A Roskopf, pin-lever, or pin-pallet escapement is an inexpensive, less accurate version of the

lever escapement The lever escapement, invented by the English clockmaker Thomas Mudge in 1754 (albeit first used in 1769), is a type of escapement that is used in almost all mechanical watches, as well as small mechanical non-pendulum clocks, alarm clocks, a ...

, used in mechanical

alarm clock An alarm clock or alarm is a clock that is designed to alert an individual or group of people at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they can sometimes be used for o ...

s, kitchen

timer A timer or countdown timer is a type of clock that starts from a specified time duration and stops upon reaching 00:00. It can also usually be stopped manually before the whole duration has elapsed. An example of a simple timer is an hourglass ...

mantel clock Mantel clocks—or shelf clocks—are relatively small house clocks traditionally placed on the shelf, or mantel, above the fireplace. The form, first developed in France in the 1750s, can be distinguished from earlier chamber clocks of simi ...

s and, until the 1970s, cheap

watch A watch is a timepiece carried or worn by a person. It is designed to maintain a consistent movement despite the motions caused by the person's activities. A wristwatch is worn around the wrist, attached by a watch strap or another type of ...

es now known as pin lever watches. It was popularized by German watchmaker Georges Frederic Roskopf in its "proletarian watch" from 1867. It was invented in 1798 by Louis Perron, of Besançon, and suggested to Roskopf by Jules Grossmann.

Background

escapement An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy to t ...

is the mechanism in a mechanical timepiece that gives the

balance wheel A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position b ...

pushes to keep it moving back and forth, and releases the timepiece's gears to advance a fixed amount with each swing of the wheel, thus moving the hands forward at a steady rate. The pin pallet escapement is similar to the lever escapement, which is used in quality watches, except that the horizontal jewel

pallets A pallet (also called a skid) is a flat transport structure, which supports goods in a stable fashion while being lifted by a forklift, a pallet jack, a front loader, a jacking device, or an erect crane. Many pallets can handle a load o ...

on the

lever A lever is a simple machine consisting of a beam (structure), beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, l ...

are replaced with vertical metal pins, and the shape of the escape wheel teeth is modified. The pin pallet escapement was widely used as it had many of the advantages of the lever escapement but was easier to manufacture. The pallets in a traditional lever escapement have two angled faces, the locking face and the impulse face, which engage the escape wheel teeth. They must be adjusted to precisely correct angles for the escapement to function. In the pin pallet escapement these faces are designed into the shape of the escape wheel teeth instead, eliminating the need for costly adjustments. However, the metal pins used instead of pallets have much higher friction than jewelled pallets, and combined with the looser manufacturing tolerances this made pin pallet timepieces less accurate. The metal pins also wear more quickly. Pin pallet timepieces are usually too cheap to justify repairing, and are usually thrown away when they break down or wear out.

History

Roskopf used the escapement in his visionary project to manufacture a 'laborer's watch', a

pocket watch A pocket watch is a watch that is made to be carried in a pocket, as opposed to a wristwatch, which is strapped to the wrist. They were the most common type of watch from their development in the 16th century until wristwatches became popula ...

, which would sell for less than a week's wages of an unskilled laborer. The innovative Roskopf watch, which came out in 1876, won awards and was widely imitated, being made in various forms until about 1925. In the US, the escapement was used in cheap dollar watches. It continued to be used in cheap wristwatches when they gained popularity after

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. To keep costs down, pin-pallet watches usually didn't have any jeweled bearings, using plain steel bearings instead, although sometimes one jewel was incorporated for advertising purposes. An exception is Timex and Oris who in the 1960s produced fully jeweled pin-pallet watches. By 1980 inexpensive quartz watches took over the market for low-end watches which pin pallet watches had dominated, and production ceased. Quartz technology is gradually replacing the last uses of pin pallet movements in timers and alarm clocks.

Brocot escapement

Another escapement also called a "pin pallet escapement", unrelated to the Roskopf above, is the Brocot escapement, invented in 1823 by Louis-Gabriel BrocotFrench patent 02903 and improved by his son

Achille Achille (, ) is a French and Italian masculine given name, derived from the Greek mythological hero Achilles. It may refer to: People Artists * Achille Beltrame (1871–1945), Italian painter * Achille Calici (c. 1565–?), Italian painter * ...

, and used in 19th century French pendulum clocks. It is a variation of the

anchor escapement In horology, the anchor escapement is a type of escapement used in pendulum clocks. The escapement is a mechanism in a mechanical clock that maintains the swing of the pendulum by giving it a small push each swing, and allows the clock's wheels ...

in which the pallets are semicircular pins. The escapement is often revealed in a cutout on the clock's face.

References

External links

* *:Has a picture and schematic of the pin-pallet escapement mechanism. * * {{Authority control Escapements Watches Watchmaking Timekeeping components