Abstract
This paper presents a study on the effects of addendum modification on root stresses and bending fatigue strength of helical gears. Theoretical analysis was made regarding the effect of addendum modification on the root stresses. Bending fatigue tests were performed on helical gears with various amounts of addendum modification, using a bending fatigue testing machine of hydraulic type. In the case of helical gears, the increase in bending strength due to positive addendum modification is much smaller than that in the case of spur gears and the effect of addendum modification on bending strength differs depending on the addendum modification coefficient of mating gear. Furthermore the validity of ISO and JSME formulas for bending strength of profile shifted gears was examined on the basis of the experimental results.
