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Help with design project

  1. Apr 13, 2016 #1
    I am a civil engineering student and have been tasked with creating an enrichment object for elephants at the national zoo in DC. I don't know much about pulleys, and am wondering if there are some mechanical engineers out there who could give me some hints on how to achieve this!
    My idea is for a system of one (or more) pulleys. On one end of the rope would be a bucket and on the other, a large heavy object (such as log). The goal is this: once an elephant lifts the log the bucket will be lowered so that another elephant could grab the goodies inside the bucket.
    I need a system that will allow the bucket to be lowered at controlled rate, so that it will be safe for the elephants/zoo keepers. I also need to prevent the bucket from getting too high and tangled in the system.

    Is this at all possible, and what are your ideas?

    Thanks SO much!!
  2. jcsd
  3. Apr 13, 2016 #2


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    Sounds like an interesting project.
    Do you have any ideas of your own?
    What research have you done?
  4. Apr 15, 2016 #3
    I would say this: you will want to tighten the pulley so that it will come down slow and controlled but not so tight that MR. Elephant can't pick up the log. or what would be better is that you could have a samll hole that the rope (bucket side) goes through that ever so slightly smaller than the rope (for restriction) and so the bucket doesn't go past the designated point. :partytime: (p.s., and why does the other elephant get all the goodies?)
  5. Apr 15, 2016 #4
    You could do away with the pulley system all together and go with a long lever mounted up high attached to a weighted object. Basically a seesaw. :smile:

    You could also presumably make this lever out of the log. You could make it so the bucket doesn't have to come all the way down. Just include a tipping mechanism at a point which the bucket can not pass.
    Last edited: Apr 15, 2016
  6. Apr 15, 2016 #5
    you can use a damper (which can be many things) to control the free-swing rate of the system. this could be a teflon block that the rope has to pass through where the block provides some friction. constant force of the damper can be spring assisted, good until the teflon block wear away to nothing, etc.
  7. Apr 16, 2016 #6


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    An eddy-current brake (at a wheel supporting a rope) would avoid wear on the rope. Braking directly at the rope sounds dangerous - at some point it will fail, and bucket and/or log fall down.

    The restriction for the bucket can be independent of this brake.
  8. Apr 18, 2016 #7
    good pints.

    or what about just a friction pad on the wheel axle, like a spring loaded brake pad which provided friction to make it harder to just free wheel.
  9. Apr 19, 2016 #8
    I personally think the use of pulleys and ropes in an elephant enclosure could be dangerous for the animal



    not that the idea wouldn't work but there are other safety concerns aside from falling buckets and breaking ropes.

    The lever method I spoke of could be made safe by adding an air shock to the weighted end of the lever so that the lever comes down slowly and controlled it would have only a few ridged mechanical parts and so could stand up to a lot of punishment without failure. No rope for the animal to get tangled up in. the log would always have a gap under it so it would be less of a pinch hazard.

    Some times simple is better.
    Last edited: Apr 19, 2016
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