gears
A mechanical part of a clockwork system, a gear is a wheel with so-called flanks so it will interlock with other gears and spin. Radius of the wheel and edge sizes allow spinning at different speeds and thus make processing different. Obviously used the most in non-digital watches. An important part of steampunk culture.
See also
The following tags are aliased to this tag: cog, cogs, and gear (learn more).