First of all, just let me say those gears are not my own design. I took them from this model on warehouse: http://sketchup.google.com/3dwarehouse/details?mid=595bce5d40b60f7f94909ccb7e2cf912
I must thank 3 times and I do it most gladly: first for the congrats ( 😎 ); second for the class (better than right my wrongs, your explanations help me with some other issues I've been wondering lately); and last but not less important, for the attached file. Your solution is not only more efficient, but also more elegant.
The top bar was supposed to be grouped with the vertical bars, just to be easier to see how it behaved.
Once more, thanks for the explanations and the corrected file