Calculation of load capacity of spur and helical gears — Part 6: Calculation of service life under variable load

ISO 6336-6:2019

ISO 6336-6:2019

Calculation of load capacity of spur and helical gears —
Part 6:
Calculation of service life under variable load

SCOPE: This document specifies the information and standardized conditions necessary for the calculation of the service life (or safety factors for a required life) of gears subject to variable loading for only pitting and tooth root bending strength.

If this scope does not apply, refer ISO 6336-1:2019, Clause 4.

FOREWORD: ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see

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This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear capacity calculation.

This second edition cancels and replaces the first edition (ISO 6336-6:2006), which has been technically revised. It also incorporates the Technical Corrigendum ISO 6336-6:2006/Cor.1:2007.

The main changes compared to the previous edition are as follows:

  • in Annex A, examples have been revised;
  • integration of Annex B "Equivalent cumulative damage".

A list of all parts in the ISO 6336 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at

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