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paulmadry
Aug 28, 2007, 1:22 PM
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which pulley should i get for 3:1 hauling.
(i'm asking about a regular pulley , not pro trax etc)
for example is petzl mini enough???
thanks
(This post was edited by paulmadry on Aug 28, 2007, 1:55 PM)
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shoo
Aug 28, 2007, 2:00 PM
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It's a little more involved than that. I'm assuming you're only hauling around body weight. At that level, pretty much any climbing pulley will do the trick just fine. I personally avoid pulleys with plastic drums, as I've had a rope burns through the plastic at high tensions. You could also consider getting a prussik minding pulley if you're using it for haul systems.
What is the petzl mini? There is a petzl mini minder and a mini traxion. Please be more specific.
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paulmadry
Aug 28, 2007, 2:20 PM
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i meant Petzl Mini Prusik Minding Pulley
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shoo
Aug 28, 2007, 2:39 PM
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That'll do just fine. Won't make much of a difference either way, but are you using this pulley as the redirect or straight off the anchor? I assume the anchor piece, as you specified prussik minding.
Edited for clarity
(This post was edited by shoo on Aug 28, 2007, 2:39 PM)
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majid_sabet
Aug 28, 2007, 4:57 PM
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For pulley to correctly do its MA job, the diameter of pulley wheel has to be correctly chosen. Most smaller climber type pulley will work for hauling. REI use to sell PM pulley for $11 ( CMI or some other brand ) .
there it is
$12 http://www.rei.com/...1755?vcat=REI_SEARCH
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paulmadry
Aug 28, 2007, 10:33 PM
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i mean
the setup is 3:1, pro trax at the anchor and two extra pulleys for redirect. i see the pulley differ in efficiency from 70-95%. mini is 91% which seems good but i havent used in under 150-200lb that i'm planing to. which pulleys seem to work best??
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majid_sabet
Aug 28, 2007, 10:55 PM
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paulmadry wrote: i mean the setup is 3:1, pro trax at the anchor and two extra pulleys for redirect. i see the pulley differ in efficiency from 70-95%. mini is 91% which seems good but i havent used in under 150-200lb that i'm planing to. which pulleys seem to work best??
@ 200 lbs via 3:1, you are pulling near 80 LBS and that is going to be little hard. most smaller pulleys should work fine. If you are going to be on the wall, you could use one pulley and your jumar or a prusik to lock the load.if you are going to haul a person ( in case) you want to use 2 prusik with a bigger PM pulley instead.
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kvella
Oct 15, 2007, 12:35 PM
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If you check any of the rescue manuals, they state that the minimum sheave size should be 4:1 ratio in order to maintain the existing tensile strength of your rope. For example, if you are using a 1/2" rope then the minimum sheave is 2". Rescue equipment is the best choice if you want guaranteed peace of mind. Hauling a large, heavy pig can get you into trouble in a hurry. If you lose your pig on a static line, it can rip the whole team off the wall. The hauling system that pete explains is great because the pulley system does not maintain the load, the wall hauler does. If your pulley system falls apart, you don't lose the pig because it is held by the wall hauler.
Prof
(This post was edited by kvella on Oct 16, 2007, 3:30 AM)
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microbarn
Oct 15, 2007, 1:55 PM
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majid_sabet wrote: For pulley to correctly do its MA job, the diameter of pulley wheel has to be correctly chosen. Most smaller climber type pulley will work for hauling. REI use to sell PM pulley for $11 ( CMI or some other brand ) . there it is $12 http://www.rei.com/...1755?vcat=REI_SEARCH
Pairing the pulley diameter with rope is a new idea to me. Is it possible you could give an example of a bad pulley diameter and why? Could you also give an example of a good pulley diameter and why?
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skiclimb
Oct 15, 2007, 3:29 PM
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I personally like the larger CMI pulleys. The larger diameter reduces drag in the system. It just happens that my old petzl ascenders fit perfectly below them on the same biner that it makes a great system that has no slip ..ie they fit like 2 peices in a puzzle... dunno if the newer ascenders fit that well.
still puts all the load on the axle of pully so i back up by clipping the haul line trough a couple draws at least.
(This post was edited by skiclimb on Oct 15, 2007, 3:29 PM)
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kvella
Oct 16, 2007, 3:20 AM
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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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