Question

In a simple planetary gear drive, the sun gear is used to give drive a plant carrier mounted with 3 planetary gears, while ring gear is held stationary. If sun gear and all other planetary gears have 20 teeth each and ring gear has 60 teeth, the gear ratio will be __________

(a) 4:1

(b) 4.5:1

(c) 5:1

(d) 5.5:1

The question was asked in a job interview.

This interesting question is from Mechanical Power Transmission in section Mechanical Power Transmission of Farm Machinery

Answer 1

Correct option is (a) 4:1

The best explanation: \(\frac{ns}{nc}=1+\frac{60}{20}\)=4

Gear ratio = 4:1.