I think my team has a lot of 6 wheel drive experiance. We have build 1 practice robot with 6 wheels with the middle 2 lower to the ground which allows us to turn but still be stable. We used the 6 inch pneumatic wheels from the 03-04 competition kit (i think). We also used drill motors in custom built gear box (only made w/ drill press, no milling or cnc machienes). Then we went to a rather complex chain system that connected all 6 wheels to the motor. I believe we had a top speed of 8 ft/s.
Here is that bot, the so called NoodleBot since we attached pool noodles so we didnt hurt the walls:
http://nemesis2.com/phs/robotics/gal...logged=&inc=15
Here are some movies as well:
http://www.plainedgeschools.org/hsro...otinaction.wmv
http://www.plainedgeschools.org/hsro...eo/cartweb.wmv
http://www.plainedgeschools.org/hsro...battlebots.wmv
Although 6 wheels has many benefits of a 6 wheel bot, IMO there are also many setbacks that you will come across. Here are the problems we had with noodlebot and why we could not use that drive train design in the competition last year. It was so low to the ground that there was no way with those wheels we were getting over the step. A bigger problem is that it is extreamly difficult to get a 6 wheel bot with the teetering middle 2 wheels to go strait. A gyro or some other method of keeping it strait is really needed to accurate manuvering. There are also a lot of weight issue, noodlebot was 70pnds without anything else on it.
Right now we are in the middle of building a 6 wheeled robot that can go up the step and uses the 12 inch pneumatic wheels. We also shaved a lot of weight off the drivetrain by using a lot less chains then we used in noddle bot. We now only have 4 chains for the drivetrain instead of 8 and use all but 2 little sprockets. Right now its at 42 pounds. Once we get it moving and take some pictures of it I will show them to you.
If you are interested in more details just PM me and I would be glad to share.
