In the first part, this document describes all the types and aspects of wear which can occur on the gear
teeth in operation, with causes and explanations concerning their appearance.
For each type of wear, the possible evolution and the limits which should not be overpassed to avoid a
failure or severe damage to the teeth, thus reducing the life of the gear, are clearly specified.
Aspects of wear types which can be considered as normal, medium or progressive are also described and
solutions are presented as a guide for wear stabilizing.
This document is illustrated with numerous pictures of all types of wear.
The other types of gear failures such as surface fatigue, corrosion, plastic flow and breakage are not
included in this paper which is only dealing with wear.