Hi !
I'm trying to design a winch powered by air motor via self breaking worm gear for use on ships for hoisting and lowering acc. ladders. What I'm lookin' for are calculations of selfbreaking worm gear and winch with splited drum (not grooved).
Are any of you familiar with this design? Please help me with these calculations.
Thanks in advance.
Norm
I'm not sure what calcs you are looking for. Gearing? A single threaded worm against a 30 tooth worm gear is 1:30 .
Many winches use worm gears. Seems to me that this would be an off-the-shelf item. I imagine that winch makers offer prime movers in air, electric and hydraulic for their winches.
I take it this is a homework assignment. You are worrying too much about it. . You know the expression for work is distance times force. You know the expression for power is force times velocity. (expr 1) Force being the weight you want to lft.
You know the winch cable velocity is given by winch diameter times pi times winch drum revs/sec
You know the air motor speed for this power is winch drum speed (revs/sec) times the total number of teeth on the winch drum gear which meshes with the motor worm gear. You should expect the compressor/ air motor combination to be inefficient, so you allow twice the power given in expr 1
If the angle of the worm in contact with the winch drum gear teeth is less than 15 degrees, the drum is guaranteed not to back-drive the worm.
That should be enough to resolve the design, I'd think. If you take all units in SI (meters, watts, newtons, joules, seconds) there are no scaling constants needed in the equations given above.
Brian Whatcott Altus OK
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