From Germany new false crotch

G

Greenman

Location
Minnesota
I just returned from a couple of months working in Germany and you should see what Mr. Strasser has come up with. A false crotch with no friction; it is amazing. We have named it the, “STRASSER.” After a lot of testing they discovered that with the classic FC (pulley on one side carabineer on the other) you are pulling 83% of your weight when moving upwards in the tree. Beddes was also unhappy with the added friction when walking out on a branch. So his final product is a FC that your rope runs through only one Petzl Fixy and its retrievable. Oh did I mention that you don’t need a crotch to install the Strasser?
OK, OK so how do you get your hands on one? I have been told that soon you can get one in any hardware store. But I can’t imagine that we will see them any time soon.
Tony

[ December 30, 2001: Message edited by: Greenman ]

[ January 01, 2002: Message edited by: Greenman ]
 
Craig
I do not have a camera that will do it.
confused.gif
I will try to get a pic from Beddes by next week. Tony

[ January 01, 2002: Message edited by: Greenman ]
 
Well; to my math it is just over 50# light of 5k tensile; if conservatively rated that might be realistically acceptable to sum. Especially if it was only one of two legs. Plus, is aluminum; would like to keep such things at steel durability, personally.

i think that the biggest factor would rather be the tight bight on climbing line going through system of this pulley only; i think that would be main compromising factor. As i believe this is a 1" pulley, for a 1/2" line to ride. Samson, New England and Wall spec department have previously echoed my own beleif of not loading a 1/2" on such a tight bight; less than 2".

Murph gave me an idea that i have been playing with; basically an FC; with a 2.37" pulley on the small ring. It works real well! For the bigger ring i use a 30k rigging ring from Sherrill; it is smaller in diameter than 1/2" ring on FC. i think it gives less drag coming out of pulley, yet allows overhand knot to pass thru on removal, and jam into pulley for removal of device.

i use an eye spiced 5/8" 3strand to connect pulley and ring over branch like FC. Am considering; going to webbing for more grip/ less slide on anchor due to wider footprint on branch.

Originally, was setting it as choker from ground; with pulley carrying1/2" line. Less friction, but hassle to set and remove. So i came back to Murph's idea of sometime ago!

Thanx again Murph!
-KC
 
Tony,

Do you mean that the line is run only through the Pixe?

The Petzl Pixe is rated at 22kn, and thus would not meet the minimum strength requirements based on the ANSI Z133.1 -2000 standard:

"3.13 false crotch. A system used to support an arborist climbing line other than a natural crotch. A false crotch shall incorporate rings or a pulley, or some other device that will protect the system and/or arborist climbing line from damage or failure. Each component of the system shall have a minimum tensile strength of 5,000 pounds."

Thanks,

TMW

Originally posted by Greenman:
[QB]I just returned from a couple of months working in Germany and you should see what Mr. Strasser has come up with. A false crotch with no friction; it is amazing. We have named it the, “STRASSER.” After a lot of testing they discovered that with the classic FC (pulley on one side carabineer on the other) you are pulling 83% of your weight when moving upwards in the tree. Beddes was also unhappy with the added friction when walking out on a branch. So his final product is a FC that your rope runs through only one Petzl Fixy and its retrievable. Oh did I mention that you don’t need a crotch to install the Strasser?
OK, OK so how do you get your hands on one? I have been told that soon you can get one in any hardware store. But I can’t imagine that we will see them any time soon.
Tony

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Click to expand...
 
Yes my computer crashed ……..but I am back up now! No pic because some changes are to be made before it goes world wide. And the Fixe dose not meet ansi but will work for European standards. There are some other pulley options that will still work and meet ansi. Now, the theory of bend radius is vary interesting to me because I sell arborist supplies for Fresco and walking through the show room looking at rope savers ( the ring and ring style )from the major manufactures I find none that have grater than a 1” bend radius. What is up with that? Tony
 
Good point Greenman! I have always felt that it was overlooked, but I personally don't feel threatened by a 2-1 bend ratio when dealing with climbing. I don't think that it is that crucial since body weight of many climbers is way below working load limits of that 5,000# setting. It seems more important when working in the 10%(or greater) range of a line.

The only consideration here may be if an aerial rescue was needed, and the rescuer made the decision to place two bodies on that line. Then maybe the raio could become a factor. Anyone disagree? Anyone agree?
 
I'm not too concerned about the bend radius of false crotches either. Even the two ring system. With the strength of modern climbing ropes compared to natural fiber ropes, we're still in a safer working system.

Mark brings up an interesting point: two person loads on a climbing system. This is a practice that should be reconsidered by our profession. Without carefully considering the strenght of the anchor point, the rescuer could overload the system and fall with the patient. Ooops, two patients now~~~

In search and rescue standards there are protocols set up for two person rescues. They require either sperate ropes or systems that are assured to be strong enough for a two person rescue load.

There are times when I use a crotch that I know would support me in any static climbing position. If my climb takes me out of a vertical loading of the anchor, I always keep my flip line attached as a back up. Swings and falls could overload that tie in point which could lead to a ground fall. Bad day. Those anchor points would NEVER support a two person rescue, even without going off lead. When I climb in that postions, I realize the danger that I'm putting myself in and act accordingly. I can't remember being that high in a tree and even having a chainsaw around. That's Silky territory.

Strong limbs and snug ropes!

Tom
 
Well, i have never been comfortable with it and have said so a number of times; let me gently say hear to ya guys; it is not the most popular view!

Samson's people were very helpful said flatly not to send their 1/2" arborist lines around any less than 2" bight. Notice this is for moving line and not a static eye. New England, Wall (rope division) chimed in. Yale didn't make any comment. Though, noone would single the product out; they just didn't seem to like the math either.

i believe at a 2" bight strength of the line is cut in 1/2, and the strength nose dives from there as diameter of bight decreases; i think in a braided eye termination max strength is @1 1/2" on up; so a line working over a 1" bight has always bothered me.

i try to keep my lifeline safety factor many x that of my rigging; so i wouldn't rig a load through that bight; so don't care to sit in it!

-KC
 
KC,

you can buy false crotches without the rings at Karl Kuemmerling. They're not as stiff as the B'hams, thus could have a bit more difficulty flipping out of a tight crotch.
http://www.karlkuemmerling.com

Online catalog doesnt show option of separate purchase, try calling and asking. I'm going to get a large steel ring, which allows a knot passage, which the alum rings very grudgingly do, even the new B'ham bigger rings. I have problems retrieving with my normal ring or maillon oblong link when using a pulley on the small ring, so want to switch to a knot, thus the need to get a steel ring. Better than tying up a pear biner.
 
Rodger is it true that a fall factor of two would kill you? I heard this in a training program I attended. I suppose that this test you quote would nearly kill a cat twice. Tony
grin.gif
 
No, a fall factor two will not kill you. It all depends on the rope used though. Most tests, CSA and ANSI (i believe) test gear with a 12 ft fall factor 2. Rock climbers very often take fall factor 2 falls but their ropes are designed just for that. You could take a fall factor of just .5 but if you were using cable instead of rope (no stretch) you would suffer severe injury or death.

Dave
 
i'm hearing ya Rog.!

Just have pounded that in my head, and also; my test for lifeline stuff; has been would i rig a weight many times myself out of it. That is my increased safety factor for lifeline stuff. Perhaps such multiplying isn't due to bend ratio factors as too wieght factors?

Must ponder that...........

Thanx,
-KC
 
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