Pin-pallet escapement

Pin-pallet escapement

A Roskopf, pin-lever, or pin-pallet escapement is an inexpensive, less accurate version of the lever escapement, used in mechanical alarm clocks, kitchen timers, mantel clocks and, until the 1970s, cheap watches now known as pin lever watches. It was invented and patented by German watchmaker Georges Frederic Roskopf in 1867, although the idea was conceived by French watchmaker Louis Perron in 1798, and suggested to Roskopf by Jules Grossmann.cite web
last = Bretscher
first = Ulrich
authorlink =
coauthors =
title = The Roskopf Watch
work = Pocket Watch Page
publisher = Ulrich Bretscher home page
date = November 9, 2007
url = http://www.musketeer.ch/watches/roskopf.html
format =
doi =
accessdate = 2008-07-05]

An escapement is the mechanism in a timepiece that gives the balance wheel pushes to keep it moving, and releases the timepiece's gears to advance a certain amount with each 'tick', or swing of the wheel. The pin pallet escapement is similar to the lever escapement, except that the horizontal jewel pallets on the lever are replaced with vertical metal pins, and the shape of the escape wheel teeth is modified.

The pin pallet escapement was widely used because it had many of the advantages of the lever escapement but was easier to manufacture. The pallets in a 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 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 quicker. 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 pocketwatch which would sell for less than a week's wages of an unskilled laborer. [cite book
last = Schaeder
first = Albin
authorlink =
coauthors =
title = The Proletarian Watch - A celebration of George Frederic Roskopf and his idea to produce a reliable and affordable watch for the great masses in the 19th century
publisher = Published by the author
date = undated (but 2007)
location = Sweden
pages = 215
url =
doi =
id =
isbn = 978-91-631-9608-9] . 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 USA, the escapement was used in cheap dollar watches. [cite web
last = Paige
first = Richard
title = The miracle of the pin lever movement
work = Community Articles
publisher = TimeZone.com
date =
url = http://www.timezone.com/library/comarticles/comarticles0031
format =
doi =
accessdate = 2008-07-02] It continued to be used in cheap wristwatches when they gained popularity after WW1. 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 [cite journal
last = French
first = Richard
authorlink =
coauthors =
title = Watches: Building a Collection, Part 1
journal = Horological Journal
volume =
issue =
pages = P.222-224
publisher = British Horological Institute
location = UK
date = June 2005
url = http://www.bhi.co.uk/hj/June%2005%20AOM.pdf
doi =
id =
accessdate = ] [cite web
title = The Oris Wristwatch
work = Wristwatches
publisher = Antique Pocket Watch Collecting for Pleasure and Profit
date =
url = http://www.antique-pocket-watch.com/oris-wristwatch.html#Auctions
format =
doi =
accessdate = 2008-07-06] who in the 1960s produced fully jeweled pin-pallet watches. By 1980 inexpensive quartz watches took over the market for pin pallet watches, and production ceased. Quartz technology is gradually replacing the last uses of pin pallet movements in timers and alarm clocks.

External links

*cite web
last = Bretscher
first = Ulrich
title = The Roskopf Watch
work = Pocket Watch Page
publisher = Ulrich Bretscher home page
date = November 9, 2007
url = http://www.musketeer.ch/watches/roskopf.html
format =
doi =
accessdate = 2008-07-05
*cite web
last = Paige
first = Richard
title = The miracle of the pin lever movement
work = Community Articles
publisher = TimeZone.com
date =
url = http://www.timezone.com/library/comarticles/comarticles0031
format =
doi =
accessdate = 2008-07-02

Footnotes


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