Used in
mechanical watch
A mechanical watch is a watch that uses a Movement (clockwork), clockwork mechanism to measure the passage of time, as opposed to quartz watches which function using the vibration modes of a piezoelectric quartz tuning fork, or radio clock, radio ...
es and
clock
A clock or chronometer is a device that measures and displays time. The clock is one of the oldest Invention, human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, a ...
s, a barrel is a cylindrical metal box closed by a cover, with a ring of gear teeth around it, containing a spiral spring called the
mainspring
A mainspring is a spiral torsion spring of metal ribbon—commonly spring steel—used as a power source in mechanical watches, some clocks, and other clockwork mechanisms. ''Winding'' the timepiece, by turning a knob or key, stores energy in ...
, which provides power to run the timepiece. The barrel turns on an arbor (axle). The spring is hooked to the barrel at its outer end and to the arbor at its inner end. The barrel teeth engage the first
pinion of the
wheel train of the watch, usually the center wheel.
[{{Cite book , last=Hood , first=Grant , url=https://books.google.com/books?id=1UQxAQAAMAAJ , title=Modern Methods in Horology , date=1904 , publisher=Kansas City Jeweler and Optician , pages=44 , language=en] Barrels rotate slowly: for a watch mainspring barrel, the rate is usually one rotation every 8 hours. This construction allows the mainspring to be wound (by turning the arbour) without interrupting the tension of the spring driving the timepiece.
Types
; Plain barrel: I.e. without teeth, used in
fusee watches and clocks. A chain, or cord, was wound around the plain barrel, connecting it to the fusee.
; Going barrel: The form used in modern watches, is wound by turning the arbor and drives the watch movement by a ring of teeth around the barrel. This enables the mainspring to continue running the watch while it is being wound. Invented by
Jean-Antoine Lépine.
; Hanging barrel: A version of the going barrel that to save space is supported by the movement only at its upper end.
; Motor, or safety, barrel: Used in
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 ...
es around 1900, a reverse variant of the going barrel in which the spring is wound by turning the barrel, and turns the watch movement by the central arbor. The purpose of this arrangement was that if the spring breaks, destructive recoil forces would not be applied to the vulnerable
gear train
A gear train or gear set is a machine element of a mechanical system formed by mounting two or more gears on a frame such that the teeth of the gears engage.
Gear teeth are designed to ensure the pitch circles of engaging gears roll on each oth ...
.
References
External links
FH glossary
Timekeeping components