countershaft in Prob. 3–72, p. 152, is part of a speed reducingcompound gear train using
20° spur gears. A gear on the input shaft drives gear A. Gear Bdrives a gear on the output
shaft. The input shaft runs at 2400 rev/min. Each gear reduces thespeed (and thus increases
the torque) by a 2 to 1 ratio. All gears are to be of the samematerial. Since gear B is the
smallest gear, transmitting the largest load, it will likely becritical, so a preliminary analysis
is to be performed on it. Use a diametral pitch of 2 teeth/in, aface-width of 4 times the circu-
lar pitch, a Grade 2 steel through-hardened to a Brinell hardnessof 300, and a desired life of
15 kh with a 95 percent reliability.
1) if b is meshing with another gear with a diameter d=16 inwhat would be the required teeth on Fb?
2)Determine factors of safety for pitting
