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 10^6 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 20o 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.