LEGO Master Akiyuki of Akiyuki Brick Channel built a beautifully engineered LEGO clock using a mangle rack system. The system features a rack that moves in a reciprocating continuous circle on either side of the pinion. Akiyuki masterfully timed the completion of the circle every 60 seconds, allowing the clock to accurately tell the time.
I made a clock using mangle rack mechanism using LEGO bricks.
Here are other mangle rack ideas by the same channel.
via The Awesomer