Question

Two spur gears of 20° full depth involute system are transmitting motion with a gear ratio of 2. The ratio of the base circle radii of the gears would be
1. 0.5
2. 0.68
3. 0.72
4. 1.00

Answer 1

Correct Answer - Option 1 : 0.5

Concept:

For Involute gears in mesh, the gear ratio is given by

\(G = \frac{T}{t} = \frac{{{N_{Driver}}}}{{{N_{Driven}}}} \)

From the law of gearing,

r₁ω₁ = r₂ω₂;

\(\Rightarrow \frac{r_{Driver}}{r_{Driven}} = \frac{{{N_{Driven}}}}{{{N_{Driver}}}}\)

Calculation:

Given G = 2;

From the above explanation,

the ratio of the base circle radii of the gears will be

\(\Rightarrow \frac{r_{Driver}}{r_{Driven}} = 1/G = 1/2 = 0.5\)