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What is the force on the wire given the information below...

  1. Sep 4, 2015 #1

    wzrdstrm

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    Need a little assistance, and yes I should know how to answer this but...

    The project is from an Oil and Gas system. Deadline anchor and load cell. a reel has wire rope on it that acts on an arm that puts pressure on a load cell. I'm trying to back calculate the force in lbs on the wire rope. The load cell is just a simple cylinder, where the cap area is 36.7 square inches. The output of the load cell goes to a hydraulic gauge and shows 50.6 PSI.

    The center of the force pulling on the wire rope below pushes on point 19 below. The load cell is located on the gap below and centered on point 19
    If the cyclinder is pushing 50.6 psi (measured on a gauge at the output of the cylinder)
    the force of the arm acting on the cylinder is p=f/a or 50.6 = F/36.7 = 1858.8 lbs
    to determine the force pulling on the wire rope would by 1858.8 * 23.63 = 43923.4 lbs ? Correct?
    Or... is it 1858.8 * (23.63 + 14.75) = 70876 lbs?

    The wire rope is wrapped around the reel and secured at point 14 and does not slip. The reel does rotate and how the force acts on point 19.

    Correct?
    Reel.png
     
    Last edited: Sep 4, 2015
  2. jcsd
  3. Sep 7, 2015 #2
    Well, no, you're multiplying a force times a distance, so that would give you lbf-in of torque.
    If I'm correct that the wire rope leaves the cylinder vertically upward, I get a force, Fw of 4832 lbf in the rope by doing a torque balance around the shaft of the cylinder: 14.75Fw = (14.75 + 23.63)1857
     
  4. Sep 7, 2015 #3

    wzrdstrm

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    I actually did it wrong, the reel acts as a fulcrum, so there is some mechanical advantage. I know the actual force pulling on the wire is between 50klbs and 72klbs, per the load attached.
     
  5. Sep 8, 2015 #4
    How is this known? Given? Calculated?
     
  6. Sep 17, 2015 #5

    wzrdstrm

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    OK, So solved this with the help of a couple others. The rotating reel has an arm attached to it that puts pressure on a a cylinder. We now the dimensions of the reel as per above and the surface area of the cap of the cylinder and the current pressure the cylinder is developing. We also know that the reel acts as a fulcrum.

    load lbs X Radius of reel (center reel to center rope) = Acting load lbs (on cylinder) X Arm length (center reel to center of cylinder).
    P = F/A or pressure the load cell is developing = force lbs/surface area of the cap.
    If pressure at load cell is 50psi and surface area of cap is 36.7 in^2, then the Acting load is 1835 lbs
    then if we want to know the force pulling on the reel from the rope:
    Load lbs(14.75) = (23.63 + 14.75) 1835 lbs
    Load lbs = 70427.3/ 14.75 = 4774.27 lbs
     
  7. Sep 17, 2015 #6
    Which is the same as my method from post #2........you're welcome.
     
  8. Sep 17, 2015 #7

    wzrdstrm

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    My apologies for not understanding you comment, I appreciate the time.
     
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