Torques in Shafts (1) and (2)  
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Diagram shows two shafts A B and C D of 35 millimeter diameter and 300 millimeter and 900 millimeter respectively, are connected using two gears, B with 100 millimeter diameter and C with 200 millimeter diameter. A torque T is applied at the end of C D at D. Parameters: d = 35 millimeter, G = 80 gega Pascal, T = 685 Newton meter.

In summary, the internal torques in shafts (1) and (2) are:

T1=-342.5 N-mT2=+685 N-m

Note: While we are primarily interested in the magnitude of shear stresses in the shafts, the calculation of rotation angles in the system is a little easier if we use a consistent sign convention for the internal torques.