I first created a cyclinder, then made it editable.
step 2 of 4
I then selected some of the edge faces and extruded them.
step 3 of 4
Then I selected some of the inner faces and extruded those also...
step 4 of 4
I then created a tude and extruded some of the edges to make a steel rod.
Next I used the same technique but created different sized gears.
Next I added some texture and lighting, then rendered it. Enjoy.
Could do with a little Oil :)