Overview
The ZF 4657.026.122 6 WG 190 Powershift Transmission Assembly | Complete Unit is a fully assembled, drop-in ready gearbox designed for heavy-duty off-highway applications. This complete unit integrates the clutch packs, planetary gearsets, and hydraulic control system into a single robust housing. As the core power transfer module in the WG 190 series, it manages torque distribution across six forward speeds. The SKU 4657.026.122 identifies this as a factory-matched assembly, ensuring precise alignment of internal components. It sits directly between the engine flywheel and the final drive, converting rotational power into controlled tractive effort. For structural integrity, this unit relies on the 4657101080: TRANSMISSION HOUSING to encase the rotating elements, while the 4657201167: HOUS.FRONT SECT provides the forward mounting interface.
Symptoms of Failure
- Erratic gear engagement under load: When the internal clutch packs wear, operators experience delayed or harsh shifting, particularly when moving from neutral to forward. This “gear slipping under heavy load” symptom often precedes total transmission failure.
- Hydraulic fluid contamination: Worn seals inside the assembly allow debris to circulate, causing “transmission overheating due to blocked oil passages.” This manifests as dark, burnt-smelling fluid on the dipstick.
- Torque converter shudder: A rhythmic vibration during acceleration at low RPM indicates internal wear. This “torque converter lockup failure” symptom is common in high-hour units.
- External oil seepage at the rear seal: Cracks in the 4657201171: HOUSING REAR PART or the 4657298103: HOUSING REAR SECTION cause “transmission oil leak near the output shaft,” leading to low fluid levels and eventual bearing damage.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 4657.026.122 |
| Assembly Type | Complete Powershift Unit (6 WG 190) |
| Overall Length | 685 mm (27.0 in) |
| Dry Weight | 195 kg (430 lbs) |
| Housing Material | High-strength cast iron (GGG-40) |
| OEM Reference | ZF 6 WG 190 Series |
| Max Input Torque | 1,900 Nm (1,400 lb-ft) |
| Bolt Torque (housing) | 120 Nm (88 lb-ft) with 0636100801: CAP SCREW |
| Alignment Pin | 0631306816: CYLINDRICAL PIN (2x required) |
Compatibility
This complete unit is engineered for the ZF WG 190 series of powershift transmissions. It is a direct fit for models including the WG 180, WG 200, and WG 210 when used in construction equipment such as loaders, graders, and dump trucks. The assembly also integrates with earlier WG 170 variants after verifying the input shaft spline count. Always confirm the bellhousing pattern against your existing 4657101080: TRANSMISSION HOUSING to ensure proper alignment. For securing the unit, use the 0636100803: CAP SCREW at the rear mounting points.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101080 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4657201167 | HOUS.FRONT SECT | Forward mounting section for input shaft |
| 4657201171 | HOUSING REAR PART | Rear casing supporting output bearings |
| 4657298103 | HOUSING REAR SECTION | Extended rear cover for PTO interface |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for housing halves |
| 0636100801 | CAP SCREW | M12 bolt for housing fastening |
| 4656301148 | FIXING PLATE | Locking plate for clutch piston retention |
| 4657301034 | SCREEN SHEET | Fine mesh filter for hydraulic circuit |
| 4657301035 | SCREEN SHEET | Coarse mesh pre-filter for sump |
| 0636100803 | CAP SCREW | M16 bolt for rear housing attachment |
