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Unread 09-01-2015, 10:21
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Re: Drive Train Gear Ratio

Quote:
Originally Posted by Ether View Post
5310/3.7 = 1435 wheel rpm

1435/60*2*pi = 150 radians/sec

6" diameter wheel = 3/12 foot radius

150*(3/12) = 37.5 fps free speed.

37.5*80% = 30 fps rough estimated top speed

Could you share your team's thought process that lead to this decision?
You're being kind in not pointing out that they'll never actually hit 30fps before they run into the step or a wall. Just a back of the envelope kinetic energy/max power calculation says it'll take them about 2 seconds to hit that speed. And that's assuming max power output the whole way, which is certainly not the case. Also it's entirely too fast to control even with 4" wheels.

Thorn, I'm trying to figure out how on earth you're getting a 3.7:1 ratio out of the TB mini. Andymark only specs down to a 5.95 : 1 ratio. Which is still too fast for 6" wheels, but anyways. I don't see any parts on Andymark that can get that ratio. There's Spinbox gears that would get you to 3:1 or faster. The closest I could find was swapping in a 30 tooth and 34 tooth Vex gear, for a 4:1 ratio...

So, with the note that 3.7:1 is a horribly fast gear ratio, how on earth were you guys going to hit that, anyways?
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