Optimal Safe Factor for Surface Durability of First Central and Satellite Gear Pair in Ravigneaux Planetary Gear Set

Abstract

Ravigneaux planetary gear sets provide great amount of tooth contact resulting reduction of safety coefficient for surface durability (SCSD). Because, they carry huge torque distributing load evenly among multiple satellite gears. They are being used widely in many passenger car vehicles. This article deals with optimal input variables such as gear material, gear width and module for the minimum SCSD of the first central gear pair in Ravigneaux planetary gear set. Modified Taguchi approach is followed to carry out the above task. Empirical relation is developed for SCSD in terms of the input variables. Taguchi’s L9 orthogonal array is well suited for the 3 levels of 3 input variables. In this process, minimum number of test data is considered to construct ANOVA table for assessing the contribution of the input variables on the overall SCSD value. Estimated range of SCSD is presented for all combinations of the input variables and their levels. Test data is found to be close to/within the estimated range.