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Question from a non-engineer: Pulley Systems

  1. May 24, 2012 #1
    Hello from a non-engineer. This post has a very practical purpose:

    I'm about to move into a small loft apartment with high ceilings but limited living and closet space. I'd like to find some way to mount a pipe to the ceiling via pulleys and rope or cable that can be lowered and raised with a hand crank. My dilemma is how to keep the pipe level, since I'd like to use only one hand crank.

    I've looked at a setup something like this (a repurposed bike rack), but I can only imagine that it could be difficult to keep a heavy rack of clothes level while raising and lowering it.

    Any suggestions? (Thanks for the help).
     

    Attached Files:

  2. jcsd
  3. May 24, 2012 #2

    Danger

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    Welcome to PF, Loudpipe.
    I am also not an engineer, but I have a thought. If you use a separate cable for each end, both attached to the same reel, they have to take up and play out at the same rate. Assuming no glitches in the pulleys, that should force it to remain level.
     
  4. May 24, 2012 #3
    I agree. That would work. I was hoping to avoid the potential mess of having two cables run onto one spool though. The other thought was using two spools, and use gears so only one handle is required, but I don't know if anything like that exists, and I don't have the means to machine it.
     
  5. May 24, 2012 #4
    A slight variation to that idea works better. I've used it in many material handling designs. Use two ropes, but attach them to a third rope that terminates on the hoist drum. Or the first two ropes can be one rope with each end attached to opposite ends of the rod. The idea in this picture won't do what you want it to do. That is how you rig it if you want to adjust the angle it hangs at, not to keep it level.
     
  6. May 24, 2012 #5
    Are you advocating something like this? I could see it working if wires were put on either side to apply tension and keep it balanced, something like you typically find on either side of a garage door. (Do those have a specific name?) Otherwise I think the racks could slide down and cause it tilt strongly to one side.
     

    Attached Files:

  7. May 24, 2012 #6
    Nevermind. Figured out a solution. I feel silly for not having thought of it before. Just mount two drums to a second rod attached to the ceiling, just like a garage door. I can probably even source parts from a garage door manufacturer.
     

    Attached Files:

  8. May 24, 2012 #7

    Danger

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    That puzzles me as well, although I'm willing to defer to Pkruse's expertise since he's used the system a lot.
    One way to avoid that imbalance, however, would be to put "stops" all along the rod to prevent sliding. Of course, you would then have to manually balance it each time you add or subtract a garment.
    If you choose to go with the dual cable system that I mentioned, you need use only one reel, but segregate it into 2 zones by use of a spacer disk in the middle.
    I'm not doubting you, Pkruse, but I just can't quite grasp the concept. It looks like a coathanger in your picture, and I've never been able to get one of those things to hang straight.

    edit:
    That works too. You posted while I was composing, so I didn't see it until I posted my own.
     
    Last edited: May 24, 2012
  9. May 25, 2012 #8
    Getting close. The ropes attached to each end of the rod must go straight up, each to its own pulley. Then you can route them through as many pullies as you need to bring them together at a common location. At that point you tie them together and connect them to the hoist line. It works well for the first two lines to be a single piece of rope. Then form a bight in it and connect the hoist line with a double sheet bend.
     
    Last edited: May 25, 2012
  10. May 25, 2012 #9
    I found all the parts you need in the rock climbing section of the Campmore web site. I'd recommend a kernmantle static line. Good wear resistance with little stretch. Also works well with a sailboat cam cleat to secure the line.
     
    Last edited: May 25, 2012
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