What is the number of teeth in gearing?
The number of teeth on a gear is called the number of teeth.
In the figure below, the number of teeth on the gear on the left side is 15 and the number of teeth on the pinion on the right side is 9.
The number of teeth of the gear divided by the number of teeth of the pinion is called the gear ratio.
The tooth profile of an involute gear changes with the number of teeth.
If the number of teeth becomes too small (if the number of teeth is less than 17 when the pressure angle is 20°), the root of the teeth is gouged during gear cutting and becomes thin. This is called undercutting. A positive correction to the gears has the effect of preventing undercutting.
On the other hand, when the number of teeth is increased, the tooth profile becomes straight like a gear rack, the root of the teeth becomes thicker, and the strength of the teeth increases.
