The "Clock Works" - The Escapement

“Just like clock works” is a saying often used today, but what makes a clock go “tick tock”? Often described as “clock works” is something more accurately known as the escapement. The escapement is the heard of any clock, whether powered by electricity, weight or spring, it is the action of the escapement that allows the clock mechanism to proceed forward and mark off the passage of time. It is also what makes the familiar tick tock sound.

The very earliest clock works or escapement was the Verge Escapement. Here a wheel that looked a bit like a crown (hence the name – crown wheel), was allowed to move forward by the action of two pallets that would in turn make contact with the crown wheel teeth stopping then allowing the movement to occur.

The earliest form of the verge was controlled by a Foliot, a rotating horizontal bar that had two adjustable weights positioned at the end of the bar. To make the foliot run faster the weights could be positioned closer to the centre of the bar, further out to make it run slower. This was the only adjustment that could be made, apart from adding or subtracting weight to the driving weight. This type of clock escapement will be found in the very early clocks right up to the bracket clocks of the mid to late 1800s.

The verge escapement was accurate to about 30 minutes per day, which although now seems awful, back in the early 1300s it was a revolution.

A replacement the verge, the Anchor Escapement, was not achieved until about 1670. Nobody knows for certain who the actual inventor was, but famous names such as Knibb, Hooke & Clement are associated with the examples of such clock escapements from the 1670s. Another name for the Anchor escapement is the Recoil Escapement, so-called because the escape wheel can be seen to recoil backwards after each advancement.

In a longcase clock works many recoil escapements will be seen with a second hand connected directly to the escape wheel. The recoil can be easily seen by watching this hand move backwards after each tick and tock. In order that the second hand moves through 60 seconds the escape wheel will more often than not comprise of 30 teeth, each accounting for 2 seconds of time.

Although the anchor escapement was a vast improvement in terms of clock works accuracy, it still suffered from various errors that were discovered as technology and understanding of the science of horology improved.

Various escapements were developed after the anchor to try to improve timekeeping, some notable developments are the Lever and Detent Escapements. The Lever, by Thomas Mudge was an important improvement that became widely used, especially in watches. It improved accuracy by way of its almost detached balance wheel.

This escapement was further developed by Antoine Lechaud who, in 1842, assisted the Swiss establish a better machine production facility. The Swiss were seriously lagging behind the US in this regard and when they sent an envoy to the US to discover why, they were stunned by the progress the Americans had made in automated clock and watch part manufacture.

The Detent Escapement – an important escapement developed especially for the Marine Chronometer, in which the balance wheel moves a detent, releasing the escape wheel which then moves forward to contact the detent once more. Moving only in one direction and with a detached movement helps to make this a highly accurate timekeeper used universally for accurate clocks worldwide.

Happy Collecting!

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