HOME WEB NEWS IMAGES CLASSIFIEDS YELLOW PAGESPOLLS - SURVEYS WIKI COUNTRIES PHOTOS US UK INDIA
Cities Stocks Weather Movies Coupons Travel Blogs Health Horoscope Maps ASIA EUROPE Classifieds Yellow Pages
 1
|
|
|
It has been suggested that this article or section be merged into Mechanical watch. (Discuss) |
An automatic watch (also called a self-winding watch or, in Rolex movements, "perpetual") is a mechanical watch, typically with a balance wheel escapement, whose mainspring is wound by the motion of the wearer\'s arm automatically, instead of having to be wound manually every day.
Contents |
To accomplish this, the watch contains a fan-shaped rotor (a.k.a. a weight or an oscillating mass) within the watch case. The normal movements of the user\'s arm and wrist cause the rotor to pivot back-and-forth on its staff which is attached to a ratcheted winding mechanism. The motion of the wearer\'s arm is thereby translated into the circular motion of the rotor that through a series of reverser and reducing gears, eventually winds the mainspring. The fully-wound mainspring in a typical watch can store enough energy reserve for roughly two days; however, some models made specifically to have longer power reserves can last longer. Many automatic watches can also be wound manually by turning the crown (a notable exception is Seiko\'s wide-range of watches based on the company\'s 7S26 movement, which cannot be hand-wound).
On June 16, 1863, Adrien Philippe (of Patek Philippe) is credited with Patent No.58941, for the "slipping mainspring". This particular invention allowed the simultaneous winding of two or more mainspring barrels, certainly a different invention with a different purpose. However, the technology of his invention is said to be the foundation for the development of self-winding wristwatches.
This "slipping" spring allows the mainspring to slide or slip a few degrees relative to the inside of the barrel while still staying fully wound. The end of the slipping spring moves from one groove to another on the inside the barrel, stopping each time, and thus keeping the spring under constant tension.
This attachment of spring steel is sometimes referred to as a “bridle”. This bridle slips along the barrel wall before excess pressure is passed to the going train and causing a defect known as “banking.” Banking occurs when the balance amplitude is too high and the impulse jewel strikes the back of the horns of the pallet fork. The “bridle” must also grip the barrel wall sufficiently to not slip down either too rapidly, or too slowly, a defect known as “mainspring creep” which results in a shortened reserve power time. http://www.bhi.co.uk/hints/automsp.htm The slipping bridle on the outer end of the mainspring is illustrated here. (1). the bridle (in the barrel), (2) maintains outward pressure on the outermost coil of the mainspring (3). At less than full wind, the bridle pressure causes the outer tip of the spring to catch in a notch in the barrel wall (4) and maintain its position. As the mainspring reaches full wind, the outer end of the spring jumps out of the notch and releases tension by slipping across the smooth section of the barrel wall (5) until it catches in the next notch. See the photo illustration at TimeZone click here. "What exactly is...a slipping spring," hr: Watches March/April 2005 at page 90.
On some automatic watches the rotor and its action are visible through a transparent case back, called a display back or exhibition back. In these watches, the rotors are often engraved or decorated in some way. Rolex is one of the few automatic watch manufacturers that traditionally eschews the transparent case back, mainly for enhanced water resistance.
For people who do not wear their automatic watch every day, watch winders are available to store automatic watches and keep them wound. This is particularly advantageous if the watch had complex or perpetual calendars or moon phases. A watch winder is a device that can hold one or more watches and moves them in circular patterns to approximate the human motion that otherwise keeps the self-winding mechanism working. A mechanical watch should be kept wound and running as much as possible to prevent its lubricants from congealing over time, which diminishes accuracy. A full service (which involves disassembly, cleaning and re-lubrication) should be performed at least every five years to keep the movement as accurate as possible.
A more recent evolution of the automatic watch uses a self-winding mechanism to charge a battery or capacitor which in turn powers a quartz movement. This automatic quartz arrangement provides the accuracy of quartz without the need to replace the battery or capacitor until it reaches the end of its life, which may be decades.
The Swiss watchmaker Abraham-Louis Perrelet invented a self-winding mechanism in 1770 for fob watches. It worked on the same principle as a modern pedometer, and was designed to wind as the owner walked, using an oscillating weight inside the large watch that moved up and down. The Geneva Society of Arts reported in 1776 that fifteen minutes walking was necessary to wind the watch sufficiently for eight days, and the following year reported that it was selling well.Biography of Abraham Louis Perrelet
Perrelet sold some of his watches to a contemporary watch making luminary, Abraham-Louis Breguet who improved upon the mechanism in his own version of the design, calling his watches "perpetuelles" the French word for perpetual and possibly the source for Rolex\'s name for its automatic movements, the "Perpetual".Who invented the automatic watch? Timekeeping in Europe and China : Watches & Wonders timeline at Worldtempus.com
The mechanism was more successful in wristwatches because the rotor could operate every time that the owner moved his or her arm. However the first version did not appear until the 20th century. It was invented by a watch repairer from the Isle of Man named John Harwood in 1923Press release by UK Patent Office on 80th anniversary of self-winding watch patent, who took out a UK patent with his financial backer, Harry Cutts, on 7 July 1923, and a corresponding Swiss patent on 16 October 1923.Brainy History - 16 October 1923 The Harwood system used a pivoting weight which swung as the wearer moved, and which in turn wound the mainspring. When fully wound, the watch would run for 12 hours autonomously. It did not have a conventional stem winder, so the hands were moved manually by rotating a bezel around the face of the watch. The watches were first produced with the help of fine swiss watch manufacturer Fortis and went on sale in 1928 and 30,000 were made until the Harwood Self-Winding Watch Company collapsed in 1931 as a result of the Great Depression.
The Rolex Watch Company had taken up the design in 1930 and used it as the basis for the Rolex Oyster Perpetual, in which the centrally mounted semi-circular weight could rotate through a full 360 degrees rather than the 300 degrees of the original design. Rolex\'s version also increased the amount of energy stored in the mainspring, allowing it to run autonomously for up to 35 hours.
Most mechanical watches sold today are automatic. A notable exception is the Omega Speedmaster Professional "Moonwatch", the model first used by NASA astronauts during the Apollo Program, and which remains standard issue on all manned space flights.
Because a manually wound wristwatch does not require the weighted rotor which is necessary for an automatic watch, some extremely fine watch companies, such as Patek Philippe, continue to design manually wound watches, which can achieve a case thickness as low as 1.77 millimeters.
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia
