# Homework Help: Removing a crane cylinder, force calculation

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1. Sep 16, 2016

### ted potts

Hi I'm working on a project out in the North Sea on an oil rig, we need to remove a hydraulic cylinder from a crane, I have attached a drawing the red cylinder B needs to be removed.

To do this we will move the crane boom to the position shown by the orange lines and rest the end down on the ground (pipe deck) we will then remove the red cylinder B, now all being well the main boom will support the outer boom and their will be no movement, however should the green cylinder A fail there is the potential for the main boom to drop and the outer boom slide out, so to prevent this happening we intend to put a tensioned cable (green Line) between the main crane pedestal AP to the end of the outer boom,

my question is what strength of wire do we need to use to prevent this from collapsing if effectively there were no cylinder's supporting it? Maybe best to add I am no mathematician but do like to read up and have a go, am I any where near with 18.8kn? I also got the friction coefficient as 0.45 so am I right in thinking steel on steel this shouldn't slip anyway and without any extra added forces should support itself. Ive based my working on the ladder against a wall physics problem, I haven't shown all of my workings out just the last bit. so.....how did I do?

Thanks for taking a look guys :)

#### Attached Files:

• ###### Crane Fx2.pdf
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307.4 KB
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Last edited by a moderator: Sep 16, 2016
2. Sep 16, 2016

### ted potts

I've attached the PDF which is slightly clearer than the image

3. Sep 16, 2016

### Staff: Mentor

Thread closed temporarily for Moderation...

4. Sep 16, 2016

### Staff: Mentor

Sorry, you should not be asking this question on an Internet forum. Ask your supervisor to get a professional Mechanical Engineer involved to help with this problem. Thread will stay closed.

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