Thursday, 5 December 2013

Bessler's wheel & reciprocating mechanisms - some more musings.

I should think everyone's heard of reciprocating engines, but put simply, each employs a means of converting rotary motion into linear motion or the reverse - using pistons and cranks for instance.  Although they achieved their pinnacle of achievment in the steam engines a couple of hundred years ago, they are used extensively today - and were also used by the Romans;  an early known example of rotary to reciprocating motion can be found in a number of Roman saw mills dating to the 3rd to 6th century AD, in which a crank and connecting rod mechanism converted the rotary motion of the waterwheel into the linear movement of the saw blades.  So it seems to me that we are seeking to convert the fall of a weight, linear motion, to make a wheel rotate, rotary motion.  Perhaps there are clues to be found by studying these ancient techniques and combining them with parametric oscillation, swinging or Kiiking, to achieve the impossible!

Reciprocating motion, is a repetitive up-and-down or back-and-forth linear motion. It is found in a wide range of mechanisms, including reciprocating engines, rack and pinion steering gear and pumps.  A crank can be used to convert circular motion into reciprocating motion, or conversely turn reciprocating motion into circular motion.

For example, inside an internal combustion engine the expansion of burning fuel in the cylinders periodically pushes the piston down, which, through the connecting rod, turns the crankshaft. The continuing rotation of the crankshaft drives the piston back up, ready for the next cycle. The piston moves in a reciprocating motion, which is converted into circular motion of the crankshaft, which ultimately propels the vehicle or does other useful work. The vibrations felt when the engine is running are a side effect of the reciprocating motion of the pistons.




I just included a couple of images, (see above) but there are many more but all include linear  and rotary motion.

So in place of the piston and its up and down movement, we need the weight to move up and down.  We have the down-movement powered by gravity, but we also seek to raise it through gravity, - that's not so easy.  One might think that the flywheel effect might contribute to the rotation but it doesn't because the force of gravity which provided the initial force to turn it has been used up.  In a combustion engine the force is continuous and more than enough to get the flywheel spinning faster and faster. However in Bessler's wheel the force is provided by weights working in pairs and perhaps one of them falls into an outer position thus overbalancing the wheel, and subsequently the second weight falls into a neutral position therefore having no effect on the balance of the wheel, but in doing so moves the first weight back to its starting position?

We know that in all seriousness we cannot expect the single second weight to lift the first weight upwards more than a fraction of its fall, but we can imagine it being able to just tip the first weight over sufficiently to begin the process again - can't we?  Picture a bicycle wheel spinning.  To keep it going requires a light flick of your finger on the top of it to accelerate it or just keep it spinning.  Or a hoop and stick; you just keep tapping it forward and it rolls along  All we need to do is get the second weight to push the first weight over that small hill which represents the loss due to friction/work between start and finish of each rotation.

JC

10a2c5d26e15f6g7h10ik12l3m6n14o14r5s17tu6v5w4y4-3,’.

or to put it another way.

aaaaaaaaaaccdddddeeeeeeeeeeeeeeeeeeeeeeeeeefffffffffffffffgggggghhhhhhhiiiiiiiiiikllllllllllllmmmnnnnnnoooooooooooooorrrrrrrrrrrrrrssssstttttttttttttttttuvvvvvvwwwwwyyyy-----,,,

11 comments:

  1. John,

    just another idea using the " unmentioned" pendulums, and the stampers.
    Imagine a large T pendulum swinging, when it travels one way, it lifts a stamper on the opposite side, by use of a double lever.
    The stamper is latched in place
    On the back swing, the latch is released, the stamper drops, and gives the pendulum a push.
    A mechanical example of a person being pushed on a swing.

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  2. Any energy we transfer from the pendulum to the stamper reduces the swing - if the pendulum begins with 4 Joules and raising the stamper costs 2J, then returning it on the back swing restores our initial conditions, whereas returning it on the subsequent down-swing locks the system stationary.

    This last option is kinda interesting in that it seems to have got rid of the energy, but it's a dissipative loss so not an asymmetry.

    However, are the pendulums really pendulums - is this an explicit clue, or a metaphor for cyclical PE-KE or oscillating systems per se?

    Likewise, the stampers might seem a good means of exchanging linear and rotary motions, but only up to a point - in a large, fast spinning wheel there won't be much of a window for significant radial displacements each cycle, because of the pre-requisite that "everything must go around together".

    This leads us to a further complication of the issue, encapsulated by the following problem:

    - suppose you're on a playground carousel, or 'roundabout' as we used to call 'em. By what means can we apply torque to it, while riding it?

    How do you spin up a roundabout that you're standing on? Isn't this like trying to lift yourself by your own boot laces?

    The only answer I could identify was to add a further mass to the system, to act as an intermediary for shuffling the energies around. So for one example, suppose you have a flywheel with a ripchord, AKA a yoyo, and some kind of clutch mechanism - say, a spiral shaft, AKA a drill bit.

    So, you could drill the bit thru the center of the yoyo, then remove it, stick it end-up in the center of the roundabout, replace the yoyo on top and then yank the chord... the flywheel thus spins up, winding downwards on the shaft until it slams into the deck, transferring its RKE to the roundabout.

    You could repeat this any number of times, getting ever faster, at least until you lost your breakfast.

    This is an interesting system because it isn't pushing against anything stationary - the whole system is always spinning, and the thing driving it is being carried with it - the system relies on nothing external to the rotating frame.

    It's just a thought experiment, to try highlight the issues... the components from the Merseburg illustrations just seem too large and unwieldy to be literal depictions.

    Perhaps these prints are also hieroglyphs, like many of the later MT sketches..?

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    Replies
    1. @ Vibrator,
      yes I see your point, one way to power a carousel while you're riding it is to make it like a giant pump handle spinning top, hmm let me think ! :-)

      Delete
    2. Yes, basically, except there has to be a free intermediary mass to accept the torque first - or else the handle will turn as it descends, instead of imparting torque.

      Sorry to prattle on, it's just something that keeps recurring in my search - especially wrt converting linear force to torque..

      Delete
    3. @ Vibrator,
      I could be wrong, but would the stampers be something momentarily levering against the wheel ?
      This would allow whatever is free to rotate inside the wheel to continue moving, perhaps to flip to its next position, or work a lever to lift a weight etc.

      Delete
    4. The stampers are obviously a great way of converting between linear and rotary motions, and notches in Bessler's axle (punctured all over with holes) might couple with pegs on a linear or radially moving mass..

      However i tend towards skepticism re. this type of mechanism, for several reasons - the window of opportunity for a 'stamper' inside the wheel to torque it in this way is inversely proportional to speed - it wouldn't be able to fall very far in a fast-spinning frame. Also Bessler's explicit denial of anything being stationary on his axle, and that on the contrary, "in a true PM everything must go around together"..

      That may well turn out to be a specious criticism, but for now this type of mechanic scores a low 'consistency rating' for me, mainly for those reasons..

      Delete
  3. http://www.youtube.com/watch?v=rvMZ-dzz2Cg

    ReplyDelete
  4. I just want to make a note here : Bessler has been misinterpreted and misrepresented by virtually everyone including Jim_Mich and wiki . I know what's coming . It takes a hell of a lot of thought to get there ... inventiveness , clever ideas , etc . Btw John did you ever notice that Bessler used x's in place of "etc" in DT ?

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  5. Yes Chris. , it has been discussed at length on the forum. The x's are really shorthand for ec or et cetera.

    It has been much debated whether the x'c are part of a code. My own opinion is that they do relate in some way to a code but I cannot prove it.

    JC

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  6. @ Chris,

    if you put the X's and the -'s together you get the astrological sign of Pisces, this is of importance in the alignment of the star chart.
    If you remember, Oystein has also worked out a connection to the stars in his decoding efforts.

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  7. I've speculated more in the area of " decoding " all the suggestions that Bessler made...like what he did or didn't say exactly . I only mentioned the x's because I only recently noticed it .

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