how to find gear ratio
Start with a two-gear train. To be able to determine a gear ratio, you must have at least two gears attached to each other â this is called a gear train.. Usually, the first gear is a drive gear attached to the motor shaft and the second is a driven gear attached to the load shaft.. Divide the teeth numbers of the drive and driven gears. The important thing to remember when dealing with gear trains with more than two gears is that only the driver and driven gears (usually the first and last ones) matter. In other words, the idler gears don't affect the gear ratio of the overall train at all.