Overview
The ZF 4661.004.028 4 WG 94 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the clutch packs, planetary gear sets, and hydraulic control components into a single, ready-to-install package. As a core element of the WG 94 series, the SKU 4661.004.028 replaces the entire transmission core, eliminating the need for piecemeal rebuilds. It sits at the heart of the drivetrain, managing torque distribution across four forward and reverse speeds. For proper sealing and structural integrity, this assembly must be paired with a new TRANSMISSION HOUSING and the HOUSING II to ensure correct alignment of the internal shafts.
Symptoms of Failure
- Delayed or harsh engagement: When the 4661.004.028 assembly wears, you will notice a pronounced lag between shifting and actual gear engagement, often accompanied by a jarring clunk. This indicates worn clutch discs or degraded hydraulic seals within the unit.
- Intermittent gear slippage under load: A failing assembly will cause the transmission to momentarily lose power during uphill climbs or heavy hauling, with the engine revving but no forward motion. This is a classic sign of worn piston rings or valve body issues.
- External oil leaks near the bell housing: Cracks in the assembly casing or failed gaskets lead to ATF pooling around the transmission pan. Check for leaks originating from the CYLINDRICAL PIN bores, which often indicate housing fatigue.
- Overheating and burnt fluid smell: Internal friction from worn clutches generates excessive heat, causing the transmission fluid to darken and emit a burnt odor. This symptom often precedes total unit failure.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number / SKU | 4661.004.028 |
| Assembly Type | Complete Powershift Unit (4 WG 94) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length | 620 mm |
| Overall Width | 480 mm |
| Overall Height | 510 mm |
| Housing Material | High-Strength Cast Iron |
| OEM Reference | ZF 4 WG 94 |
| Fluid Capacity (system) | 22 liters |
Compatibility
This complete assembly is engineered for the ZF WG 94 series of powershift transmissions. It is directly compatible with the following models: WG 94, WG 98, WG 100, and WG 120. These transmissions are commonly found in telescopic handlers, wheel loaders, and agricultural tractors from manufacturers like Manitou, JCB, and Claas. The 4661.004.028 unit also serves as a direct replacement for earlier 4 WG 92 variants with updated clutch pack configurations. Always verify the TYPE PLATE on your existing unit to confirm model matching before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101023 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4661301051 | HOUSING II | Rear section housing output shaft bearings |
| 4661301093 | TUBE | Hydraulic fluid passage between valve body and clutch |
| 0631306174 | CYLINDRICAL PIN | Alignment dowel for housing mating surfaces |
| 0769123894 | TYPE PLATE | Identification tag with serial number |
| 0750100022 | SCREW PLUG | Seals oil drain port in housing |
| 0636302602 | SCREW PLUG | Closes pressure test ports |
| 0634100633 | O-RING | Seals plug-to-housing interface |
| 4661301029 | NOZZLE | Lubrication jet for planetary gears |
| 4661301027 | NOZZLE | Secondary lubrication orifice for clutch pack |
