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

alarm clock An alarm clock (or sometimes just an alarm) is a clock that is designed to alert an individual or group of individuals at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they ar ...

s, kitchen

timer A timer is a specialized type of clock used for measuring specific time intervals. Timers can be categorized into two main types. The word "timer" is usually reserved for devices that counts down from a specified time interval, while devices th ...

s, mantel clocks and, until the 1970s, cheap

watch A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached ...

es now known as pin lever watches. It was popularized by German watchmaker

Georges Frederic Roskopf Georges Frederic Roskopf (15 March 1813 – 14 April 1889), the inventor of the pin-pallet escapement, was born in Germany and became a naturalized Swiss citizen. Early life and introduction In 1829, when Roskopf was 16, he went to La Chaux-de ...

in it "proletarian watch" from 1867. It was invented by Louis Perron, of Besançon, 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 ...

is the mechanism in a mechanical timepiece that gives the balance wheel 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. A pallet is the structural foundat ...

on the

lever A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or '' fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is d ...

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 (or pocketwatch) 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 wristwa ...

, 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 watch A dollar watch was a pocket watch or later, a wristwatch, that sold for about one US dollar. History of development Attempts to make a watch that could be sold for as little as a dollar began in the 1870s. By 1880, the Waterbury Watch Company, ...

es. It continued to be used in cheap wristwatches when they gained popularity after

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

. 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 Oris SA is a Swiss luxury manufacturer of mechanical watches. The company was founded in 1904 and is based in Hölstein in the canton of Basel-Landschaft. History Genesis and early growth Oris was founded by Paul Cattin and Georges Christ ...

who in the 1960s produced fully jeweled pin-pallet watches. By 1980 inexpensive

quartz watch Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical fo ...

es 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, and used in 19th century French pendulum clocks. It is a variation of the anchor escapement 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 Timekeeping components