Some fibers my loopie sling was melt

[Grigory]

Hi all from Russia. At us in Moscow the snow depth is waist-high - such at us spring Soon Bear`s on streets will go

Yesterday i took down a tree. The complete set of the rigging equip for the first time was used (see attached pics)

However I had some problems: Some fibers my loopie sling was melt in the "bend point" (White circle in pic.)
The separate strands have torn on 1/4 thickness . The weight of section approximately 140 kg (300 pounds)

Anybody collided with such phenomenon? It be necessary to put in this place a protective sleeve, how on woopie sling?

 

[Treeman14]

That piece looked like more than 300 pounds, but it's hard to tell from a picture. You also had some dynamic loading involved, so the actual force on the rigging would be significantly higher. You've definitely compromised the integrity of that sling.

One more thing, I'd be careful about allowing your rigging sling to ride over your climbing line/lanyard as in the picture.

Stay safe and stay warm.

 

[woodchux]

Looks like maybe the log slid across it as it came over.

Let me suggest that you place your sling BELOW your tie in point...

You're asking for trouble tied in like that !!

BE SAFE

 

[Dadatwins]

Looks like maybe the log slid across it as it came over.

Let me suggest that you place your sling BELOW your tie in point...

You're asking for trouble tied in like that !!

BE SAFE

Welcome Grigory, good to hear from you again, I would agree that it looks like the log slid and burned the sling as it passed over, I would have put the sling lower than where it is and I prefer a marl in addition to the single hitch tied on that smooth of a log.
We actually had snow here first time since December, 1/2" covered all the grass, but it was melted by the afternoon after temp reached 50.

 

[Bermie]

Looks like you over stressed the sling.
Also have a close look at the pin on the top of the pulley where the sling is attached, below the white circle, looks like it has popped out! Anybody else see that?

 

[trevmcrev]

Keep in mind the "fall factor" , because you are not rigging from a high point above, but off itself from below you get a multipled loading. If the tie off point is 1 metre above the pulley the log free falls 2 metres. The acceleration in that freefall then shock loading when it grabs can more than double the load.

I'd lower that size log from an anchor point above, but think youre pushing the limits of you equipment doing it off itself.

Trev

 

[coydog]

from what it looks in the picture that piece was pretty close to the ground, not allowing much time and space to let it run. A piece that big from 40 or 50 feet wouldn't stress the sling so much with a good groundman, but if it's only got a few feet to run go smaller, like half that length. I personally don't care for whoopie slings for dynamic rigging.

 

[notahacker]

I'd recommend reading The Art and Science of Practical Rigging

If you are certified this helps you build CEU's.

Be safe.

 

[xtremetrees]

Welcome brother from the USSR.
Awsome pics bro. Is that a dead tree? Thats high speed dude, smokeing good job. Id say thats normal wear on the sling. I know you know your trees in your area that tree looks like a pine or a conifer and dead! that piece looks huge to be so dead. Dude you rock!

 

[John Paul Sanborn]

What happend was that when the sling loaded it ran across itself. the rop on rope friction is wat caused the burn.

You need to snug these things up as tight as possible when slam ing big wood into them.

I too prefer using eye slings with a stilson in these situations, when I do not have big hollow-braid on hand to replace a damaged one.

I would second the amonishment on keeping personal attatchment lines away form the sling. Todd Kremmer and Mahk Adams gave a talk on this at the TCIA Expo and are recomending placing flipline and climbing line above the rigging anchor as a precaution to its slidding down.

 

[John Paul Sanborn]

, looks like it has popped out!

That pin is spring loaded with a bayonet like locking pin.

You worry only if it is not sticking out.

I have three of them and like them very much, because you never deop a nut or a sheave into the hostas below you.

 

[Grigory]

Hi all! Thank by all answered.
The removed tree is common spruce. It has a long time withered (killed with a bark beetle's). In our climatic conditions its wood very strongly dries up and becomes very easy. Therefore that log weighs only 120-140 kg. Such log of an alive birch would weigh 200-250kg (550 lbs)

The majority of the versions answering relate to that dynamic stress on a loop was too great. Similar logs we take down there are a lot of years with the help of the equipment with the maximal breaking strength only 2300 kg (5100 lbs) Top and bottom loop in our case were made of a rope of 11 mm (7/16) diameter, with a smooth cover. We never observed so strong burning of the cover.
This comparison shows that most probably maximal loading on loopie is limited not to its breaking strength, but abrasive wear, and refractoriness of fibers. I shall try equalizing these two parameters of a loop, having protected it from fray through by the protective sleeve.

I have carried small research out about the not closed pin of a pulley. Has increased a photo so that the pulley was in the natural size, and has compared the present roller to its image under the same visual angle. - the pin has appeared is closed! The not closed pin sticks in twice many out (on 2 inches)

 

[TheTreeSpyder]

i wuz thinking the dynamic loading and slack gave enough allowable slip and speed to cause choke to burn itself(?) Pulley is high in first pic; low in next 2.


Edit-looks like i didn't get 2nd part of thread outline when i posted; where JP already mentioned this

 

[xtremetrees]

I agree tightin things up a bit. Thou after all day of it I'm sure you excell my pratice. Awsome job !.Nice pics. It is more difficult for me to tighten up the rigging block and reduce the fall impact when using a notch. Especially on conifers I will use the verticle snap cut and no notch. No nothc helps me get my rigging within 1 foot fall factor consistently.

I never rig out or rope out dead trees such as the conifer you have done.! As dead trees I do not know how dead they really are. And the forces of rigging are to unpredictable.I know you know your trees in your area of the world and thank you for posting your rocking photos brother from the mother land of russia.

More more rocking photos!

 

[murphy4trees]

The force on that sling was huge... by no means twice the amount of the load... As I recall... you take the distance between the center of gravity of the laod when it started and the center of gravity when it was caught, in feet. Distance between Center1 and center2= y'. Force on sling = 2x (load + [y x load]) So if that 300 lb load fell 10 feet you'd be looking at 2 x (300 + 3000)= 6600 lbs. Now you are well beyond the 10:1 safe working load factor. And it gets worse than that. After 5 feet of fall the forces go even higher as that log really gets some momentum going. That's why those long pieces create so much force. the longer they are the more the distance from C1-c2.

The one thing that the above formula does not account for is the amount of stretch in the lowering line. Spidy showed with the rigging software that the elasticity of that line is a huge factor in determining the actual effective forces in dynamic loading. And of course the other huge factor in determining shock loads is who is running the ropes...

 

[doggonetrees]

What is sticking out of the trunk in line with your left shoulder- a stub or a metal pin to keep your rigging from sliding down. Cool pics!

 

[BigJohn]

Just throw that whoopie away. Go with a straight sling and choke her down tight. And yes I agree with everyone tie your ass in above that pulley and stand up You wont fall off if your above the the top of the spar.

 

[BigJohn]

You want your head above your cut. When the log comes over you dont want to see any spar in from of your face. If you get one that rocks you your gonna look like a hockey player cause your face is gonn be all over that spar. Don't be a sissy and stand up.

 

[xtremetrees]

I partly agree with John. Especially the standing your head above the cut part. Bust your chest,crush your ribs, bust your jaw to the back of your neck its your choice..lol But if your flip line flips off your toast unless youve a second tie in wheich you seem to have., You could wrap the flip line twice which I dont like ,these are sticky points that should be addressed frequently.

 

[Grigory]

What is sticking out of the trunk in line with your left shoulder- a stub or a metal pin to keep your rigging from sliding down.

It's the stub.

To murphy4trees

Thank for your account.
That the force of shock loads depends not only on weights a logs, but also from its length- interesting fact for me. And whether probably to calculate the decrease the shock load, If the following parameters are known: starting length of the rope from port-a-wrap up to log is 12m (40 feet), total length is 52 feet (the rope slippage is 12 feet); 2 wrap in port-a-wrap; the rope brand is "Samson Stable Braid", size 5/8'' ?

Thank by all for the remarks, concerning my positioning on a tree. However we use other system of climb and positioning on tree. I do not use gafs, I stand on a trunk by one leg in a rope loop. Second my loop goes from a trunk to my harness. I occupy such position, that safely I can go through of any force impact on the trunk.