The area of a tooth flank that actually carries load, made visible by coating teeth with marking compound and rolling the pair under light load. Its position and shape reveal misalignment, helix errors, wrong mounting distances and deflection. Parallel-axis gears should show a pattern centered across the face, while bevel and hypoid sets are adjusted until the pattern sits correctly between heel and toe and between top and root.
Contact pattern is running hard on one end of the face, the bores aren't parallel, shim the bearing housing.
A pattern read under light load moves under full load, usually toward the heel and the ends that deflect most, so set it with that in mind.
Also heard as
- tooth contact pattern
- tooth bearing
- mesh pattern
Related terms
Bluing
Shop word for marking compound brushed on gear teeth to read the contact pattern after running.
Set the pattern
Shop phrase for adjusting pinion depth and backlash on a bevel or hypoid set until the contact pattern is right.
Heel and toe
The outer, wide end (heel) and inner, narrow end (toe) of a bevel or hypoid gear tooth.
Edge loading
Tooth load piling up at one end of the face width because of misalignment or deflection.