There are many different gear rating methods in use today, and they can give substantially different results for any given gearset. This paper will make it easy to understand the choices and the impact the choices have on gearbox design. Eight standards are included - AGMA 2001; AGMA 6011; AGMA 6013; ISO 6336; API 613; API 617; API 672; and API 677. (Click HERE for the Appendix to this article).

I have a query (regarding) calculated gear life values. I would like to understand for what % of gear failures the calculated life is valid? Is it 1-in-100 (1% failure, 99% reliability) or 1-in-one-thousand (0.1% failure)?

This is the third article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are htose of the author as an individual. They do not represent the opinions of any organization of which he is a member.

One of the best ways to learn the ISO 6336 gear rating system is to recalculate the capacity of a few existing designs and to compare the ISO 6336 calculated capacity to your experience with those designs and to other rating methods. For these articles, I'll assume that you have a copy of ISO 6336, you have chosen a design for which you have manufacturing drawings and an existing gear capacity calculation according to AGMA 2001 or another method. I'll also assume that you have converted dimensions, loads, etc. into the SI system of measurement.