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.