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Homework Help: Gear train system dynamics

  1. Feb 17, 2014 #1
    1. The problem statement, all variables and given/known data

    See attachment.

    2. Relevant equations

    3. The attempt at a solution
    Equations (1) and (2) describe this gear train system. I'm confused about them.

    For (1):
    If I rewrite it (∑F=0 format) I get:
    T-T1-Jθ''-Bθ' = 0
    The figure clearly shows θ1 positive spinning towards the bottom. Why then is T1 negative if it is spinning in the same direction as θ1? I understand the inertia and damping is always opposite to the defined positive direction.

    For (2):
    T2-TL-Jθ''-Bθ' = 0
    Since the figure doesn't show the direction TL is going, why is it negative?

    Also why is there a T1 and T2 if I only apply a load T? Shouldn't it just be T-Jθ''-Bθ' = 0 ? Where did T1 and T2 come from if I only applied T? And what exactly is a load torque?

    Now I'm thinking isn't it physically impossible for a single shaft to have two torques going in opposite directions?

    I'm obviously very confused on this. Any help would be appreciated.

    Attached Files:

  2. jcsd
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