Overview
The ZF 4657.026.121 6 WG 190 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. This assembly integrates the main gear cluster, clutch packs, and hydraulic control components into a single, ready-to-install package. As the core of the WG 190 series, it manages torque distribution across six forward speeds, enabling smooth power shifts under load. The SKU 4657.026.121 identifies this as a fully assembled unit, distinct from individual subcomponents. For proper installation, this assembly must be paired with a structurally sound 4657101082: TRANSMISSION HOUSING to ensure correct alignment of the internal shafts and bearings.
Symptoms of Failure
- Erratic gear engagement under load: When the internal clutch packs wear, the transmission may hesitate or slam into gear, particularly during forward-reverse shifts. This is a common sign that the 4657.026.121 assembly requires replacement.
- Persistent hydraulic oil leaks at the bell housing: Cracks in the main casing or degraded seals around the 4657201166: HOUS.FRONT SECT can cause fluid loss, leading to low pressure and slipping.
- Metallic grinding noise from the center section: Worn planetary gears or damaged bearings produce a distinct whine or grind, often worsening as the transmission heats up.
- Delayed or no reverse operation: A failing torque converter or blocked hydraulic passages within the assembly can prevent reverse gear from engaging, requiring immediate unit replacement.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4657.026.121 |
| Assembly Type | Complete Powershift Unit (6 WG 190) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Overall Length | 620 mm |
| Overall Width | 480 mm |
| Overall Height | 510 mm |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| OEM Reference | ZF 6 WG 190 |
| Torque Capacity | 1,900 Nm (1,401 lb-ft) |
| Number of Speeds | 6 Forward / 1 Reverse |
Compatibility
This complete assembly is engineered for the ZF WG 190 series of powershift transmissions. It is directly compatible with models including the WG 180, WG 190, and WG 200 when used in wheel loaders, graders, and industrial tractors. The unit also fits select ZF 6 WG 200 variants with identical bell housing patterns. Always verify the rear mounting points; the 4657201170: HOUSING REAR PART and 4657298102: HOUSING REAR SECTION must match the chassis interface of your specific machine.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101082 | TRANSMISSION HOUSING | Main structural casing for the assembly |
| 4657201166 | HOUS.FRONT SECT | Front section housing the torque converter |
| 4657201170 | HOUSING REAR PART | Rear casing supporting output shaft bearings |
| 4657298102 | HOUSING REAR SECTION | Extended rear section for PTO mounting |
| 0631306816 | CYLINDRICAL PIN | Alignment pin for housing mating surfaces |
| 0636100801 | CAP SCREW | M12 fastener for housing assembly |
| 4656301148 | FIXING PLATE | Locks clutch pack retaining nuts |
| 4657301032 | SCREEN SHEET | Fine mesh filter for hydraulic circuit |
| 4657301033 | SCREEN SHEET | Coarse mesh pre-filter for oil sump |
| 0636100803 | CAP SCREW | M10 fastener for cover plate |
