Question

The flywheel of a power operated chaff cutter receives the power through belt and pulley arrangement from an electric motor, running at 1600 rpm speed. The motor pulley has a diameter of 10 cm, while that of the pulley mounted on a flywheel shaft is 50 cm. The speed ratio between the flywheel and worm gear of diameter 15 cm is 7:1. What would be the rpm of flywheel and worm gear?

(a) 320rpm; 46 rpm

(b) 220rpm; 36 rpm

(c) 120rpm; 26 rpm

(d) 20rpm; 16 rpm

This question was addressed to me in quiz.

My doubt is from Processing Equipments topic in portion Processing Equipments of Farm Machinery

Answer 1

The correct answer is (a) 320rpm; 46 rpm

The explanation is: \(\frac{Nm}{Nf}=\frac{Df}{Dm} \)

Nf=\(\frac{Nm*Dm}{Df}=\frac{1600*10}{50}\) = 320 rpm

Speed ratio = \(\frac{7}{1} = \frac{Nf}{Nwg} \)

Nwg = \(\frac{Nf}{7} = \frac{320}{7}\) = 46rpm.