The history of gears can be traced back 300 BC, gears were explained in “Mechanical Problems” written by Aristotle, a famous Ancient Greek philosopher.
In Eastern Han Dynasty, about the 1st century AD, herringbone gears had emerged.
To the 14th century, gears began to be used on the watch and clock.
After the 18th century, the Industrial Revolution, a lot of researches on gears resulted in the rapid development of technologies.
After this, the involute gears became the most widely used gears.