Calculation of Load Capacity of Cylindrical Gears: Review of Different Approaches and Calculation Tools

Abstract

Gear design has been subjected to extensive standardization by different organizations with slight differences or different approaches taking into account the multiple aspects of the gear strength. In 1996 the International Organization for Standardization started publishing the ISO 6336 standard for calculation of load capacity of cylindrical spur and helical gears, which is composed of several parts that were not simultaneously made available. This article analyses the calculation of form and stress corrections factors (Y _F and Y _S ) proposed in different sources, including the two versions of the ISO 6336 Part 3 standard (1996 and 2006). The 2006 version withdrew one of the methods for the bending strength calculations, the method C, which allows the calculation of the bending strength based on parameters obtained in published charts for the most common gear rack geometries; the 2006 method requires computational codes that should be implemented or acquired by the designers in order to solve some of the equations iteratively. The use of the earlier approach is however still of interest given the availability of charts for Y _F and Y _S determination based on load applied at the tooth tip. This paper discusses a MATLAB code for Y _F and Y _S calculation presenting an enhanced determination of the contact ratio factor $Y_{\varepsilon }$.