What is the speed ratio of gears?
The speed ratio of gears is also called the gear ratio, the reduction ratio, etc.
In a single-stage gear train with a pair of meshing gears, as shown in the figure below, if Gear A (z1, n1) is the drive gear and Gear B (z2, n2) is the driven gear, the speed ratio of gears(i) can be calculated as follows.
(In this case, let z be the number of teeth and n be the number of gear rotations)
Speed ratio of gears (i)
= Number of teeth of Gear B (z2) / Number of teeth of Gear A (z1)
= Number of rotations of Gear A (n1) / Number of rotations of Gear B (n2)
In this case, Gear A is used as the drive gear, so it is decreasing in speed.
In all cases, the direction of rotation of both gears in this gear pair is opposite.
