Model: X12 English Clock Striking Train
This striking mechanism is sometimes called a rack and snail. The latter refers to shape of a stepped cam mechanism used to count the hours. According to the book by Britten (7th Ed.1956), it was invented by Edward Barlow in 1675. It gradually displaced the count wheel striking mechanism (X11) invented around 1330. It uses a fan damper to control the speed. This is one of Reuleaux's most complicated models and is clearly a dynamic machine rather than a pure geometric mechanism.
The input motion in this model is provided by the crank. In an actual system, this regular motion is supplied by the clock escapement as in Models X-1 to X-10. In this respect the combination of the 19th century escapement and striking mechanisms was a mechanical analog of the clock and CPU units of late 20th century computers.

Francis Moon 2001-00-00

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