Abstract
A primary design parameter of gearboxes is the transmission ratio. A transmission ratio dictates the ratio of input to output speed and, when it is great enough, is commonly split into several partial transmission ratios via multiple gear stages. The method of splitting up a total transmission ratio is often left to best judgment. This study presents an optimization algorithm for selecting the partial transmission ratios of two-stage non-reverted spur/helical gearboxes. The optimization is accomplished by minimizing the volume of the gears within the transmission while ensuring that each gear maintains a minimum bending and contact safety factor. Results of the optimization performed over a range of total transmission ratios showed a strongly linear model that will allow powertrain designers to quickly select partial transmission ratios by only considering the total transmission ratio. It was additionally shown that, despite the many parameters involved in gearbox design, the most significant factor in this optimization model is the total transmission ratio.
