Cylinder Escapements

The cylinder escapement is one of the most important and iconic components of a mechanical watch. It is a key component that regulates the timekeeping accuracy of a watch, and it has played an important role in the history of watchmaking.

History of the Cylinder Escapement

In 1695, Thomas Tompion, a renowned English clockmaker, invented the cylinder escapement, also known as the horizontal escapement due to its orientation. George Graham, an apprentice of Tompion, further refined the invention in 1726. The cylinder escapement replaced the vertical verge escapement that was used prior.

Despite its advantages, the cylinder escapement did not receive widespread adoption among English watchmakers. However, it was widely used in France and Switzerland until the early 20th century. The advent of the English Lever escapement in the early 19th century eventually led to the abandonment of the cylinder escapement in England.

The cylinder escapement’s main advantage was its relatively thin design, which allowed for the creation of thinner pocket watches compared to those made with the verge escapement. However, like the verge escapement, the cylinder escapement suffered from excessive wear due to the constant contact between its components throughout the cycle. This issue was particularly prevalent in brass and steel movements used by English watchmakers. In contrast, French and Swiss watchmakers reduced wear and tear by using hardened steel and jewelled cylinders made from ruby.

Mechanics of the Cylinder Escapement

The cylinder is part of the balance staff, on top of which, the balance wheel sits. A section of the cylinder has been cut out, as seen in the diagram. As the escape wheel’s teeth engage with the cylinder, they interact with both the cylinder’s inner cut-out section and its solid outer wall. When a tooth enters the cut-out section, it pushes against the inner wall to transfer power from the gear train to the balance wheel. The subsequent tooth on the escape wheel then locks against the outer wall of the cylinder. Consequently, the balance wheel rotates, which causes the cylinder to turn and reveal the cut-out section. This action allows the tooth to be released from the outer wall and enter the cut-out, transferring more power to the balance wheel. This cycle repeats, allowing the watch to function smoothly.

The pros and cons of the cylinder escapement

The cylinder escapement was a significant innovation in the field of watchmaking. It was widely used in France and Switzerland until the early 20th century. Although the cylinder escapement had several advantages, it also had some limitations. Here are the pros and cons of the cylinder escapement in antique pocket watches:

Pros:

1. Thinness: The cylinder escapement was thinner than the verge escapement, allowing watchmakers to create thinner pocket watches, which were in vogue during the 18th century.
2. Simplicity: The cylinder escapement had a simple design, which made it easier to produce, assemble and service.
3. Durability: The cylinder escapement was more durable than the verge escapement because it had fewer moving parts and less friction, which reduced wear and tear.
4. Accuracy: The cylinder escapement had a steady and consistent motion, which made it more accurate than the verge escapement.

Cons:

1. Friction: The cylinder escapement had a lot of friction because its components were in constant contact throughout the cycle. This resulted in excessive wear and tear, particularly in brass and steel movements used by English watchmakers.
2. Limited power reserve: The cylinder escapement had a limited power reserve because it required a higher frequency of oscillation to function correctly.
3. Vulnerability to shock: The cylinder escapement was vulnerable to shock, which could disrupt its delicate mechanism and affect the watch’s accuracy.
4. Poor isochronism: The cylinder escapement had poor isochronism, meaning that its timekeeping accuracy was affected by the amplitude of the balance wheel.

In summary, the cylinder escapement was a significant advancement in watchmaking, with its thinness, simplicity, durability and accuracy making it a popular choice in France and Switzerland. However, its friction, limited power reserve, vulnerability to shock and poor isochronism were significant drawbacks. Despite these limitations, the cylinder escapement remained in use until the advent of the English Lever escapement in the early 19th century, which eventually led to its abandonment in England.