Gear ratios

Equation 
A gear ratio compares how many times one gear turns relative to another. 

It’s written as a fraction:
Gear Ratio = Number of teeth on output gear ÷ Number of teeth on input gear

So, if a gear with 10 teeth (input) turns a gear with 20 teeth (output):

Gear Ratio = 20⁄10 = 2⁄1

This means:

 The input gear must spin 2 times for the output gear to spin once
 The output gear spins slower, but with more torque

Likewise, if the input gear has 20 teeth and the output has 10 teeth:

Gear Ratio = 10⁄20 = 1⁄2

This means:

 The output gear spins twice as fast, but with half the torque

 Gear Ratio Efficiency 

 Higher ratio (>1) = more torque, less speed
 Lower ratio (<1) = more speed, less torque

 References 
 "Determine Gear Ratio". WikiHow. A step-by-step guide and diagram explaining how to calculate gear ratios by comparing gear teeth or diameters. Available at: https://www.wikihow.com/Determine-Gear-Ratio
 "Gear Ratios". HowStuffWorks – Auto. An article explaining how gear ratios affect vehicle speed and torque in practical settings. https://auto.howstuffworks.com/gear-ratio.htm

Category:Engineering