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Clutch torque calculation

  1. Feb 20, 2016 #1
    Hi, first time poster.

    I'm trying to calculate the clutch torque output using the following formula:
    torque = force (450KG ((pressure plate calculated force) x gyration radius ( 0.09 Metres (( square root of inner radius squared x outer radius squared divided by 2) x coefficient of friction ( .30) x 2 (number of surfaces.

    When i do the calculation the answer I get is 83.4- this has to be wrong. If i do the same calculation but with imperial values ( 950lb x 0.3 ft x 0.3 CF x 2 surfaces) I get 142ft lb, which equals 192Nm.

    Is my error using kg when i should be using newtons? If so, I'm still baffled as to how to solve this. Apologies if this is a basic question.

    Thanks in advance for any help.
  2. jcsd
  3. Feb 20, 2016 #2


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    Science Advisor

    Please use the homework template, it makes it much easier to help.

    Where did this come from? Is kg a unit of force?
  4. Feb 20, 2016 #3
    I believe that to Kg rating is a industry standard for Pressure plate Clamp load. I've seen it quoted that 950Lbs (430Kg) is a rough guideline for a 10" (254mm) clutch disc
  5. Feb 20, 2016 #4


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    Science Advisor

    I get the same answer in SI and imperial and neither match yours, I'd guess you've made some calculation errors.
    You can use any units you like, as long as you are consistent the answers will always be right.

    Show all your working with all units, so we can see where you went wrong.
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