The purpose of this article is to provide the design formulas and acceptable stress levels so that calculations of the gear surface compressive and bending stresses at which the gears will operate in a known application can be made. It will be necessary to know the complete gear information for all gears, such as number of teeth, diametral pitch, pressure angle, gear width, type of material, and type of heat treatment, if any.
The surface compressive and bending stresses are based on American Gear Manufacturers Association (AGMA) formulas and tables, and the applications stress limits are based on Machine Design recommended safe stress levels and authors past experience. By combining the proper number of teeth with the proper size tooth, the proper pressure angle, the proper material and heat treatment, a durable gear box can be designed to offer a long life under any operating conditions.