The formulae in ISO 10300 are intended to establish uniformly acceptable methods for calculating the pitting resistance and bending-strength capacity of straight and helical (skew), zerol and spiral bevel gears except hypoid gears. They are applicable equally to tapered depth and uniform depth teeth. The formulae take into account the known major factors influencing gear-tooth pitting and fractures at the root fillet, as well as allowing for the inclusion of new factors at a later date. The rating formulae are not applicable to other types of gear-tooth deterioration such as plastic yielding, micropitting, case crushing, welding, and wear. The bending-strength formulae are applicable to fractures at the tooth fillet, but not to those on the tooth-working profile surfaces, nor to failure of the gear rim or of the gear blank through the web and hub. Pitting resistance and bending-strength capacity rating systems for a particular category of bevel gear can be established by selecting proper values for the factors used in the general formulae. ISO 10300 is not applicable to bevel gears which have an inadequate contact pattern. ISO 10300 is restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of ?v < 2. The given relations are valid for gears of which the sum of addendum modification factors of pinion and gear is zero, i.e. the normal operating pressure angle of the gear pair is the same as the normal pressure angle of the basic rack. NOTE Methods for the calculation of the load capacity of hypoid gears are indicated by the manufacturers of gear-cutting machines. CAUTION — The user is cautioned that when the methods are used for large spiral and pressure angles, and for large face width b  10 mmn, the calculated results of ISO 10300 should be confirmed by experience.