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Thread: Statics problem, roller supports

  1. #1
    Associate Engineer
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    Mar 2017
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    Statics problem, roller supports

    Hello, I have a simple statics problem that's frustrating me.
    The diagram shows a drum supported on free-spinning rollers, with an eccentric centre of gravity balanced by a torque applied to the drum with a universal joint. I am attempting to resolve the reactions at the roller supports. The rollers can only exert reactions radial to the drum.
    Vertical components seem straightforward enough, by moments, but I'm baffled by the horizontal components. Where is the mystery force that will balance the horizontal components?
    Thanks for any help.
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  2. #2
    Technical Fellow jboggs's Avatar
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    The rollers will also see the reaction forces imposed upon them by their support bearings. Their FIXED support bearings.

  3. #3
    Lead Engineer
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    The horizontal reaction on each drum Fh = Weight x Tan (angle between the vertical and a line drawn from the centerline of the drum to the centerline of the roller). This only accounts for the drum Weight and does not include any reaction force from the drag due to the bearing friction as stated above.

  4. #4
    Associate Engineer
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    Mar 2017
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    it seems like live ring (part of cement kiln contain with clinker, etc) which support by supporting roller. based on free body diagram the vertical force is balance. horizontal forces will be come from supporting roller, it should be positive and negative and plus friction from the roller.

  5. #5
    Administrator Kelly Bramble's Avatar
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    I think you need to sum the reactions through the center of mass. See the following webpage equations and statics calculator.

    Cylinder Supported by two rollers Statics equations and Calculator
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

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