Geneva Drive?

[NanoDuke]

I just came across this little piece of machinery while browsing the Makezine.com website:
http://en.wikipedia.org/wiki/Geneva_wheel

By having two "overlapping" wheels and some geometry trickery, you essentially have a very tight gear(?) with a very distinct ratio. For every 360* turn of the primary gear, the secondary turns by 60 degrees (or 90 degrees, depending on how you cut the channels). I think that 90* is the largest rotation you can have.

The mechanism feels like the internal workings of the Master Lock "Speed Dial".

I've posted this in TOSL on the idea that having such a tight mechanism could be beneficial in improving dial/combination locks. Or maybe it could be applied to a lever lock, somehow.

[98AB49DC5A]

master axis lock uses a stepping cam similar to a pen which turns three of four wheels within the lock each time the user enters a step
more info here

http://toool.nl/images/e/e5/The_New_Mas ... k_V2.0.pdf

simple simulator here

http://theopensourcelock.huebler.org/re ... V2.0_p.swf

[alexdwsn12]

The Geneva drive or Maltese cross is a mechanism that translates a continuous rotation into an intermittent rotary motion. The drive wheel also has a raised circular blocking disc that locks the driven wheel in position between steps. Its really effective and reliable driver.