Flywheel Issues (Spin Up)

Any help would be greatly appreciated. This is the first year any team from our school has built a flywheel, so we don’t have any experience to go off of. We have 2 motors with 84 tooth gears to a 12 tooth gear that is powering our wheel. It can get started without much issue, but it doesn’t seem to ever reach max speed. As far as I can tell there isn’t any major source of friction, but if you see any please let me know. Any idea what might be causing this?

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Put 1/4inch spacers between the plate and the metal axle locks. This should allow those axles to spin more freely also what rpms is the motor reaching? Can you send a video it might help us a little


I might be wrong about this, but couldn’t the blue tape produce some friction? Also, it would be helpful to others if you posted a few more photos. It would also be a good idea to place bearings on the other side of the flywheel as well. (The motor side of the 12 tooth gear.)

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Try these:

  1. Free spin the flywheel without connecting to motor
  2. Check your code, make sure while declaring motor obj, all parameters are correct. Like, ratio6_1
  3. Change both motors

It doesn’t look like you guys have a ratchet gear to allow the wheel to come to a stop on its own. Are you guys starting the flywheel up by just running it at full power? Also, how are you guys stopping the flywheel after you’re done using it?

Try switching out your sheet metal inter part to a piece of C-Chanel, and support it on both sides. Would reduce friction from wobble and decrease the chance of it shaking apart. Good luck!


As others have indicated, this is not robust enough construction for a flywheel gearbox. You are fighting friction because the structure making up the gear box is not rigid enough.

The motor axle in the bottom part of the picture is effectively cantilevered. The plate and bearing are keeping the gears meshed but provide no support to prevent the motors twisting. You want to build a robust gear box that supports both ends of the all driven axles with structure that is joined across the gear box.

While building the better gear box, make sure the axles turn smoothly when spinning each axle independently by applying manual force and watching for the wheel or gear to spin for 20 seconds +. It is wise to tighten everything in the gear box incrementally. So get everything just barely snug, then test the spin of each axle. Tighten and test in 1 or two more steps until it is fully secure AND the axles turn smoothly. Vey tiny misalignment will degrade the function of the flywheel. Also, a small amount of lithium grease on the bearings and gears is not a bad idea.

As others have mentioned having the motors drive a ratchet that transfers power to the free-spinning flywheel via a pawl attached to the flywheel is the best method for reducing stress on the motors. At the very least, have your motors in breakType coast.

Poke around this forum or video sites for examples of flywheels from the Turning Point season to see some explainers on best practices.

[And welcome to the forum]


Thank you! Switching to a c-channel helped a lot.

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Thanks for the more in depth explanation! Switching to a c-channel helped a lot and testing it free-spinning helped us find a few other sources of friction. Unfortunately we wont have access to the robot again for a few weeks so we wont be able to test out many of the other things you mentioned yet.