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GhoulweJ
Trad climber
Sacramento, CA
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Mar 16, 2009 - 06:55pm PT
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I own both a Kong Block Roll and a Pro Traxion.
I use them both. When I have a monster load, the Kong owns it baby!
If I will be doing alot of free climbing, the Kong is a bit of a drag because it is heavy and clunky to carry.
Is a device good or bad? We all have opinions and as climbers, we LOVE to voice them as gospel. I know I get this way sometimes.
Typically, a system of redundancy is better choice (in my opinion). We also all know that no matter how right we do things, it may not be our to day to survive weather the gear fails or a meteor comes through our windshield while driving through a tunnel.
All we can do is use our critical thinking skills when we buy or use gear.
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tom woods
Gym climber
Bishop, CA
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Mar 16, 2009 - 07:01pm PT
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Any rescue or engineer types know what force it takes for a pair of ascenders to cut a rope?
I seem to recall it being very low, in the 2-4 KN range.
In this case the 15 foot fall onto the ascenders led to a cut rope, the ultimate nightmare for us climbers. It probably generated more force than that.
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Mar 16, 2009 - 07:12pm PT
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The Kong Block-Roll is a superior hauling device for large loads, although it is bigger and klunkier than the ProTrax. I use it exclusively. If you need one, let me know, I will have one for sale shortly.
Tom, ascenders are typically rated for 5 kN - it takes more than that to have the cam cut the rope. A kN is about 220 lbs force, I believe.
The Kong is rated to haul 10kN loads, or 5kN 'live' loads, I think. I don't have one in front of me to look at it. It's fine to jug off of, but you should still back it up [with less than 15 feet of slack!]
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WBraun
climber
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Mar 16, 2009 - 07:13pm PT
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GhoulweJ -- "All we can do is use our critical thinking skills when we buy or use gear."
Yes ....
So .... use a prussic below your haul device to load the rope if you're going to rap off your haul device with the cam engaged.
A prussic is pretty strong and has no teeth.
People should actually see how all these different devices work and operate under extreme loads and how they fail.
People put way too much trust in all these mechanical devices beyond their intended use.
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tom woods
Gym climber
Bishop, CA
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Mar 16, 2009 - 07:46pm PT
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PPP- are you sure about that? The five KN is for the gear breaking I imagine.
I seem to recall the rope cut at far less then the gear. It was shocking when I heard the results, though I don't know if it was a drop test or a pull test or whether that matters. I just remember hearing the number and thinking that I better not fall on the ascenders.
Werner- do you remember at what force the petzl ascenders cut the rope? None of the other ascenders fared any better.
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WBraun
climber
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Mar 16, 2009 - 07:48pm PT
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I don't know Tom, I don't have the data at hand.
But .... I hate Petzl jumars. I hate them. They suck.
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steelmnkey
climber
Vision man...ya gotta have vision...
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Mar 16, 2009 - 07:52pm PT
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tom woods wrote:
"Werner- do you remember at what force the petzl ascenders cut the rope?"
Paging Russ! Paging Russ! Fish please to the white phone.
(sounds like a good pull test for Russ)
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Darnell
Big Wall climber
Sequoia Ntl. Pk.
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Mar 16, 2009 - 07:53pm PT
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Another factor that might cause the rope to be cut by ascenders is how wore down they are where the rope comes out of the ascender at the top. I just retrired my last set of jugs, they lasted about 20 walls.
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Colt
climber
Midpines
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Mar 16, 2009 - 08:12pm PT
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Tom,
Very hard to calc a cutting load. This number would be best determined from testing.
However, here is a quick calc of where the fall load was compared to some manufacuter specs.
PPP is right with 5kN. Petzl Ascension ascenders, for example, are rated to hold between 4kN and 6.5kN while loaded on a rope. A climber weighing 150lbs (with a 104lb pig attached) taking a 15' factor one fall on a static line generates about 13kN.
With the assumption listed above, it appears that loading in this case was likely in the range of double to triple what manufacturs provide.
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Mar 16, 2009 - 08:18pm PT
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How did you calculate that 13kN number, Colt?
Dang - even if 13kN didn't break your rope, it sure as hell would break your back.
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Mr_T
Trad climber
The 7th Pin Scar on Serentiy Crack
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Mar 16, 2009 - 08:32pm PT
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4kN (a measure of force) = 400kg * 10 m/s*s = the amount to accelerate a 400kg block at 10 m/ss. [Since it's been decades since physics for many] 10m/s*s is the acceleration due to gravity. 1G is the force of gravity. 4kN is force to move a rather large 100kg human at "4G's".
So above 4G's, an ascender fails. Intuitively, this is the max acceleration an ascender can sustain, above which it likely fails.
The difference between a fall onto a static and dynamic line is like slamming on the breaks in your car, vs slowly easing them on - in both cases you do the same work, but one has a higher maximum force.
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Mr_T
Trad climber
The 7th Pin Scar on Serentiy Crack
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Mar 16, 2009 - 08:38pm PT
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And to follow up, there is no "fall factor" here - the static rope is not dissipating energy. At best, it's a fall factor 1,000,000 - very little rope dissipation vs distance the climber has fallen.
Think of this fall as the dissipation of energy by a system over time. The energy of the falling climber and bag is transferred to the climber's body, the haul bag, the anchor, a very little to the static rope. Again this is a transfer of energy over time - performing work. (This is not an transfer of momentum like in high school physics.) Failure happens once the force exceeds a maximum force threshold of 4kN.
This particular fall is a 50-100kg (110-220lb) man onto a static line that catches a 40kg haul bag. There is not much to dissipate energy in this system (the climber's vertebrae and organs, the haul bag stitching, and ruptured water bottles inside the bag may be the best). There is a tremendous maximum acceleration (and force) on the ascender's cam. Above a certain threshold (4kN), the rope cuts. Since the rope is already loaded by the haul bags, it likely cuts at a lower threshold than an unloaded line (3kN).
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tom woods
Gym climber
Bishop, CA
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Mar 16, 2009 - 10:52pm PT
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I just remembered where I might have that cutting info with jugs. I'll see what I can dig up once the kid falls asleep.
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tom woods
Gym climber
Bishop, CA
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Mar 17, 2009 - 12:09am PT
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Okay, I went and looked. The info I had in writing was for an old gibbs ascender which broke the rope at close to 9KN.
So here's the question for you physics guys. If an ascender cuts the rope at 5Kn, how far does a guy have to fall on ascenbers to cut the rope?
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Tom
Big Wall climber
San Luis Obispo CA
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Mar 17, 2009 - 12:24am PT
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The Kong Block Roll is strong enough to not have this sort of issue. The ratchet is a jumar-type device, and the pulley is hella strong on a 3/8" axle, and about 3 inches diameter for good efficiency.
PTPP swears by this device, and he is so sure of it, he's now a reliable source for it.
Those weak hauling devices have been inviting disaster for a long time, and, here it came.
I thought the Wall Hauler would be the first to claim a fatality, but even the Pro-Traxion isn't up to the task.
KONG BLOCK ROLL - A very strong device, weight be damned.
At what point is saving weight the main issue? I want safety.
 Dr. Johnson
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healyje
Trad climber
Portland, Oregon
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Mar 17, 2009 - 12:27am PT
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"But .... I hate Petzl jumars. I hate them. They suck. "
Well as a guy who probably spends a lot of time on jumars - what do you like...?
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Smack
Trad climber
Utah
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Mar 17, 2009 - 12:45am PT
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I remember that the original post describing this terrible tragedy mentioned that the haul bag fell to the ground along with the climber. This suggests that he was jugging a line weighted with the haul bags. Sad sad sad.
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John Mac
Trad climber
Littleton, CO
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Mar 17, 2009 - 01:06am PT
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Any piece of equipment that is not used correctly can fail.
This isn't a case of a bad design, but rather using a piece of equipment (Protrax) incorrectly and with no backup. Same thing could have happened to any other pulley system, including the Kong Block roll or whatever it is called.
Even if you soloing there is no reason to rap off a hauling device. Just tie off the haul line, below the device and then do a mini haul to re engage the cam. There is no need for any trickery. Its dead easy.
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WBraun
climber
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Mar 17, 2009 - 01:24am PT
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John Mac
Why tie off the haul line below the device and then do a mini haul?
Just put a prussic there. Simple, ... and you don't have to do any mini haul, just start hauling again and it's strong.
Healyje, For rock jumaring the old grey original jumars were the best, although kinda weak. But they were fast and efficient to maneuver with.
I now use CMI Ultrascender because YOSAR does not allow use of the gray jumars. The saftey trigger mechanism of the CMI Ultrascender sucks for efficiency though!
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dirtineye
Trad climber
the south
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Mar 17, 2009 - 03:38am PT
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really awful news, but two mistakes, what can you do?
No energy to read it all or anaalize, I gues I am pretty much done in myself, but the idea of theextra 100 pounds plus 15 feet of slack plus improper closing of pro-traxion plus toothed ascenders apparently was too much.
damn still that sucks bad.
I had ( now shannon has em ) rescue ascenders from Austrailia, non-toothed, but my pro-taxion has teeth and one could certainly screw up and not close it correctly. Damn damn damn.
Every time is like the first time, get it right every time and forget about " oh I've done this a lot, what can happen?" , please.
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