Author Topic: JRB Hitch, a secure, quick release hitch  (Read 1018 times)

roo

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Re: JRB Hitch, a secure, quick release hitch
« Reply #15 on: February 03, 2021, 06:47:02 PM »
It is interesting and a little unorthodox, but it seems like it does what you need it to do.  I don't recall seeing it before. 
JRB, I was experimenting with variants that would allow a more direct pull of the slip bight and realized there is a relative that you may be interested in.  Andy753421 eventually updated his original post to show tying instructions here:

https://igkt.net/sm/index.php?topic=1621.msg11100#msg11100

It pulls bights around alternating sides of the standing part in a chain stitch manner.  The standard three final tucks would probably suffice for many applications, but an extra bight tuck may help in certain circumstances.
« Last Edit: February 03, 2021, 06:49:37 PM by roo »
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JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #16 on: February 04, 2021, 07:13:44 AM »
Roo, thanks for your time and research and experimentation.  When you say "allows a more direct pull", are you looking for it to be smoother releasing under load? Less "clicking" in the stages? Or less or more jamming under load? As tied in the original video, i would describe the JRB hitch as having medium level of jamming under load. I selfishly would have preferred it has more jamming under load for my preferred applications, but understand there's other applications which would want the opposite. Just trying to understand where you're headed. Thanks.

roo

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Re: JRB Hitch, a secure, quick release hitch
« Reply #17 on: February 04, 2021, 04:54:12 PM »
Roo, thanks for your time and research and experimentation.  When you say "allows a more direct pull", are you looking for it to be smoother releasing under load?
I just noticed that the release line was a bit embedded into the knot and was looking to see what would happen if the hitch was a bit snug after use and the release line was more exposed.
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JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #18 on: February 05, 2021, 08:08:41 AM »

I'd like to see a test where the release is triggered - while 100kg load is applied to the SPart. That is, while the JRB hitch is under 100kg load, initiate the first stage of the release sequence - to see how fault tolerate the JRB hitch is. A video would be good...

Agent Smith, I am preparing to execute this test this weekend with a video recording. I just did a few in preparation and got the idea that I should measure how much force i need on the release line in order to release through each if the stages, using my scale. Let me know if you disagree.  Assuming i repeat the test a few times, the camera
Could get the scale as well as the hitch as it's released.

JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #19 on: February 07, 2021, 07:06:09 AM »
[ ] Test 'fault tolerance' - while 100kg mass is held, initiate first release sequence.
If the hitch maintains integrity up to the first stage of the release sequence, this is good.
[ ] repeat your tests with at least 3 different rope types.
-record the exact rope type you used for your testing (so others can purchase those rope types and attempt to repeat your results). Supply all rope info (eg diameter, EN/ANSI standard, brand/model, etc).
[ ] You will need to consider statistically valid sample - normally at least 5 tests is considered adequate
Agent Smith and Team, I just completed the following video, exploring the properties of the release mechanism under a load of 100kg.  I will work on the other suggested tests next.

https://youtu.be/82b8AMMctyQ
« Last Edit: February 07, 2021, 03:52:16 PM by JRB »

SS369

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Re: JRB Hitch, a secure, quick release hitch
« Reply #20 on: February 07, 2021, 11:14:15 PM »
Good video JRB, Thank you.

I tied it using a BlueWater ProTac 10.5 static rope between two trees and bounce tested with me in the middle. Held well and released well.
As with any releasable anchor set up, getting the release line away from accidental tugging is still an item to be careful with. But, I believe there is enough built in resistance to avoid that, especially with the release bight long and possibly with the bight wound into the encircling parts. Which I have not tried as of yet.
I?d have no qualms employing this on my next climbing session.

A set of tying sequence photos would be helpful to some.

Again, thank you for sharing your work.

SS

agent_smith

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Re: JRB Hitch, a secure, quick release hitch
« Reply #21 on: February 11, 2021, 09:13:09 AM »
Hi John,

Thanks for making the time and effort to produce your video - I appreciate that it represents a significant investment of effort - and its often a thankless task.

Okay - we need to focus on some crucial aspects - which are missing from your tests.

Can you please give due attention to the following:

1. After initiating the first stage of the release sequence, you need to pause. It is at this crucial stage where you need to test the security of the hitch.
After triggering the first stage of the release sequence - apply load the remaining hitch structure as follows:
  [ ] cyclic loading
  [ ] slack shaking
  [ ] impact loading - send a sudden shock wave 'pulse' down the line
The intent is determine how well the remaining hitch structure withstands further loading - which will indicate how 'fault tolerate' your hitch is.

2. Load test to its MBS yield point (ie pull-it-till-it breaks) - with the rope terminated at both ends using the same identical JRB hitch.
Each JRB hitch (at both ends) must be identically tied and dressed (as best you can).
One JRB hitch will yield first - leaving you with a 'survivor' specimen to examine.
Its the surviving JRB hitch that is of interest.
  [ ] has it jammed?
  [ ] has any damage occurred to the rope material?
  [ ] has it deformed or suffered any structural anomaly?

3. When you initial the release sequence, don't pull at 90 degrees to the SPart. You should be triggering the release sequence along the same axial direction as the SPart.
In your videos, you appear to initiate the release sequence perpendicular to the SPart. If you think about it, this wouldn't be possible in a deliberate (or accidental) retrieval process...

Please pay close attention to detail - ensuring you address each of my points.

JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #22 on: February 13, 2021, 12:20:44 AM »

1. After initiating the first stage of the release sequence, you need to pause. It is at this crucial stage where you need to test the security of the hitch.
After triggering the first stage of the release sequence - apply load the remaining hitch structure as follows:
  [ ] cyclic loading
  [ ] slack shaking
  [ ] impact loading - send a sudden shock wave 'pulse' down the line
The intent is determine how well the remaining hitch structure withstands further loading - which will indicate how 'fault tolerate' your hitch is.

2. Load test to its MBS yield point (ie pull-it-till-it breaks) - with the rope terminated at both ends using the same identical JRB hitch.
Each JRB hitch (at both ends) must be identically tied and dressed (as best you can).
One JRB hitch will yield first - leaving you with a 'survivor' specimen to examine.
Its the surviving JRB hitch that is of interest.
  [ ] has it jammed?
  [ ] has any damage occurred to the rope material?
  [ ] has it deformed or suffered any structural anomaly?

3. When you initial the release sequence, don't pull at 90 degrees to the SPart. You should be triggering the release sequence along the same axial direction as the SPart.
In your videos, you appear to initiate the release sequence perpendicular to the SPart. If you think about it, this wouldn't be possible in a deliberate (or accidental) retrieval process...


Agent Smith, I very much appreciate your detailed description.  Just to increase the chances that I get this right, please advise:

1. Because the hitch does hold in both a lengthwise pull and in a perpendicular pull, the test you described could be done either between: 1) using a single (fallen) tree trunk, creating lengthwise pull as I performed in prior videos or 2) between the bases of two standing trees.  Do you have a preference for which?

2. Is it acceptable that I do the test with a cordage that is in the 5mm range rather than a climbing line which is double that diameter and much stronger? Because I would need to get much more creative with my rigging if i need to break an 8mm cord instead of a 5mm.

3. When you say "the first stage in the release sequence", I assume you mean after the "drawloop" has pulled through the first munter/loop in the hitch itself.  Because as you are aware from your diagram, there are 3 stages to the structure of the hitch, but when I am actually executing the release, it feels like only 2. And so I am inferring you want me to determine how secure the hitch is in an intermediate state, partially compromised, even if such a state would be difficult to achieve in a real field situation.

4. I don't know the best hitch with which to attach my pulling rig in the center. Follow this logic: JRB hitch is quite strong, stronger than the scaffold knot used in a prior test. I don't have the hardware I would need to rig up a frictionless hitch, actually 2 of them, on either side of my winch in the center... and so what would you recommend as the STRONGEST means to attach the test line to my winch in the center, which terminates with a carabiner has a small bend radius?  A Palomar?  All I can think of is to tie another JRB hitch, perhaps the 3 turn variant onto the carabiners.   I don't know which will fail first: one of the JRB hitches on the tree or one on the beaners, but would guess the latter.  What is the strongest hitch for attaching a carabiner?  The 'hitch to beat' in terms of strength? 

thanks in advance.  I am not certain I will get to it this weekend as the ground is snow covered and more expected.  But looking forward to it!

agent_smith

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Re: JRB Hitch, a secure, quick release hitch
« Reply #23 on: February 17, 2021, 03:28:27 AM »
Quick reply...

Quote
1. Because the hitch does hold in both a lengthwise pull and in a perpendicular pull, the test you described could be done either between: 1) using a single (fallen) tree trunk, creating lengthwise pull as I performed in prior videos or 2) between the bases of two standing trees.  Do you have a preference for which?

I don't believe it would make any significant different in terms of what we are trying to determine.
That is, the idea is to load the 2 hitches till MBS yield point is reached.
One knot will fail first - and you will have a 'survivor' specimen to examine.
The 'survivor' will have been maximally loaded - and if it can be easily untied, you can pop the champagne cork (assuming no obvious damage caused by heat build up).
When untying the 'surviving' hitch - take note of which rope segments have sustained evidence of stress/crushing. Try to pinpoint where (location) within the hitch where these stress concentrations occur. This is valuable information.

Quote
2. Is it acceptable that I do the test with a cordage that is in the 5mm range rather than a climbing line which is double that diameter and much stronger? Because I would need to get much more creative with my rigging if i need to break an 8mm cord instead of a 5mm.
It is always preferable to test with the same type of rope material/diameter that would be used in the field.
This means that you need robust test equipment - with ability to achieve peak load of around 3 metric tons (3000kg).
Using lesser diameter material would serve as a pathfinder - but you need to go full scale to be 100% certain of your results.

Quote
3. When you say "the first stage in the release sequence", I assume you mean after the "drawloop" has pulled through the first munter/loop in the hitch itself.
Yes.
Quote
Because as you are aware from your diagram, there are 3 stages to the structure of the hitch, but when I am actually executing the release, it feels like only 2.
Correct, only 2 stages.
What we are trying to investigate is whether your hitch is survivable after having triggered the first step of the release sequence (ie how fault tolerate your hitch is).
Triggering the second stage of the release sequence means death or serious injury (if you manage to survive the free-fall).

Quote
And so I am inferring you want me to determine how secure the hitch is in an intermediate state, partially compromised, even if such a state would be difficult to achieve in a real field situation.
Correct.
I am hoping that you can see that the default 'pull-it-till-it-breaks' mindset is a dead-end path that doesn't provide meaningful information.
For many knot testers, this is the only way they can conceptualize knots. There are some promising signs that one or two knot testers are starting to expand their mind - and look at other factors (but once a leopard has spots, its hard to change those spots).
However, you can use the 'pull-it-till-it-breaks' mindset in a contest between 2 identically tied knots/hitches - where one will always yield first - leaving a 'survivor' to closely examine. Carefully untie the surviving hitch - and examine which segments of rope have been crushed or heat glazed. Mark these segments (with permanent marker pen) and re-tie the hitch, noting where these segment are located.

Quote
and so what would you recommend as the STRONGEST means to attach the test line to my winch in the center, which terminates with a carabiner has a small bend radius?  A Palomar?  All I can think of is to tie another JRB hitch, perhaps the 3 turn variant onto the carabiners.   I don't know which will fail first: one of the JRB hitches on the tree or one on the beaners, but would guess the latter.  What is the strongest hitch for attaching a carabiner?  The 'hitch to beat' in terms of strength? 

One of the key concepts with all types of testing is to engineer out any experimental bias.
Eye knots are easier to test (obviously) - but, your creation isn't an eye knot.
Have a look at the attached image (extract from EN892).
Note how the rope is terminated.
I suggest that you try to adopt a similar method of terminating (but more turns to create a 'capstan effect').
A large size shackle with 30mm diameter pin would be okay...

Edit note:
The image is fair use under copyright laws - it is just one small extract.
« Last Edit: February 17, 2021, 05:01:27 AM by agent_smith »

JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #24 on: February 28, 2021, 08:13:51 PM »
After initiating the first stage of the release sequence, you need to pause. It is at this crucial stage where you need to test the security of the hitch.
After triggering the first stage of the release sequence - apply load the remaining hitch structure as follows:
  [ ] cyclic loading
  [ ] slack shaking
  [ ] impact loading - send a sudden shock wave 'pulse' down the line
The intent is determine how well the remaining hitch structure withstands further loading - which will indicate how 'fault tolerate' your hitch is.

Agent Smith, The attached video link demonstrates a concatenation of three successive videos of the same test.  I am not sure that it meets what you were looking for, but I hope it is of interest and has some value.  When playing it back, I see that the lighting was not ideal.  Unfortunately, I had no camera operator, and this was the only window of daylight and weather I had this weekend.

Here are my observations: In earlier tests, when I was releasing a 100kg load, tied on a smaller diameter 30mm bar, when releasing under load, it WAS possible to pause when the release line had slipped through the first munter, but only by visible observation; I could not feel any change in resistance after the first stage had been passed.  Some differences here are that I am loading using my own body weight in a realistic climbing situation, and pulling in the direction of the load, and so I was releasing under little or no load:  A portion of the load (by body weight) had to be diverted to the release line, and as the was ready to release, my feet were on the ground, ready for the release and ensuring my safetly, and so there was little load on the line. In this configuration, you can see the results: with the described load profile and with the different tension geometry of a large diameter tree trunk compared to a 30mm bar, the hitch lost its integrity and could be released after the bight passes the first stage. 

https://youtu.be/vB9G48DD1Ho

JRB

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Re: JRB Hitch, a secure, quick release hitch
« Reply #25 on: March 01, 2021, 07:26:45 AM »

That is, the idea is to load the 2 hitches till MBS yield point is reached.
One knot will fail first - and you will have a 'survivor' specimen to examine.
The 'survivor' will have been maximally loaded - and if it can be easily untied, you can pop the champagne cork (assuming no obvious damage caused by heat build up).
When untying the 'surviving' hitch - take note of which rope segments have sustained evidence of stress/crushing. Try to pinpoint where (location) within the hitch where these stress concentrations occur. This is valuable information.
.......
This means that you need robust test equipment - with ability to achieve peak load of around 3 metric tons (3000kg).
Using lesser diameter material would serve as a pathfinder - but you need to go full scale to be 100% certain of your results.

Agent Smith, I did attempt a break test this weekend, just a 7mm cord for starters, with 10.7 kN breaking strength.  In preparation, I borrowed some heavy duty hardware in an attempt to make a crude version of a pair of tensionless hitches (similar to what you referenced).  Unfortunately for the test, the break occurred in my crude tensionless hitch, and the JRB hitch held.  And so, I did not bother to produce a video for the test, but I did upload the ending which was the the only part with new information: My pulling device was a pickup truck in a 2:1 system, and so after breaking a 10.7 kN cord, I am guessing I had approximately 5kN on the towing hitch on the back of the truck. I had not previously loaded anything that small or that heavily, and so I was pleased at how easily I could release it. 
https://youtu.be/WIPyPqpTkZ0

And so, regarding the quoted test you prescribed, I am going to send this out to a lab.  After this attempt at much lower forces, I don't feel it would be smart for me to attempt these kinds of tests given my lack of proper test equipment, protective equipment or training.  I will be paying for this and so I was planning on proceeding this way; see steps below. I hope you don't mind that I added steps 4 and 5.  My rationale is simple: getting access to a rig exerting these kinds of forces will not be a frequent affair and so I would like to know how the hitch releases under HEAVY loads. 

1. Based on their inventory, I will select a climbing rope in the 3000kg range that you described, which is probably a 10.5mm climbing rope, perhaps 28-30kN break strength.
2. Tie two identical JRB hitches to a pair of 4inch bollards on either sider of the pulling apparatus.
3. Pull until HALF of the MBS of the rope is achieved.
4. Release the load and test the ability to release the rope by pulling the drawline, specifically by pulling it in the same direction as the load.  Is it jammed, or can a firm tug on the release line spill the hitch?
5. Re-tie that end of the system, and resume the pull test until failure.
6. After failure, as per your instructions above, first examine the end that failed. 
7. Next and most importantly, carefully examine the end which survived, looking for damage, deformation, marking any visible spots with a marker.  Attempt to release the line with the drawline, to determine how badly it has jammed.  Carefully release the line and examine the damage with the rope in hand. 


How is that? Any suggested changes? 
thank you