This standard provides a means to describe the appearance of gear teeth when they wear or fail. The study
of gear tooth wear and failure has been hampered by the inability of two observers to describe the same
phenomenon in terms that are adequate to assure uniform interpretation.
The term “gear failure” is subjective and a source of considerable disagreement. For example, a person
observing gear teeth that have a bright, mirrorlike appearance may believe that the gears have “run-in”
properly. However, another observer may believe that the gears have failed by polishing wear. Whether the
gears should be considered failed or not depends on how much change from original condition is tolerable.
This standard provides a common language to describe gear wear and failure, and serves as a guide to
uniformity and consistency in the use of that language. It describes the appearance of gear tooth failure
modes and discusses their mechanisms, with the sole intent of facilitating identification of gear wear and
failure. The purpose of the standard is to improve communication between equipment users and gear
manufacturers for failure and wear analysis. Since there may be many different causes for each type of gear
tooth wear or failure, it is not possible in the standard to identify a single cause for each type of wear or failure,
nor to prescribe remedies.