Per the research at Sterling ropes, best evidence available suggests that's just not the case so long as the dynamic rope is the attachment to the system. The numbers suggest no shockloading and, at times, lower forces than the initial impact.

Until someone can point me to *other* available evidence suggesting otherwise, I'm sticking with the best evidence we have at this time.

I'd love to see the Sterling link. I could buy that as long as no piece falis, but if a piece fails, it's obvious that the system will extent and it's self evident that sudden extension equals shock-loading. What am I missing here?

Peace

karl

I was going to hold off on making a definitive statement on "Shock Loading" till I had time to work up what Jim at Sterling had actually found from his tests. But since it seems some folks simply can't let the thing go (nor should they till the data's in), here's basically what Jim scribbled down after doing some tests to try and create a shock load in a normal set up with a pretty stout dynamic fall (factor 1--80 kilo load dropped on 10.2 nylon rope connected to a two annchor point equalette).

Wrote Jim:

Leg failure test of Equalette.

All the same set up as previous unequal leg tests but with the short leg
connected with a 'fuse'. The 'fuse' is meant to break around 2kN. To save some time I also kept using the same cord and dynamic rope that I had just tested the Equalette unequal_arm with (see results below). Note: Using the same piece of climbing rope increases the chances of a shock load since after repeated drop testing, the rope looses it's stretch and becomes little more than a piece of static line.

The force/time curve is quite jagged at the beginning indicating lots of vibration. I can see on the curve the point at which the 'fuse' fails. Immediately after the 'fuse' blows there is a sharp drop in force followed by a normal looking curve. The peak force varied depending on the tenacity of the 'fuse'. The stronger the 'fuse' the lower the peak force on the remaining leg, the weaker the 'fuse' the higher the peak force on the remaining leg. Predictable but still interesting. No catastrophic shock load occurs a result of the extension.

6mm PC Equalette

short long

3.11 2.99
3.58 3.93
4.38 4.26
4.45 5.21
---------------------

The important thing to see is that the secondary loading is roughly the same as the initial loading--meaning there is no "load multiplication" between the initial leg failure and the mass slamming onto the remaining anchor point. Half the time it's less--the rest it's the same or a little more--at most about .75 kN, or 168 lbs. And that's only on the last drop, when the nylon rope was already stretched like crazy. And that's all on a rig with the limiter knots basically 10 inches apart--pretty far by normal standards.

My impression is that a true shock load can be understood in terms of the kind of shock we see in human beings. Shock usually means the level of stress or injury was greater than the resilience of the person's biology. In climbing systems, all the components have a degree of resilience, and these are by and large only maxed out when a section of unbelayed static line or high tensile strength cord sustains a dynamic load that is transmitted directly to the anchor. Like when a leader clips off to an anchor with a tech cord daisy, climbs up two feet and slips, falling 4 feet directly onto the anchor. You can bust biners this way, because the gear can't handle mass decelerating that quickly. Stretch and give allow the mass to decelerate slower. In a shock load you basically have the equavilant of a head on collision--something that's not going to happen when you're on a dynamic climbing rope that is running through a belay device, and when you're clipped into the anchor with the climbing rope.
Here, extension simply means that the next anchor that holds will be subjected to basically the same load--maybe a bit less--as that which blew out the first leg/piece. In other words, the initial loading is not multiplied through extension, it is simply passed on, sometimes at a lesser weight, depending on the strength of the "fuse" (failed arm).

JL

Sometime soon I'll throw some samples of the all three versions (Equalette, Tripplette, ELET) onto the pull tester and get video of how they behave under load with one or more legs cut, but until then here's some non-ASCII pics.

First, the power point loop should be stronger since it incorporates 2 strands of cord on one side and 2 strands of runner on the other, where the Tripplette has 2 strands of cord on one and one on the other.

Secondly, it has one fewer knot and...

I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents

I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents

knudeNoggin made a posting on Page 4 (Link) about another alternative that sounds interesting (the ELET). He only provided an ASCII art diagram, so I threw one together yesterday and took some pics.

Basically you take your cordalette tied in a loop (I used a DF) and use a pair of sheet bends (or any of a number of other knots) to splice a runner into the middle of it for the powerpoint. Playing around with it I have to say I think there's some significant advantages over the Tripplette. First, the power point loop should be stronger since it incorporates 2 strands of cord on one side and 2 strands of runner on the other, where the Tripplette has 2 strands of cord on one and one on the other. Secondly, it has one fewer knot and is much easier to tie and untie. I found the Tripplette a bit fiddly to tie and set neatly with the strangle knots backed up tight against the overhands. The sheet bends in this version were quite simple to tie and easy to adjust. The runner I used was shorter then he suggested, but seems to work fine. I think I'd actually prefer a longer runner though, as it would give room to put an overhand on each end to provide some redundancy in case one of the strands of the runner was cut (tie the sheet bends through the loop the overhand creates on the end).

Sometime soon I'll throw some samples of the all three versions (Equalette, Tripplette, ELET) onto the pull tester and get video of how they behave under load with one or more legs cut, but until then here's some non-ASCII pics.

[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchor.jpg[/image]
Detail of front:
[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchorfront.jpg[/image]
Detail of back:
[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchorback.jpg[/image]

I suppose the biggest advantage would be that its much easier to untie should you ever need a full length looped cordelette, but if you don't feel that you'd ever need to do that then its pretty much on par with the Triplette. I will say that the biner slid on the loop easier on the ELET, but that's not really anything to call home about.

Just for the record, it isn't my design and I don't have a vested interest in it. I just felt it looks promising and deserves some looking into. As I mentioned earlier, sometime soon I'll put a couple of each on the puller and see what they do under load.

Personally I'm not too thrilled with the 2-knot, 3-strand ring bend version of the Tripplette since ring bends are known to roll when loaded like they would if one side of the anchor failed. Although I suppose worst case would be that it rolls until you're only on 1 strand instead of 2..... The ring bend/strangle backup version looks fine since it would prevent the rolling; I just found it a bit fiddly to get tied neatly. And with the ELET, I have no idea how the sheet bends will behave when ring loaded. Hence wanting to bring it up for discussion and do some testing.

-aric.

I am sorry but,the climbers round here are not looking for your logical $0.02 input. These guys are constantly challenging each other on CF eqalette bullsh*t till someone actually breaks one and dies while setting it up .Till then this myth will continues.

there was no such
sling-cutting case demonstrated; if you had paid attention, you'd have seen
a bunch of people making wild conclusions to support their agenda (dental
floss is bad, bad, bad, esp. when knotted), which was ridiculous on its
face, and subsequently tested and proved so by both Kolin Powick's (BDel)
sling testing and Mammut's investigation of the infamous John Sherman sling.
.:. It was cut by a SHARP object (think: knife), NOT by fibre.

Mammut's investigation:

http://www.mammutusa.com/...%20Sling%20Break.pdf


Two BD investigations of sling-on-sling attachment:

http://www.bdel.com/...p_archive.php#110906
http://www.bdel.com/...p_archive.php#052107


C'mon Jay, you know how to use the internet.

Two BD investigations of sling-on-sling attachment:

http://www.bdel.com/...p_archive.php#110906

i looked into this a while ago after i saw that alot of you guys dont like the equalette and didn't find what i was looking for. what is the problem with the equalette? i use it from time to time as the powerpoint for my toprope anchors.