CIM Motor Backdrive

[potatoshane]

Hey Everyone,

I was wondering if there was anyway to prevent backdrive from a CIM Motor. We currently are using a CIM Motor to turn two spools on our robot which has rope attacked to it and it allows us to move our arm up and down, but the probably is when hanging, we have a 50% chance of staying on the bar without haivng the CIM motor back driving. We do have another hook system installed, but we ended up using an illegal motor so that did not really work out for us at CVR. It would also be much easier to take the robot off the pyramid without the hooks too. Is there anyway we can prevent the CIM Motor from having backdrive? Our robot weighs around 100 pounds.

Thanks

[MichaelBick]

Switching to a worm drive would help prevent backdriving. Also the motor controllers can be electronically set to brake. They won't be completely backdriveable but it might slow down the fall enough so that you are still hanging 5 seconds after the match ends.

[Tom Line]

I assume you only lift once. If that is the case, go to your local hardware store, get a rachet-wrench. Drill and tap the end of your spool drive shaft, and put a 1/4-20 hex head on it. Stick the rachet on it so it can only turn one way.

[Lil' Lavery]

There are several options to mitigate or eliminate back drive.

1) Increase your reduction
2) Use a less efficient form of power transfer (worm gear, lead screw, etc.)
3) Add a mechanical brake/pin
4) Add a ratchet & pawl system
5) Counterbalance the load on your mechanism