Question

Which of the following is not necessary to find normal module of helical gear?

(a) Number of teeth

(b) Pitch diameter

(c) Helix angle

(d) Tooth thickness

I had been asked this question by my college professor while I was bunking the class.

This key question is from Terminology of Gear Tooth in portion Measurement and Testing of Gears of Engineering Metrology

Answer 1

Right choice is (d) Tooth thickness

For explanation I would say: The formula for normal module of helical gear is mn = (D/N) cosα where N is number of teeth, D is pitch diameter and α is helix angle. Also, mn = pn /π where pn is normal circular pitch.