Question

A tractor has 8 forward speeds. The speed ratio varies in exact geometrical progressions. If the speed ratio in highest and lowest gear are 14.9:1 and 108:1, the geometrical constant will be __________

(a) 0.328

(b) 1.328

(c) 2.328

(d) 3.328

The question was posed to me by my school principal while I was bunking the class.

Question is taken from Mechanical Power Transmission topic in division Mechanical Power Transmission of Farm Machinery

Answer 1

The correct option is (b) 1.328

To elaborate: 1^st speed = \(\frac{Ne}{a}\) = 108

8^th speed = \(\frac{Ne}{ar^2}\) = 14.9

\(\frac{ar^2}{a}=\frac{108}{14.9} \)

r=\((\frac{108}{14.9})^{\frac{1}{2}}\) = 1.328.