The Swiss lever escapement is a detached lever escapement whose escape wheel has club-shaped teeth. It is prized for being robust, accurate and fairly easy to manufacture. Since around 1900, nearly all mechanical watches and other portable timepieces have used a lever escapement. The Swiss club-tooth form replaced the older English one.
How does a Swiss lever escapement work?
It is a detached escapement. For most of each swing, the balance wheel moves freely and does not touch the escapement at all. The pallets are set at an angle. Because of this, the escape wheel has to turn back slightly when it is unlocked. This is known as draw. On the balance sits a double roller. It is made of a large roller and a small roller, joined by a pipe. The teeth of the escape wheel can take one of two shapes, ratchet or club. The Swiss form uses club teeth.
Where it comes from
Thomas Mudge, a British clockmaker, is credited with inventing the lever escapement. His design was simple. That simplicity made it well suited to precise mass production, since a simple part is easier to make the same way many times over. The Swiss horologist Georges-Auguste Leschot helped to industrialise the Swiss lever escapement.
Not to be confused with
The English lever escapement is the older form. Its escape wheel has ratchet teeth, and those pointed teeth caused wear. The Swiss form gives the teeth a club shape instead. It wore less, and its pallet stones could be adjusted. For those reasons, the Swiss club-tooth form replaced the English ratchet-tooth form. Both are lever escapements, and both are detached.
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