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Lifting a 60' Hinged Tower

  1. Oct 19, 2016 #1
    Hello folks,
    I am new to the forum and have read threads on different topics that have help me out with problems with my projects. Each of the threads I read everyone was helpful and friendly, so I decided I would try with one of my own problems.

    I read one thread that has given some of the info I need but not all. What I have is a 60' antenna tower triangular shaped weighing roughly 300 lbs. The base is hinged onto a cement base footing roughly 18" by 18" by 36". I am trying to determine the best location on the tower to attach my line to pull the tower up. I may be using the formula wrong but this is what I get: 300 * (30/7base section height) = 1284. My questions:

    If I move the location to say 25' or 20' will this formula hold?
    When a pass the 40 degree mark raising the tower does this weight decrease as well as the line tension?

    Thank you,
     
  2. jcsd
  3. Oct 20, 2016 #2

    Stephen Tashi

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    Science Advisor

    What's happening at the other end of the line? Are you holding it in your hands? Do you have room to walk along the ground as you pull the tower up ? - or must you stand still ?
     
  4. Oct 20, 2016 #3
    Thanks for your response. I have a 3/4 ton rope puller I am using to pull the tower up to the house bracket. The 1/2" rope is three strand rated for 6,500 lbs. On my roof there are two antenna tripods I plan on using a pulley on each to guide the rope to the other side of the house, where I plan on anchoring the other end of the puller to a large tree. There is room for someone to walk beside the tower but I was hoping the puller would be sufficient enough, but I need to lesson the side to side movement of the tower if I can.
     
  5. Oct 20, 2016 #4

    Stephen Tashi

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    Science Advisor

    To do a mathematical analysis of the problem would require diagrams of the set-up, or a very detailed description.

    Can you simply experiment with various schemes for attaching the line - without breaking something in the process?
     
  6. Oct 20, 2016 #5

    berkeman

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    Staff: Mentor

    How sturdy is the hinge against side-to-side movement? I'd think you would want 3 lines for pulling it up, and at least 1 line for slowing and stopping it at the top. Raising large antennas takes positive control at all angles (don't ask me how I know this...). How does the antenna get stopped and locked in the upright position?

    https://i.ytimg.com/vi/jHfyrookXzc/maxresdefault.jpg
    maxresdefault.jpg
     
  7. Oct 20, 2016 #6

    JBA

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    What is the height above the ground of your two pulley connection points?
     
  8. Oct 20, 2016 #7
    Hi all,
    Thanks for all the questions. It helps to think the process through.

    To begin the hinges are 1/4" think flat steel which is 1 1/4" wide and 36" long. There will be a steel plate on each side of the base tower section legs. I have debated getting 3/8" think steel or thicker just to make sure. The hinges are almost 3" above the top of the footing.
    I was thinking that some of the other questions asked would be better answered with some pictures and diagrams. I'll put that together tonight and post it for everyone to take a look at. It is said a picture is worth a thousand words. Thanks again and standby for the pictures.
     
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