Overview
The ZF 4661.001.018 4 WG 90 Powershift Transmission Assembly | Complete Unit is a fully assembled, drop-in replacement for heavy-duty powershift applications. This unit integrates the clutch pack, planetary gear set, and hydraulic control components into a single, pre-tested assembly. As the core rotating assembly within the WG 90 series, it transfers torque from the engine to the driveline. The SKU 4661.001.018 is specifically engineered to match OEM tolerances for ZF off-highway transmissions used in loaders, graders, and industrial tractors. This complete unit replaces the need to source individual internal components, reducing downtime during rebuilds.
Symptoms of Failure
- Delayed engagement or gear slipping under load: When the internal clutch packs wear, operators experience hesitation when shifting from forward to reverse, or the transmission slips during heavy digging operations.
- Low hydraulic pressure and erratic shifting: A failing unit often causes pressure drops in the main circuit, leading to harsh or unpredictable gear changes that worsen as the transmission heats up.
- Metallic debris in the oil filter or pan: Worn bearings or planetary gears shed metal particles, which can be detected during routine oil changes and indicates imminent internal failure.
- External oil leaks near the bell housing or output flange: Cracks in the housing or worn seals around the assembly allow transmission fluid to escape, often visible as drips after the machine sits overnight.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4661.001.018 |
| Assembly Type | Complete Powershift Unit (4 WG 90) |
| 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 (GGG-40) |
| OEM Reference | ZF 4661.001.018 |
| Max Input Torque | 900 Nm |
| Operating Pressure | 14–18 bar |
Compatibility
This complete unit is designed for the ZF WG 90 series of powershift transmissions. It is a direct fit for models including the WG 90, WG 120, and WG 150 found in compact wheel loaders and telehandlers. While the assembly is specific to the 4-speed WG 90 variant, it shares mounting patterns with the WG 180 and WG 200 series when used with the correct adapter housing. Always verify the bell housing configuration before installation.
When installing this unit, it is critical to inspect the surrounding components. The 4661101020: TRANSMISSION HOUSING provides the structural base for the assembly, while the 4661301046: HOUSING II encloses the rear planetary set. The 4661301093: TUBE routes lubrication oil to the upper clutch pack, and the 0631306174: CYLINDRICAL PIN aligns the assembly to the main case during installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101020 | TRANSMISSION HOUSING | Main structural casing for the gear train |
| 4661301046 | HOUSING II | Rear housing covering the output planetary set |
| 4661301093 | TUBE | Lubrication oil delivery tube for clutch packs |
| 0631306174 | CYLINDRICAL PIN | Alignment dowel for housing-to-case fitment |
| 0769123894 | TYPE PLATE | Identification plate with serial number |
| 0750100022 | SCREW PLUG | Magnetic drain plug for oil pan |
| 0636302602 | SCREW PLUG | Hexagonal fill plug for transmission housing |
| 0634100633 | O-RING | Seal for plug and pressure port connections |
| 4661301041 | NOZZLE | Oil spray nozzle for planetary gear lubrication |
| 4661301038 | NOZZLE | Secondary oil nozzle for clutch cooling |
