Question

A speed reducer has 20° full-depth teeth with a diametral pitch of 4 teeth/in, a face width of 3.25 inches, and with the pinion having 22 teeth and the gear having 60 teeth. The pinion is driven by a 40 HP motor rotating with a shaft speed of 1145 rpm. The pinion is designed to last for 5 years operating around the clock. The gears are manufactured using 4340 through-hardened grade 1 steel, both heat treated to 250 HB using a process that equates to a quality number of 6. The load is moderate shock and the power is considered as a light shock source. For a reliability of 99% determine the following a) Factor of safety against both bending and wear failure for the pinion, determining which is most likely to cause failure b) Change the pinion to a hardness of 390 and determine the new critical safety factor c) If the material from part (a) is upgraded to grade 2 steel calculate the change in the critical safety factor d) Returning again to the gears in part (a), if the material is changed to class 40 ASTM A48 gray cast iron calculate the effect on the critical safety factor e) Out of all these cases (a) - (d) which is the best option for this particular gearset? Is there a better option? Be sure to support your conclusions.

Answer 1

719 다. 24 2T dl 3.97 x10 13-91 XLO = 35C1-202N 60 501 43 V/ &5.4mm)