This is one of the haul systems we study for rescue when we go to Texas A&M. They have one of the nations top fire and rescue training programs. It is called a Z-Rig unlike a regular pulley system like 2-1, 3-1, or 4-1 which reduces your ropes hoisting length. The Z-Rig will give you most of your ropes length. It works well for change of direction haul systems. Say if some one was stuck in a ladder cage you could use one pulley on the ground to a pulley over the person who is stuck to lower them down. A diagram would explain things better but I'm tired and lazy lol.tomatkins wrote:To be sure that the comment in my previous post was correct, I made a little model from some rope and some pulleys. After doing so I found the answer to another person's question about whether or not the system would slide back into a "full power", if an extreme amount of force was placed on the chicken loop. It appears that this arrangement of pulleys, rope and ring resists an extreme force and is perfectly balanced in any of its infinitely adjustable length positions.
WOW! What a great concept for any number of uses, where a quick and stable length adjustment is required. I have never seen this length adjustment system used for any other application. Did you create this concept, yourself, or did you find such a system in use for another purpose, such as adjusting the line lengths of a piece of equipment used on a sailboat or the lines of a tent?
Have you applied for a patent for this "infinitely variable length adjustment device"?
I can think of a possible application of this type of device where the rope and pulley system would serve not only the use of a "powerline adjuster", but also as the "safety system" for the type of a kite which uses a mini-fifth line safety system.
As an example, the Cabrinha Crossbow, uses the IDS (mini-fifth line) system, and it seems that a kiter could substitute the ZEEKO style system for the IDS system... by using about 30 feet of powerline, which would allow the bar to slide a distance of 10 and one-half feet, up the power line, when released.
This is the distance needed to engage the mini-fifth line system to bring the kite down to the water, where it would land in a depowered (flagged) state. It would seem that this system could function WITHOUT the "stopper/Prussic knot" adjuster device, and that the kiter could just reach up and grab one of the two power lines, in order to make an adjustment to the trim length. The rope might be slippery, but I would think that the kiter could head downwind, in the same way a kiter with a 'below the bar' cleat system must do, at times, in order to decrease the tension on the power line, before making an adjustment.
With this arrangement, without the stopper, the kiter could just let go of the bar and the kite would flag out. The kiter would then just pull in about 10 feet of the doubled power line to retrieve the bar.
If there was a severe problem the kiter could release everything by triggering the ONE safety release.
Anyway, I must congratulate you on this interesting and unique concept for a line length adjustment system.
Where did you get the idea?
Here is a picture of the "Z-Drag" system of pulleys and lines and 2 Prussic Knots, that is very unique, also, but of course is very different from your "Zeeko system".
Zigzag,ZigZag wrote:Here is a force diagram of the Zeeko depower arrangement. The tension in the powerline T is split equally between the two lines coming up from the chicken loop, so each of these lines has a tension of T/2. The steel ring in the middle sees a tension of T/2, so the two lines entering and leaving the steel ring will each have a tension of T/4. This means that the line between the top pulley and the top attachment point sees a tension of T - T/4 = 3T/4. And this is also equal to the sum of the tension in the two lines descending from the top pulley, i.e. T/2 (left line) + T/4 (right line) = 3T/4.
I too am very impressed by the ingenuity of this arrangement. I made a Zeeko depower loop using steel rings (no pulleys) and 10mm polypropylene line, no stopper, and used it to fly my kite on the beach this afternoon. Pulling on the right line depowers the kite, pulling on the left powers it up. The force required to depower the kite is more than the force required to power it up. So I wondered whether this arrangement would be stable during times of high tension, like jumps, or whether it would slip and power up unexpectedly.
It worked perfectly. It is completely stable. The reason for the differential tension is because in the one direction (depowering) , you are pulling against the tension in the kite, while when pulling on the left side to power up, the tension in the kite is helping you.
I would need a stopper if I had to spin the bar, but I hardly ever do that, so I will leave it without a stopper.
At one of the knots or at a ring. As far as safety goes I personally only use one and thats the one on my leash. I'm sorry but if your truelly in trouble best thing to do is ditch the kite all together than to hope flagging works and you need to release a second time. You just might not have time for it.tomatkins wrote:ZigZag wrote:So, would you want to try to guess where the weakest point is in the rope, pulley, ring, and axle system?
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