broke a biner

chicken89

chicken89

we recently shock-loaded a steel biner, actually 2. /forum/images/graemlins/aaa.gif has this ever happened to anyone?
 

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Without some sort of details your question is the same as asking:
I wreaked my truck, here is a picture, has this ever happened to you before?

In other words to quote Nick; ?details, details.....what'd you break it with?
Frans
 
How did you asure that the all loading was totally maintained over the spine/ was connection a too large to carry just over spine? Gate secured and not facing any hard surface or chance of being 'slapped'? Are you saying the devices were loaded in series/ different positions; or pairallell/side by side / both as a single support link?
 
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we recently shock-loaded a steel biner, actually 2. /forum/images/graemlins/aaa.gif has this ever happened to anyone?

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In twenty years of biner use I've never done that to a biner. Any damage done to people or property? I hope you got lucky.

Dan
 
Did you say steel?
What rope did you use that didn't fail first?
what was the biner rated to?
"shock load" right? not pulling or skidding?
Story please.
 
rope- orange samson, 21,000 lbs min break
straightened biner- 50Kn
other biner- 40Kn
20000 pulley tied in tree with 50Kn biner
porta wrap connected to skid steer with 40Kn biner
rope was hard locked to porta wrap on skid steer. limb got caught in crotch so we used skid steer to raise/lower limb to free it from crotch. i assume shock load was too much, i was looking down so if anything broke (as it did) nothing would hit me in the face. broken branches did hit my helmet and broke pelton ear guards
 
Well, there ya go. Put a skid steer onto our tree type rigging and yank and pull on it and your stuff starts to break.
Did you really expect any more or less?

When I am working with tractors, skid steers, PTO or hydrolic tractor winches, log loaders etc etc I bump up the rigging gear to steel snatch blocks, minimum 1/2" or 3/4" STEEL cables, Steel clevis' etc.

on a survival note, if you expected something to break, why in the world would you stand close enough for something to come down and hit hard enough to actualy break your peltors?

Maybe next time, (heaven forbid) stand far far away.
Thats my advice, and good luck!

Frans
 
Maybe a good spot for a stout clevis?

What are y'alls preference for connecting a porty to the tree? I like a whoopie girth hitched to the porty, all that girth hitched to the tree.

love
nick
 
we attach all of our porta-wraps with a long Tenex sling girt hitched to the porta-wrap and cow hitched to the tree. I have numerous slings up to about 30 ft long for those really big trees. And if for some circumstance I don't have a sling long enough for a cow hitch, I simply put on a timber hitch. With atleast five wraps evenly spread out or more if i have enough sling.
 
The rope didnt break first because it wasnt the weakest link in the system.
I avoid using biners when doing heavy rigging, and try to stick with shackles where possible. And for sure, if I were to put the force of a skidsteer on the line.
 
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Seriously. Why didn't the rope break first? Why didn't the rope fail at a knot? Curious.

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Because the biner was rated 50kn which is 5000KG or 11000lbs and the rope was rated 21000lb. Even if he lost 30% of the rope strength with knots it was still way stronger than the biners, so the system was poorly matched.

The assy holding the top pulley and the top pulley itself should be rated double that of the lowering rope. The top attachment is going to experience a minimum of double the force.

The assy holding the Portawrap should also be atleast as strong as the lowering rope

So there was a whole heap of fundamental errors, also when the skidsteeer was pulling up to free the hanger the top pulley assy was copping double the force.

If the 40kn biner at the portawrap broke then we know that the biner at the pulley and the pulley itself may have experienced up to 80kn of force, but obviously it failed when the load went over the 50kn ... in theory it should have failed before the one on the portawrap due to the doubling effect but sometimes you get lucky. Some of the 100kn breaking strength pulleys I have used actually went as high as 180kn in tests before failing ... the manufacturer just wanted to be extra safe.

So all components of that system should now be thrown in the bin as all have exceeded their Safe Working Load limit which is in the USA 10% of the breaking strength.

May I kindly suggest to you Mr Chicken89 that you purchase a copy of The Art &amp; Science of Practical Rigging with <u>Videos</u> and learn about this stuff. They will also show you the loads generated, the effect of vectors and poor bend ratios in your hardware ... a genuine must if you do rigging.
 
Very nice breakdown; i think top attatchmeant will see up to a max of double input force, not minimum(?)though.

i think also we must be a good enough technician to make sure the forces are carried right through the devices for maximum strength. Any, non maximimum positioning/ how force is ushered through device; being referred to commonly as 'leveraged' against the device, giving lower SWL. i think connections to carabiners are best made very narrow sling and inine with spine. Even a wider sling, placing more loading towards open hook/ moused gate of carabiner that gives earlier failing. Carabiner Loading- Works in Progress only 10/13 slides done (Runs in full or partial screen, with no color or speed loss; bunch of info @ 26k filesize fer GlenS!)

A clevis is a dual legged device, a carabiner is not; it is single with some help for forces that don't stay inline with spine of krab.

Also, if power source (loader)is not within SWL of devices per their positions; it is not equitabley matched. It should then only be used as gentle giant; realizing it can do as much good as bad in one swipe of paw. Anytime, load goes to jam, gentle giant should relax, back off allow releaf of force, not building; unless it is just soft brush that load itself can overcome and break and relieve jamming; allowing free flowing force again.
 
Thanks for the heads up Spydie, yes 2x max + some friction perhaps.

Hey, did you know the way that they rate carabiners is by pulling them apart in a machine that uses 1/2" dia pins.

They tear it apart along the spine with 1/2" pins ... so if your rope starts to exceed the 1/2" dia you also weaken the biner as more load gets placed toward the gate.

Also, the bend radius on the rope is extremely poor. A 5/8 rope should have a USA std 4x dia bend radius for 90% strength ... Australian standards are 5X rope dia for 100% breaking strength of rope ... and finally, worst case scenario its recommended not to go under 3X dia of rope ... I think the latter works on the principal the 30% strength loss is about equal to what most knots will do etc.

Anyway, using the USA std of 4X .... means the carabiner should be 2.5" thick! This is where arborist blocks come to use as the rope sits in the block on a decent radius.

Now with the porty, I girth hitch mine and tie it to the tree with a cow hitch or timber hitch. This still loses a lot of strength again due to bend radius but I have double line.

It is obviously clear that manufacturers of biners didn't think about us whacking big ropes in for rigging. Also, manufacturers of the portawrap should have made a section of the lower attachment a lot larger in dia to compensate. Just need to remember where rope attaches ... bigger bend radius ... and thimbles on splices is smart.
 
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