PROBLEM: One way motor!?!?

One of the motors on our holonomic drive has been malfunctioning recently. For some reason, it will only turn one way. I’ve had to fix this motor twice now and it keeps on giving me this problem. The first time it happened the internal gears were shredded. But this time the gears seem to be in good condition. One thing worth noting is that it’s our front right motor and the majority of the weight is in back.

Should I replace the entire motor (plus encoder) or is it something else?

Swap out the motor controller if it is a MC29 or change port if it is 1 or 10 (internal motor controller).

See if that works.

Its not the motor controller, I physically can’t turn it the other way. Also it’s not port 1 or 10.

Are you using a 269 motor? I had the same problem with those a couple years back building test beds for a pltw class, and I never actually figured out why it wouldn’t turn the other way. If you are using a 393 motor, I don’t really see how that happens.

We are using the 393 motors on our robot.

Replace the motor. Also, if you have a holonomic drive base that is not carrying equal weight on each wheel, it will not work correctly. Look for ways to distribute the weight evenly.

If you physically can’t turn the motor, and you still physically can’t turn the motor once you’ve removed it from your drivetrain (putting a shaft and wheel directly on the output and turning it by hand), replace the motor. There’s some mechanical binding in the internal gearbox, or perhaps the motor itself. I would replace the motor and then see if you can fix that particular motor later if you have some down time or something.

I would check to make sure there aren’t loose screws in the gearbox that bind when pushed just the right way. This is usually the problem in my experience.

Holonomic drives aren’t unworkable if the weight distribution isn’t even, but they are a lot harder to deal with. You’ll need a gyro and a patient programmer to make field centric work with any kind of repeatability. It’s not fun but it’s doable. In any case, this probably isn’t the cause of your motor’s mechanical problems.