tensil strength and working strength

[DangerTree]

The weak link is the deadeye sling with a WLL of 3400 lbs Which means you should limit your lowering load to 1700lbs. I guess I am going to have to figure out how to splice amsteel now too and make a deadeye sling.

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You can buy pre made tie backs with an eye in em' any dia. and several length options. Sampson is my choice in 7/8" run through 1" blocks and as I said before The spar tree can be tied back for extra strength.
Really though some may find these topics helpful but most folks need to work with more experienced guys for a while to learn what can be done. Many of the guys on these forums have been doing this type of work all their lives. Rigging is my business it's what I'm good at. I rig just about anything in high places including lighting for stages to zip lines for amusement parks but mostly large trees. There are usually guys in the business around that would be happy to show you the ropes and maybe even pay you while you learn. The hard knocks school of tree rigging is not recommended.
Be smart and be safe. Extreme overkill is the best way ALWAYS.

 

[Ghillie]

You can buy pre made tie backs with an eye in em' any dia. and several length options. Sampson is my choice in 7/8" run through 1" blocks and as I said before The spar tree can be tied back for extra strength.
Really though some may find these topics helpful but most folks need to work with more experienced guys for a while to learn what can be done. Many of the guys on these forums have been doing this type of work all their lives. Rigging is my business it's what I'm good at. I rig just about anything in high places including lighting for stages to zip lines for amusement parks but mostly large trees. There are usually guys in the business around that would be happy to show you the ropes and maybe even pay you while you learn. The hard knocks school of tree rigging is not recommended.
Be smart and be safe. Extreme overkill is the best way ALWAYS.

Thanks for the warning, I'll be fine.

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[DangerTree]

Yes, stretch will decrease the load. But if your gear will not meet the WLL of a worse case scenario (dead stop, no stretch) why take a chance. Why risk your "cycles to failure" being equal to or less than 1?

At one time, I had the rigging program that SherrillTree offered and it factored in length of run. It would say "not safe" to some drops and then when you added 50` of run to the right, it would be okay. It was interesting but I do not have the formulas on hand to do the math.

And I am not sure what you are talking about 1:1 on the pulley? Straight up (vertical) is doubling the forces on the block and sling.

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I think I was unclear with my description I'm sorry.
If the pulley is tied to the top of the tree and the weight to be raised is at the bottom as are you the rope will be in the shape of a U but upside down. If you were to pull down to raise 100lbs the resulting force applied to the pully would be 2 times the load as 100lbs is applied to both sides. As the angle of the rope being pulled increases the resulting force on the pulley decreases until the puller is standing above the pulley. The rope would be straight up and down and no force would be applied to the pulley. If the weight were at 6 o'clock and the puller was standing at say 1 o'clock and the pulley was in the center of the clock there would be very little force being applied to the pulley. As the puller gets later in the day the force increases.

Is my description a bit more clear?

 

[Ghillie]

I think I was unclear with my description I'm sorry.
If the pulley is tied to the top of the tree and the weight to be raised is at the bottom as are you the rope will be in the shape of a U but upside down. If you were to pull down to raise 100lbs the resulting force applied to the pully would be 2 times the load as 100lbs is applied to both sides. As the angle of the rope being pulled increases the resulting force on the pulley decreases until the puller is standing above the pulley. The rope would be straight up and down and no force would be applied to the pulley. If the weight were at 6 o'clock and the puller was standing at say 1 o'clock and the pulley was in the center of the clock there would be very little force being applied to the pulley. As the puller gets later in the day the force increases.

Is my description a bit more clear?

Yes, I thought that is what you were trying to say. I just don't like to make assumptions when dealing with this type of information.

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[outofmytree]

I think I was unclear with my description I'm sorry.
If the pulley is tied to the top of the tree and the weight to be raised is at the bottom as are you the rope will be in the shape of a U but upside down. If you were to pull down to raise 100lbs the resulting force applied to the pully would be 2 times the load as 100lbs is applied to both sides. As the angle of the rope being pulled increases the resulting force on the pulley decreases until the puller is standing above the pulley. The rope would be straight up and down and no force would be applied to the pulley. If the weight were at 6 o'clock and the puller was standing at say 1 o'clock and the pulley was in the center of the clock there would be very little force being applied to the pulley. As the puller gets later in the day the force increases.

Is my description a bit more clear?

Danger what you have said is true on paper but may mislead many people in practise. I would urge anyone reading this who doesnt understand why the angle between the ascending and descending sides of the line governs relative force to stick with SoM's basic rule of doubling the weight of the piece being lifted to gauge the load on the pulley.

Of course all this is moot when you consider that the tree it is tied to isn't rated at all.......

 

[DangerTree]

Danger what you have said is true on paper but may mislead many people in practise. I would urge anyone reading this who doesnt understand why the angle between the ascending and descending sides of the line governs relative force to stick with SoM's basic rule of doubling the weight of the piece being lifted to gauge the load on the pulley.

Of course all this is moot when you consider that the tree it is tied to isn't rated at all.......

You have obviously never been high lead logging. Spar poles can support tons and tons of weight when properly rigged. Remember before you came to cut down a tree it has bee subjected to high winds since the day it saw sun. When you cut branches out of the tree is loosing weight that it normally supported. Also all of it's sail! Imagine the amount of power being generated by a 150' branch heavy fir in a 50 mile an hour wind. You can barely lift a branch with no wind. And there are hundreds of them all being pushed by the wind.
In your support it would clearly be wise to give more than ample respect to forces being applied in the entire chain of rigging. As I have said before not many of us are engineers and even fewer of us have the time to pull out the slide rule to figure all of this out. A good rule of thumb is never pull a rope with something that can break it. It is not wise to stretch a 1/2" rope with a 1 ton truck for example as if it doesn't break you may have over stretched it and now it would be unsafe to use as a rappelling rope.

 

[Panama]

Ad an extra pulley to reduce the rope load nearly 50%. Tie to ash, through pulley on leaner, back through pulley on ash, down to lowering device. Use a rope at least three times longer than your highest rigging point. pre-load rope to prevent shock. If you are not confident in your set-up, ad a second bull rope on a strong natural crotch as a back-up.

 

[DangerTree]

Ad an extra pulley to reduce the rope load nearly 50%. Tie to ash, through pulley on leaner, back through pulley on ash, down to lowering device. Use a rope at least three times longer than your highest rigging point. pre-load rope to prevent shock. If you are not confident in your set-up, ad a second bull rope on a strong natural crotch as a back-up.

That doesn't reduce rope loading only reduces work effort or increases the amount of effort that can be applied. The forces at either end of the connection will be identical.

 

[Panama]

That doesn't reduce rope loading only reduces work effort or increases the amount of effort that can be applied. The forces at either end of the connection will be identical.

Draw it out, then look at it again. There are more legs supporting the same load, two on both the load and the support. Each attachment to the ash will hold only half the weight being lowered. Pulleys allow for loads to basically equalize on each leg. Does not lower the load where the pulley is attached to the tree being lowered (loopie etc.), but does lower the load on the rope, as there are two legs to the pulley. Ask a pro like spyder.

 

[DangerTree]

Draw it out, then look at it again. There are more legs supporting the same load, two on both the load and the support. Each attachment to the ash will hold only half the weight being lowered. Pulleys allow for loads to basically equalize on each leg. Does not lower the load where the pulley is attached to the tree being lowered (loopie etc.), but does lower the load on the rope, as there are two legs to the pulley. Ask a pro like spyder.

Sorry it would appear that you were misunderstood also by me. What you are referring to is equalization with additional contact points. Yes given long enough rope and numerous slings and pulleys it is possible to divide the work up to the point that the friction and weight of the rope going through the pulleys alone would be enough to slow or even stop the tree from moving. In mountaineering that equalization is used at nearly every belay station that made and is very useful for increasing safety by the addition of extra points of contact, in case of the failure of a bolt or piton for example. Also it shares the load between the points. A belay station would consist of three points of contact in the rock face, a caribiner for each point and a sling that is clipped into them. The sling is grabbed at 2 points in between to make a W shape. A twist is then put into the grabbed portion to ensure that the sling will not slip through the caribiner inserted at the two points, should one of the other three fail. An equalized belay is one of the first things that is taught when learning to climb rock.

The main drawbacks of weaving a complicated system in tree work is the time it takes to set up and remove. The amount of rope and pulleys is often not available to the average Joe. And quite often there are easier ways to accomplish the same task. But more importantly does the person doing the work have the experience to know what is done is safe.

 

[lone wolf]

Put all that science aside and just hook up a 3 ton come along with chain and pull it the hell out! :hmm3grin2orange:and be done with it already.

 

[Panama]

Sorry it would appear that you were misunderstood also by me. What you are referring to is equalization with additional contact points. Yes given long enough rope and numerous slings and pulleys it is possible to divide the work up to the point that the friction and weight of the rope going through the pulleys alone would be enough to slow or even stop the tree from moving. In mountaineering that equalization is used at nearly every belay station that made and is very useful for increasing safety by the addition of extra points of contact, in case of the failure of a bolt or piton for example. Also it shares the load between the points. A belay station would consist of three points of contact in the rock face, a caribiner for each point and a sling that is clipped into them. The sling is grabbed at 2 points in between to make a W shape. A twist is then put into the grabbed portion to ensure that the sling will not slip through the caribiner inserted at the two points, should one of the other three fail. An equalized belay is one of the first things that is taught when learning to climb rock.
The main drawbacks of weaving a complicated system in tree work is the time it takes to set up and remove. The amount of rope and pulleys is often not available to the average Joe. And quite often there are easier ways to accomplish the same task. But more importantly does the person doing the work have the experience to know what is done is safe.

Wow, I guess I was clear as mud. Not that I disagree, but didn't think this was a forum of "average Joes". Thought it was mostly Professional tree guys, whom I had presumed would own at least two pulleys (blocks) and a two hundred foot bull rope, and not consider it a "complicated system". I agree wholeheartedly with your last sentence, and that is why I hesitate to answer many posts like this.

 

[squad143]

and now it would be unsafe to use as a rappelling rope.

Never mix your rigging lines with your life lines.

 

[DangerTree]

Wow, I guess I was clear as mud. Not that I disagree, but didn't think this was a forum of "average Joes". Thought it was mostly Professional tree guys, whom I had presumed would own at least two pulleys (blocks) and a two hundred foot bull rope, and not consider it a "complicated system". I agree wholeheartedly with your last sentence, and that is why I hesitate to answer many posts like this.

No this is a place where in the knows and average Joes goes. They come here to learn from the pros'. And as such simple is usually better. Many of the people on these forums have only one saw some are looking for advice on buying the first saw.

 

[DangerTree]

Never mix your rigging lines with your life lines.

I totally agree and I do not mix my ropes. That being said if you read the previous comment many of the folks on this site may have limited gear and experience. For that reason if you must rig a tree with a 1/2" rope that you would trust your life on then only apply force you can deliver with the body and retire ropes that show signs of stress or excessive wear.

 

[knudeNoggin]

Sorry it would appear that you were misunderstood also by me. What you are referring to is equalization with additional contact points. Yes given long enough rope and numerous slings and pulleys it is possible to divide the work up to the point that the friction and weight of the rope going through the pulleys alone would be enough to slow or even stop the tree from moving.
...

The main drawbacks of weaving a complicated system in tree work

// [AND AFTER THE EARLIER ... : ]

That doesn't reduce rope loading only reduces work effort or increases the amount of effort that can be applied. The forces at either end of the connection will be identical.

This shows enough misunderstanding that it calls for a clear response.

What was suggested was hardly "complicated" : it was simply anchoring
one end of the bull line to the standing spar,
running it then down through a block slung to the leaner,
back up through a block slung on the standing spar,
and down to ground control. One extra sling & block;
50% more line.

The load on the rope is one half the force of the leaner
(to become *dangler* ); the load on the leaner's block
is equal to the force from the leaner;
and the load on the standing spar is 1.5 times the leaner
(3 x tension on bull line).

Compared to the originally suggested simple re-direction,
the force on the rope is halved, the force on the blocks is
halved, and the load on the standing spar is 3/4.

*kN*

 

[Ghillie]

This shows enough misunderstanding that it calls for a clear response.

What was suggested was hardly "complicated" : it was simply anchoring
one end of the bull line to the standing spar,
running it then down through a block slung to the leaner,
back up through a block slung on the standing spar,
and down to ground control. One extra sling & block;
50% more line.

The load on the rope is one half the force of the leaner
(to become *dangler* ); the load on the leaner's block
is equal to the force from the leaner;
and the load on the standing spar is 1.5 times the leaner
(3 x tension on bull line).

Compared to the originally suggested simple re-direction,
the force on the rope is halved, the force on the blocks is
halved, and the load on the standing spar is 3/4.

*kN*

I like your style.

 

[DangerTree]

I like your style.

I like his style also. What if you tied the rope off at the top of the spar ran through the pulley on the leaner and directly to the lowering device at the bottom of the spar? Would not the angle through the pulley be greater thus reducing loading on the leaner pulley? Also removing one pulley from the system? Also reducing loading on the spar by not connecting at the top two times? Also reducing the length of rope needed a tad ? Just curious.

 

[DangerTree]

This shows enough misunderstanding that it calls for a clear response.

What was suggested was hardly "complicated" : it was simply anchoring
one end of the bull line to the standing spar,
running it then down through a block slung to the leaner,
back up through a block slung on the standing spar,
and down to ground control. One extra sling & block;
50% more line.

The load on the rope is one half the force of the leaner
(to become *dangler* ); the load on the leaner's block
is equal to the force from the leaner;
and the load on the standing spar is 1.5 times the leaner
(3 x tension on bull line).

Compared to the originally suggested simple re-direction,
the force on the rope is halved, the force on the blocks is
halved, and the load on the standing spar is 3/4.

*kN*

If you must insert the second pulley on the spar pole what would be the effect of moving it's position up and down the pole with respect to loading of the spar and reduction of load on the leaner pulley? Remember equal and opposite reaction applies here too. So no matter what, the setup does not eliminate the force, it divides it in a geometrically proportionate fashion. If I were to have 4 pulleys in the leaner and 4 pulleys in the spar TOP. I would reduce effort needed but not the load applied to the spar. Example only. I believe this type of dialog stimulates thought and promotes learning, please don't assume I'm an ahole cuz I'm not. And I'm not trying to win anything here I would be happy to move on if you would prefer it. It is interesting to note that most guys don't realize that simply running a rope over a branch on a tree being pulled and tying it to the base of the same tree gives mechanical advantage.
Anyway I have trees to kill got to go have a safe day guys.

 

[Ghillie]

I like his style also. What if you tied the rope off at the top of the spar ran through the pulley on the leaner and directly to the lowering device at the bottom of the spar? Would not the angle through the pulley be greater thus reducing loading on the leaner pulley? Also removing one pulley from the system? Also reducing loading on the spar by not connecting at the top two times? Also reducing the length of rope needed a tad ? Just curious.

That sounds like a vertical speedline.