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Pinion movement

  1. Mar 17, 2014 #1

    Can someone please provide a more detailed explanation for the attached image? :) i need to explain this to my 6yr old nephew and I honestly cannot find an explanation for his age.

    Thank you.

    Attached Files:

  2. jcsd
  3. Mar 17, 2014 #2

    jack action

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    Animated images are one way:




    Using simple cylindrical objects (little wheels for example) on one another or with a cord to represent the belt (twisted or not) may help visualized as well.

    In any case, the next gear always turn in opposite direction, except with the non-twisted belt.
    Last edited by a moderator: Apr 15, 2017
  4. Mar 17, 2014 #3
    Thank you so much for the great reply. It helped a lot :) Thank you
  5. Mar 17, 2014 #4
    Can you determine if the box will close or open without following the pinions one by one? Only by the number of pinions involved in the whole structure?
  6. Mar 17, 2014 #5


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    Yes you can do it numerically but it is not as safe.

    Concepts needed, crank handle, meshed gears, parallel belts, crossed belts, and winch drum.

    Where two gears mesh the rotation direction reverses.
    Where a belt connects two pulleys there is no change of rotation, unless the belt is crossed.

    There are two ways to solve this puzzle.
    1. Draw more direction arrows as you work along the gears and belts of the mechanism.

    2. Count using tokens such as “clock” and “anti”, flipping the token for every reversal.
    Use = for a parallel belt, x is a crossed belt. c is clockwise, a is anticlockwise.
    The sequence here is “ ca = acaca x cacac x aca ”
    So output is opposite direction to input. The box opens.
  7. Mar 18, 2014 #6
    Thank you, Baluncore.
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