I know little about cars, but I like to try, so please don't consider me stupid, yet.
But from what I understood from
HowStuffWorks the crank just... 'connects' to the transmission and then down to the driving axle, in a very simplified way of speaking. I'm a little confused on how it is actually connected, but that's a question for another day.
Anyway, how do two seperate cranks work? Do they have gears on the end that connect to the same transmission 'rod' somehow?