Why do cars (transmissions I assume) sound different when they are backing up than they do when they are going forward?

Question

In reverse they tend to make a whining noise. Isn’t it the same parts doing basically the same thing either way?

In: Engineering

Answer 1

Reverse gears are straight cut gears, vs helical (angled) gears for forward. Straight cut gears make more noise but can give better torque, as you only have 1 reverse gear vs multiple forward.