Gearbox/ Dual Motor Setup

[sanddrag]

We never had a problem with them and we used drills and chias linked together for a total of a four motor drive. 1 drill + 1 chia per side. You can make out a half link in this pic

EDIT: This is also a pic of one way to do a dual motor drivetrain. You'll find a couple more pics here As a note, do not use nylon spacers under the pilllow blocks like we did. Make your own pillow blocks the correct height or use aluminum or steel spacers. While structurally safe, the nylon compressed when the mounting bolts were tightened making for horrible alignment at times.

[Rob Colatutto]

If your looking for a very simple 4 motor drive, probably one of the most simple I've seen that don't use gears would be from my high school teams (263) 2001 robot. Simply just the fp/bosch. (2001 was before the Atwood was added to the kit for anyone newer) fp(with its gearbox) geared up 1:3 to mate with the bosch(and its gearbox in low) and then geared 1:3 back down to a 12 inch wheel and ran about 5.5ft/s. Simple and elegant, 2001 LI regional winner and 2001 LI Delphi Driving Tomorrow's Technology winner. you could take that from the bosch and gear 1:1 to an 8 inch wheel and go approx 10ft/s if you are looking for a faster drive. A good approx of the robot speed can be done by taking
(wheel rpm X wheel diameter X pi) / 12 / 60
There are many old threads on this if you just look for them.
Another 4 motor drive example without gears is a timing belt combiner. (263 2002) The Atwood added in 2002 had a cluster gear given with it that mated with its output shaft. Then we attached a small 5:1 timing belt reduction onto that and it mated well with the bosch (and its gearbox in low). Then we did a sprocket reduction to the wheel. However both these designs required us to take appart the bosch gearbox and modify the output shaft to a standard 3/8 axel. Not a hard modification to do on your own.