C.o.B. CenterofBalance is where it will seesaw balance horizontally on a vertical pivot (from under or above), as TimT. says. It defines an awful lot in all of this, sometimes is the most important thing to spot out.
The hinge is the pivot (no rigging here), and the C.o.B. is the point that you calculate pull on the hinge from etc. This is the input power of the machine, how much leverage you allow it to take on your rigging, is dictated by PivotPoint to C.o.B. relationship.
Hitch is below C.o.B. so that hitch pulls closed positively and half hitch to, if C.o.B. is below leading 1/2 and running bowline then the lacing could pull open. The final position, would be C.o.B. between half hitch and running bowline, this will be sloppy and not positive.
TJK- Balancing that strategy with tree damage (bark,cambium damage in non-removel of support), loss of dynamic load area (less rubberband to any shock), undissiapated heat buildup etc..
It is tradeoffs per situation, more shocking needs more line area to absorb, so pulley gives that. Weaker UpperSupport might not handle increased loads of pulley, add friction high and/or other supports. Or put pulley back in and commit to running the load, to pull less on system.
It all depends, on all componenets and elements, assesing what you have and how many routes you can take from that point, what you have time and gear for and you dream is maximum.
In many things i go for high friction on UpperSupport, to decrease the amonunt of dynamic line area, which also decreases the amount of line i need to stretch, as i am trying to get the line to prestretch itself before tearoff automatically, to it's own specification; thereby eliiminating most buildup in force, by handing load off to line gradually, rather than dropping the load into the line. For, if i pre stretch to 435#, and load is 500#, very lil dynamic loading, drop etc., which also helps to lessen SupportLoad, as well as the high friction.
It does that as it builds resistance to load as line stretches, just as it takes 10#pull to resist 10#pull, so i place that pull at a high leverage point of the load just insside the C.o.B. (making almost perfectly balanced seesaw 1stclass lever, when line provides firm enough support to be a pivot), and slowly cause the hinge to begin to fail. If i can get the load to move from a second class lever pivoting on the hinge and controlled by the line, and rearange that with loading to the point that the line is the pivot; and faairly well balanced load, so that the lins is pivot and hinge is control!!!! After tearoff the hanging load will always be a 1st class lever, before tearoff, generally a 2ndclass lever. If i can cheat, and get a fairly balanced load to slip from 2nd class lever status, to 1st class lever status before tearoff, almost magic is possible. i am answering a question to the images and theories i've presented, that wasn't in the focus of this post, i am speaking now of overhead support, not catching a top from underneath on it's host spar. If i can get that pull to high leverage on the load from the side, the pull of resistance from the tightline can pull it around. The length of spar from the hinge to hitch now doubles as a pivoting reach to move the hitch right under the UpperSupport before tearoff, so there is no force from swing to that plumb bobbing point.
Iff at tearoff the hitch is between you and UpperSupport then load swings away, iff at TearOff UpperSupport is in between hinging and LoadHitchPoint then load comes back at you. In betwixt, iff at tearoff LoadHitchPoint is in the 3rd scenario or lined up under UpperSupport at TearOff, then no swing. C.o.B. outside of Hitching on load, pulls hitches closed, puts softer green forgiving end down first, and lifts stob up at tearoff (towards chin away from roof) if unimpeded..
i break levers into 2 classes, pivot in between input and output forces (seesaw) is 1st class lever. Otherwise (pivot on either end) non1st class. If a nonfirstclass lever increases power/loses speed, it is 2nd class by the book. If nonfirstclass lever, and gain speed/lose power therefore 3rd class lever by the book.
In a non 1st class lever, seeing as the pivot is on the end, the system is more space efficient for what it does, place the pivot in the center and the same trick takes more space, but the trade off is in the write situations, a 1st class lever can do some of the work by balancing the load, for one side is the ballast.
We were lifting logs onto a heavy equipment trailer for someone the other day, puling with a truck to overhead pulley. i showed the guys on that crew, not to hitch the load at the end, it takes more clearance and hard to manipulate. Hitch near center, length above hitch point rides free, you don't have to lift higher to clear obstacles. Also in arranging the logs and seating them, if they are hitched close to center, the light side is trying to help you lift the heavy. So, they start lifting and guiding and thought that was okay. But i wasn't happy, that puts you straining and under the load. i hung on the light side, that picked up the other heavier end, they drifted like magic into place without me lifting. If something went wrong, you are more likely to fall clear too. then we put tag lines on the light ends, and that was safest, best.
Now if fly weight here can pull down on a spar and spirit the other end around, so will/same as moving a load into 1st class position before tearoff, as the hinge has more holding power than me to balance the heavy end and sweep it around. Close to the C.o.B. hitching, pulling on the farthest leverage point (hinge position at end of log).
im sorry some of that goes back to the wheel barrel. Before lifting into position, the C.o.B. is between lift and the pivot of axle on ground, harder to work. Lift it further/ rearrange weight to put 1/2 on the opposite side of the axle, and the C.o.B. is now over the axle. And it is easier to work, the axle carries the weight, with deft balance from operator, as the weight has now shifted and the axle is under the C.o.B. and load is floating along, one side balancing the other. move the C.o.B. out from you some, almost no effort, but handles push more positively against your hands, for deft control, like tree rig with C.o.B. just outside the hitch point.
Or something like that
Brother Daniel, i'm still thinking that if you set up your rig, and i stupidly forgot to hold the line or put it into the porty even, you cut, and nothing hung up, that running load would put less than 60% pull on UpperSupport; 3 raps, forget to hold more force, but with an real loading, and no hanging up still low resistance, line flying etc. i really think that, there is no force on system, that system doesn't resist. Kinda martial artsy/ Zen, but both physics and philosophy life sciences? Whereby, every action must have an equal and opposite reaction i guess i am saying (wow did i just make that up?); without resistance to the force, the force can't be invoked. It can be present, it can blow by, but only things that resist it, will incur it; a sail more than a screen, a tree with leaves or same tree in dormancy etc.
i think that the braking friction would be taking force out of the load, but placing it on the system in trade, i think that running a load can get it away from climber, keep load from accelerating and gaining force, direct to ground; sometimes snubbing out the last part of force into the ground like a cig butt. Any could not go well or at maximum, depending on the tweaks.
i totally agree that the rubber band (stretchy nylon) and how much of it is available before friction, to share the absorption of the dynamic loading is of top consideration after minimizing the amount of force that is handed to that next factor. In dynamic loading, i think that within a line's range, that dynamic lines properties are more important than a static lines strength. But in static situations of tight rigging a static line's rating, or strength rating or a dynamic line pushed/stretched to it's static characteristic range per the load would lead. So situation dependant.
