Overview
The ZF 4657.026.120 6 WG 190 Powershift Transmission Assembly | Complete Unit is a fully integrated, factory-built drop-in solution for heavy-duty off-highway machinery. This complete assembly serves as the central power distribution hub within the WG 190 series, managing torque flow from the engine to the driveline through six forward speeds. The SKU 4657.026.120 designates a remanufactured or new-build unit that includes all internal clutches, planetary gear sets, and hydraulic control valves. In the transmission architecture, this assembly sits between the engine bellhousing and the rear output flange, directly interfacing with the 4657101082: TRANSMISSION HOUSING to form the main structural shell. The unit is precision-balanced to eliminate vibration and is pre-filled with ZF-specification lubricant for immediate installation.
Symptoms of Failure
- Delayed engagement or gear slipping under load: When the complete unit wears, internal clutch packs fail to hold torque, causing the machine to hesitate or lose power during acceleration.
- External oil leaks at housing seams: Cracks or gasket degradation in the 4657201166: HOUS.FRONT SECT or the 4657201170: HOUSING REAR PART allow transmission fluid to weep, leading to low pressure and eventual overheating.
- Erratic shifting or harsh engagement: Worn valve body components inside the assembly cause pressure spikes, resulting in jarring shifts that stress the driveline.
- Unusual whining or grinding noises: Bearing failure or planetary gear damage within the unit produces metallic sounds, especially in neutral or low gear.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4657.026.120 |
| Assembly Type | Complete Powershift Transmission |
| Series | WG 190 |
| Number of Speeds | 6 Forward / 1 Reverse |
| Dry Weight (approx.) | 385 kg (849 lbs) |
| Overall Length | 720 mm |
| Overall Width | 510 mm |
| Overall Height | 580 mm |
| Housing Material | High-Grade Cast Iron |
| OEM Reference | ZF 4657.026.120 |
| Max Input Torque | 1,900 Nm |
| Fluid Capacity | 18.5 liters |
Compatibility
This complete unit is engineered specifically for the WG 190 series, but it also shares mounting patterns and hydraulic interfaces with the WG 180 and WG 200 families. It is a direct replacement for machines originally equipped with ZF 6 WG 190 transmissions, including certain models of loaders, graders, and industrial tractors. The assembly integrates with the 4657298102: HOUSING REAR SECTION for extended wheelbase configurations. Always verify the bellhousing pattern and output flange spline count before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101082 | TRANSMISSION HOUSING | Main structural casing for the gear train |
| 4657201166 | HOUS.FRONT SECT | Front section housing input shaft and pump drive |
| 4657201170 | HOUSING REAR PART | Rear section supporting output shaft bearings |
| 4657298102 | HOUSING REAR SECTION | Extended rear housing for longer wheelbase models |
| 0631306816 | CYLINDRICAL PIN | Alignment pin for housing dowel holes |
| 0636100801 | CAP SCREW | M12 fastener for housing bolt connections |
| 4656301148 | FIXING PLATE | Retaining plate for clutch pack preload |
| 4657301032 | SCREEN SHEET | Fine mesh filter for hydraulic circuit |
| 4657301033 | SCREEN SHEET | Coarse mesh pre-filter for sump pickup |
| 0636100803 | CAP SCREW | M10 fastener for valve body mounting |
