Right or Wrong Technique?

[Tom Dunlap]

Both of those are 2:1. In the first example the top pulley is just a redirect.

Look at these illustrations:

http://www.alberta-ck318.freeserve.co.uk/tackles.htm

Tom

 

[TheTreeSpyder]

i don't think that would be a 3/1; but some time ago quereid that myself.

i think that the distance from the top turn to the hitch matters, if it didn't then i think it would be an inefficient 2/1 (less friction, rope angles). For a while i tried to view it as that length from turn to hitch mattered because of the stored amount of energy in the elasticity of the line length, perhaps then fed into the inefficient 2/1.

i really feel that the lenght from the turn to the hitch matters in the sense of the push position from turn staying at one point, yet moving the pull position from the hitch farther apart, ...... by which examination, that would be more leveraged arching?

Kinda makes sense,as now, more line must be drawn for same motion of tree, as the tree was the pulley and now was being pulled from farther down. this is more noticeable at non obtuse line angles methinx.

Then, aside from the motion, the lower hitch point takes more command of the C.o.B. of the tree to compound the above in tandem. IMLHO.

Many times forces work from their pull, and how they are recieved as 2 different things to watch. Very nice when they line up!


OOrrrrrrrrr something like that!
:alien:

 

[Kneejerk Bombas]

Actually Tom, I think the top example is one to one. Both pullies are just redirects.
It is confusing trying to tell between redirects and actual mechanical advantages.

PS, I like that link.

 

[Kneejerk Bombas]

An easy way to tell what the mechanical advantage is exactly, is to pull the rope x number of feet, then measure how far the load has moved.
In Spyders example, a pull of 10 feet on the rope would move the spar top about 12 feet (greater than ten feet because of that pesky triganometry thing Stumper mentioned), the same as if he just tied it straight to the spar. There is no mechanical advantage.

 

[TheTreeSpyder]

Tryyyyyyyy it, You'lllllll Like it!

It feels to me, like if that line passed over the top of my head and traced down the back of my spine and tied to my ankles as a final wrap it would have more action snapping me forward, than if it only came down to where i should have hips, in the same configuration then pulled.

i didn't start to look at it like that till i thought i witnessed differences from the configuration, in all of these ways for years. A rose is a rose, even if i'm not naming it quite right yet, i believe there is something special here.

Sometimes i imagine that the 'bend' wants to 'dump its load' and come out, more so with more pressure, more bend. In rigging, i try to get that leveraged to be powered by the weight of the limb set against itself.

Been following the scent of what is happening here for some time, could use some help sorting it out; but it has always been my friend!

In the 'over the top' configurations; if i tie the first choking half hitch high or low has always seemed to make a differance. i observe that the only thing that changes force wise is that the pull force comes from a lower place; but in doing so some things change.

The length from the pull of the hitch and the push of the bend changes (and so the length of tightened up line bracing and pushing forward). The relationship between the C.o.B. and the pull of the hitch changes. And a few other things perhaps, but that is enough ta get started....

i refute none of the ideas, have had some of them myself, as this puzzle has helped me and kept me awake for some time!

 

[murphy4trees]

Spydie and all,
The other day I was felling a dry dogwood against the lean and used a low branch on the backside to push up on... lots of leverage out there....
I still maintain that the forces of pull, up and down, on the trunk caused by lacing a pull line rather than tying it off, will cancel each other out and offer no more pull needed to move the tree into the face.... However...... what about tying that line out to a limb on the backside, as described above.... That, seems to me, might do something for you.

 

[Stumper]

Murph, You have just descibed the way that a leverage gain can actually be made with an over and down lacing. Kudos!

Of course to gain much you still need to have the rope run over an outside support instead of the spar itself.

 

[TheTreeSpyder]

i've done it like that on branches Daniel, or just bend over top, wide across tracing behind rear branches, then back to spar and down, or to the side through branches. Every bend, direction before first choking half hitch seems to matter (till it's power is pinched off). Usually our ropes just pull a load, if you try to push with a rope it crumples into the tree; but here we get push with every bend with force running through it, that can push and wants to dump it's load (bend), as it still is pulling too.

i think that the lacing asks the tree to not only come down when pulled to release tension, but spin to relieve tension. And the farther apart the pull from the hitch to the push of the bend seems to give more action.

Tom says 2/1, i think if were standing toe to toe witht he base of the tree and pulling straight down on a siirarily laced telephone pole (vertical) that would be right with parallel line, discounting friction. If we slant the pole, or ask it to slant things seem to change.

Pic shows not a direct pull.

Orrrrrrr something like that

 

[Kneejerk Bombas]

What Muphy felt was the increased power of lifting, compared to pushing forward at a sharp angle.

Spyder, now you are still trying to advance on this lacing technque and we have agreed that it give no more pull.

First prove the origanal theory, then go on to different uses.

Do a mock up scale model and pull on it with fishing scales, or something, to prove your theory.

 

[TheTreeSpyder]

Fishing scale would be for line tension?

Hinge pressure, C.o.B. towards target from the same line tensions is the elusive 'prize' though? A better way with what ya got? i think it looks different if you assume compression or spinning the spar as the goal/ easiest arrived at from pressures.

It just always seems to help, even laced like over the hill, lowering into that as a rig, if nothing else, more stabilized from the tensed, bracing line on the back.

i think that the last pic definitely gives leveraged control against lean, and less if it came thru at Red X. If the hinge fiber was eliminated under the lean, and wide to the nonlean side, tree could twist with pull; it would twist better as red line is laced, taking more line, than taking shorter route around at X. i can see more question on over the top and straight down.

i agree i slanted 'issue' a bit, but not to evade, rather to give different view.

 

[John Paul Sanborn]

Originally posted by TheTreeSpyder
i feel that if the line was laced over my head, down my back and to my ankles, the bend would want to come out and push my head forward,

Which is why some call it a "fishpole tie-off".

you do loose some of the force of the pull from a high tie (with a running bo'lin' for example), as Dan equates, but that is the tradeoff for the ease of instalation because you don't have to isolate it.

You can often tie higher because the force is distributed down the pole more then as in a high tie.

 

[Kneejerk Bombas]

I suggested the use of a scale to test loads.

In your last drawing you are assuming 170 lbs ae generated from a 100 lb pull, this is not the case. You will only get 100 lbs of pull.
The 170 lbs would only happen if you tied the terminal end of the rope like in this drawing:

http://www.arboristsite.com/attach/7326.jpg

 

[TheTreeSpyder]

i 'drew' that number outta the air, that is fare.


Just as a climber's DdRT 2/1 can be elusive, as a self contained system; perhaps there is something here. In your own drawing, if the anchor point was not the seperate stump, but rather the base of the spar pulley pulls on was the anchor. The pulley and connection would still take 2X load at that bend. The more parallel the legs on the bend are the closer to 2/1. So as the bend straightens out, the effect is reduced.

What if the bend is a pivot, and the pull from clove etc. placed farther from that pivot (that eventually gives, passing force to hinge), because we are trying to arc.

If line was over your head, laced ot your waist, it seems it would pivot over your head and pull at your waist, if it went down to your feet, that pull would come form further away from the pivot (head) than if tied at waist.

Head might not form good pivot, for it would give up as it was loaded with pressure. If it was trying to act as pivot, a pull from a more leveraged distance could be placing more pressure on the given pivot of the bend, causing failure of machine (pivot moving). But here, that loaded failure is goal?

Perhaps i've counter intuitvaededead mys-elf into a coroner, mesmerized at staring at this so long, (ab)using it in different ways through years. Many positive things about it, very worth using even ya don't buy this part of the mechanics. Took quite a while with as few chances as ya might get, to look at this so many ways; it just works for me.....

:alien:

 

[TheTreeSpyder]

Sometimes viewing things in reverse, allows a different view into workings. i look for patterns in these things. Instead of felling, as i went for the final direction to drop something (UP! ), i saw what i thought even more bared out the model of these mechanics that i saw.

i think!:alien:

 

[John Paul Sanborn]

Originally posted by YUKON 659
.was this the right or wrong technique?

Like they said, strong hinge and steady pull works well.

Now you need to get some pullies , slings a rigging pplate to set up some MA fun.

or better yet, get a GRCS winch

 

[TheTreeSpyder]

Right or Wrong Technique?

So what is right/wrong on lifting, tearing off safety scenario, preset with climber clear?

:alien:

 

[John Paul Sanborn]

Originally posted by Tom Dunlap
In the first example the top pulley is just a redirect.


Tom

Would that be true only if the knotch is between the two blocks?

 

[John Paul Sanborn]

How'bout this scenario;

Running the rope through multiple large stems so that a back stem is employed. Then securing the the tag rope end to the working end with a (fixed) bo'lin' ?

I do this eithe climbing or throwball quite frequently with the idea that it will assist getting a straight pull and increase force by pulling on the back limb too,