Jeff's exactly right, the two rear drivewheels are fixed, and there are two casters in the front capable of pivoting 360. Here's http://img401.imageshack.us/img401/7127/74589885ds7.jpg" (real early, ignore that the casters are floating in space and that the one support strut doesn't go...
Hi folks, my first post here, looks like a very helpful website though, so i thought i'd share my problem.
I'm a mechanical engineering student working on a vehicle that has a zero turning radius system, which is to say (for the purposes of this problem) that it's controlled by 2 drivewheels...