Dorrin K Mace, Horologost

Dorrin K Mace, Horologost
The Clock Man in a pensive moment

Thursday, March 8, 2012

What is an escapement

What does clock escapement mean?
It can be answered in a few words. It allows the power of the wound clock or watch to be allowed to 'escape' isochronously, or in equal time. If there was no escapement, you'd wind you watch and it would simply wind down at a terrific speed, the hands whipping around, until there was no more power left in the mainspring.
This, therefore, would render the watch useless as a timekeeper. At the top of the watch's or clock's gear train, there's a saw toothed wheel, into which stop pieces dip in and out of the teeth with each swing of the pendulum, or beat of the balance.
The pendulum runs to the left, then to the right. The balance, under the influence of a spring, oscillates much faster, but again to the left and the right. As soon as these pass a certain point, the stop piece that's been holding up the train from moving, is lifted clear and immediately the other one takes its place, causing the saw toothed wheel to revolve for half a tooth.
This, then, is the escapement. In the earliest clocks and watches, there were no balance springs in watches, nor any pendulums. The escapement, the saw toothed wheel together with the stop pieces, came under the direct influence of the mainspring. Now, this made for the most appalling time keeping. If the clock or watch kept time to within ten minutes an hour, it was doing very well!
This is purely an overview of the subject, so I don't intend to give dates or the names of inventors at this stage, but a very clever gentleman came up with the idea of actually controlling the escapement by way of a pendulum. The problem with this was that the arc of swing, or the distance it swung to the left and right, was so great, in excess of 100 degrees in many cases, that although it definitely improved timekeeping, for various other reasons, the timekeeping proved still to be very erratic.
Let's move into more modern times and by that I mean a couple of hundred years ago, when a brilliant clockmaker brought out an escapement that was regulated by the same sort of saw teeth, but this time the pendulum was relatively much heavier, and controlled the rate of the teeth leaving their stop pieces to a much finer degree.
This was known as The Royal Anchor Escapement, mainly because the stop piece frame was in the form of an anchor. These stop pieces, by the way, are known as 'pallets.' When you hear a clock or watch ticking, the sound you hear is the slap of the pallets on the teeth of the saw toothed wheel, which is known as the escape wheel.

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