Cuckoo Clock Information

I’m not yet in France, but today is Wednesday and time for a “How To” article.

As I mentioned yesterday, the verge escapement, is the mechanism in a mechanical clock like a grandfather clock, that controls its rate by advancing the gear train at regular intervals or ‘ticks’. The verge escapement drives a horizontal bar with weights on the ends called the foliot, a primitive type of balance wheel to oscillate back and forth.  Here’s how it works ….

The verge escapement consists of a wheel shaped like a crown, with saw tooth-shaped teeth protruding axially to the front. In front of it is a vertical rod, the verge, with two metal plates, the pallets, that engage the teeth at opposite sides of the crown wheel. The balance wheel (or the pendulum of a grandfather clock) is attached to the verge. The pallets are positioned so only one catches the teeth at a time. As the clock’s gears turn the crown wheel, it pushes the first pallet, rotating the verge in one direction, and rotating the second pallet into the path of the teeth, until the tooth pushes past the first pallet. Then a tooth on the wheel’s opposite side catches the second pallet, rotating the verge back the other direction, and the cycle repeats. The result is to change the rotary motion of the wheel to an oscillating motion of the verge. Each stroke of the foliot or pendulum thus advances the wheel train of the clock, moving the hands forward at a constant rate.
The crown wheel must have an odd number of teeth for the escapement to function. The usual angle between the pallets was 90° to 105°, resulting in a foliot or pendulum swing of around 80° to 100°.

More from Italy tomorrow.