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Re: [trenchdigger] Building mechanical advantage part II:
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stymingersfink
Aug 7, 2007, 3:49 AM
Views: 19136
Registered: Aug 12, 2003
Posts: 7250
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trenchdigger wrote: One thing to keep in mind with this system is that one of the pulleys endures twice the load of the other two pulleys (80% of the weight of the tire). If you have pulleys of different strengths, choose their locations wisely.
Um, I'm thinking along a different set...
The first red pulley above the tire would experience 200% of the weight of the tire, no? 100% of the initial weight, plus the 100% necessary on the other side to perform the lift.
Am I totally off with that line of thinking? If pulley strength were a consideration, I'd definitely put the strongest one in the position mentioned above. Hopefully it has the largest sheave, too.
edit to add:
Durr... the system with the blue rope will provide a portion of the lift, thereby relieving the pulley mentioned above of x-percentage of the entire load. The top pulley will hold 100% of the load while resetting the haul (if it were a pro-traxion lets say, with ratchet engaged!), but the pulley would experience less load when actually hauling due to the secondary pulley system taking some of the load off??!?
I guess I haven't spent enough time working with complex pulley systems...
(This post was edited by stymingersfink on Aug 7, 2007, 4:07 AM)
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