Author Topic: Trucker's Hitch force  (Read 4370 times)


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Trucker's Hitch force
« on: April 26, 2014, 11:54:42 AM »
My favorite way to tie a Trucker's Hitch; is as part of a  series of "stacked multipliers"; and adjustable if necessary. 
i use a Trucker's Hitch in series of leveraging steps, not a crowning achievement!
Take a loose piece of line, create an iron bar(tightened TH) within it, use that bar to tighten load!
In this strategy, TH is not the end of tightening, but rather beginning base module!
But, it is the only real setup time/ materials, the rest is almost just about style of application/ things you do in concert, then perhaps snug more etc.  2 people can seem to do about the same thing, with very varied outputs.  The old man with science of polished moves can (many times) overtake the younger rabbit that has less direction and intent to targeted point..

Acknowledge any inevitable frictions (d'Lehman 1.5x actual output after frictions example to lessen David's position against Goliath load).;
But then try to make lemonade/turn that around by using the same frictions to help hold a taken purchase; while deploying another tightening strategy.

For example the youTube vid shows impacting (as a multiplier) body-weight into Trucker's Hitch .  So have impact x weight exerted x 1.5 etc.  i'd add some more things though(not to pick apart, just example burnt into both brain cells).
Another thing i'd do over rough timber (assuming line spans over to the other side), is karate chop the line to help equalize your now higher tensioned side with the other lesser tensioned span of line on other/off side of the truck, then reTighten your side etc.  i might try to swig/sweat more into rig, by  tensioning and locking input_1 to something, then bending it, and capture purchase behind the frictions we are fighting.  Then lock off and throw line under spars, and around line other side, and bend it/both lines.

The 2 pics below bend the rules by using 2nd piece of line/prusik cord , but if this is part of your kit(i even have pulley to slap in here)..
This can be very helpful, because can take purchase, pinch/line off at friction to hold and slide prussik up for another purchase/ compression of the rig (climbers call this a Z-rig). If having to lift something a long way, may piggy back a short z-rig on main line, take purchase of line, lock off line, extend rig for another go etc., all the same...  In resetting prussik, always found it best to pull out 90degrees sharply, then tighten in opposite direction sharply, then sharply in real direction of pull, to set.

The first pic shows input force_1 at arrow pull, will put 3x(if no friction) on top ring, if bottom anchor can take 2x the input.  However if the bottom ring was moving when pulled line, you'd have a 2x(if no friction) over that bottom ring.  You could elect to use that as a lift or it could be a failing rig working against you..

If lace out a TH, and continue with working end, to put TH, pulling on TH=3x3=9x input_1 with straight  lines in friction free world!

So even at 1.5x input_1 yield from basic Truckers, we can impact into it, we can over tighten to 1 side, then straighten by tightening off side, vibrate /leverage to equalize tightness when friction over a load, sweat more purchase from rig; then after tweaking all that to iron bar tight,  bend it (leveraging similar to swig/sweat line tight)! 

So TH is only a single leveraging multiplier, in a series of multipliers; sometimes breaking/bending stuff. 
The real tightening here, is bending the TH rig; all else is setup to make TH resist the bending more; yielding higher output.
It is not just how good is this hammer; but how you use it as a tool that matters(or sometin'like that).
« Last Edit: April 26, 2014, 02:27:20 PM by TheTreeSpyder »


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Re: Trucker's Hitch force >> M rig for 6x
« Reply #1 on: April 26, 2014, 12:46:07 PM »
pic : Many times, a top tie down point is ring, hook, eye, handlebar etc. we can then easily slip over, back to floor anchor and double the friction free potential.   As shown this could rate at 6x input_1, in perfectly straight lines in the theoretical/impossible friction free world.  The more the lines are angled the less the friction free potential, but then more chance to bend in trade.

This is just more of look what you have,but not just toll resources; but rather know several scenarios and how present puzzle lends to them(in open view/ no blinders).   Once again looking at stand alone TH as part of a means, not end.

Many times the upper point has less rope friction, so; feeding 1.5x input_1 (from zrig mechanics) into will get closer to full 3x.
Especially if when line is full tight on rig side of purple friction ring (leaving lower tension on left side of ring), we lock rig and bend, shake etc. to equalize tension more, leaving rig side at lower tension/ able to be tightened more.

Note green rig still has 2x input_1, and where yellow line terminates (now at new blue anchor ring/ not purple ring) is still 3x.  Pull on red krab & prussik  itself remains at 2x input_1

-"Nature to be commanded, must be obeyed " - sir Francs Bacon
« Last Edit: April 26, 2014, 03:13:15 PM by TheTreeSpyder »


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Re: Trucker's Hitch force >> 2 handing for another input
« Reply #2 on: April 26, 2014, 01:09:22 PM »
Another available, easy way to stack multipliers into this, is using your other hand...
BUT, not on the same input_1 point.

Pix show input_2. 
If pull up on input_2 only/ not input_1 in 1st pic will get 1x at purple ring, but still 2x at green ring(could use to lift green).

If you weigh 150# and hang on line you input 150# at input_1.
If, while hanging, you reach down and pull up 50# on a branch, you will input 200# on input_1
If you stand on a scale and weigh 150#, and lift up or hold 50# box, scale will show 200#.

Target: use other hand to deliver another 1x pull to rig side of purple ring (from input_2),
ALSO: in same mechanic use equal and opposite of that effort at input_2 to pull again on 3x/6x of input_1
(just as lifting box on scale exerted 50# on box while at same time exerting bodyweight + equal/opposite of lift on box)
Here we just capture all that in a system bodyweight, effort, equal/opposite of effort, by closing the system: conserving it's forces to itself,( even own equal and opposites) instead of exerting/wasting same forces outside of system(open system).

Simply hang 150# bodyweight on input_1, and lift 50# up on input_2, will then also exert the equal/opposite on input_1 (another 50#).
So, in friction free, straight lines, would get 3x bodyweight + 4x effort in pic_1. (150# bodyweight + 50# effort>> 650#)
And, in friction free, straight lines, would get 6x bodyweight + 8x effort in pic_2.   (doubled).

But, those are static values.  Would try to dynamically load by jumping on input_1, and at same time, snatch up hard (impact) on input_2.  Even if just stand up on toes, and sharply pick up legs/let body weigh drop hard even get 8inch drop whatever is more than just static force load.

On larger scale, can hang on rig, with foot in loop(or rope cam etc.) on input_1, and hold line on input_2; and not pull up on input_2, but rather input effort with leg force down on input_1, capturing equal/opposite to input_2.
In 1st pic this yields 3xBodywieght + 4xLegLift !!!!!!!
For a 150# person able to lift own weight + 50# (200#);
 this changes formulae to (3 x 150) + (4 x 50) = 650# to  (3 x 150) + (4 x 200) = 1150# etc.
Note, the greater part of multiplier (4xEffort) is right where folks that do leg lifts can get to it...

Notice also, that effort at input_2 lessens frictions on red carabiner/karabiner/krab.
So, at krab serving 2x input_1, only the bodyweight input bears friction on krab, not effort(so much) because are pulling the on input_1 with effort thru krab, but at same time feeding it slack form input_2 pull!!
(This should be 2 krabs wide if possible or pulley etc./1 shown for clarity.  Also, prussik cord characteristically smaller (but 2 legs to loading point/krab) than thicker host leg/line span hitched to; so is not desirable to bend larger arc host around smaller arc prussik diameter.)

Would take all this further, with impacts, jump on input_1, slam down with leg/snatch up with arm at same time in orchestration.
Know you are magnifying efforts so much as to do each polished step with hard focused intent to target; but so cleanly, looks same as next person just setting and giving some hand tug to input_1.

Stacking multipliers, can still swig/sweat line, vibrate tight as needed and then eventually bend the iron bar you've produced in the line, to then use that iron bar as a lever to tighten load!  TH is not the end of tightening, but rather beginning/ base!

« Last Edit: April 26, 2014, 02:19:34 PM by TheTreeSpyder »


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Re: Trucker's Hitch force >> sweating/swigging/bending for leverage
« Reply #3 on: April 26, 2014, 01:49:49 PM »
i've reffered to, and rely heavily on swigging/sweating a line; and also it's 'sister' strategy of bending a tightened line.
They are both the same math of line leveraging.

Our magic rope is unlike other things we generally work/load with.  A bar, spar, rock etc. are all tools of weight that resist/work along their length and across their length axis-es; and, in both the compression inward and tension apart on those axis-es.
But rope, is light, flexible, but only resists / works along it's inline axis, and not across.  Also, it only resists/works in the tension(not compression) direction on that inline axis.

But, when we tighten a line along it's length, it now resists bending across that length(a property it did not have before).  So, we can now leverage it by bending it a few degrees.  Can use to raise tension in line, if we then take purchase of loaded line length to behind frictions/nip  it is called sweating or swigging the line tight.  The practice has a very rich heritage of secret (possibly if stranded) life saving force to be tapped!

edit: i made this bent line force calculator (adobeFlash) some time ago to show leveraging of bent line.  The tighter a line is, the more it takes to bend it to a given angle, giving higher amplified /leveraged return for effort . 

Note, that the paradigm is achieved( get less output return than effort input/ but faster speed) at the break even point of 120 degrees spread(60degrees deflection from inline or 30 degrees from flat on each leg to bend).  At 60 degrees :cosine = .5 x2 legs to bend = 1, so line tension = 1x load or your pull at bend; no leveraged gain unless bending line stops flatter/ closer to 180 degrees spread.
« Last Edit: April 26, 2014, 03:11:39 PM by TheTreeSpyder »


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Re: Trucker's Hitch force
« Reply #4 on: April 26, 2014, 03:25:28 PM »
   Very informative posts - and the drawings are great. However, are they about the Trucker s hitch KNOT, or about the block & tackle mechanism / simple machine, implemented without the use of pulleys ? What you are talking about sounds to me that it is not about any knot, as I, for one, think of what a "knot" is, but about a rope mechanism - which is supplemented by some knots, at some points of it ( the Prussik knot you use, for example ). However, keep offering us more such posts, please !  :)
« Last Edit: April 26, 2014, 03:43:27 PM by xarax »
This is not a knot.


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Re: Trucker's Hitch force >> Git'er done!
« Reply #5 on: April 27, 2014, 02:06:47 PM »

Truckers is the same math of rope/load/angle as 3x tackle only TH has greater friction values at the re-directs/bends.
The straight sections of line just transfer line tension more distance(and dampening length in dynamic scenarios)  , no angle math/multipliers.
This higher friction value stands as foe against efforts as usual, but can also can be friend if called upon at some points to help hold load/lock tension into rope span.
If reader were helping rescue own child up 200ft., seconds count, slow/barely can be done as is proceeding etc.  ; all of this would be pertinent to look at situation/lead/deploy

i started"Trucker's Hitch force" thread to reFocus on the big picture, really several..
The thread focus is on the work needed/why are you needing TH in 1st place, how the work can be achieved; and not the knot per se.
Also, being that knots are made in same materials, usher the same forces, bound by same principals as rigs; the more we can L-earn about rigs, the more we could understand about forces inside the microcosm of a knot lacing. 
So big picture of work scenario that needs force multiplier and big pic of forces in microcosm of knot/ when seen in rig as if under microscope.

i introduced the prussik, as alternative with a real change(adjustablility) to already presented solutions.
(also shows, that can have a set aside jig like this and prussik to real lines to tighten them; maybe have pulley in small piggyback jig).
This is how you'd use a TH that loop can be only set 5ft. away, but needed to pull 30ft. etc.
But, except for adjustability, piggybacking etc.; the rest of the strategies can be applied to the TH proper.

Then, facing d'Lehman's charge that rope-on-rope friction we are losing half our prized 3xEffort;
>>deflating and taking the fun out of this somewhat...
>>i reTorte that if we use equal effort to push slack to the effort at end of line, we can reduce the friction loss on effort input!
>>Many times lower redirect/anchor is lower friction than rope on rope, and in 2 handing line, that is most friction against Effort
>>also we can in doing so raise this to 4xEffort, and in hanging add 3xBodyWeight(but at full quoted frictions)
>>also, take the 1.5x anyway, and just use in series of multipliers

All pertinent i think, especially if can do in roughly same span of time/materials as regular deploy TH scenarios/ or as presently presented; where it just comes down to technique  to get more out of easily etc.! 
Look at situations more in size up, could i use more power, does this lend to Mrig type scenario if needed, could i impact drop, evade friction/ or use frictions etc.

As ye David; size up your prey/ contestant: Goliath load/work ; be able to see what other options might easily help!
Choose your weapons and battles(friction, force, distance etc.) to fight with those weapons!
Some of this is like martial arts flip of a wrist from lil'olde man, that can make all the difference in power and displacement yield, easily!
Masters of working rope/knot man/persona should know these moves, lores and secrets of their craft; especially if leading others into real/daily battles with said tools(?).
« Last Edit: April 27, 2014, 02:34:23 PM by TheTreeSpyder »


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Re: Trucker's Hitch force
« Reply #6 on: April 27, 2014, 02:27:46 PM »
The rig's forces are just a knot's under a microscope!

 +1 ! ! !  :) :) :)

  The use of the Prusik in the Trucker s hitch is very clever, too !
This is not a knot.