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Big Wall and Aid Climbing:
Re: [microbarn] which pulley best for hauling:
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kvella
Oct 16, 2007, 3:20 AM
Views: 2699
Registered: Jul 7, 2007
Posts: 13
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Microbarn,
If you look at the tensile strength of certain knots you will notice that they are all based on how sharp the bends in the rope are when tied. The same goes for pulley diameters. When you have a tight bend, the inner fibers are compacted together and the outer fibers are stretched apart. The rope fibers on the outside of the bend receive the greater share of the load, and those on the inside of the bend receive very little of the load or none at all. That is why some knots are stronger than others. If you wrap your rope around a 30" tree 10 times and use it for an anchor, you will still have 100% tensile strength of the rope without any loss. Loss begins when you exceed the 4:1 bend ratio whether it is a knot or the sharp bend of a small pulley. Large wheel pulleys roll better, produce less friction and maintain higher tensile strengths when hauling heavy loads like dead people or overstuffed pigs. Small diameter pulleys usually do not have bearings because the they are so small and inexpensive.
http://www.amazon.com/...-Vines/dp/0815195001
Prof
(This post was edited by kvella on Oct 16, 2007, 1:20 PM)
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Edit Log:
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Post edited by kvella
() on Oct 16, 2007, 3:27 AM
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Post edited by kvella
() on Oct 16, 2007, 3:30 AM
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Post edited by kvella
() on Oct 16, 2007, 12:49 PM
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Post edited by kvella
() on Oct 16, 2007, 1:20 PM
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