Ships of all sizes use them, Oil services use them some gears are so
large that they have to be on 80' heavy duty trailers mounted on an
angle so the width would fit in 1 or 2 lanes and still under mandatory
overpasses. Lufkin Industries here in town before being bought out
by GE used to move some rather large gears to be used world wide.

They had a gear box group that still works here - 'black magic' you
don't mess with in the works. Large industrial air handlers and
mills.... the gear boxes have to be designed right considering
many parameters that are often ignored until the box blows up.

Martin

On 8/16/2017 1:47 AM, Christopher Tidy wrote:
Any gearbox experts here? Just puzzling over why really big gearboxes are commonly avoided. Locomotives mostly use electric transmission and the reliability of gearboxes in things like wind turbines isn't great.

Is there some reason to do with scaling the geometry, like if you double the size of every dimension, the shaft can transmit more torque than the teeth? At a quick glance, it doesn't seem that simple. Or is there more slip between the teeth and more wear? I can't figure out a concrete reason and it's bugging me :-).

Chris