Robot Weight

I am a 1st year coach with a MS team heading to Worlds. In our teams quest to try and build a semi decent robot after qualifying, they have built a tank! We mostly only have steel parts. Our lifts work well and no issues there, but my question is how much weight can 4 wheel motors with 4” Omni wheels handle? The wheels burn out after long use with mogo and multiple cones on it but only one side. Thanks in advance!

Friction is your enemy. 4 motor 100RPM (torque/standard) geared drives will handle a lot of weight, but friction is killer. If one side of your drive is clearly always dying first, evaluate where you can reduce friction. Pictures would certainly help diagnose some problems. Another obvious solution is to reduce the amount of metal needed - many new teams far over estimate the amount of structural material needed. If you have aluminum, your first priority should be to replace the lift with it. If you have any other questions - feel free to ask.

@WARCoachL I usually use this formula: *this is your robot weight including game elements, so try to be a few lbs under this weight

((amount of motors)(14.76in/lbs of torque))/((wheel radius)*(gearing))

In your case: (I am assuming stock torque internally geared motors directly driven)
(4m*14.76)/(2"*1) = 29.52 lbs.

*Note this formula is originally from team 929X. Got to give credit cause this formula has worked great for me.

Does that formula work only for high strength motors?

No, you would just replace the 14.76 in/lbs of torque with the torque rating of high speed motors, which is 9.2 in/lbs (Per VEX specs)


Or just divide by 1.6 or 2.4 for hi-speed and turbo gearing, respectively.

So that you get the right units, I’d like to point out that these torques are in*lb, not in/lb.