Required Allowable Bending Stress Number

$9\mathrm{.}43.$

Compute the required allowable bending stress number, $\backslash ($ s$\_\{\backslash$mathrm$\{$at$\}\}\backslash ),$ using Equation $(9-30).$ Assume that no unusual conditions exist unless stated otherwise. That is$,$ use a service factor, $\backslash ($ S F $\backslash ),$ of $1\mathrm{.}00.$ Design for a reliability of $0\mathrm{.}99$ and a design life of $8000$ h $.$

Then specify a suitable steel grade and required hardness for both the pinion and the gear based on bending stress.

Use the data and results from Problem $37.$