Synsets for "fusee drive"

Synset: fusee_drive.n.01

Synonyms: fusee_drive

Part of Speech: NOUN

Definition: a spirally grooved spindle in a clock that counteracts the diminishing power of the uncoiling mainspring


Lemmas: fusee_drive fusee

Hypernym: drive




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Fusee (horology) Most fusee clocks include a 'winding stop' mechanism to prevent the mainspring and fusee from being wound up too far, possibly breaking the chain. As it is wound, the fusee chain rises toward the top of the fusee. When it reaches the top, it presses against a lever, which moves a metal blade into the path of a projection sticking out from the edge of the fusee. As the fusee turns, the projection catches on the blade, preventing further winding.
Fusee (horology) The gear on the fusee drives the movement's wheel train, usually the center wheel. There is a ratchet between the fusee and its gear (not visible, inside the fusee) which prevents the fusee from turning the clock's wheel train backwards while it is being wound up. In quality watches and many later fusee movements there is also a "maintaining power" spring, to provide temporary force to keep the movement going while it is being wound. This type is called a "going fusee". It is usually a planetary gear mechanism (epicyclic gearing) in the base of the fusee "cone") which then provides turning power in the opposite direction to the 'winding up' direction therefore keeping the watch or clock running during winding.
Fusee (horology) The mainspring is coiled around a stationary axle (arbor), inside a cylindrical box, the barrel. The force of the spring turns the barrel. In a fusee clock, the barrel turns the fusee by pulling on the chain, and the fusee turns the clock's gears.
Romain Gauthier Logical One is a reinvention of the chain-and-fusee constant force mechanism, with a snail cam replacing the cone-shaped fusee.
Pocket watch Many keywind watch movements make use of a fusee, to improve isochronism. The fusee is a specially cut conical pulley attached by a fine chain to the mainspring barrel. When the spring is fully wound (and its torque the highest), the full length of the chain is wrapped around the fusee and the force of the mainspring is exerted on the smallest diameter portion of the fusee cone. As the spring unwinds and its torque decreases, the chain winds back onto the mainspring barrel and pulls on an increasingly larger diameter portion of the fusee. This provides a more uniform amount of torque on the watch train, and thus results in more consistent balance amplitude and better isochronism. A fusee is a practical necessity in watches using a verge escapement, and can also provide considerable benefit with a lever escapement and other high precision types of escapements (Hamiltons WWII era Model 21 chronometer used a fusee in combination with a detent escapement).
Fusee (horology) The fusee was a good mainspring compensator, but it was also expensive, difficult to adjust, and had other disadvantages:
Singing bird box All the above mentioned Swiss renowned maestros employed a fusee-driven movement without exception.
Stackfreed The stackfreed was a very inefficient device. Since it worked by exerting an opposing friction force on the mainspring, it required more powerful mainsprings and higher gear ratios in watches, which may have introduced more variation in drive force. The fusee, the other mainspring compensation device, was much more efficient. The only advantages of the stackfreed were that it was easier to make and much thinner than the fusee, which, combined with the fact that it was located in unused space on the outside of the back plate, allowed stackfreed watches to be flatter. With the development of narrower, more compact fusees, the stackfreed disappeared from timepieces around 1630.
Fusee (horology) Around 1726 John Harrison added the maintaining power spring to the fusee to keep marine chronometers running during winding, and this was generally adopted.
Jean-Antoine Lépine The Lépine calibre uses bars and bridges instead of pillars and upper plates. As mentioned, the movement has no fusee which equalizes the driving power transmitted to the train, replaced instead by a going barrel to drive the train directly. This improvement was facilitated by using the cylinder escapement and enhanced springs.
History of watches The going barrel invented in 1760 by Jean-Antoine Lépine provided a more constant drive force over the watch's running period, and its adoption in the 19th century made the fusee obsolete. Complicated pocket chronometers and astronomical watches with many hands and functions were made during this period.
Fusee (horology) The origin of the fusee is not known. Many sources erroneously credit clockmaker Jacob Zech of Prague with inventing it around 1525, but it actually appeared with the first spring driven clocks in the 15th century. The idea probably did not originate with clockmakers, since the earliest known example is in a crossbow windlass shown in a 1405 military manuscript. Drawings from the 15th century by Filippo Brunelleschi and Leonardo da Vinci show fusees. The earliest existing clock with a fusee, also the earliest spring-powered clock, is the "Burgunderuhr" (Burgundy clock), a chamber clock whose iconography suggests that it was made for Phillipe the Good, Duke of Burgundy about 1430, now in the Germanisches Nationalmuseum The earliest definitely dated fusee clock was made by Zech in 1525. The word fusee comes from the French "fusée" and late Latin "fusata", 'spindle full of thread'.
Fusee (horology) Two solutions to this problem appeared with the first spring driven clocks; the "stackfreed" and the fusee. The stackfreed, a crude cam compensator, added a lot of friction and was abandoned after less than a century. The fusee was a much more lasting idea. As the movement ran, the tapering shape of the fusee pulley continuously changed the mechanical advantage of the pull from the mainspring, compensating for the diminishing spring force. Clockmakers apparently empirically discovered the correct shape for the fusee, which is not a simple cone but a hyperboloid. The first fusees were long and slender, but later ones have a more squat compact shape. Fusees became the standard method of getting constant force from a mainspring, used in most spring-wound clocks, and watches when they appeared in the 17th century.
Fusee (horology) At first the fusee cord was made of gut, or sometimes wire. Around 1650 chains began to be used, which lasted longer. Gruet of Geneva is widely credited with introducing them in 1664, although the first reference to a fusee chain is around 1540. Fusees designed for use with cords can be distinguished by their grooves, which have a circular cross section, where ones designed for chains have rectangular-shaped grooves.
Fusee (horology) Used in antique spring-powered mechanical watches and clocks, a fusee is a cone-shaped pulley with a helical groove around it, wound with a cord or chain which is attached to the mainspring barrel. Fusees were used from the 15th century to the early 20th century to improve timekeeping by equalizing the uneven pull of the mainspring as it ran down. Gawaine Baillie stated of the fusee, "Perhaps no problem in mechanics has ever been solved so simply and so perfectly."
Flare Fusees are also known as "railroad flares" and are commonly used to perform hand signals in rail transport applications. Since they can be used only once, fusees nowadays are usually intended for emergency use (as opposed to the lanterns typically used during normal operating conditions). However, in the days before train radio communications, fusees were used to keep trains apart in dark territory. A railroad fusee was timed to burn for ten minutes and quantities were dropped behind a train to ensure a safe spacing. If a following train encountered a burning fusee it was not to pass until the fusee burned out. Fusees made specifically for railroad use can be distinguished from highway fusees by a sharp steel spike at one end, used to embed the fusee upright in a wooden railroad tie.
Fusee (horology) Achieving isochronism was recognised as a serious problem throughout the 500-year history of spring-driven clocks. Many parts were gradually improved to increase isochronism, and eventually the fusee became unnecessary in most timepieces.
Verge escapement In pocketwatches, besides its inaccuracy, the vertical orientation of the crown wheel and the need for a bulky fusee made the verge movement unfashionably thick. French watchmakers adopted the thinner cylinder escapement, invented in 1695. In England, high end watches went to the duplex escapement, developed in 1782, but inexpensive verge fusee watches continued to be produced until the mid 19th century, when the lever escapement took over. These later verge watches were colloquially called 'turnips' because of their bulky build.
Balance spring There is also a Barrow Regulator, but this is really the earlier of the two principal methods of giving the Mainspring "set-up tension"; that required to keep the Fusee chain in tension but not enough to actually drive the Watch. Verge Watches can be regulated by adjusting the set-up tension, but if any of the previously described Regulators is present then this is not usually done.
Mechanical watch As new kinds of escapements were created which served to better isolate the watch from its time source, the balance spring, watches could be built without a fusee and still be accurate.