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Problem 3.80

Delivered power (to the machine tool at F) is computed by multiplying the torque in shaft EF times the angular speed: .

(Note that the torque in EF is the same as the torque on gear E, so I am using E as the subscript rather than EF.)

Where two gears mesh, the forces are equal but opposite; the tangential speeds are the same:

Thus, 
Of course, this would have to be true if there are no frictional losses. The power transmitted is , where .

To determine the torque at B, I have to consider the allowable shearing stress:

But these torques are related through the equations developed above. For TB = 60.3, TE would have to be 377 N-m - too large! So far, then, we would have to choose a TE of 323.3 N-m.

However, checking the relation between TC and TE, if TE is 323.3 N-m, TC = 150.8 N-m. This is larger than the 117.8 that is allowed in shaft CD, so TC = 117.8 N-m is the limiting torque.

Using the relation between TB and TC, for TC = 117.8 N-m, TB = 47.1 N-m.

Now I can find the power:

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