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).
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.
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