I have a DC motor with a shaft with a diameter of x. It would produce some torque T because torque is proportional to radius. If I stuck a pulley on the shaft of radius 2x, then I would produce twice as much torque, right? And then if I attach this to a gear with a ratio of 2:1, I would again double the torque.
Here is an image to clarify:
This bugs me because it means the larger a pulley I can fit on a shaft the more torque I get. What am I missing? Are the RPMs reduced?