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Unread 19-02-2016, 23:43
kitare102 kitare102 is offline
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AKA: Eric
FRC #3042 (Cobalt Catalysts)
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Join Date: May 2014
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Re: Dual versaplanteary's with different reductions question

I would't be worried about the 100:1 fighting the 10:1. Just moving a 10:1 with your hand should show you that there isn't all that much to fight against.

However, I'd be worried about driving the 10:1 at any reasonable speed, because you'll have to turn the motor (unpowered) on the 100:1 stage 10x as fast as the motor (powered) on the 10:1 stage. If the final output is only spinning at 500RPM driven by the 10:1 stage, the motor on the 10:1 is spinning at 5000RPM, and the motor on the 100:1 stage will need to go 500*100=50000RPM.

I'm not familiar with the internals of the motors, but I don't think any motors in FRC would have bearings rated for 50000RPM. I believe the fastest free speed of any FRC legal motor is ~18000RPM, and I'd be surprised if any motor would be designed to handle a substantial amount past it's own top speed.

I'm not an electrically oriented guy, but another problem with driving a motor that fast is that when being driven, motors act (in some form or another) as generators. This means spinning the motor shaft with another power source will generate back voltage that I'm not sure the system is able to handle.

Sorry for the wall of text, this is actually a very interesting question.

Last edited by kitare102 : 19-02-2016 at 23:46.