaces units in 6 WG 200(555/5) applications found in Liebherr, Volvo, and Case wheel loaders from the mid-2000s. The assembly is not backward-compatible with the older WG 150 series due to different bell housing bolt patterns. For proper sealing during installation, always replace the 4644301298: COVER PLATE and its associated gasket to prevent contamination ingress.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Rear housing for output shaft support |
| 4644301298 | COVER PLATE | Seals the valve body access port |
| 0634306323 | O-RING | Hydraulic seal for clutch piston circuits |
| 0636305026 | SCREW PLUG | Seals oil gallery test ports |
| 4644301279 | SCREEN SHEET | Fine mesh filter for hydraulic return line |
| 4644301088 | SEALING CAP | Protects exposed splines during storage |
| 4644298503 | REPAIR KIT | Contains gaskets, seals, and O-rings for overhaul |
| 4644309001 | OUTPUT FLANGE | Connects driveshaft to transmission output |
| 4475280079 | SCREW PLUG | Magnetic drain plug for debris collection |
