Our drivetrain motors slow down and stop working

Our robot (on the cortex system yet) has a 6 wheel drivetrain, with two motors per side. During competition, the motors stop working after less than thirty seconds. Only the drivetrain motors, and they will work a few seconds afterwards, but quit again very quickly. It isn’t friction nor weight, as when picked off the ground, the motors will still only run for a half-minute or so. It isn’t tripping a breaker in the cortex because the other motors (intake and tray motors) still work. We’ve replaced all of the motors and wires, as well as the cortex, with no problems. Several teams from the area have looked at it, and couldn’t find the problem.

Having on the ground is not the only cause of friction.

Overtighten chain or misaligned bearings could create a lot of friction too.

Then there could be one of the motors gone bad.

I would first pull axles from all drivetrain motors and see if they still die early. Then I would disconnect/run only one motor at a time and see if it makes difference.

Replacing all motors is last resort step.

Do you use power expander?


We do not use power extenders, and the wheels can spin freely without the motors attached. We’ve tested individual motors, and they work fine without dying. There isn’t any extra tension or misalignment from our build either.

Another possibility is that one of the motors is misaligned with the axle. So when axle it out friction is minimal, but when you force it into the motor it causes a lot of friction.

Also, you need to check that internal motor gears are all the same. Otherwise fast and slow motors are going to fight each other.

Finally, unlike new V5 system, legacy Cortex has ports 1 and 10 that have slightly different power levels. You want all your drivetrain motors to be on ports 2-9 with half of them on ports between 2-5 and another half between ports 6-9 for even power draw.