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Tension in a catenary curve  Cable Camera 
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#1
Mar414, 08:11 PM

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Hi, my problem is this; I am designing a cable camera system to film downhill pursuits. I need to calculate how much tension is required to hang a cable over a 100m span with no more that 0.5m sag in the middle, when is it fixed at two point, both at the same hight. From the research I have done I have found out that a catenary curve will calculate the sag in a chain when subject to gravity. I am having trouble working through the equations associated with this and would appreciate some help working though it with me.
Many thanks in advance, Alex T 


#2
Mar414, 08:41 PM

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What kind of chain? What is it's mass per unit length? Is a camera going to be hung from this chain? What is the mass of the camera and its attachments? Does the sag criterion apply with or without the camera being suspended from the chain?



#3
Mar414, 09:29 PM

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"What kind of chain? What is it's mass per unit length? "
This is the specification of the cable; DIN 3055 2mm Steel C7 ( Mn + Si) , hotdip galvanized with 1770 N / mm nominal strength SPECIFICATIONS: Cable diameter 2.0 mm Construction 6x7 + FC Tensile strength of 1770 [N/mm2 ] [ Mpa ] Weight / meter 0.0146 kg Breaking load 260 kg "Is a camera going to be hung from this chain? " Yes, the idea is that I will build a carriage which will be remote controlled with a drive motor to run the length of the cable. "What is the mass of the camera and its attachments? " The total weight of the carriage plus camera is, 1.26Kg "Does the sag criterion apply with or without the camera being suspended from the chain? " The sag needs to be calculated with the camera applied to the cable. My aim is to know what tension need to be applied to the cable so that when then camera travels up and down the cable, it does not sag to much that it hits the ground. 


#4
Mar414, 11:30 PM

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Tension in a catenary curve  Cable Camera
Here is a calculator, but without extra load:
http://www.spaceagecontrol.com/calccabm.htm 


#5
Mar514, 12:02 AM

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Adding a weight to the cable changes the problem somewhat. It becomes similar to analyzing what happens to a cable tramway:
http://www.tramway.net/Advanced%20Equations.pdf 


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