The number of repetitions of these three different loading cycles varies with the vessel duty cycle and life. The
published values of allowable design stress for teeth are based on pulsing loads, which must be modified for
this third loading cycle. The tooth may also be subjected to mean stress due to shrink ftting of the gear onto a
hub.
This paper evaluates the derating factor for marine reversing main gear tooth allowable bending stress
using the Goodman fatigue line and Miners equation as a function of the average number of changes in
vessel direction per hour, shrink ftting stress values, and different materials based on the AGMA values
for allowable stress and life factor.