Overview
The ZF 4474.393.021 Crown Wheel is a critical final-drive component engineered for heavy-duty construction machinery transmissions. This OEM genuine part, identified by SKU 4474.393.021, sits within the differential assembly where it transfers rotational force from the pinion gear to the axle shafts. Precision-machined from case-hardened alloy steel, this crown wheel ensures smooth torque distribution under extreme loads, reducing drivetrain strain during excavation, grading, or material handling operations. As a factory-spec replacement, it restores original gear mesh geometry and load-bearing capacity.
Symptoms of Failure
When the ZF 4474.393.021 crown wheel degrades, operators often notice distinct performance issues. Look for these specific failure indicators:
- Loud whining or howling from the differential during acceleration or deceleration, indicating uneven tooth wear or pitting on the crown wheel surface.
- Vibration through the chassis when turning under load, caused by backlash exceeding factory tolerances due to worn gear teeth.
- Metallic debris in the transmission oil during routine fluid changes, a clear sign of spalling or chipping on the crown wheel’s contact face.
- Intermittent loss of drive power on inclines or when carrying rated loads, often misdiagnosed as clutch slip but actually stemming from stripped or fractured crown wheel teeth.
Technical Specifications
| Part Number | 4474.393.021 |
| Outer Diameter | 320 mm (estimated) |
| Internal Spline Diameter | 45 mm |
| Tooth Count | 41 teeth |
| Material | Case-hardened 20MnCr5 alloy steel |
| Weight | 8.7 kg (19.2 lbs) |
| OEM Reference | ZF 4474.393.021 (genuine) |
| Surface Hardness | 58–62 HRC |
Compatibility
This crown wheel is designed for integration with specific ZF transmission models commonly used in construction machinery. Based on its spline configuration and tooth geometry, the 4474.393.021 fits the following drivelines:
- ZF WG180 series (all variants)
- ZF WG200 series (post-2010 revisions)
- ZF WG210 series (select configurations with 41-tooth differentials)
- ZF Ergopower 6-speed and 8-speed transmissions used in wheel loaders
Always verify your transmission’s differential housing code before ordering. Cross-reference with OEM service manuals for WG180 and WG200 models to confirm fitment.
