Also a 180" X 1" diameter acme lead screw would develop a good deal of twist at the far end when rotated under load, a ball screw would be a far better choice for such an application, nearly zero friction.
Arvidj
This elevator is just for moving material only, correct?
I just read the document from Ram Manufacturing, the idea there is CHEAPER then everyone else.Thanks for the thought but a quick look at the costs associated with a pair of 15 foot long ball screws puts it far outside my budget. Four digit numbers for just one screw in the cases where I could find anything long enough to work while a 12 foot long acme from McMaster is only about $63.
This company ... Ram Manufacturing ... seems to have been successful using acme screws in their commercial lift applications, to the point where they actually provide some justification for their choice of acme over ball screws.
Yes ballscrews will back drive and require a brake. Most all commercial traction elevators also require one or more brakes, also a governor in the event that it overspeeds either up or down.
Old elevator controls are truly fascinating to watch in operation, simple relay logic top to bottom.