Dr Storricks new tree devices

George Hayduke · 26th August 2007, 06:07 PM

Quote:

Originally Posted by Tree Machine

Here is the 2:1 system in hard lock.

In this setup you're using a screwgate biner it looks like...that trail has been trodden severely...need we go down it again? I hope not...since you're in the US and doing work for hire OSHA and ANSI apply...

Tests have shown that loading the small end of a biner with more than one rope reduces the breaking strength because the load is shifted towards the gate leg. Why not invert your setup?

newguy18 · 26th August 2007, 07:58 PM

Besides some people not screwing them shut what on earth is wrong with screw locking biners?I use one on my climbing line and have only once forggoten to screw it shut.I was in no real danger though only 10' of the ground.After that I always double checked before climbing.

Ekka · 26th August 2007, 10:38 PM

Very nice Jim!

There was somewhere, and I have no clue where but definately from UK, that research was done on the safety of biners.

They actually focused on our industry and found the probability of triple lock biners opening the gate was more likely than screw gate biners.

A rope wrapped a certain way can open the biner quickly, most tri-locks open with about half a turn.

Where as to open a properly set screw gate is many turns.

However, the problem is the climber not screwing it shut and not checking it often.

I climbed on Kong 50kn steel screw gate biners up till 2005. Only changed when college insisted we use trilocks. I personally feel more secure and would prefer to climb on screw gates, however I sight in my gear and check often.

I personally have found and seen tails of ropes and flip lines wrapped in that biner so odd that it had the potential to open.

That study I cannot find or reference any more, they were recommending going back to screw gates.

We do not really have such mandated standards here like ANSI. However the college course was enforcing ANSI standards onto us.

There was one chap who disputed it and asked where it was written that screw gates could not be used, the wording is two definate actions isn't it, and unscrewing is a definate action.

newguy18 · 27th August 2007, 03:40 PM

That cleared some things up thanks but like I said only one mishap and I am always checking my gear.

gdstorrick · 28th August 2007, 03:58 PM

Quote:

Originally Posted by Ekka

Very nice Jim!

There was somewhere, and I have no clue where but definately from UK, that research was done on the safety of biners.<SNIP>

No need to quote your whole post; I agree with you. After personally witnessing the failure of a locked carabiner, I decided to only use Maillons for my harness attachment. Carabiners are only strong along their long axis, with most of them, you can tear the gate off with your bare hands (well, at least you can ruin it, maybe it won't come off). Carabiners are not rated by their greatest weakness - side loads on the gate.

A true maillon (threaded on both sides of the opening) is quite strong in all directions, and takes quite a few turns to open. More of a pain to use, but easier for me to trust.

...and of course, my opinion only applies in caves...

----> Gary

Ekka · 28th August 2007, 04:14 PM

exactly, and most guys have their flip lines mallioned to their harness on the adjustable side. Spanner tightened of course.

I still today am more paranoid climbing on those tri-locks than a decent screw gate.

Then hows those Petzel ball lock ones, the plastic breaks and then what?

newguy18 · 28th August 2007, 07:51 PM

I'm with Ekka I think the screw locking biners are safer.

gdstorrick · 29th August 2007, 03:03 AM

Quote:

Originally Posted by George Hayduke

Tests have shown that loading the small end of a biner with more than one rope reduces the breaking strength because the load is shifted towards the gate leg.

True, but I've met Jim, he ain't that heavy to go breakin' 'biners.

Once you have enough strength, having more doesn't mean much. As anyone who's read my site knows, I don't subscribe to the "bigger is better" theory any more. Used to as a kid, but that was long ago.

Big strength numbers are an illusion, and they distract people from other safety issues that are more important... at least in caves...and on cliffs...and mountains...and frozen waterfalls....maybe in trees too?

----> Gary

Stephen Attaway · 29th August 2007, 09:33 PM

Treeguy,

One of my uncles was a professional Arborist. When I was 14, I worked with him for a couple of weeks taking down a tree. Even though my job was to haul the limbs and debris away, I did learn to respect the difficult job the Arborist faces each day. The forces generated from catching a falling limb really impressed me. I really don't know much about the systems used for tree work, so it will take me some time to understand the issues and make meaningful comments.

You are welcome to use/post/cut and past/reference all or part of my article as you wish. A copy of the powerpoint presentation that was presented at the International Technical Rescue Symposium (ITRS 99), Fort Collins, Colorado, 1999 can be found at http://www.attawaygems.com/ITRS2006/Friction_talk.ppt. The paper can be found at http://www.attawaygems.com/ITRS2006/Friction_ITRS99.pdf. You may use the images in the powerpoint as needed.

A follow up to the friction theory paper was a paper by Tim Manning which tested the theory for rope friction on rock. Tim's report can be found at:
http://www.mra.org/services/grants/ManningPaper.pdf

Some of our latest efforts to understand rope behavior in dynamic falls can be found at Strike Rescue: Research

Stephen Attaway

TreeCo · 30th August 2007, 05:08 AM

Great power point presentation!

Welcome to TreeWorld and thanks for stopping by.

newguy18 · 30th August 2007, 12:45 PM

Great links and welcome to tree world.

Tree Machine · 30th August 2007, 10:08 PM

Goodness!

Dr Attaway, welcome to Treeworld, Let me introduce you to Ekka, he's our grand Poobah. Also, meet Dr Gary Storrick, owner of the most extensive collection of aerial devices in the world, as well as being a dedicated caver and and an exceptionally cool dude. Dr Gary, like yourself, has answered our call and stepped in to contribute to our conversation. Dr. Gary's collection and expertise are the 'shoulders' upon which this topic stands. The topic revolves around the control of friction, and friction is an area you clearly have a very thorough handle on.

THE TOPIC: Just to summate what this thread is about. It is about friction control in the professional world of tree climbing, namely tree care or Arboriculture.

Friction has historically been accomplished through rope-on-rope friction using friction hitches, rope fashioned around itself in a constricting manner to apply a firm and adjustable pressure to the rope. The advantage is the setup can be used to both ascend and descend the rope. Form a pure climbing standpoint, that is where the benefits stop. Economically, it can be very economical, requiring no gear other than the rope itself. This system was devised long before ascenders or even modern, synthetic ropes. The system has been a number of varying setups, each improvment trying to overcome the inherent disadvantages one must accept when using a friction hitch system. The main disadvantage is that it is a full-time 2:1 mechanical advantage system. The other is managing slack in the rope. Friction is created at the point of the friction hitch, but also overhead where the rope passes over top of a limb before coming back down and anchoring to the climber.

Descent is OK on a 2:1 system, but ascending is anything but joy. Friction in two places and only getting one unit of altitude gain for every two units of rope pulled through those two points of friction. Unavoidable slop in the system diminishes efficiency further. Tending slack also means pulling double the length of rope over top and then through the hitch just to keep the climbing line tensioned. Tending slack is a continuous process and must be maintained for safety.

These 2:1 friction hitch systems are used worldwide by Arborists and have been since the earliest of times. History has passed this working knowledge from treeman to treeman as that is generally how professional tree climbing is taught; by experienced treeclimbers who have learned from treeclimbers before them.

Mechanical devices have been slow to impact our industry. The friction hitch is unique to modern climbing disciplines and by pure convention has continued on.

Ascenders have been gaining popularity, but often are subbed in for the friction hitch on the ascent, removing one of the two sites of friction. Slings with rings can be installed up high in the tree canopy and the rope passed through this to diminish friction further and create a more 'predictable' friction element. This is called a friction saver, or often called a cambium saver as the rope is no longer passing over a natural limb or crotch, but rather through an aluminum ring.

Improvements in tending slack have been made through hitch configurations incorporating a micropulley. Arborists call it a 'self-tending' configuration. It is an improvement over the more basic hitch setups.

The current cutting-edge tree climbers use modern-day hitch setups and friction savers. The way cutting-edge dudes use access lines to support their climbing lines. The access line is an SRT line, up which the climber may ascend with a single handled ascender, a 1:1 ascent with near zero friction. Once to the top, a backed-up single ascender holds a pulley through which passes the climbing line, configured in traditional 2:1 style, minus the normal friction encountered as the rope passes over the tie-in point. This setup overcomes more friction and now just about 100% of the friction is concentrated in the hitch. In this 2:1 setup, the climber's weight is supported equally on each of the two legs of the system, meaning the side that the friction hitch is on handles half the climber's weight. This is what allows the friction hitch to be effective, that it only need control 50% of the climber's weight, but at the expense of twice the amount of rope being pulled through per amount of gain in altitude.

2:1 descent is OK, a few disadvantages, but with gravity as your constant companion, it helps overcome some inefficiencies inherent in the system. As long as you're moving laterally or down, the friction hitch system is OK, though heat is created in the hitch, frictional wear eats away and changes the performance characteristics of the hitch over time. The hitch needs to be re-tuned in accordance with the wear and changes when the rope gets wet or when you change the diameter size of your climbing line.

The variables affecting the performance of the climbing hitch are many, and without going into all of them, it is accurate to say that the learning curve on using a hitch is long and slow. I would guess to say that when a novice climber finally comes upon something that he or she is 'comfortable' with, thay may never move beyond that, fearing complexity and a new, long, slow learning curve to again be faced, new techique, new style, new setup, but still a 2:1 mechanical advantage arrangement. This keeps a lot of guys from moving beyond their 'comfort zone', and this is what gets taught to the next guy on down the line.

Tree Machine · 30th August 2007, 11:50 PM

2:1 is not right or wrong, it just is what it is.

From the standpoint of physics, a 2:1 mechanical advantage system with a frictionless pulley at the top, and on the weight is great for hoisting a dead load. But for our situation where the weight IS the climber, 2:1 doesn't serve that much advantage, only in that the friction hitch functions in 2:1.

Friction hitches, for all practical purposes, do not work well in a 1:1 system where it would have to hold 100% of the climber's weight. This is why very few tree climbers have ventured out of the 2:1 world. This traditional 2:1 rope method has been currently coined in our literature dynamic doubled rope technique (Mark Adams, Arborist News, June 2007).

Non-familiarity and general lack of availability of friction devices for climbers in our Arborist gear catalogs, as well as very little published about the two main 1:1 rope methods in our Arborist publications keeps our aerial discipline firmly rooted and growing in 2:1 friction hitch systems. That, and resistance to change. Ahead of the resistance to change, however, is just that most tree climbers do not know what other options there are.

There are other options, namely using a metal device to control friction. Coming down a dual, parallel line in a 1:1 fashion (static doubled rope technique) or down a single line (SRT). These are the other two rope methods outside of the traditional 2:1 friction hitch system.

The simple metal device can allow a climber to escape the sentence of a career limited to the less efficient 2:1 method. The simple metal device will allow the climber to use his familiar 2:1 dynamic doubled rope technique, but will also allow 1:1 static doubled rope technique, as well as SRT. The climber can choose which method to use based on which method will work best, depending on the current situation. The metal device will allow the climber to use any of those three methods, at will, in response to the ever-changing situations encountered during the climb.

Versatility and freedom. The joy of being able to choose the most efficient means. Being able to change to another method when one is not serving you well.

I honor the friction hitch for what it is. I have climbed on them all, but they are very limiting and I feel keep the climber from experiencing the full wealth of what climbing can be, from reaching his full climbing potential.

As climbing Arborists, being that we climb frequently throughout every day, we should be amongst the best (human) climbers on the planet. But if we as a profession stay stuck in the 2:1 rope method, we can only be the best 2:1 climbers and that's because what other aerial disciplines climb 2:1?

None. It's uniquely a Treeguy thing.

If we don't have knowledge of 1:1 doubled rope technique and single rope technique, we are simply isolated from the rest of the disciplines; we have our way, they have theirs.

We Arborists should know and understand both ours AND theirs and be fluent in all. That's what this thread is all about. Bringing that up as a possibility. Well-rounded expertise in all things climbing.

Since there is currently no one device that will allow all three rope techniques and cater to the unique working needs of the climbing Arborist, we're using this thread to explore current friction devices. Through Dr Storrick, his experience and his fine collection, Dr Attaway and your intense knowledge of the physics of friction, as well as the collective talents and imaginations of all the Treeworld members involved in, or reading, this thread, our belief is that, if the ideal device does not currently exist, we can create it.

To date, we have explored the simplest of simple friction control devices (ovals and rings), we have created one (pear-shaped) for the experience of showing how relatively easy it can be. We look forward to creating a design, in concept, here online using images and Photoshop. From that virtual digital design we would create the actual device and test it in the trees.

Dr. Attaway's knowledge and written work on ropes and frictional dynamics can help us with the engineering of the device here, within this forum. By being able to calculate from where, and how much friction is created in what parts of the device, over what shape surfaces, we can determine why a specific device would (in concept) work.

I think I've succeeded in making this project SEEM complicated. It's really not. We're just approaching it more scientifially rather than through the potentially endless strategy of trial and error.

I think we can explore some current devices, determine where they are strong, where they are deficient, figure out how to improve upon them (the engineering part) and then choose the superior elements, combine them with our improvements (the artistic part) and build it (fabrication).

Our 'needs list' is fairly vast and specific, so much that the design possibilities are not unlimited. In fact, our ideal device is fairly limited in its number of design possibilities. This helps.

Ekka · 31st August 2007, 05:41 AM

Welcome Dr Attaway

I did pinch your document I found online and posted it in a thread somewhere, glad you didn't mind.

I see from your ppt that when frictions is broken we get jerky movement, in our case we bounce down not up.

The problem with many mechanical friction devices is they are not smooth, we muck around with minor adjustments not abseil great distances unless it's cuppa tea time!

But seriously, trying to eliminate that bounce factor when friction is first broken would be good. Believe it or not the hitches we use on 2:1 rope systems do a good job of this, not a lot of bounce.

The real problem also is advancing these devices for the climb up, for instance, a figure 8 would be a right PITA to try and advance if you just want to move up and over a limb.

Perhaps for you to get an idea of what we do in a few methods view the video in this thread, you'll see the advancing issues.

Spikeless DRT access, trunk walk etc. Featuring Brother Colin.

26th August 2007, 07:58 PM	#177 (permalink)
newguy18 Part of the Furniture Join Date: Jun 2007 Location: Live Oak Florida home of the crapiest trees you will ever see. Posts: 2,857	Besides some people not screwing them shut what on earth is wrong with screw locking biners?I use one on my climbing line and have only once forggoten to screw it shut.I was in no real danger though only 10' of the ground.After that I always double checked before climbing. __________________ Have your say join us today. http://www.youtube.com/watch?v=Xzkd_m4ivmc http://www.youtube.com/watch?v=Xzfzb...eature=related http://www.youtube.com/watch?v=x-OqK...eature=related

26th August 2007, 10:38 PM	#178 (permalink)
Ekka Admin - Dip Arb & Hort Join Date: Jan 2007 Location: Brisbane Posts: 7,748	Very nice Jim! There was somewhere, and I have no clue where but definately from UK, that research was done on the safety of biners. They actually focused on our industry and found the probability of triple lock biners opening the gate was more likely than screw gate biners. A rope wrapped a certain way can open the biner quickly, most tri-locks open with about half a turn. Where as to open a properly set screw gate is many turns. However, the problem is the climber not screwing it shut and not checking it often. I climbed on Kong 50kn steel screw gate biners up till 2005. Only changed when college insisted we use trilocks. I personally feel more secure and would prefer to climb on screw gates, however I sight in my gear and check often. I personally have found and seen tails of ropes and flip lines wrapped in that biner so odd that it had the potential to open. That study I cannot find or reference any more, they were recommending going back to screw gates. We do not really have such mandated standards here like ANSI. However the college course was enforcing ANSI standards onto us. There was one chap who disputed it and asked where it was written that screw gates could not be used, the wording is two definate actions isn't it, and unscrewing is a definate action. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping \| Stump Grinding and Stump Removal Brisbane Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports Forum Sponsors

27th August 2007, 03:40 PM	#179 (permalink)
newguy18 Part of the Furniture Join Date: Jun 2007 Location: Live Oak Florida home of the crapiest trees you will ever see. Posts: 2,857	That cleared some things up thanks but like I said only one mishap and I am always checking my gear. __________________ Have your say join us today. http://www.youtube.com/watch?v=Xzkd_m4ivmc http://www.youtube.com/watch?v=Xzfzb...eature=related http://www.youtube.com/watch?v=x-OqK...eature=related

28th August 2007, 04:14 PM	#181 (permalink)
Ekka Admin - Dip Arb & Hort Join Date: Jan 2007 Location: Brisbane Posts: 7,748	exactly, and most guys have their flip lines mallioned to their harness on the adjustable side. Spanner tightened of course. I still today am more paranoid climbing on those tri-locks than a decent screw gate. Then hows those Petzel ball lock ones, the plastic breaks and then what? __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping \| Stump Grinding and Stump Removal Brisbane Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports Forum Sponsors

28th August 2007, 07:51 PM	#182 (permalink)
newguy18 Part of the Furniture Join Date: Jun 2007 Location: Live Oak Florida home of the crapiest trees you will ever see. Posts: 2,857	I'm with Ekka I think the screw locking biners are safer. __________________ Have your say join us today. http://www.youtube.com/watch?v=Xzkd_m4ivmc http://www.youtube.com/watch?v=Xzfzb...eature=related http://www.youtube.com/watch?v=x-OqK...eature=related

29th August 2007, 09:33 PM	#184 (permalink)
Stephen Attaway I'm new here so be nice Join Date: Aug 2007 Location: Albuquerque,NM Posts: 2	Hello from Stephen Attaway Treeguy, One of my uncles was a professional Arborist. When I was 14, I worked with him for a couple of weeks taking down a tree. Even though my job was to haul the limbs and debris away, I did learn to respect the difficult job the Arborist faces each day. The forces generated from catching a falling limb really impressed me. I really don't know much about the systems used for tree work, so it will take me some time to understand the issues and make meaningful comments. You are welcome to use/post/cut and past/reference all or part of my article as you wish. A copy of the powerpoint presentation that was presented at the International Technical Rescue Symposium (ITRS 99), Fort Collins, Colorado, 1999 can be found at http://www.attawaygems.com/ITRS2006/Friction_talk.ppt. The paper can be found at http://www.attawaygems.com/ITRS2006/Friction_ITRS99.pdf. You may use the images in the powerpoint as needed. A follow up to the friction theory paper was a paper by Tim Manning which tested the theory for rope friction on rock. Tim's report can be found at: http://www.mra.org/services/grants/ManningPaper.pdf Some of our latest efforts to understand rope behavior in dynamic falls can be found at Strike Rescue: Research Stephen Attaway

30th August 2007, 05:08 AM	#185 (permalink)
TreeCo Mature tree Join Date: Jan 2007 Location: Georgia, USA Posts: 268	Great power point presentation! Welcome to TreeWorld and thanks for stopping by.

30th August 2007, 12:45 PM	#186 (permalink)
newguy18 Part of the Furniture Join Date: Jun 2007 Location: Live Oak Florida home of the crapiest trees you will ever see. Posts: 2,857	Great links and welcome to tree world. __________________ Have your say join us today. http://www.youtube.com/watch?v=Xzkd_m4ivmc http://www.youtube.com/watch?v=Xzfzb...eature=related http://www.youtube.com/watch?v=x-OqK...eature=related

30th August 2007, 10:08 PM	#187 (permalink)
Tree Machine Over mature heritage tree Join Date: Mar 2007 Location: Indianapolis Posts: 569	Goodness! Dr Attaway, welcome to Treeworld, Let me introduce you to Ekka, he's our grand Poobah. Also, meet Dr Gary Storrick, owner of the most extensive collection of aerial devices in the world, as well as being a dedicated caver and and an exceptionally cool dude. Dr Gary, like yourself, has answered our call and stepped in to contribute to our conversation. Dr. Gary's collection and expertise are the 'shoulders' upon which this topic stands. The topic revolves around the control of friction, and friction is an area you clearly have a very thorough handle on. THE TOPIC: Just to summate what this thread is about. It is about friction control in the professional world of tree climbing, namely tree care or Arboriculture. Friction has historically been accomplished through rope-on-rope friction using friction hitches, rope fashioned around itself in a constricting manner to apply a firm and adjustable pressure to the rope. The advantage is the setup can be used to both ascend and descend the rope. Form a pure climbing standpoint, that is where the benefits stop. Economically, it can be very economical, requiring no gear other than the rope itself. This system was devised long before ascenders or even modern, synthetic ropes. The system has been a number of varying setups, each improvment trying to overcome the inherent disadvantages one must accept when using a friction hitch system. The main disadvantage is that it is a full-time 2:1 mechanical advantage system. The other is managing slack in the rope. Friction is created at the point of the friction hitch, but also overhead where the rope passes over top of a limb before coming back down and anchoring to the climber. Descent is OK on a 2:1 system, but ascending is anything but joy. Friction in two places and only getting one unit of altitude gain for every two units of rope pulled through those two points of friction. Unavoidable slop in the system diminishes efficiency further. Tending slack also means pulling double the length of rope over top and then through the hitch just to keep the climbing line tensioned. Tending slack is a continuous process and must be maintained for safety. These 2:1 friction hitch systems are used worldwide by Arborists and have been since the earliest of times. History has passed this working knowledge from treeman to treeman as that is generally how professional tree climbing is taught; by experienced treeclimbers who have learned from treeclimbers before them. Mechanical devices have been slow to impact our industry. The friction hitch is unique to modern climbing disciplines and by pure convention has continued on. Ascenders have been gaining popularity, but often are subbed in for the friction hitch on the ascent, removing one of the two sites of friction. Slings with rings can be installed up high in the tree canopy and the rope passed through this to diminish friction further and create a more 'predictable' friction element. This is called a friction saver, or often called a cambium saver as the rope is no longer passing over a natural limb or crotch, but rather through an aluminum ring. Improvements in tending slack have been made through hitch configurations incorporating a micropulley. Arborists call it a 'self-tending' configuration. It is an improvement over the more basic hitch setups. The current cutting-edge tree climbers use modern-day hitch setups and friction savers. The way cutting-edge dudes use access lines to support their climbing lines. The access line is an SRT line, up which the climber may ascend with a single handled ascender, a 1:1 ascent with near zero friction. Once to the top, a backed-up single ascender holds a pulley through which passes the climbing line, configured in traditional 2:1 style, minus the normal friction encountered as the rope passes over the tie-in point. This setup overcomes more friction and now just about 100% of the friction is concentrated in the hitch. In this 2:1 setup, the climber's weight is supported equally on each of the two legs of the system, meaning the side that the friction hitch is on handles half the climber's weight. This is what allows the friction hitch to be effective, that it only need control 50% of the climber's weight, but at the expense of twice the amount of rope being pulled through per amount of gain in altitude. 2:1 descent is OK, a few disadvantages, but with gravity as your constant companion, it helps overcome some inefficiencies inherent in the system. As long as you're moving laterally or down, the friction hitch system is OK, though heat is created in the hitch, frictional wear eats away and changes the performance characteristics of the hitch over time. The hitch needs to be re-tuned in accordance with the wear and changes when the rope gets wet or when you change the diameter size of your climbing line. The variables affecting the performance of the climbing hitch are many, and without going into all of them, it is accurate to say that the learning curve on using a hitch is long and slow. I would guess to say that when a novice climber finally comes upon something that he or she is 'comfortable' with, thay may never move beyond that, fearing complexity and a new, long, slow learning curve to again be faced, new techique, new style, new setup, but still a 2:1 mechanical advantage arrangement. This keeps a lot of guys from moving beyond their 'comfort zone', and this is what gets taught to the next guy on down the line.

30th August 2007, 11:50 PM	#188 (permalink)
Tree Machine Over mature heritage tree Join Date: Mar 2007 Location: Indianapolis Posts: 569	2:1 is not right or wrong, it just is what it is. From the standpoint of physics, a 2:1 mechanical advantage system with a frictionless pulley at the top, and on the weight is great for hoisting a dead load. But for our situation where the weight IS the climber, 2:1 doesn't serve that much advantage, only in that the friction hitch functions in 2:1. Friction hitches, for all practical purposes, do not work well in a 1:1 system where it would have to hold 100% of the climber's weight. This is why very few tree climbers have ventured out of the 2:1 world. This traditional 2:1 rope method has been currently coined in our literature dynamic doubled rope technique (Mark Adams, Arborist News, June 2007). Non-familiarity and general lack of availability of friction devices for climbers in our Arborist gear catalogs, as well as very little published about the two main 1:1 rope methods in our Arborist publications keeps our aerial discipline firmly rooted and growing in 2:1 friction hitch systems. That, and resistance to change. Ahead of the resistance to change, however, is just that most tree climbers do not know what other options there are. There are other options, namely using a metal device to control friction. Coming down a dual, parallel line in a 1:1 fashion (static doubled rope technique) or down a single line (SRT). These are the other two rope methods outside of the traditional 2:1 friction hitch system. The simple metal device can allow a climber to escape the sentence of a career limited to the less efficient 2:1 method. The simple metal device will allow the climber to use his familiar 2:1 dynamic doubled rope technique, but will also allow 1:1 static doubled rope technique, as well as SRT. The climber can choose which method to use based on which method will work best, depending on the current situation. The metal device will allow the climber to use any of those three methods, at will, in response to the ever-changing situations encountered during the climb. Versatility and freedom. The joy of being able to choose the most efficient means. Being able to change to another method when one is not serving you well. I honor the friction hitch for what it is. I have climbed on them all, but they are very limiting and I feel keep the climber from experiencing the full wealth of what climbing can be, from reaching his full climbing potential. As climbing Arborists, being that we climb frequently throughout every day, we should be amongst the best (human) climbers on the planet. But if we as a profession stay stuck in the 2:1 rope method, we can only be the best 2:1 climbers and that's because what other aerial disciplines climb 2:1? None. It's uniquely a Treeguy thing. If we don't have knowledge of 1:1 doubled rope technique and single rope technique, we are simply isolated from the rest of the disciplines; we have our way, they have theirs. We Arborists should know and understand both ours AND theirs and be fluent in all. That's what this thread is all about. Bringing that up as a possibility. Well-rounded expertise in all things climbing. Since there is currently no one device that will allow all three rope techniques and cater to the unique working needs of the climbing Arborist, we're using this thread to explore current friction devices. Through Dr Storrick, his experience and his fine collection, Dr Attaway and your intense knowledge of the physics of friction, as well as the collective talents and imaginations of all the Treeworld members involved in, or reading, this thread, our belief is that, if the ideal device does not currently exist, we can create it. To date, we have explored the simplest of simple friction control devices (ovals and rings), we have created one (pear-shaped) for the experience of showing how relatively easy it can be. We look forward to creating a design, in concept, here online using images and Photoshop. From that virtual digital design we would create the actual device and test it in the trees. Dr. Attaway's knowledge and written work on ropes and frictional dynamics can help us with the engineering of the device here, within this forum. By being able to calculate from where, and how much friction is created in what parts of the device, over what shape surfaces, we can determine why a specific device would (in concept) work. I think I've succeeded in making this project SEEM complicated. It's really not. We're just approaching it more scientifially rather than through the potentially endless strategy of trial and error. I think we can explore some current devices, determine where they are strong, where they are deficient, figure out how to improve upon them (the engineering part) and then choose the superior elements, combine them with our improvements (the artistic part) and build it (fabrication). Our 'needs list' is fairly vast and specific, so much that the design possibilities are not unlimited. In fact, our ideal device is fairly limited in its number of design possibilities. This helps.

31st August 2007, 05:41 AM	#189 (permalink)
Ekka Admin - Dip Arb & Hort Join Date: Jan 2007 Location: Brisbane Posts: 7,748	Welcome Dr Attaway I did pinch your document I found online and posted it in a thread somewhere, glad you didn't mind. I see from your ppt that when frictions is broken we get jerky movement, in our case we bounce down not up. The problem with many mechanical friction devices is they are not smooth, we muck around with minor adjustments not abseil great distances unless it's cuppa tea time! But seriously, trying to eliminate that bounce factor when friction is first broken would be good. Believe it or not the hitches we use on 2:1 rope systems do a good job of this, not a lot of bounce. The real problem also is advancing these devices for the climb up, for instance, a figure 8 would be a right PITA to try and advance if you just want to move up and over a limb. Perhaps for you to get an idea of what we do in a few methods view the video in this thread, you'll see the advancing issues. Spikeless DRT access, trunk walk etc. Featuring Brother Colin. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping \| Stump Grinding and Stump Removal Brisbane Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports Forum Sponsors