"This standard presents the fundamental formula for rating the surface durability (pitting) of spur gear teeth. It contains all of the factors which are known to affect the resistance of gear teeth to pitting. This formula is not applicable to other types of gear tooth surface deterioration such as plastic yielding@ scoring@ welding@ etc. This standard is based on AGMA Information Sheet 215.0 I@ ""Information Sheet for Surface Durability (Pitting) of Spur@ Helical@ Herringbone and Bevel Gear Teeth"" and is coordinated with the durability ratings for helical@ herringbone@ and bevel gears. Pitting of gear teeth is considered a fatigue phenomenon. The two kinds of pitting - 1) initial@ and 2) destructive - are illustrated in Standard AGMA 110.03@ ""Gear-Tooth Wear and Failure."" Corrective and non-progressive initial pitting is not deemed serious. The aim of this standard is to design the gear teeth so that destructive pitting does not occur. Surface durability rating practices for a particular field of gearing may be established by selecting the proper factors for this general formula. Proper evaluation of the various factors in the basic formula will produce suitable ratings for any application. Where no applicable specific AGMA standard exists@ numerical values may be estimated for the factors in this general formula and an approximate surface durability rating calculated. The symbols used@ wherever applicable@ conform to Standard AGMA 112.04@ ""Gear Nomenclature Terms@ Definitions@ Symbols@ and Abbreviations"" and@ ""Letter Symbols for Mechanics of Solid Bod- @ ies@"" (ASA ZlO.3-1948) (RI953)"