Inadequate lubrication
Oil outside specification, low levels, overdue oil changes or leakage reduce the lubricant film between tooth flanks. The results appear as scuffing, overheating and accelerated wear.
Overload and startup shocks
Operation above design load, jamming and abrupt starts impose stress peaks far above normal operating levels. Typical consequences are tooth-root cracks or localised breakage, often affecting one tooth.
Misalignment and installation problems
Misaligned shafts, a distorted base, incorrectly adjusted coupling or loose fasteners concentrate load over part of the face width. A contact pattern displaced towards one end is the classic indication.
Contamination
Dust, process residue, water and metal particles in the oil act as abrasives. This is common in mining, steelmaking and pulp and paper environments, and in equipment with compromised breathers or seals.
Bearing and seal wear
Excessive bearing and bushing clearance changes relative shaft positions and meshing conditions. Deteriorated seals allow oil loss and contaminant ingress, accelerating tooth deterioration.
Incorrect component geometry
A replacement with only approximately matching geometry, such as a different module, pressure angle or profile, produces uneven contact from assembly. The gearbox resumes operation but with reduced service life.
Dimensional assessment of the original component is therefore essential when no technical drawing is available.