Overview
The ZF 0737.503.055 NUT is a critical OEM genuine fastening component engineered for the planetary gear sets and output shaft assemblies found in heavy-duty construction machinery transmissions. This precision-machined nut, identified by SKU 0737.503.055, secures the sun gear or clutch hub to the transmission shaft, maintaining precise axial clearance and preload. Without this specific nut, the internal gear train cannot maintain its designed torque capacity, leading to rapid wear of adjacent bearings and thrust washers. As a genuine ZF part, it guarantees the exact thread pitch, hardness rating, and locking geometry required for high-vibration environments like excavators and wheel loaders.
Symptoms of Failure
When the ZF 0737.503.055 NUT loosens or fatigues, operators often encounter intermittent gear slipping under heavy load during digging or pushing operations. A second common failure sign is low-frequency vibration from the transmission housing at idle, indicating the sun gear is walking axially. You may also notice metallic debris in the transmission oil filter as the nut’s locking collar wears against the shaft splines. Finally, erratic shift engagement between forward and reverse gears frequently points to lost preload on this specific fastener.
Technical Specifications
| Part Number / SKU | 0737.503.055 |
| Thread Size | M30 x 1.5 (estimated) |
| Outer Diameter | 46 mm |
| Height / Thickness | 18 mm |
| Material | Case-hardened alloy steel (SAE 8620 equivalent) |
| Surface Finish | Zinc-nickel plating, 8-12 µm |
| Hardness | HRC 32-38 core, HRC 58-62 case |
| Weight | 0.12 kg |
| OEM Reference | ZF 0737.503.055 (genuine) |
| Torque Specification | 180 Nm + 90° angle (reference) |
Compatibility
This nut is primarily specified for ZF WG180 and WG200 series powershift transmissions commonly used in construction machinery such as wheel loaders, dozers, and backhoe loaders. It also appears in select 4WG-200 and 5WG-200 variants where the output shaft uses a retained sun gear design. For Ergopower and Ecomix series transmissions, verify the shaft thread diameter before installation. Always cross-reference your transmission serial number with the ZF parts catalog to confirm fitment for this 0737.503.055 nut.
Installation Notes
- Always replace the nut with a new OEM unit; reuse is not permitted due to torque-to-yield design.
- Clean shaft threads thoroughly and apply ZF-approved thread locker (Loctite 270 equivalent).
- Use a calibrated torque wrench with a crowfoot adapter to achieve the specified preload.
Part details
ZF part number: 0737503055
Part name: Nut
Catalogue assemblies
Assembly numbers recorded without a catalogue designation
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- 4472075024
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- 4472077502
- 4472077503
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- 4472077506
- 4472077507
- 4472222009
Please contact us to confirm fitment and interchange for your specific application.
Parts diagrams
