In: Mechanical Engineering
15.33 A spur gear reducer has an 18-tooth pinion driven 1500 rpm
by an electric motor and a 36-tooth gear that drives a load
involving “moderate shock.” A life of 106 pinion revolutions is
required, and the transmitted load, Ft, is 100 lb (this figure
includes a
safety factor of 2). Conditions are such that Km = 1.8 and kt = 1.
It is proposed that standard 20° full-depth gears be used, with
both pinion and gear teeth being cut with a low-cost,
average-quality, form-cutting process from steel of 235 Bhn for the
gear and 260 Bhn for the pinion. Diametral pitch is to be 10, and
face width 1.0 in. Estimate the reliability with respect to bending
fatigue failure.