Curving Jack

[Jonathan]

I've been fiddling with jacks and came up with something that I thought was neat. Doubtful that it's original, but I don't remember having seen one before. I haven't thought of any particular use yet, maybe you guys could (Ant?).
It's like MT138, but instead of the levers getting smaller as they get farther from the handles, in this all the small lever arms are on one side. I haven't tried making the size of the levers vary, they're all the same in the model I built, and in the following picture. It's similarity to the Star of David is coincidental, just a result of 2:1 lever arm ratio and the fact that it was easiest to draw when fully extended (when not extended it is short and wide like all other jacks). The dots are the joints and the one red lever is to clarify where levers start and end.

[Jonathan]

I was mistaken, that isn't fully extended. When it is fully extended it looks like a bunch of chevrons linked corner to corner (the small lever arms fold in the same direction as the large ones, as opposed to the asymetrical diamond shape it has before reaching the position shown).

[Tinhead]

Which one would be the fixed one? The long one (see pic) or the short one?

Cheers,
Rainer

[Lightwave]

ok that is very cool... what did you use to draw that gif?

[Tinhead]

Workingmodel 2d for the simulation .. it can save AVI files... & a demo version of Camtasia Studio to convert it to GIF .. the AVI was TOO big.

http://www.workingmodel.com

Cheers,
Rainer

[Jonathan]

You got it exactly right Tinhead, that's how my model is put together and moves. But how you connect it depends only on what you want it to do. I think there are really quite a number of novel uses this thing could have. Something interesting I've noticed is that in addition to the hydraulic-like linearly directed exchange of force and distace that occurs in other jacks, this one does the same thing along a curve in addition to having interesting torque-related properties. The apparatus, for lack of a more creative name, I've been fiddling with recently is shown in the following picture. What I've noticed is that like an unbalanced wheel, as the device extends to the point that the end of the curving jack reaches the zenith, point A, it takes energy, like lifting the weight from 9 to 12. Then, as just it goes past A, it resists contraction, and strongly wants to continue extending, like the weight on the wheel wanting to move from 12 to 3.
Have any of you seen one of these before (what was it used for)?
EDIT
Oops, forgot to attach it. :)

[Jonathan]

I thought up something else that I think is kind of neat. Two jacks are merdged as shown so that one lever arm is stationary (the one with the big block), and multiple lever arms are medged into two long ones, the red and green. The result is that if one jack is extended the other contracts, just like a normal jack where one of the pivots are fixed. But in addition to this it also turns the direction of the force by and angle dependent on the ratios of the lever arms.

[Jonathan]

Correction! I have built a model of that previous device, and have realized that I was premature to post it, it doesn't work the way I thought (a little confused) for reasons that are now glaringly obvious, I don't know how I didn't see it. If you extend two of the lever arms to form one long one like the red one, parallel to it and the same size, but with it's extreme ends at the ends of each jack, one sees that it doesn't do anything very neat at all. Sorry!

[Jonathan]

I was drawing a curving jack and in the process turned the paper and saw this. From this orientation of a portion of the curving jack, there is a resemblance to the Freemason symbol.
Also, I made a model of a curving jack where the ends were connected so it made a ring (in hopes of an avalanche-drive-like weight redistribution scheme). I found that the ring made that way was incapable of flexing, so I've dropped that. But I did notice in the process that it looked like the MT dodecagram drawing.
Coincidences? Almost certainly, interesting though.

[TommyK]

For those that may be working with jack methods here is an interesting video.

http://www.siege-engine.com/babyscissor/scissortreb.mpg

It's a scissor jack/trebuchet and has an interesting "FLAIL".

[Jonathan]

That's a neat video.
I've come up with another incarnation of the device, I'm hoping that as I make new things with it I might come up with a use for it. It must be good for something.
The are two small normal jacks that connect to two curving jacks, which through sliding joints connect to the large jack. The sliding joints are necessary because the curving jacks don't follow a circular arc, I'm not sure it's possible with any chosen parameters to get it to do that.

[TommyK]

Another interesting video.
Not wheel or jack related but interesting.

http://www.media.ebaumsworld.com/honda-ad.swf

Requires Flashplayer.

[Lightwave]

i love that video "Cog" it must have taken months to set that up
and the weighted tires rolling up hill was good.
the honda site said it took 606 takes.
Rube Goldberg devices are cool

[Jonathan]

I came up with another jack that I thought was neat today. It is like a cross between the curving jack and the Hoberman mechanism, having the connection and angle scheme of the Hoberman mechanism, but the lever arms are not of uniform length like the curving jack. I've made a quick sketch below, showing fully contracted, somewhat extended, and quite extended, in that order. Adjacent levers are drawn with different thickness for clarity. I think it is neat how it curves one way when contracted, but curves the other way when extended (note that because of this, it is unable to be made into an endless circular chain without it locking up, unlike the original Hoberman mechanism). The movement of the 'center' of curvature from one side to another is reminiscent of a slinky walking down stairs.

[jim_mich]

Very interesting jack, Jonathan!