How to Make a Slow Rpm Gear Drive a Faster Rpm Shaft Gear ratios and chemical compound gear ratios Working out simple gear ratios (two gears) A feature often requested in my gear plan is that information technology should calculate and display the gear ratio. The reason it does not have this feature is that the gear ratio is also the tooth count ratio (of the 2 gears), and that is a value that the user has to enter. At left, the two meshing gears with 7 teeth and 21 teeth volition take a ratio of 7:21 (which is the aforementioned every bit one:three). That is to say, the 7-molar gear will turn 3 times for ever ane plough of the 21-tooth gear. The logic is simple, each gear needs to rotate past the aforementioned number of teeth for them to mesh, so the 7-tooth gear, having one tertiary the teeth, needs to turn three times equally much Determining what gears you lot demand