trenchdigger
Aug 6, 2007, 3:13 PM
Views: 19316
Registered: Mar 9, 2003
Posts: 1447
|
j_ung wrote: Does this system reduce friction over a more simple set up that might achieve the same theoretical advantage?
Nice job, Jung... 5:1 is correct, as is "complex".
The cool thing about this system is that it's a simple mod to turn a 3:1 system into this 5:1. Sure, you could just stack a Z-rig on a 3:1 system with the same extra equipment to get 6:1, but with this 5:1 system, you still only have one prusik to reset with each haul. With the 6:1, you would have two prusiks to reset.
The 5:1 shown will surely get the tire to the top - and without retying anything. Simply haul until the pulley on the blue rope gets to one end of the rope, reset the prusik on the main line, and haul again.
There isn't much difference friction-wise if you assume all pulleys have the same loss, though the 6:1 is ever so slightly less efficient.
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.
(This post was edited by trenchdigger on Aug 6, 2007, 3:28 PM)
|
