pic: Traction test

[Nuttyman54]

Originally Posted by Paul Copioli

I do not know much about vex motors, but I am willing to bet that due to the less available torque for the one on the right due to the inverted gear ratio that it's acceleration was below the acceleration needed to break free.
Breaking free means reduced friction coefficient ...

I agree with Copioli here, and the results are corroborated by our own experiments. We noticed that a single CIM driving a single rover wheel with all the weight on it (120lbs total or so) running on a Toughbox had much better acceleration than the same robot with two CIMS into two Toughboxes running one wheel each (with the same 120lbs).

We then measured the actual maximum tractive force provided by each setup, and discovered that there was no noticeable difference in the total force available. The reason for the difference, as we determined, is that since all the weight was on one wheel, that wheel itself could source twice as much force (and thus double the torque), but a single CIM could only input half the torque of two CIMs. Therefore, the single wheel accelerates better because it essentially has built in traction control, as it takes a lot more to put enough torque through the single wheel to slip it.

I assume you're going full power with your two robots, in which case the robot with the lower torque will be slipping the wheels less (or maybe not at all), and will have more traction than the robot that has more torque and is slipping all the wheels.