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Types of counterweights

  1. Jun 30, 2016 #1
    I have been trying to gather a list of counterweight devices that are designed to do some kind of physical work. I was wondering if anybody could clarify or add to my list?

    List:

    1. pulley ( simple or compound)
    2. lever
    3. hydraulic cylinder (with equal dimension cylinder and equal mass on each side
    4. Weighted wheel?

    I was wondering if something like a large Ferris wheel with an equal distribution of large weights (say 1 ton) were installed all around -- is this a counterweight of a sort? The only power needed to turn the wheel is the power needed to overcome the friction? I don't know what kind of work this wheel could do but my query is how hard it would be to turn even though there are heavy weights distributed evenly.
     
  2. jcsd
  3. Jun 30, 2016 #2

    Baluncore

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  4. Jun 30, 2016 #3
    Hmmm..I guess you are right -- I am not thinking of a mechanical advantage (less force more distance) as much as devices that uses a counterweight where when one weight is moved up against gravity, it has the other one or more weight being pulled down with the assist of gravity to totally balance that. The result would be only small amount of external force being applied to overcome any friction in the movement.

    I know how the top 3 works. But the weighted wheel can have 2 or more weights in the balance placed at the other side of the diameter of the wheel. This balance would allow the wheel to be moved without any more force other than that required to overcome any friction at the center axial correct?

    So isn't the crankshaft with counterweight considered as a lever type classification? Is there any other device or method... especially in the classical machine category?
     
  5. Jun 30, 2016 #4

    Nidum

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  6. Jun 30, 2016 #5
    Thanks..I have seen this before -- this would fall under the weighted wheel category? I guess if it could only go up and then down but not all the way around it could be a lever huh?
     
  7. Jun 30, 2016 #6

    berkeman

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    Garage door springs serve the same function, but without the need for all the weight (and are more compact)... :smile:
     
  8. Jul 2, 2016 #7

    CWatters

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    That's not quite correct.

    Energy is also needed accelerate the mass from stationary up to operating speed. Adding counterweights to a Ferris wheel would mean more energy is needed to accelerate the wheel. More power as well if you want it to take the same time to reach operating speed.

    You might be able to recover that energy when the wheel slows down again but it depends how you slow the wheel down. If you use a friction brake then it's wasted as heat.
     
  9. Jul 2, 2016 #8

    Nidum

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    Have a look at ' water balance funicular railways ' . Delightfully eccentric but quite practical as well .
     
  10. Jul 2, 2016 #9
    Oh that's pretty cool too - Thanks! :)
     
  11. Jul 2, 2016 #10

    Baluncore

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  12. Jul 3, 2016 #11
    In a domestic setting the sash window.
     
  13. Jul 5, 2016 #12
    This is more like a pulley system no?
     
  14. Jul 5, 2016 #13

    Baluncore

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    Yes. One problem with the OP question is the archaic concept of categorising fundamental classes of machine components.

    Both the Falkirk wheel and the Foxton Locks Inclined Plane solve the same problem, but in different ways and with similar efficiency. One has a balanced wheel, the other has a wedge and a pulley system. The water passed in both cases is only the difference in displacement of the boats being transported, plus leakage. The system is balanced so acceleration and friction are the only cost.

    When a small, partly patronised, Ferris wheel is being loaded they try to balance the position of the mass of people on the wheel so as to minimise the resultant torque. The small wheel can be stopped and started. Big wheels such as the London Eye turn continuously so they do not have to accelerate and decelerate the entire 320 tonne mass of capsules, only the people who step on as a capsule passes need be accelerated.
     
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