Classic sources on gears:

- "Spinning Levers", a Jam Handy film.[1] This is a good basic intro to what gears really do.

- "Gearology" from Boston Gear.[2] This is what you need to know to buy gears.

The original article talks a lot about involute gears, but doesn't explain a key motivation for that tooth form. An involute gear will mesh with a straight-sided rack, which can be thought of as an infinite-radius gear. All gears which will mesh with the same rack will mesh with each other. So you only need N gear sizes, not N^2.

This only works for spur gears. Worm gears and helical gears are matched pairs.

[1] https://archive.org/details/0762_Spinning_Levers_04_45_20_00

[2] https://web.archive.org/web/20100602093101/https://www.bosto...

See also https://www.youtube.com/@thang010146/videos - more than 3000 mechanical animations

What js library is being used for the visuals?

Here is previous discussion about that: https://news.ycombinator.com/item?id=27000223

It is very interesting how pure JS is so light weight. The page just runs blazingly fast.

Compare it with websites bloated with all those tracking scripts that fail to load in 30 seconds.

Damn, the latest "new" reddit takes few seconds to render, when i.reddit / old.reddit was blazingly fast.