Question

Which of the following is true for Length of arc of contact?

(a) Sum of Arc of recess and Arc of approach

(b) Difference of arc of approach and arc of recess

(c) Twice the arc of approach

(d) Twice the arc of recess

This question was posed to me during an interview.

This interesting question is from Path of Contact topic in chapter Toothed Gearing & Gear Trains of Machine Kinematics

Answer 1

Right answer is (a) Sum of Arc of recess and Arc of approach

To explain: The arc of contact is given by the sum of Length of arc of approach and length of arc of recess. Numerically it is the ratio of length of path of contact and the cosine of the pressure angle.