Rings of Gears and the British Two Pound Coin

Gears turn in alternate directions. In the example, left the blue gear turns anti-clockwise, the two green gears on either side of it are then driven clockwise, these in turn drive the yellow and purple gears anti-clockwise and so on...

A ring of gears containing an even number of gears turns freely, as you can see, but imagine a ring with an odd number of gears , image that the blue gear is removed, you will see that the two green gears be turning the same direction and so would not be able to turn, the gears would lock together.

Now, look at the ring of gears around the centre of the British two pound coin. Nineteen gears...!