- Poor design, with insufficient end relief or crowning
- Transient loading from gusts, grid faults or emergency stops
- Bearing or housing misalignment
- Operational wear resulting in geometry changes that shift the contact patch.
Initial markings can develop very early in the service life of a gearbox, but will generally arrest after the run-in period. However, in some circumstances it may progress. Initially this will be into polishing, but later perhaps also micropitting. Nonetheless, although light markings are common, edge loading is rarely cause for immediate or serious concern. The main focus would be to increase the inspection frequency in case any micropitting developed into macropitting.
|Visual inspection||✓✓✓||The fixed location and characteristic markings mean edge loading is visually identifiable on accessible (parallel stage) gear teeth. Planetary gears will require a borescope.|
|Borescope inspection||✓✓✓||Edge loading is identifiable with a borescope.|
|Vibration analysis||✓||Edge loading will not be detectable from vibration data.|
|SCADA data||✓||Edge loading will not be detectable from SCADA data.|
|Oil debris sensor||✓||Edge loading does not cause substantial enough material removal to be detectable.|
|Oil sample analysis||✓||Edge loading does not cause substantial enough material removal to be detectable.|
The formation of micropitting at the ends of multiple teeth would be indicative of underlaying design issues. These include a substantial lack of end relief, insufficient crowning, or misalignment. Ensuring suitable load distribution and microgeometry modification can help to eliminate this kind of wear.
Romax Technology have a large body of gearbox design, review and modification experience. We can accurately model gear tooth contact as our RomaxWIND software enables the construction of a fully integrated drivetrain model, in which misalignment from bearing and housing deflection can be accounted for. The image below compares a RomaxWIND contact patch with an operational gear that has a marking compound applied.