Gear Ratios
 

How do u come up with gear ratios? I would be doing it with roller chain and sprockets if that makes a difference.

It wont make any difference as such- gears are gears, whether they are connected by a chain/belt, or mesh against each other. I would use BrianG's calculator, or draw out your own diagram, and work out the ratios from there.

That's just it, if i was doing something completely different (robot wheelchair in this case) how do i figure up the final ratio, i really have no idea how to figure this. I would like a ratio of at least 7.14:1. What number of teeth on each sprocket would it take to get this in gearbox form (would be using 4 sprockets) because i'm limited on space and smaller sprockets are cheaper.

I think you divide the 2nd gear by the first, then the 4th by the third and so on, until you have all the ratios identified, then multiply them together to get the final ratio, or something like that- its been far to long since I was at school to remember the exact method. Im sure Brian could help though, he's better at that stuff than most... :yes:

Yeah, just divide the output gear (usually larger) by the input gear (usually smaller) together. And then multiply those ratios together.

If there are 3 gears (like the idler gear setup in the emaxx tranny), just divide the output gear by the input gear. You could divide the idler by the input, and then the output by the idler, but the result is the same.

Here is a file I found on my computer, you'll find it very usefull

Yea that helps, thanks:wink:.