動力伝達といえば歯車でしょう。歯車と言ってもその種類は様々で、特殊な動きをする歯車もあります。

Non-circular gear
Even if the gear is non-c...

Intermittent gear
Intermittent gears can tr...

Geneva gear
Geneva gears can transmit...

Bevel gear
A gear used when the rota...

Pin gear
The pin gear has a number...

rack & pinion
A rack with gear teeth ar...

Internal gear
An internal gear is a gea...

Spur gear
The spur gear is an eleme...