Question

The maximum efficiency for spiral gears is

(a) sin (θ + φ ) + 1/ cos (θ − φ ) + 1

(b) cos (θ − φ) + 1/sin (θ + φ ) + 1

(c) cos (θ + φ ) + 1/ cos (θ − φ ) + 1

(d) cos (θ − φ) + 1/cos (θ + φ ) + 1

This question was posed to me in examination.

I need to ask this question from Toothed Gearing in portion Toothed Gearing & Gear Trains of Machine Kinematics

Answer 1

Correct answer is (c) cos (θ + φ ) + 1/ cos (θ − φ ) + 1

The best explanation: ηmax = cos (θ + φ ) + 1/ cos (θ − φ ) + 1

where θ = Shaft angle, and φ = Friction angle.