Decision Method of Optimum Specification of Involute Helical Gears for High Load Carrying Capacity (1st Report, Gear Specification Variables and Induced Stresses)

Abstract

Small and light drive train is strongly demanded for vehicles and for e. g. aerospace crafts to accomplish comfortable transportation and large space for passengers. Gears used for those drive trains must therefore be small but excellent in load carrying capacity. At designing those gears, simulation of gear performance is one of the best methods to be taken today, because multiple failure modes must be considered simultaneously. It is however difficult to analyze all of possible combinations of dimensions and tooth flank forms of gears, because of large number of parameters. Today, those parameters are usually decided by trial and error by experienced designers. In this report, the characteristics of gear dimensions to satisfy the requirements against tooth breakage, pitting and scuffing of tooth flank are investigated under geometrical and other limitations of gears, where center distance, gear ratio and face width are fixed. The optimum combination exists in pressure angle and tooth depth, if optimum addendum modification factor and helix angle are given. Optimizing decision method of pressure angle, helix angle, addendum modification factor and tooth depth for high load carrying capacity is proposed.