Author Topic: Adjustable loop-tensioner  (Read 7060 times)

xarax

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Adjustable loop-tensioner
« on: April 08, 2011, 11:47:42 PM »
    I have tried to combine three elements here :
   1. A sufficiently long coil "tube", that :
   a . accumulates constricting forces around the line(s) that go through it, (as in the case of the climbing hitches). In the fight to secure the tail, this serves as a third line of defence.
   b. keeps the second leg of the inverted "U" of the tail in place, properly oriented towards the bight side of the loop. This serves as a second line of defence.
   2. An "anchor bight", that takes the place of the loop(s) we meet at tucker s hitch and Versatackle binder.
   3. A very simple blocking mechanism, that makes the slippage of the rope towards the one end much more difficult than towards the other. The second end, "the blocking end", can slip through the mechanism, and so can be pulled to tighten the loop, but the first end, "the blockied end", is blocked by the second end and the anchor bight, and so it can not slip at all. This serves as the first line of defence.( For the time being, I call this mechanism a "one way tensioning mechanism", until somebody will come up and suggest a decent name.)

   To adjust / tighten this loop, we have, first, to pull the proper second "blocking" end of the rope that goes through the "one way" mechanism, and, second, to pull the tail so that any slack rope is eliminated. The tensioned tail leg of the bight keeps the second, "blocking" end of the "one way" mechanism aligned with the first, "blocked" end, so the whole mechanism will not fall apart.
« Last Edit: April 09, 2011, 12:33:33 AM by xarax »
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xarax

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Re: Adjustable loop-tensioner
« Reply #1 on: April 09, 2011, 01:49:23 AM »
  If we connect two of those adjustable loops-tensioners into a binder, we can align the "blocking" with the "blocked" ends of the "one way" mechanism, take care of the slack and secure the tail(s), without the use of multicoil loop knot(s) See the attached picture for another, simpler solution.
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Dan_Lehman

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Re: Adjustable loop-tensioner
« Reply #2 on: April 09, 2011, 09:10:07 PM »
  If we connect two of those adjustable loops-tensioners into a binder, we can align the "blocking" with the "blocked" ends of the "one way" mechanism, take care of the slack and secure the tail(s), without the use of multicoil loop knot(s) See the attached picture for another, simpler solution.

Xarax, this structure is more complex than simple, and hardly functions
as desired --it (as Hensel&Gretel often give as their sole gem of information)
"has no practical value."

I'll wager that only two people have bothered (and it IS that) to tie
this, and that only one has tried its working (non).


 ;)

xarax

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Re: Adjustable loop-tensioner
« Reply #3 on: April 10, 2011, 12:14:40 AM »
this structure is more complex than simple

  It is simpler than the previous one !  :) Our situation does improve... (To use a remark by Indiana Jones father...)

 
... only one has tried its working.;)

  It was/is/will be always like that...I hope that if one builds it, they/many more will come...
  Now, the structure might look complex, that is true, but the three elements, one by one, are all very simple, aren t they ? What might be considered as complex ? A multi-coil noose ? A bight, like the one in Tucker s hitch? Or the simple "one way" blocking mechanism, that might well have been ABoK#0.5 ? ( As ABoK#1 is the somehow similar - but more complex ! - Sheet bend )
   When we have three simple elements, can their simple arrangement, the one after the other, in a whole, be considered as complex ?   
  I suggest that the reader starts by testing how (miraculously) well works the "one way" mechanism:
  1. Tie a loop, - any kind of loop-, and fasten it somewhere, with its bight coming towards you.
  2. Pass the one end of a cord through it, in the way shown in the picture.
  3. Hold the two ends of the cord with your two hands, so that the two legs are tensioned, and parallel to each other.   
  4. Release the tension of the one or the other leg, trying to pull the one or the other end.
  5. See how easy is to pull the one end, and how difficult, indeed almost impossible, is to pull the other.
   That is the crux of the matter. We have a mechanism that can be pulled, to tighten a tensioner/binder based on it, but can not be released by the slippage of the rope towards the other way. It is a "one way" blocking mechanism of the rope that passes through the bight. All the other elements of this adjustable tensioner are complementary of this simple mechanism, and of secondary importance only. I would be glad if somebody could point out a simpler way to incorporate the same mechanism into a reliable binder.
   My theory is that no known hitch around a rope can secure a tail in a way that, once and after the hitch is locked, will allow us to adjust the tension/ binder based on this hitch even further, by pulling the free end - without this same end be free to be pulled and move the other way too, and release the hitch. What is needed is a "one way" mechanism, and the one presented here is the simpler one possible, I believe.
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xarax

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Re: Adjustable loop-tensioner
« Reply #4 on: April 10, 2011, 01:34:09 AM »
...only two people have bothered (and it IS that) to tie this, and that only one has tried its working (non). ;)

 I would advice the second person to sit on the chair and try if it IS working or non...but I would not recommend to anybody to change which end is tied to which object... ( unless the whole structure is put inside a properly adjusted Bitter ceiling-binder. See (1), (2))

1) http://en.wikipedia.org/wiki/Bitter_electromagnet
2) http://en.wikipedia.org/wiki/File:Frog_diamagnetic_levitation.jpg
« Last Edit: April 10, 2011, 01:42:51 AM by xarax »
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xarax

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Re: Adjustable loop-tensioner
« Reply #5 on: April 10, 2011, 02:52:01 PM »
   An effort to simplify the complementary structure of this "one way" mechanism even further. "2 B sure" that the second leg is under some minimal tension, we can possibly drive it to pass it through a nipping double eight knot tied on the first leg. (When the two legs are aligned, the mechanism that has already been "locked" effectively, does not run the danger to fall apart.)
   This structure is shown in two stages/pictures.  In the first, we see the "handle" made during the adjusting procedure, from which we grasp the rope to adjust the length of the binder - just before the next stage, when we have to pull the tail, and minimize the slack of the second leg.( Notice that, while we are pulling the "handle" of the second leg to adjust the binder, the first leg should not be under much tension, so this pulling/adjusting action is made as easy as possible). In the second picture, we see the same knot, fully adjusted and tighten.
« Last Edit: April 10, 2011, 03:19:56 PM by xarax »
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Dan_Lehman

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Re: Adjustable loop-tensioner
« Reply #6 on: April 10, 2011, 04:22:38 PM »
 :D  Ahhhhh, at last, the cook's in the kitchen-lab !

It is not questioned that the particular self-locking structure
(which one might as well call a blackwall hitch ) will lock,
but that it works in the binding structure at all efficiently.
(So, you might have dispensed with the lightweight strainer.)

There's no need for some hard-locking binder that cannot first
*bind* --with tension holding together-- some collection.


The testing to be shown is perhaps this same chair as a masss
to be drawn upwards by these supposed binding structures,
and to see how much greater a mass is needed in order
to achieve any such movement (and in the process what parts
of the structure, theorized to convey force/tension, are actually
slack, courtesy of the great friction of cordage-on-cordage).
Now, the slack just referred to can be a good thing in being
a frictional/locking part out of the way during tensioning
and thus not impeding that; but it cannot be a steadily growing
quantity, to be absorbed only by binding loss upon release
--it needs to be somehow consumed, to flow, during the
process.  (One can see such slackness in the Versatackle with
several passes, e.g..)

--dl*
====

xarax

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Re: Adjustable loop-tensioner
« Reply #7 on: April 11, 2011, 01:42:11 AM »
one might as well call a blackwall hitch

  I think that the "Blackwall hitch", (ABoK#1875), is tied around solid hooks, not flexible U shaped bights - and the "Becket hitch", (ABoK#1900), around eye splices . However, the main characteristic of this mechanism, the "one way" capability that makes it suitable to be incorporated into a binder, is not what the "Blackwall hitch" or the "Becket hitch" are mainly used for, I believe. "Blackwall / Becket hitch on a bight", may be ??

...you might have dispensed with the lightweight strainer.

   No, I could not. As I have seen in practice and explained in my previous posts, some minimal tension on the second leg is necessary indeed, otherwise the mechanism will run the danger to collapse : it will change its initial geometry into a double loop around the "horizontal" lower portion of the "U" shaped bight - a double loop which will revolve around this portion just as a loop around an horizontal axis, and release the rope. How to maintain this tension, and "B sure" that the second leg remains somewhat tensioned and parallel to the first, that was my concern from the moment I realized that this blocking mechanism is absolutely reliable when tied in a flexible bight.
 
...a mass to be drawn upwards
...to see how much greater a mass is needed in order to achieve any such movement

   Actually, MUCH SMALLER than the mass required to be drawn downwards ( which is, for all practical purposes, infinite, or indefinitely large.
  I have seen and said that :
while we are pulling the... second leg to adjust the binder, the first leg should not be under much tension, so this pulling/adjusting action is made as easy as possible
 As the tension of the first leg becomes smaller, the required tension of the second leg becomes MUCH smaller . Of course, it can never be "much greater"...so it is not wise to reverse the ends on which those two objects are attached on.

...the slack just referred to can be a good thing in being a frictional/locking part out of the way during tensioning and thus not impeding that

   It is not only "a good thing", it is a necessary thing. We pull the second leg by the "handle" allowed because of this slack rope. We can not pull the second leg by the tail, because the two legs will be aligned, and what is good for the "blocked" stage, is not so good for the "blocking" stage. The mechanism is better adjusted and tensioned in two steps, as I have seen and said in my previous post.

-it needs to be somehow consumed...during the process.

  It will be consumed at the final stage, by pulling the tail. Until there, it is necessary because it serves as a "handle" by which we adjust the length of the binder.

  Any difficulties in the understanding of how and why this mechanism works, will fade away after one gets the "feeling" of the knot in practice. I advice the reader to test the "one way" characteristic by himself, following the simple instructions given in my previous post, which I repeat here :
  1. Tie a loop, - any kind of loop-, and fasten it somewhere, with its bight coming towards you.
  2. Pass the one end of a cord through it, in the way shown in the picture.
  3. Hold the two ends of the cord with your two hands, so that the two legs are tensioned, and parallel to each other.  
  4. Release the tension of the one or the other leg, trying to pull the one or the other end.
  5. See how easy is to pull the one end, and how difficult, indeed almost impossible, is to pull the other.

 
  
« Last Edit: April 11, 2011, 03:25:43 AM by xarax »
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xarax

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Re: Adjustable loop-tensioner
« Reply #8 on: April 12, 2011, 04:03:52 AM »
   The most simple "one way" mechanism I was talking about in the previous posts, was, in fact, the second such mechanism I had arrived at. The first one, a somewhat more complex structure, is shown in the attached pictures.
  In the first picture, it is shown in its "unlocked" state, where we can pull the one/the first "orange" leg (the lower, in the picture s frame), and the other, second "orange" leg, will follow very easily. In the second picture, it is shown in its "locked" state. The "orange" bight has been rotated 180 degrees, and has reached a position where it cannot be rotated any further, because, in its orbit, it is now hindered by the obstacle of the nub of the "white" loop. It is in this position that the second "orange" leg cannot be pulled any more : it is blocked effectively.
 Compared to the simpler mechanism presented previously, this one has a number of disadvantages : Until the "orange" bight completes its 180 degrees turn, and reaches the point where any further rotation is blocked by the "white" bight, it is releasing some rope length of the second leg. This means that any achieved maximal tensioning of the binder, by the tug of the first leg, would be relaxed a little, because of this inevitable slackening of the second leg. Also, here we have to pay much attention to the size of the "white" bight...which should be large enough, to allow the unhindered passage of the "orange" ropes through it, but, at the same time, narrow enough, to block the motion of the "orange" bight after its 180 degrees half turn. The advantage of this mechanism is the easier passage, during the adjusting stage, of the rope through the "white" bight ( provided this bight has the right size, of course ).
  
   P.S. As the highest points I have "climbed" in my life are some tops of ladders, :),  I was not aware of the "Munter" climbing hitch. However, the "one way" blocking mechanism I described in this post reminded me of something, and I have now re-discovered the "Munter" hitch (1) which is something that looks like this mechanism, tied around a carabiner or ring instead of a rope bight. As far as I know, It is used by climbers as a "belaying", release mechanism, and not as a blocking "one way", adjusting mechanism. Indeed, as its advantage, it is stated that : " One very useful aspect of the Munter is its reversibility; it can be pulled from either side of the rope and it still works just as effectively."  (1) On the contrary, the "one way" mechanism I have described in this post, is based upon the non-reversibility, directional action of the pull, because the "orange" bight can not to pass through the "white" bight.

1. http://en.wikipedia.org/wiki/Munter_hitch
« Last Edit: April 12, 2011, 04:53:06 PM by xarax »
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xarax

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Re: Adjustable loop-tensioner
« Reply #9 on: May 07, 2011, 02:07:40 PM »
   In an effort to improve the working of the "one way" mechanism described previously, I have tried it around a double-line bight. ( See attached pictures). This way the friction induced by the bight on the end that we can pull quite easily- the "blocking end"- is reduced, because the rope of this end makes a turn around a two rope diameters curve. However, the friction induced by this "blocking end" upon the blocked end ( the friction that prevents the slippage of the "blocked end") remains the same. Our situation does improve.  :)

« Last Edit: May 07, 2011, 02:41:02 PM by xarax »
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