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Unread 09-01-2015, 09:50
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JamesCH95 JamesCH95 is offline
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AKA: JCH
FRC #0095 (The Grasshoppers)
Team Role: Engineer
 
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Re: Drive Train Gear Ratio

Quote:
Originally Posted by Thorn View Post
Team 2869 used a mecanum drive train last year and it worked very well. We would like to the same for this year, but with greater speed (and less torque). The gear boxes we had last year gave us a 12.7:1 reduction (AndyMark touchbox mini) and we were able to modify these to bring it down to a ratio of 3.7:1.


If your drive worked "very well" last year on an open field, why would you gear to a faster top speed (and thus less acceleration) for a much smaller field?

Quote:
Originally Posted by Thorn View Post
We are missing some parts and it will therefore be a number of days before we can actually build the drive train and test it.
You won't like what you get...

Quote:
Originally Posted by Thorn View Post
Do you think this is too low of a ratio?
Yes, by at LEAST a factor of 2.5.

Quote:
Originally Posted by Thorn View Post
Will the robot barely be able to get started with a load on it with a gear ratio of only 3.7:1?
We have four motors, each independently controlling one wheel.
Yes.

I STRONGLY encourage you to look at the JVN motor design calculator. These motors will pull a LOT of current. They will likely overheat and/or blow breakers. You will suffer from poor low-speed control. Your robot will also be very slow as it will not be able to accelerate effectively.
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