What are the failure modes of gears?

[LaRowan]

Gear failure modes include gear tooth breakage, tooth surface pitting, and tooth surface scuffing. Gear tooth breakage: There are generally two types of gear tooth breakage: one is fatigue breakage caused by repeated bending stress and stress concentration, and the other is overload breakage caused by sudden severe overload or impact load. Tooth surface pitting: During gear operation, under the repeated action of alternating contact stress at the meshing point, small cracks will form on the tooth surface near the pitch line. Tooth surface scuffing: In high-speed and heavy-duty gear transmissions, the pressure between tooth surfaces is high, the temperature rises significantly, and lubrication is poor. When the instantaneous temperature becomes excessively high, local melting and metal adhesion occur between the two tooth surfaces. As the surfaces move relative to each other, the adhered areas are torn apart, resulting in banded or large-area scars along the sliding direction on the tooth surface.