Here are the expressions used for the gears for those who care to know.....

(odd numbered gears)
Expression for gear2 - gear2.rotateX = -gear1.rotateX;
Expression for gear4 - gear4.rotateX = -gear1.rotateX;
Expression for gear6 - gear6.rotateX = -gear1.rotateX;
Expression for gear8 - gear8.rotateX = -gear1.rotateX;

(even numbered gears)
Expression for gear3 - gear3.rotateX = gear1.rotateX;
Expression for gear5 - gear5.rotateX = gear1.rotateX;
Expression for gear7 - gear7.rotateX = gear1.rotateX;
Expression for gear9 - gear9.rotateX = gear1.rotateX;

Fairly simply, see. The difference between the expressions for the odd and even gears is the negative and positive value for gear1.rotateX. Works like a charm.

EDIT* - Also, I plan to include larger and smaller gears. I figure I can link these to gear1 through expressions the same way. All I have to do is multiply gear1.rotateX by a number for a faster or slower rotation. (bigger gears will have to rotate faster, while smaller gears will have to rotate slower) I'm learning slowly but surely.