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Pulley and Rope

  1. Dec 4, 2014 #1
    Capture.JPG Hello Guys,
    I need little help currently I am working with on a Project that includes Motor Pulley and rope combination. The previous version of our Test bench was having a Motor pulley and rope and the rope was wrapped around the pulley as in most of the cases, but now I am trying to optimize it and want have two wraps of rope around the pulley (as shown in the photo). The pulley will rotate with 70 km/h speed. I just need your suggestions what steps can I take to avoide the overlapping of rope during rotating and which angle should I use between the wraps to get optimium results. During the whole process of rotating the rope will be under tension. Any suggestions will be greatly appreciated. Thankx in advance.
     
  2. jcsd
  3. Dec 4, 2014 #2

    Danger

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    You could use some type of physical separation system such as a couple of eyelets just outside of the pulley to maintain the proper orientation.
     
  4. Dec 4, 2014 #3
    Hi first of all thank you for your reply. Can you please explain me what you exactly mean by eyelets?
     
  5. Dec 4, 2014 #4

    Danger

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    In this case, for simplicity and low cost, I was specifically thinking of "eyelet bolts" screwed into a chunk of 2x4 or similar. An eyelet bolt is essentially a "lag bolt" that has the head cut off and is bent around into a shape like a question mark but closed all the way back to the stem. Another example of eyelets are the line guides on a fishing rod.
     
  6. Dec 4, 2014 #5
    Ok I think its a good idea will surely think about it. Thankx alot for your time and reply. I really appreciate that
     
  7. Dec 4, 2014 #6

    Danger

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    No worries, mate. Let me know how it works out. If there are problems, I have a couple of other ideas that are a bit more elaborate and expensive.
     
  8. Dec 5, 2014 #7
    What does this mean? The units are for linear motion, but it looks like the pulley just rotates.
     
  9. Dec 6, 2014 #8

    Danger

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    You have a Doctorate and can't understand what he means? It's obvious to me. Jeez! I never finished high-school, but at least I'm trying.
     
  10. Dec 6, 2014 #9
    Since it is obvious to you, why didn't you answer my question?
     
  11. Dec 6, 2014 #10

    Danger

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    Uh... because you didn't ask it of me. When you don't specifically address a statement, it is assumed to be directed to the OP unless the context specifies otherwise.
    As to the answer... unless he is using some really weird kind of translator, the reference is to the linear speed of the rope outside of the pulley radius.
     
  12. Dec 6, 2014 #11

    russ_watters

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    If a single pulley doesn't generate enough torque, the typical answer is to use multiple pulleys and belts, not wrap the belt around the pulley multiple times. When you wrap the belt, it has to slide on the pulley to stay in the center, so it will wear faster and is prone to binding.
     
  13. Dec 6, 2014 #12

    Danger

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    I might in fact be mistaken about this, but I think that he is using the wraps as in a donkey engine, to provide enough friction that the pulley can positively displace the rope. He does specify that it's a "Motor Pulley", not an idler or "leverage" device.
     
  14. Dec 7, 2014 #13
    I am not gonna use any belt. I am using a rope used for "Diving" purpose, which is capable of lifting 600 kgs and multiple pulleys is not the answer as there is no space in our test bench for extra pulleys. So I have to use only one Pulley and increase the area of friction, to avoide slippage.
     
  15. Dec 7, 2014 #14

    russ_watters

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    Yes, that's the way I read it.
     
  16. Dec 7, 2014 #15

    russ_watters

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    Rope/belt/whatever. I was just pointing out that it has to slide on the pulley to stay centered. If that's ok, so be it.
     
  17. Dec 8, 2014 #16
    Hi Danger,
    I think your idea of eyelet Bolt wont work. Because when I will attach it on the pulley surace and as the pulley will rotate it will also destroy the shape of the rope. So I think it will work in opposite way rather that maintaing the rope in position. As shown in the picture, if I add eyelet bolt on the black spots and when the pulley will rotate it will come in between the rope shape. The rope is 200 meters long, one end of which is connected to a horizontal platform and other end after traveling around another pulley at other end will attach to the second end of horizontal platform that will move 80 kgs of weight with 70 km/h, so my only and primary goal is the rope should remain in this position through out the function.. Capture.JPG
     
  18. Dec 8, 2014 #17

    Danger

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    No! No, no, no, no, no! :oldsurprised:
    The eyelets are supposed to go where the arrowhead from your "Rope" label is, one for each blue line.
     
  19. Dec 9, 2014 #18
    aaaaahhhh ok I understood now. Thankx alot buddy
     
  20. Dec 9, 2014 #19

    Danger

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    No sweat. :oldwink:

    Let me know how it works out. As I said before, there are more advanced methods if necessary.
     
  21. Dec 10, 2014 #20
    Ya I am working on it. But seriously telling I doubt either this thing will work with that high speed and weight. I am not that much convinced. Do you think it will hold the position at that hight speed and weight?
     
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