Overview
The ZF 4657.026.125 6 WG 190 Powershift Transmission Assembly is a complete, factory-grade replacement unit engineered for heavy-duty off-highway machinery. This assembly integrates the main gear cluster, clutch packs, and hydraulic control system into a single, ready-to-install package. As the core rotating assembly for the WG 190 series, it directly governs torque distribution and gear engagement in loaders, graders, and industrial tractors. The SKU 4657.026.125 designates a fully assembled unit, eliminating the need to source individual internal components. This complete unit mounts directly against the TRANSMISSION HOUSING, forming the primary structural backbone of the drivetrain.
Symptoms of Failure
- Delayed or harsh gear engagement: When the assembly wears, hydraulic pressure drops, causing a noticeable lag or a jarring “clunk” when shifting from neutral to forward or reverse.
- Torque converter shudder under load: Worn clutch discs within the unit produce a low-frequency vibration during acceleration, particularly when the machine is under heavy load.
- Internal metallic grinding noises: Bearing or gear failure inside the assembly generates a distinct grinding or whining sound that changes with engine RPM, indicating imminent catastrophic failure.
- Chronic fluid contamination with bronze or steel particles: Debris found in the oil filter or magnetic drain plug signals advanced wear of the planetary gear sets or clutch friction material.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4657.026.125 |
| Assembly Type | 6-Speed Powershift (WG 190) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| Overall Length | 620 mm |
| Overall Width | 480 mm |
| Overall Height | 510 mm |
| Input Torque Capacity | 1,900 Nm (1,401 lb-ft) |
| Fluid Capacity (assembly only) | 12.5 Liters |
Compatibility
This complete unit is specifically designed for the ZF WG 190 series. It is a direct fit for the WG 190, WG 191, and WG 192 transmission models. While the WG 180 and WG 200 series share similar architecture, this SKU 4657.026.125 is calibrated exclusively for the 190 series torque and speed ranges. The assembly interfaces with the HOUS.FRONT SECT and the HOUSING REAR PART to create a sealed, pressurized oil gallery. For extended rebuilds, the HOUSING REAR SECTION is often replaced concurrently to ensure proper alignment of the output shaft bearings.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101082 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4657201166 | HOUS.FRONT SECT | Front section housing pump drive |
| 4657201170 | HOUSING REAR PART | Rear section supporting output shaft |
| 4657298102 | HOUSING REAR SECTION | Extended rear housing for PTO mount |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for housing mating |
| 0636100801 | CAP SCREW | M16 bolt for housing fastening |
| 4656301148 | FIXING PLATE | Locks cap screws in position |
| 4657301032 | SCREEN SHEET | Fine mesh filter for oil return |
| 4657301033 | SCREEN SHEET | Coarse mesh pre-filter for sump |
| 0636100803 | CAP SCREW | M12 bolt for accessory mounting |
