|
|
|
|
mother_sheep
Jun 26, 2006, 3:30 PM
Post #1 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
My partners and I were practicing hauling each other up glaciers this weekend to simulate hauling a victim out of a crevasse. In using the z pulley system for a team of 3 people, I have 2 questions.
1. What prevents the victim from sailing back into the crevasse if for some reason the hauler loses his grip, since the system is not auto locking? The victim would fall all the way back down into the crevasse the total distance that he/she was just pulled out, not necessarily resulting in death or injury, but still a fall none the less. So now we have 1 individual in the crevasse, one individual hauling and one other member at the anchor. I was thinking that the 3rd person at the anchor could put the victim on belay with the slack that comes up in the rope as the victim gets higher and higher to the lip. If the victim fell a long way into a crevasse, it seems more prudent to have some sort of a backup like this or is there some way to make the system auto-locking?
2. While hauling the victim out of a crevasse, the running pulley rises up to the anchor and can eventually rise high enough up against the ratchet prussic and cinch so that the victim can no longer be hauled out any further. How do you slide the running pulley and it's prussic back down so that you can continue to haul? I found it very difficult to just slide it back down. To prevent this from happening, you can "try" to get as close to the crevasse as possible when setting up your initial anchor. In a situation where this is not possible, is there a simple way to lower the running pulley and prussic?
|
|
|
|
|
jrathfon
Jun 26, 2006, 4:05 PM
Post #2 of 39
(9615 views)
Shortcut
Registered: Jun 5, 2006
Posts: 494
|
wow, so did you read a book?
in any pulley system you should always have a locking mechanism.
you can use a prusik loop attached to the anchor the main pulley is on, an ascender in the same fashion, or a self locking pulley (traxion, etc). a prusik minding pulley will...um...mind the prusik.
if someone loses grip, or you need to reset the lip pulley, stop, let the locking mechanism take hold, then run the lip pully back to the edge, or as close as you feel comfortable.
check out: mountaineering(freedom of the hills), or glaciers(falcon guide)
|
|
|
|
|
csproul
Jun 26, 2006, 4:12 PM
Post #3 of 39
(9615 views)
Shortcut
Registered: Jun 4, 2004
Posts: 1769
|
Not sure how you've set your system up, but mine has a friction knot at both of the z bends, where a pully might be attached. One prevents the rope from slipping back down and the other is involved in the actual raising. With each round of pulling, the first friction hitch will catch and prevent the rope from slipping and you will then "reset" the second friction hitch and pulley. A picture is worth a thousad words.
|
|
|
|
|
jrathfon
Jun 26, 2006, 4:17 PM
Post #4 of 39
(9615 views)
Shortcut
Registered: Jun 5, 2006
Posts: 494
|
that's the same system, just a prusik for an ascender/pulley at the lip, then there is a prusik at the main anchor point which prevents the slippage. that's what the author is lacking. you can use an ascender or a locking pulley for the same function as a prusik at the main anchor point.
|
|
|
|
|
mother_sheep
Jun 26, 2006, 4:17 PM
Post #5 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
Actually, I did read the book, Glacier Travel & Crevasse Rescue by Andy Selters and there was NO mention of what you just said (use of a triaxon or ascender) in this scenario, unless I missed it and I don't think I did. We followed all of the steps as they were written and I felt that something was missing, hense my post and my desire to rectify it. No need to be condescending.
|
|
|
|
|
mother_sheep
Jun 26, 2006, 4:21 PM
Post #6 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
In reply to: Not sure how you've set your system up, but mine has a friction knot at both of the z bends, where a pully might be attached. One prevents the rope from slipping back down and the other is involved in the actual raising. With each round of pulling, the first friction hitch will catch and prevent the rope from slipping and you will then "reset" the second friction hitch and pulley. A picture is worth a thousad words.
Do you have a copy of Andy's book? This will show the exact system (in the z-pulley chapter) that we set up. Would the use of friction knots work in this scenario?
|
|
|
|
|
jrathfon
Jun 26, 2006, 4:22 PM
Post #7 of 39
(9615 views)
Shortcut
Registered: Jun 5, 2006
Posts: 494
|
sorry, wasnt trying to be condescending. definetly interested in what book you read though, cause that's what sounded like the problem.
yeh, check the "glaciers" falcon guide, or freedom of the hills, they will show a prusik, ascender, or locking pulley at the anchor. when you release tension on the haul line, that lock will grab, then you can reset the lip ascender/prusik, and continue to haul again. with a prusik or ascender at the main anchor point, you will have to mind it, i.e. make sure you run it up the line so it doesnt bind into the anchor pulley.
|
|
|
|
|
mother_sheep
Jun 26, 2006, 4:28 PM
Post #8 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
In reply to: sorry, wasnt trying to be condescending. definetly interested in what book you read though, cause that's what sounded like the problem. yeh, check the "glaciers" falcon guide, or freedom of the hills, they will show a prusik, ascender, or locking pulley at the anchor. when you release tension on the haul line, that lock will grab, then you can reset the lip ascender/prusik, and continue to haul again. with a prusik or ascender at the main anchor point, you will have to mind it, i.e. make sure you run it up the line so it doesnt bind into the anchor pulley.
No worries. Is this covered in Freedom of the Hills 6? I have that one. I'll check out the Falcon Guide as well. Thanks. We have almost 3 weeks to get all of this dialed in so I'm open to any suggestions on more effective methods as well. In following the diagram in Andy's book, the system seemed flawed. If anyone has this book and knows what I'm talking about, I'd like to hear from you. I'd like to know if I misinterpreted what I read. Maybe it's just not detailed oriented for people who are as green as I am on these systems.
|
|
|
|
|
aikibujin
Jun 26, 2006, 4:40 PM
Post #9 of 39
(9615 views)
Shortcut
Registered: Dec 28, 2003
Posts: 408
|
I don't have Andy's book, but I've read it, and I'm pretty sure the Z-pulley demostrated in his book has some sort of mechanism at the anchor to grab the rope while you reset the Z-pulley, like the other posters mentioned. It doesn't matter what you use, it can be a friction knot, ascender, traxion, autoblocking belay device, or alpine clutch. The important thing is its function: to prevent the victim from falling back into the crevasse and to hold the victim when you need to reset the Z-pulley. That can be the answer to both of your questions.
|
|
|
|
|
ddoucet
Jun 26, 2006, 4:43 PM
Post #10 of 39
(9615 views)
Shortcut
Registered: Mar 27, 2006
Posts: 29
|
In reply to: Actually, I did read the book, Glacier Travel & Crevasse Rescue by Andy Selters and there was NO mention of what you just said (use of a triaxon or ascender) in this scenario, unless I missed it and I don't think I did.
You did. Miss it that is. Look on pg. 92. There is a picture there clearly showing the ratcheting system that will alleviate your problems. Not a fancy Petzl Traxion or other toy, but a good ol' fashion friction hitch, with a handy trick to make it psuedo-self tending to boot.
-Derek
|
|
|
|
|
jrathfon
Jun 26, 2006, 4:46 PM
Post #11 of 39
(9615 views)
Shortcut
Registered: Jun 5, 2006
Posts: 494
|
but then i cant use my expensive shiny toys!
nah kidding, im a grad student, $2 of cord will do for me!
|
|
|
|
|
mother_sheep
Jun 26, 2006, 4:48 PM
Post #12 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
In reply to: I don't have Andy's book, but I've read it, and I'm pretty sure the Z-pulley demostrated in his book has some sort of mechanism at the anchor to grab the rope while you reset the Z-pulley, like the other posters mentioned. It doesn't matter what you use, it can be a friction knot, ascender, traxion, autoblocking belay device, or alpine clutch. The important thing is its function: to prevent the victim from falling back into the crevasse and to hold the victim when you need to reset the Z-pulley. That can be the answer to both of your questions.
Possibly but the only friction knot that I saw close to the anchor was the prussic knot used to transfer the victim's weight from the person who is in the arrest position, on to the anchor. There was a belay device in the diagram below the pulley at the anchor. I think we didn't have an autoblock there so we used an ATC. I was under the impression that the purpose of the device was to keep the friction knot attached to the victim's rope from getting sucked into the pulley. With a self locking device in this section, I think that would prevent the victim from falling back into the crevasse. This may be where we screwed up.
|
|
|
|
|
ddoucet
Jun 26, 2006, 4:55 PM
Post #13 of 39
(9615 views)
Shortcut
Registered: Mar 27, 2006
Posts: 29
|
In reply to: Possibly but the only friction knot that I saw was the knot used to transfer the victim's weight from the person who is in the arrest position, on to the anchor.
Right. That hitch then goes on to become the ratchet in the system.
In reply to: There was a belay device in the diagram below the pulley at the anchor.
This belay device is directly behind a ratcheting hitch, also shown there. It does indeed serve "to keep the friction knot attached to the victim's rope from getting sucked into the pulley" as you say. When the haulers need a breather, it also serves to lock the load strand so the victem doesn't fall back in to the slot.
In reply to: I think we didn't have an autoblock there so we used an ATC.
There's your problem. Unless you have a self-locking pulley (ala the traxion), you must have a friction hitch there. You can do without the belay device, for sure. But you have to have the hitch, for the reasons you pointed out.
In reply to: I think that would prevent the victim from falling back into the crevasse.
Exactly. Good luck!
-Derek
|
|
|
|
|
aikibujin
Jun 26, 2006, 5:00 PM
Post #14 of 39
(9615 views)
Shortcut
Registered: Dec 28, 2003
Posts: 408
|
In reply to: Possibly but the only friction knot that I saw close to the anchor was the prussic knot used to transfer the victim's weight from the person who is in the arrest position, on to the anchor. There was a belay device in the diagram below the pulley at the anchor. I think we didn't have an autoblock there so we used an ATC. I was under the impression that the purpose of the device was to keep the friction knot attached to the victim's rope from getting sucked into the pulley.
Ah yes, that prussic used to transfer the victim's weight to the anchor also holds the victim when you need to reset the Z-pulley (and prevent the victim from falling back down). Your impression is right, the belay device between the pulley and the prussic is to mind the prussic so it doesn't get sucked into the pulley, it doesn't do anything else.
If you use an autoblocking belay device (Reverso, B-52) or the alpine clutch at the anchor, you don't have to deal with a prussic and minding it, but these two methods also add more friction to the system, make it harder to haul. The traxion is nice because it doesn't add friction to the system. With all the autolocking / autoblocking systems, keep in mind how to lower the victim. Be very careful not to haul the victim into the underside of the lip.
|
|
|
|
|
mother_sheep
Jun 26, 2006, 5:03 PM
Post #15 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
In reply to: In reply to: Possibly but the only friction knot that I saw was the knot used to transfer the victim's weight from the person who is in the arrest position, on to the anchor. Right. That hitch then goes on to become the ratchet in the system. In reply to: There was a belay device in the diagram below the pulley at the anchor. This belay device is directly behind a ratcheting hitch, also shown there. It does indeed serve "to keep the friction knot attached to the victim's rope from getting sucked into the pulley" as you say. When the haulers need a breather, it also serves to lock the load strand so the victem doesn't fall back in to the slot. In reply to: I think we didn't have an autoblock there so we used an ATC. There's your problem. Unless you have a self-locking pulley (ala the traxion), you must have a friction hitch there. You can do without the belay device, for sure. But you have to have the hitch, for the reasons you pointed out. In reply to: I think that would prevent the victim from falling back into the crevasse. Exactly. Good luck! -Derek
THANK YOU! THANK YOU! THANK YOU!!!
|
|
|
|
|
adnix
Jun 26, 2006, 5:52 PM
Post #16 of 39
(9615 views)
Shortcut
Registered: May 20, 2003
Posts: 584
|
In reply to: 1. What prevents the victim from sailing back into the crevasse if for some reason the hauler loses his grip, since the system is not auto locking?
In reply to: 2. How do you slide the running pulley and it's prussic back down so that you can continue to haul? |
|
|
|
|
skiclimb
Jun 27, 2006, 1:39 PM
Post #17 of 39
(9615 views)
Shortcut
Registered: Jan 11, 2004
Posts: 1938
|
Look up FRENCH PRUSIK
Much better than any mechanical cam, can be released under pressure. Trick is to have a descending ring blocker in order to keep the knot from fouling in the pulley.
Perhaps I'll draw a pic of the best z-pully system out there and post it.
|
|
|
|
|
tradman
Jun 27, 2006, 1:52 PM
Post #18 of 39
(9615 views)
Shortcut
Registered: Jan 14, 2003
Posts: 7159
|
http://en.petzl.com/...roduit_Image_113.jpg
Like Adnix said, use a Tibloc.
They weigh nothing and can be used for lots of stuff. The only catch is that they're not brilliant for your rope (they've got little teeth to help em grip) but it's very common for climbers here to carry them along with their prussiks, especially in winter!
|
|
|
|
|
mother_sheep
Jun 27, 2006, 2:18 PM
Post #19 of 39
(9615 views)
Shortcut
Registered: Jul 18, 2002
Posts: 3984
|
In reply to: http://en.petzl.com/...roduit_Image_113.jpg Like Adnix said, use a Tibloc. They weigh nothing and can be used for lots of stuff. The only catch is that they're not brilliant for your rope (they've got little teeth to help em grip) but it's very common for climbers here to carry them along with their prussiks, especially in winter!
I tested this last night with the tibloc and it worked very well. My only concern is will it damage the core of the rope? I have extra tiblocs too for the other people on my team so $ wise, this would work well too.
|
|
|
|
|
j_ung
Jun 27, 2006, 2:22 PM
Post #20 of 39
(9615 views)
Shortcut
Registered: Nov 21, 2003
Posts: 18690
|
Tracy, my opinion is that an autoblocking belay device is worth its weight in diamond-encrusted platinum for any type of hauling. The rigging will take a fraction of the time, it weighs no more than your standard ATC and it solves every problem you've mentioned so far. Its obvious downside is the one that always comes up: lowering under load. But with practice, it's a non-issue. When Andy Selters wrote his book, plaquette devices were not widely in use (other than perhaps the Kong Gi-gi in obscure guiding circles). And if the Trango Cinch works in wintry conditions on icy ropes (I have no actual idea), then IMO it should at least be considered.
|
|
|
|
|
adnix
Jun 27, 2006, 3:03 PM
Post #21 of 39
(9615 views)
Shortcut
Registered: May 20, 2003
Posts: 584
|
In reply to: I tested this last night with the tibloc and it worked very well. My only concern is will it damage the core of the rope? |
|
|
|
|
slacklinejoe
Jun 27, 2006, 3:17 PM
Post #22 of 39
(9615 views)
Shortcut
Registered: Nov 5, 2003
Posts: 1423
|
For another option check out the Wild Country Rope Man Mark II - it's almost as light as the Tibloc and one hell of a lot nicer on your rope.
Also, there was several recent discussions about friction hitches including some newer ones that I'd never seen but seem to work damn well.
|
|
|
|
|
therelic
Jun 27, 2006, 4:30 PM
Post #23 of 39
(9615 views)
Shortcut
Registered: Aug 11, 2002
Posts: 136
|
Hi Tracy,
A book you might enjoy browsing if you can get your hands on a copy is the book we used in my fire department career. I know the book isn't climber specific but much of the information in the book can be adapted to the climbing environment. The book is listed below. There should be a newer version of the book than the one I am listing.
As Captain of an engine company for 23+yrs that had most of our districts urban interface and rural roads in the foothills I had numerous opportunities to use Z-rigs and Pig rigs. We would haul injured people up cliffs and steep slopes, or lower them down to the road below, when they drove their cars or motorcycles straight into space rather than around the corner their road followed.
If you can't find a copy of the book and feel you would really like to read it shoot me an email.
"High angle rescue techniques: A student guide for rope rescue classes".
By: Tom Vines & Steve Hudson
A publication of: The National Association for Search and Rescue.
Publisher: Kendall/Hunt Publishing Company
2460 Kerper Bd
PO Box 539
Dubuque, Iowa
52004-0539
ISBN 0-8403-7363-5
Bill
|
|
|
|
|
|
|
|
|
1
