IN this paper the author explains a new method for the determination of the fatigue life of bevel and hypoid gears. This method is said to offer a means for comparing various tooth forms and gear mountings.
Briefly, it consists of making a layout in the mean normal section of the tooth, and of calculating the tensile stress in the fillet when the maximum load is applied at its highest position on the tooth. Consideration is given to the fact that in cases where the contact ratio is sufficient to ensure at least two teeth in contact at all times the load will be divided between the teeth. Such factors as impact, inertia, and temperature are given consideration.
A graph is plotted using this calculated stress and the number of cycles to failure resulting from extensive bending fatigue tests on both bevel and hypoid gears. With the aid of this graph the fatigue life of new gear designs may be estimated.