[Qbot2640]

Originally Posted by Rynocorn

Hi everyone, my team is working on our final drive train and we were wondering how strong the 9mm belts are compared to the 15 mm belts? How would we even go about calculating if we need the thicker belts or is it just knowlege that you should use the wider 15mm belts for drive train applications. I didn't see any calculation tools on the vex site and just wanted to try and figure it out. Thanks you guys!

From a straight-forward strength comparison, the different widths are the same material - just different width...so 9mm would theoretically have 9/15 the tensile strength of 15mm. Anecdotally, and just from my observation - it seems to me the biggest difference would be the amount of surface engagement between belt and pulley. The only problem we have had with belts is the situation where the required torque causes the belt to ratchet over the pulley. Less surface contact would lower the threshold. We have not observed this problem with a drive-train application, rather with other systems, trying to pivot exceptionally heavy mechanisms.

Originally Posted by Mr. Van

Uh - this worries me. We're trying belts ourselves for the first time - 9mm. (2 CIM driving 6" AM high-grip wheels via a SuperShifters, WCD.) What were your failure points? Why did you go back to chain?

- Mr. Van
Coach, Robodox

We used 15mm belts on the drive train for the first time last year and loved it. It seems so much smoother, quieter, and lighter than a chain-driven system. Unless presented with some special circumstance, I can't see going back to chain.