Overview
The ZF 4644.026.326 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 gear cluster, clutch packs, and hydraulic control components into a single, ready-to-install package. As a core element of the WG 200 series, it manages torque distribution across six forward speeds and one reverse, ensuring smooth power delivery under extreme loads. The SKU 4644.026.326 identifies this specific build variant, which includes the 555/5 ratio set for optimized low-speed tractive effort. This assembly is typically mounted directly to the engine bellhousing and mates with the 4644101222: TRANSMISSION HOUSING to form the primary structural envelope. For proper identification during installation, the 0730365067: TYPE PLATE must be transferred to the new unit.
Symptoms of Failure
- Delayed or harsh engagement: When the assembly’s internal clutch discs or seals degrade, operators experience a pronounced lag when shifting from neutral to forward or reverse, often accompanied by a jarring engagement.
- Progressive gear slippage under load: Worn piston seals or scored clutch plates cause the transmission to lose torque in higher gears, particularly when climbing grades or pushing heavy material.
- Hydraulic oil contamination with metallic debris: As friction material wears, fine metal particles circulate through the system, leading to erratic shift timing and eventual pump failure. This is often detected during routine oil analysis.
- External oil seepage at the bellhousing interface: Cracks in the main housing or degraded gaskets allow ATF to weep past the 4644301226: TRANSMISSION HOUSING joint, leaving visible drips after machine shutdown.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4644.026.326 |
| Series | WG 200 (6 WG 200) |
| Gear Configuration | 6 Forward / 1 Reverse (555/5 ratio set) |
| Dry Weight | Approx. 285 kg (628 lbs) |
| Housing Material | High-strength cast iron (GGG-40) |
| Max Input Torque | 1,200 Nm (885 lb-ft) |
| Overall Length (without bellhousing) | 620 mm |
| Mounting Flange | SAE 3 (with 10.9 grade studs) |
| Oil Capacity | 22 liters (ZF TE-ML 03 spec) |
| Related Housing | 4644101222 / 4644301226 |
| Identification | 0730365067: TYPE PLATE |
| Fastener | 0631311009: GROOVED STUD (qty 8) |
Compatibility
This complete assembly is engineered for the ZF WG 200 series, specifically the 6 WG 200 variant with the 555/5 ratio package. It is directly interchangeable with units originally fitted to ZF WG180, WG200, and WG210 transmissions used in wheel loaders, telehandlers, and industrial tractors from manufacturers such as Liebherr, JCB, and Caterpillar. The assembly requires the corresponding 4644301226: TRANSMISSION HOUSING for proper oil routing. Always verify the 0730365067: TYPE PLATE matches your original transmission’s serial number prefix. The 0631311009: GROOVED STUD must be torqued to 120 Nm during reinstallation to prevent housing distortion.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101222 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301226 | TRANSMISSION HOUSING | Rear housing with oil sump |
| 0730365067 | TYPE PLATE | Identification and serial number tag |
| 0631311009 | GROOVED STUD | Housing-to-engine mounting fastener |
| 4644301298 | COVER PLATE | Seals the PTO access port |
| 0634306525 | O-RING | Hydraulic circuit sealing |
| 0636305026 | SCREW PLUG | Oil drain/fill port closure |
| 4475280078 | ADAPTER | Converter-to-pump interface |
| 4644301279 | SCREEN SHEET | Suction strainer for oil pump |
| 4644301088 | SEALING CAP | Closes unused hydraulic ports |
