A 21-tooth pinion rotating at 1500 rpm meshes with a 35- tooth gear in a spur gear reducer. Both pinion and gear are manufactured to a quality level of 9. A reliability of 0.9 has been specified and the transmitted tangential load is 10 kN. Conditions are such that Kₘ= 1.7. It is proposed that standard 25°, full-depth teeth be used, with both pinion and gear hobbed from an AISI 4140 nitrided stoel. The module is. 4 and the face width 50 min. Assume that the life of the pinion will be less than that of the gear. Assume the lubricant bulk temperature does not exceed 250° F, both driver and driven devices are smooth-running, gears are solid disc. Use the average value for the uncorrected bending-fatigue strength. Assume that the reducer is used for critical service applications.
Calculate the bending stress.
Express your answer to three significant figures and Include the appropriate units.