Big gearbox design

Am Freitag, 18. August 2017 05:43:55 UTC+2 schrieb Clare:

I know. It was hypothetical. I was trying to work out why not.

The history of locomotive engineering is interesting in that the demands of being such a heavy and powerful moving vehicle made the simplest-seeming things like following a curve or wheel balance very difficult.

One consequence was the gradual weakening of cast-iron bridge components:

"A joiner who had worked on the bridge from May to October 1879 also spoke of a lateral shaking, which was more alarming than the up-and-down motion, and greatest at the southern junction between the high girders and the low girders. He was unwilling to quantify the amplitude of motion, but when pressed he offered 2 to 3 inches (50 to

75 mm). When pressed further he would only say that it was distinct, large, and visible."

In addition to hammer blow the necessary 90 degree piston offset between the two sides to avoid being stuck on top-dead-center makes the loco wiggle (yaw) sideways.

-jsw

On locomotives you need some means to connect an engine doing and requiring a couple of hundreds revs/min to wheels doing zero revs/min with some hundreds of kilonewtons drawbar power when taking off.

On huge transcontinental railways you are not limited for loco size - so you would not use the hydro-mechanical design to pack a lot of punch in a small light loco.

The different conditions here affected engineering practice, for example we didn't have an abundance of skilled labor while the frontier was open, so Americans built locos with exposed plumbing and outside cylinders that were easier to maintain.

-jsw

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.

Mart> 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.