# Gear Problem

1. Sep 7, 2015

### deuel18

I'm currently designing two gears meshed together. I know that the pinion gear must travel at 85 degrees from 0 while the driven gear must travel at 120 degrees from 0 - both gears must travel and stop at the same time. In addition, I do know that the pinion gear must be 1 inche in diameter. Is there a way, based on the information given, to calculate the radius of the driven gear? Thank you very much.

Last edited: Sep 7, 2015
2. Sep 7, 2015

### billy_joule

So for every 85 degrees the pinion rotates the other gear rotates 120 degrees.
We could also say if the pinion rotates at 85 rpm the other rotates at 120 rpm, can you work out the gear ratio now? and use that ratio to find the driven gears diameter?

3. Sep 7, 2015

### deuel18

I see. Thank you very much.

4. Sep 7, 2015

### billy_joule

You're welcome, good luck.
It's reasonably unlikely you'll be able to achieve the exact ratio with OTS (off the shelf, as opposed to bespoke) parts so you may need to alter your design.
Also, keep backlash in mind:
https://en.wikipedia.org/wiki/Backlash_(engineering)