Guide

Driving Gear Driving Gear Driving Gear
Driven Gear
Driven Gear
Driven Gear
Mechanisms: Gear Ratio
Gear Ratio Basics (Grades 2-8)
As you learned in other lessons, making a Gear Ratio change is one of the easiest ways to change
Mechanical Advantage in a mechanism or system to achieve desired speed and/or torque. Gear
Ratio expresses the relationship between a Driving Gear (the gear connected to the input power
source, such as a motor) and a Driven Gear (the gear connected to the output, such as a wheel or
mechanism) in a system.
When you have a system with a Driving Gear that is SMALLER than the Driven Gear you will
increase Torque and decrease Speed:
Making this kind of change to Mechanical Advantage is helpful when you are trying to move
slower mechanically, lift heavier objects, and/or have more pushing ability.
When you have a system with a Driving Gear that is LARGER than the Driven Gear you will
increase Speed and decrease Torque:
Making this kind of change to Mechanical Advantage is helpful when you are trying to lift or move
faster mechanically, you don’t require the ability to lift heavy objects, and/or you favor agility over
pushing ability in a drivetrain.
G.3