[RyanN]

Our 2003 robot had a belt drive. It still kind of works. Key term "kind of" Sure, after 5 years, the belts do stretch, but the problem with belt drive that I see is simply replacing a belt. On the 2003 robot, it will take at least 20 minutes to replace the belt, and one of the idlers has a broken bolt, disallowing me from just replacing them.

However, on a robot like ours this year, belts would be possible, but deadly. If we were to break a belt, there would be no way to replace the belt. Keep that in mind when designing your drive train.

For every other year's robot, we've bolted the bumpers to our axle bolts. If we were to put bolts on our robot last year, replacing them would have required us removing our bumpers, which was terrible with last year's design.

Basically, the moral I'm trying to get across, make a design that is reliable, but also easy to fix if something break.

Another problem that I can see with belt drives is if you have a design other than center wheel drive with 6WD or a 4WD with direct drive to one wheel, you have to some crazy wraps, which causes a lot of tension on the belts and the axles, something we found out the hard way in 2007 with our robot.

We had a wrap around our output shaft and an idler (I wish I had a decent picture). Our idler axle snapped at the Bayou Regional and we ended up putting something together real quick using some steel bolts.

So my words of encouragement: Make it simple, reliable, and easy to replace. I believe this is a major principle of engineering.

Looking at the picture from 125, their design looks simple, and reliable, but the bumpers and outside rail will make replacing the belts time consuming if they break. Also, the sprockets seem a little small, which places a lot more force on the belt.

We tried direct drive for the first time this year and used #25 chain. We are on the edge of the limit of #25 chain for breaking strength, but if we broke a chain, all we would have to do is get some new chain and put on a new master link. Even though we never had trouble with #25 chain, we're experimenting with bicycle chain, as it is stronger and widely available.

Also, just so I am kind of on topic, I would recommend McMaster or machining your own. Also check with the sponsor that supplied the belts this year.