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Thread: Advanced Force,Toque Question

  1. #1
    Associate Engineer
    Join Date
    Apr 2012

    Advanced Force,Toque Question

    Ok This is a long question so bear with me. BACKGROUND: I am designing a set of crush drums that counter rotate (similar to a rock crusher). One Drum is adjustable to increase/decrease distance between drums. Each drum is 170mm in diameter, 200mm long, made from 10mm thick steel. They are chain driven by a 0.75hp motor (550w, 50hz, geared down from 1400rpm to 155rpm)

    Similar to this (image unviewable admin) Ok so this is where it takes some imagination, If you could please tell me what I am missing and if I had it how to carry out the equation.

    I want to find out:

    - what the maximum force the drums could take without jamming

    - Torque (the original rpm was 1400 but from a series of sprockets the rpm is now 155)

    - What force is exhorted by the drums

    I have blades on my drums. One drum can be adjusted on the x axis. How does this affect my equations.

    Could someone please take their time to explain this to me.

    Extra Info: Each drum is welded onto a 350mm steel axle with a diameter of 25mm. Each drum has a 10mm thick plate either side with a 25mm hole in which the axle passes through. The axle sits in a heavy duty flanged bearing. The way the drums are powered are by sprockets and chains in the exact same layout as this charcoal crusher (image unviewable Admin) except instead of a handle, another sprocket leads a chain to the 0.75hp motor



    Email me images (see below) or other - target site blocking access.. Administrator
    Last edited by administrator; 04-06-2012 at 03:09 PM. Reason: Images links blocked

  2. #2
    Associate Engineer
    Join Date
    Apr 2012
    Here is the link to my CAD drawing. It is a 3D PDF document

    link removed..

    Target website wants users to download an application (executable) to view file - unable to verify application does not modify one's browser..

    If the PDF file is to big to attach tho this forum, email it to me at:

    replace (at) with @
    Last edited by administrator; 04-06-2012 at 03:06 PM. Reason: link unacceptable

  3. #3
    Associate Engineer
    Join Date
    Apr 2012
    1.Theoretically since you are using a chain drive, the torque transmitted till the sprocket to the drum would remain the same ( however to be on the safer side, assume a minimum of 2%-3% transmission loss for each sprocket.)
    2. Next the value of torque obtained at the drum sprocket is the torque available at the drum axle.
    3. From this value of torque, calculate the force with the equation Torque = Force exerted radially x radius of drum. This will give you the force exerted by drum.
    4. If the required force for crusher exceeds this value, then your motor will stall.

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