Gear Ratio

The Gear Ratio is simply the number of teeth on the driver gear compared with the number of teeth on the driven gear. It is the term used with gearing to mean Velocity Ratio.

A gear will always rotate in an opposite direction to the gear it meshes with.

Note: If both gears have the same number of teeth, they will rotate at the same speed, however if they have different numbers of teeth then the gear with fewer teeth will rotate more quickly - i.e. the Velocity Ratio (or ‘Gear Ratio’) of a pair of meshing gears is given as the Number of Teeth of the Driver Gear divided by the Number of Teeth of the Driven Gear. The Mechanical Advantage (or ‘Torque Ratio’) similarly is given as No. of Teeth on Driven divided by No. of Teeth on Driver.

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