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Getting high speed from a slow moving object.

  1. Aug 11, 2008 #1
    I am trying to figure a way to turn an automobile type generator shaft at realtively high speed (1,000 - 2,000 rpm) using a weight, say 250 lbs., on a pole. The catch is the weight can only drop at about 1 foot per hour. I thought it could be done using gears, such as rack and pinion. A gear on the generator (attached to the weight) would ride down a track on the pole, thus turning the generator as the weight dropped. Obviously, that wouldn't be fast enough. Modifying the gearing may be theoretically possible, but in reality the small gear would be too small to work with such a weight. And the large gear would have to be very large. I'm trying to keep this on the small side.
    I believe it can be done using the weight. Somehow the constant pressure of the weight should be able to generate enough torque(?) to raise the speed. Not unlike they way we would stand on our bike pedals to help climb a hill. Perhaps not unlike the child's top that has a push-down screw mechanism that causes it to spin faster as more effort/weight is pushed upon it.
    I'm not locked into pulleys, gears, belts or whatever. Those are just my current lines of thought. My only limitations are: that the weight must fall about 1 foot per hour; I want to create a reasonable amount of electricity; and I want to keep the whole thing (except the weight and the pole) within about 8-10 cubic feet.

    There must be a simple solution that I'm missing. But my brain is starting to hurt, and I need some help. Thanks
  2. jcsd
  3. Aug 11, 2008 #2


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    Staff: Mentor

    Please note: the law of conservation of energy applies. Lowering a 250 lb weight 1 foot per hour can generate a maximum of 0.1 watts (PE=mgh). That's why you are having so much trouble making this device. It can't work.
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