# Question: https://www.chegg.com/homework-help/questions-and-answers/design-pair-helical-gears-transmitting-22-kw-speed-driver-gear-1800-rpm-driven-gear-600-rp-q48820381 – Free Chegg Question Answer

A stock spur gear having a diametral pitch of 8 teeth/in, a 1.5-in face width, 16 teeth and a pressure angle of 20-degrees with full depth is available. The material is AISI 1020 steel with Sut=55 kpsi and Sy=30 kpsi and the Safety Factor is 3. What is the permissible horsepower output of this gear, based on Bending Stress Only, corresponding to a speed of 1200 rpm

a) For moderate applications (this means we can use yield strength as the failure criterion)

b) For infinite life (endurance strength as failure criterion).

Assumptions/References

You have to solve this problem assuming Lewis and NOT AGMA equation. The gear tooth will be analyzed as a rectangular beam.

The bending stress (?) at the gear tooth root has to be calculated using the historic Lewis’s equation.

Transcribed text From Image:

## Expert Chegg Question Answer:

Answer: