Considering how old this gem is, it may be a derby.
http://www.youtube.com/watch?v=yYAw79386WI
who created the first differential drive system?
i believe it was Leonardo Da Vinci during the renaissance, but some more primitive models of a similar idea were used in China in the as early as the 3rd century AD
Very cool video -- but does anyone else get the feeling that your avatar is narrating the thing?
If you were a lego nerd like me, you probably had differentials at your disposal from the tehnic set...
Now, find a video on torsen® differentials - those are a little harder to understand but beautiful in their simplicity.
mitt