Vision Perpetual Motion In This Rubber Band Engine (Dec, 1933)

Vision Perpetual Motion In This Rubber Band Engine

AN ENGINE run only by a single rubber band—does it have possibilities of perpetual motion?

Many who saw it on exhibit at the Hall of Science in Chicago’s Century of Progress Exposition believe it has. The engine, shown on the left, obtains its energy from heat directed on the rubber band. Many persons visioned the probability of substituting solar heat for the electrical heaters used in the exhibit. However, perpetual motion is an impossibility as the machine would run only during life of band.

The apparatus consists of an electrical heater on each side of a vertical support on which swings an ordinary pendulum. One end of the rubber band is attached near the top of the support and the other to the lower end of the pendulum.

The engine is started by turning on the current and giving the pendulum a starting swing. As the pendulum reaches the end of its swing, the rubber band is stretched about 300 per cent and is directly in front of one of the heaters. The heat causes the rubber to contract, forcing the pendulum back on another swing. As the rubber band passes through the shadow of the shield, it is cooled off and allows the pendulum to swing out to the other heater.

11 comments
  1. Neil Russell says: October 18, 20081:19 am

    “The heat causes the rubber to contract”
    Doesn’t that run counter to physics? Or does a 1930s rubber band have some unusual property that keeps it from softening and stretching further when heated?
    Or does rubber do that, contract when exposed to heat? I don’t know.

  2. William Deering says: October 18, 20089:06 am

    Neil, You’re right. Also, it would have been a better attempt at a true perpetual motion device if it generated power for the electric heaters. Oh well, maybe this started folks toward the path of today’s solar cells.

  3. Gregly says: October 18, 20089:08 am

    The point is moot anyway, as energy is introduced into the system via electric heaters (or solar heaters as they envision). They didn’t even try to fit the definition of a perpetual motion machine, they just called it that for the heck of it.

  4. ovyyus says: October 18, 20085:12 pm

    Neil, rubber, unlike many other materials, actually contracts when heated: http://www.physlink.com…

  5. Neil Russell says: October 18, 20088:51 pm

    Well what do you know?
    One thing I love about this site, besides the retro future stuff, is that there’s always someone with the answer! Thanks

  6. Myles says: October 20, 20083:34 pm

    Just to second that I think it is funny that this article thinks that adding heat to the system to keep it going is not cheating. Also subsituting solar heat for electrical heat would not qualify as perpetual motion. Finally they say that this machine is not perpetual because eventually the band will break :( That is not their biggest problem. I’m guessing their definition of perpetual motion is a machine that keeps running as long as the power is turned on.

  7. Kiwi ingenuity says: September 7, 20096:51 pm

    Sadly, many perpetual motors have been written off because, quote, “it will stop working in a few years”
    One machine I loved was 2 rings of magnets (one on top of the other) that resisted each other (so the top one floats), but were angled to keep in position, they were also perfectly aerodynamic (not moving, according to associated physics).
    Spinning the floating one caused perpetual rotation.
    It was written off for 2 reasons:
    It couldn’t power anything, any resistance slowed it down.
    It wasn’t powering itself, and even if it had a really good spin, the magnets would die after approximately 5-10 years (depending on type)

  8. jayessell says: September 7, 20097:32 pm

    kiwi…
    The floating spinning magnet would also have to be in a vacuum or else
    air resistance would stop it eventually.
    (Unless you mean its perfect aerodynamic shape has none.)
    ((Which I don’t see how could be possible.))

  9. Don says: September 7, 20097:37 pm

    Kiwi, ALL “perpetual motors” can be written off, because perpetual motion DOESN’T WORK. Never has, never will. Those who think otherwise don’t understand basic physics.

  10. Firebrand38 says: September 7, 20099:35 pm

    Don: Unless they’re students of the Mayan Order.

  11. Don says: September 7, 20099:54 pm

    No, not them; I didn’t mean them, of course . . . .

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