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

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Discussion Overview

The discussion revolves around calculating the force exerted on a wire rope in an oil and gas system, specifically involving a load cell and a rotating reel. Participants explore various methods to back-calculate the force based on pressure readings and mechanical advantage considerations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents a scenario involving a load cell with a pressure of 50.6 PSI and a cap area of 36.7 square inches, leading to an initial calculation of 1858.8 lbs as the force acting on the cylinder.
  • Another participant challenges the initial calculations, indicating that multiplying force by distance yields torque, not force, and proposes a torque balance method to find a force of 4832 lbf in the rope.
  • A participant acknowledges a mistake in their understanding of the mechanical advantage provided by the reel, estimating the force on the wire to be between 50,000 lbs and 72,000 lbs based on the load attached.
  • Further clarification is sought regarding how the range of 50,000 lbs to 72,000 lbs was determined, highlighting a need for more information on the calculations involved.
  • Another participant summarizes their findings, reiterating the relationship between load, radius, and arm length, and confirms their calculations align with earlier methods discussed.
  • One participant expresses gratitude for clarification on a previous comment, indicating ongoing dialogue and attempts to understand the calculations better.

Areas of Agreement / Disagreement

Participants express differing views on the calculations and methods for determining the force on the wire rope. There is no consensus on the correct approach or final value, with multiple competing calculations and interpretations presented.

Contextual Notes

Participants rely on various assumptions regarding the geometry of the system, the behavior of the load cell, and the mechanical advantage of the reel. Some calculations may depend on specific definitions or interpretations of the setup that are not fully detailed in the discussion.

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
 
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wzrdstrm said:
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?
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
 
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.
 
wzrdstrm said:
I know the actual force pulling on the wire is between 50klbs and 72klbs, per the load attached.
How is this known? Given? Calculated?
 
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
 
wzrdstrm said:
Load lbs(14.75) = (23.63 + 14.75) 1835 lbs
Which is the same as my method from post #2...you're welcome.
 
My apologies for not understanding you comment, I appreciate the time.
 

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