This publication has been prepared by the Gleason Machine Division as a handbook to provide a convenient reference for the axle designer in the choice of gear type, gear size, gear tooth specifications and load rating.Detailed instructions on the calculation of stresses, gear tooth proportions, machine settings and cutter specifications may be found in other Gleason publications.New empirical formulas and procedures are introduced in these pages. These reflect the design philosophy represented in a very high percentage of the highway and off-highway vehicles presently in production.In certain sections, historical background material has been provided for general reference for the new engineer. The emphasis of each description has been placed on the effect of the different concepts on the gears. As a result, the explanations may not be in strict accordance with definitions used by other organizations. There was no intent toward favoring particular types of axle designs, suspensions, bearings or other components. Any such conclusion drawn from these paragraphs is purely the responsibility of the reader.