how would you make a three point swivel? (and just what is that?)
I am sure this problem has been addressed in some application but I don't know where to look. Here is what I want it for. I designed and created a two point swivel for my "dog run". I have two huskie and did not want to fence in a large outdoor kennel. I put in an overhead cable running about 100' from the house to a tree, placed a trolley on the cable, a swivel on the bottom of the trolley and a bracket holding two 25' retractable cable leashes in the bracket. They can run and play without getting tangled. See photo.
The challenge! I now have three huskies. Somehow I need to attach three of the retractable leashes such that they can't get wrapped around each other. Any ideas?
Re: how would you make a three point swivel? (and just what is that?)
Shoot one dog.
I don't think what you are asking for is feasible, in theory or in practice.
To explain: they can plait the three wires, and you can't prevent them.
Re: how would you make a three point swivel? (and just what is that?)
(grin) Oh ye of little faith. I can think of one approach but I don't like it really well. My idea would need a better analysis that this off the cuff presentation but here goes. A steel half ball facing down with three or more magnetic trolleys attached to it. They would need to be rare earth magnets supported with ball bearings some how.
Re: how would you make a three point swivel? (and just what is that?)
At first I did not think it was possible but then it occurred to me that juggler can keep 3 or more things in the air so why can’t that be the model to follow. Since this is I think ‘inventing’ we are free to call it anything so maybe it should be called a ‘Juggler’. I’ll take a crack at inventing it for no apparent reason other than it will waste some time while I await the snow.
Consider the dogs to be A, B & C and the cable connection points to be 1, 2 & 3. 1 and 2 can be attached at either end of a 2 foot long bar, i.e. the Swivel, that pivots around the middle. (That is exactly the functionality of the two point swivel initially described.) Then mentally add to that a foot long bar, i.e. the Juggler, attached to the swivel in the middle and able to swing toward either end of the Swivel. Attach the connection point 3 to the end of the Juggler.
Start with A, B & C connected to 1, 2 & 3. A can run around B & C and the cables stay free because the swivel pivots, likewise when B runs around A & C and similarly for C. Further it makes no difference if they run clockwise or counter clockwise (but call that in + or – direction to limit my keystrokes.) But what happens when C runs around A and B and A and B are pulling in opposite directions? Initially the Juggler might swing to connection point 1 and connection points 1 and 3 need to exchange dogs, A goes to 3 and C goes to 1 and the exchange needs to occur in the same direction C is running. But then as C continues the run to go around B C’s connection point must transition from 1 to 3 then to 2. In the event C runs around A but not C The Juggler must pass C from connection point 3 to 1 while taking A from 1 to 3 In the required direction. Finally what must happen if A runs around B but not C. The action of the Swivel will pull the Juggler to either connection point 1 or 2. At that instant connection 3 on the Juggler must exchange C with either A or B thus putting A and B on adjacent connection points. From those positions the Juggler can keep up with the twisting by repeatedly passing A and B between the swivel and the Juggler in the required direction. There is one additional unique possible twist. Suppose C runs around A and B while they are being exchanged between the Swivel and the Juggler. In that event the action of the swivel keeps C untangled. There are lots of other letter and number combinations but I believe the actions just described are a complete set and the all other combinations can map to one of the described actions by proper substitution of names.
The invention still must address how the Juggler and Swivel pass dogs back and forth and what a + or – exchange means. I am reminded of the process that must be used in software to exchange two items in a list, i.e. there must be a spare temporary holding location. Call the variables V1 and V2 and the extra location X. The data movements are L1 to X, L2 to L1, and X to L2, or in the opposite direction L2 to X, L1 to L2 and X to L1. In the invention we must have the equivalent of the extra locations and there must be two extra connections to allow for the + and – directions. So introduce a new rotating member at each end of the swivel. Call it a Spinner and design it to have three connection points I, j & k. Define the connection point that is being used as j. Then when the Juggler is pulled to the Spinner and the dogs are going in the + direction the Juggler will pass its dog to the connection i and it will take the dog from j. If the dogs are going in the – direction the juggler must pass its dog to k while taking the dog from j. Once the exchange is complete the newly attached dog’s connection point becomes j.
In my mental image each dog is attached to one of the cable and reel units the dog walkers use to control the dogs. The reel in in the free run out and spring take up mode. The connection points could be designed to grip the mechanisms handle. I think it would be possible to make the pulling actions of the dogs trigger all the exchanges but I’d have to model it to be assured that was the case.
That is a longer and more detailed explanation than I anticipated but it does cove everything I thought of. I have no intention of going any further with this speculation.
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how would you make a three point swivel? (and just what is that?)
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