Question

What is worm lead in worm and worm gear?

(a) Nw x 2px

(b) Nw x 4px

(c) Nw x px

(d) Nw / px

This question was posed to me in semester exam.

This intriguing question originated from Terminology of Gear Tooth topic in division Measurement and Testing of Gears of Engineering Metrology

Answer 1

Correct answer is (c) Nw x px

For explanation I would say: Worm lead is represented by L and L = Nw x px where, Nw is number of threads in worm and is px axial pitch. Lead angle in worm and worm gear is represented by ψ and tanψ = L/πd where d is pitch diameter.