Overview
The ZF 4661.004.055 4 WG 94 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. This assembly integrates the planetary gearset, clutch packs, and hydraulic control valves into a single, pre-assembled module. As the core power transfer component in the WG 94 series, it converts engine torque into controlled, multi-speed output for wheel loaders, dozers, and graders. The SKU 4661.004.055 is a direct OEM replacement, ensuring precise fitment and eliminating the need for partial rebuilds. This unit sits between the torque converter and the final drive, managing all gear ratio changes under load.
Symptoms of Failure
- Delayed or harsh engagement: When the 4661.004.055 assembly wears, operators experience a noticeable lag when shifting from forward to reverse, or a jarring “clunk” during gear changes. This is often caused by worn clutch discs or degraded sealing rings within the unit.
- Intermittent gear slipping under load: A common failure symptom is the transmission suddenly losing power on a grade or during digging cycles. The assembly may momentarily disengage, causing the engine to rev without corresponding wheel movement.
- Contaminated transmission fluid with metallic debris: Internal wear of the planetary gears or bearings generates fine metal particles. If you find silver or bronze-colored sludge on the dipstick or in the filter, the 4661.004.055 assembly is likely shedding material internally.
- External oil leaks near the bell housing: Cracks in the housing or failed gaskets allow pressurized oil to escape. This often presents as drips pooling under the transmission, specifically around the joint between the assembly and the TRANSMISSION HOUSING.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 4661.004.055 |
| Assembly Type | 4 WG 94 Powershift (Complete Unit) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length | 620 mm |
| Overall Width | 480 mm |
| Overall Height | 510 mm |
| Primary Material | High-strength cast iron housing with hardened steel gears |
| OEM Reference | ZF 4661.004.055 |
| Seal Type | Viton O-rings and PTFE lip seals |
Compatibility
This complete unit is engineered for the ZF WG 94 series powershift transmissions. It is a direct fit for the following models and their derivatives: WG 94, WG 180, WG 200, and WG 211. These transmissions are commonly found in articulated dump trucks, wheel loaders, and heavy forklifts from manufacturers such as Volvo, Liebherr, and Terex. Always verify your transmission serial number against the 4661.004.055 assembly to confirm compatibility. During installation, ensure the HOUSING II is properly aligned to prevent binding, and inspect the TUBE for any blockages that could restrict oil flow. The CYLINDRICAL PIN must be replaced to maintain precise dowel alignment between the assembly and the engine flywheel housing.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101028 | TRANSMISSION HOUSING | Encloses the gear train and supports all shafts |
| 4661301049 | HOUSING II | Rear cover housing for clutch pack access |
| 4661301093 | TUBE | Oil delivery tube for clutch lubrication |
| 0631306174 | CYLINDRICAL PIN | Alignment dowel for housing mating surfaces |
| 0769123894 | TYPE PLATE | Identification plate with serial number |
| 0750100022 | SCREW PLUG | Seals oil passages in the valve body |
| 0636302602 | SCREW PLUG | Drain or fill port plug |
| 0634100633 | O-RING | Seals between housing sections |
| 4661301029 | NOZZLE | Sprays oil onto planetary gears |
| 4661301027 | NOZZLE | Secondary oil spray nozzle for clutch cooling |
