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majid_sabet
Apr 30, 2007, 5:57 PM
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greenketch
Apr 30, 2007, 7:17 PM
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I'll have to rig it and play a little. It looks like a z-pulley rigged with two ropes to gain extra distance. Although ther is no ratchet pulley. If this is the case it will give you 3-1 but the real world is that in changing pulleys to biners the effective advantage would be 2-1. Friction losses when hauling on a biner can be large.
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trenchdigger
Apr 30, 2007, 7:26 PM
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What happened to the pretty diagrams? Trial version of Rescue Rigger expired?
If he's a stick man, you shouldn't need any mechanical advantage, right?
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majid_sabet
May 1, 2007, 6:04 AM
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trenchdigger wrote: What happened to the pretty diagrams? Trial version of Rescue Rigger expired? If he's a stick man, you shouldn't need any mechanical advantage, right?
some people are just never happy
Here
better now?
[URL=http://imageshack.us]
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trenchdigger
May 1, 2007, 6:32 AM
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Yes, much better. And glad to see they're all wearing helmets now too.
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gunkiemike
May 1, 2007, 10:06 AM
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How did the prusik get next to the helpless climber? And for that matter, how did the whole second rope set up get there? Why would they pull him UP to the anchor? How did the rope holding (AKA ratchet) prusik get on the tree?
I can't figure out any way that this constitutes a realistic rescue scenario. I hope you didn't buy the book.
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microbarn
May 1, 2007, 11:28 AM
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trenchdigger wrote: Yes, much better. And glad to see they're all wearing helmets now too.
except for the injured climber, but the lack of a helmet explains why he is hurt.
As to how this is a realistic scenario:
You are in an area where you have to climb to get out. They got the rope there because another climber was top roping beside of them. This is a fat guy and the whole group is needed to lift him. There are ambulances at the top that are arriving as we speak. (ok, I agree. This isn't very realistic in my mind either.)
The mechanical advantage is 3:1 unless I am missing something.
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papounet
May 2, 2007, 11:21 PM
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majid_sabet wrote: I had an hour to kill on Sunday so I stop at the local REI to check out the gears and saw a book on how to do self rescue. Some where in there (page 134), there was a drawing showing on how to rescue your partner incase he gets hurt and hangs like a pig on the wall similar to what you see here. In this drawing, a climber is hanging from the wall via big anchor (similar to top rope climbing) with a prussic lock in place near the anchor which acts as one way lock on his rope once the other guy pulls him up. ... They called this method “Complex Spanish …. with a (? - 1) mechanical advantage. I was wondering if you know what the mechanical advantage is on this system and why.
Why don't you give the complete reference ?
"Climbing Self Rescue: Improvising solutions for serious situations"
by Andy Tyson and Molly Loomis
Published The Mountaineers Books 2006
http://www.amazon.com/...178140877&sr=8-2
The schema is of a Spanish Burton 3:1 mechanical advantage system. it is not covered into "Mountaineering, The freedom of the hill" but is extremely close to the z-pulley or "mouflage simple" (advantage 3) The good thing about the Spanish Burton is that is is easier to stack up to create double system (advantage 5) or triple system (advantage 7) (incorrectly named "mouflage double" is in the french "manuel de la montagne" (page 527 and 559 if you wish to know). Compared to a normal block and tackle setup, a spanish Burton uses moving pulleys and requires less gear. It is somewhat superior to the classical 3/1 z-pulley system as it works with gravity on the pull side.
The triple system is often taught for crevasse rescuing, although the computations show below that even that may not be enough.
Please note/
a/ in all pulley system, the most efficient pulley (with the least friction) should be used for the "most traveled " part which is the past pulley. (but I could be mistaken)
b/a self blocking pulley such as a Petzl mini traction does wonder at the first pulley (belay side)
c/ a reverso is also quite good in replacing the top pulley and prussik
The issue of setup like this is that you have to reset two prussiks every cycle. Of course, the higher the mechanical advantage, the more rope you have to pull to lift.
for forces computation please see http://club.ffme.fr/...me.htm#slide0020.htm
Edited/ fixed spelling/ it is a Burton
(This post was edited by papounet on May 3, 2007, 5:28 AM)
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rocknice2
May 2, 2007, 11:57 PM
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Majid these posts of yours remind me a bad movie, Speed. Where Denis Hopper says to Keanu Reeves
"Alright, pop quiz. Airport. Gunman with one hostage. He's using her for cover. He's almost to the plane. You're a hundred feet away. Jack?
What do you do Hotshot?"
Cut the rope. 0:1 MA
Drop the victim
Take him out of the equation. Go for a good beer .
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majid_sabet
May 3, 2007, 12:06 AM
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Tres bon
papounet
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