Nice job! But, uh, I don't get how it runs... there is the two motors, I get that, but why is there a idler gear on top of them?
[edit]
Nevermind, I get it. The motor on the end would not touch the drive gear, so.... You put that gear in there as an idler gear, and so it is all in a chain like sort of thing... I'll try to draw a diagram:
....O < this is the idler gear
..O..O < these two on this line are the motors
O < this is the wheel and the gear
Am I right?