In horology, a movement is the internal mechanism of a clock or watch, as opposed to the case, which encloses and protects the movement, and the face which displays the time. The term originated with mechanical timepieces, whose movements are made of many moving parts. It is less frequently applied to modern electronic or quartz timepieces, where the word module is often used instead.
In modern mass produced clocks and watches, the same movement is often put into many different styles of case. When buying a quality pocketwatch from the mid 19th to the mid 20th century, for example, the customer would separately pick out the movement and the case of his choice, and the movement would be installed in the case for him. Mechanical movements get dirty and the lubricants dry up, so they must periodically be disassembled, cleaned, and lubricated. One source recommends servicing intervals of: 3-5 years for watches, 15-20 years for grandfather clocks, 10-15 years for wall or mantel clocks, 15-20 years for anniversary clocks, and 7 years for cuckoo clocks, with the longer intervals applying to antique timepieces.[1]
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Mechanical movements
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| Mechanical movement, Deutsches Museum, München |
A mechanical movement contains all the moving parts of a watch or clock except the hands, and in the case of pendulum clocks, the pendulum and driving weights. The movement is made up of these parts: [2]
- Power source: either a mainspring, or a weight suspended from a cord wrapped around a pulley. The mainspring or pulley has a mechanism to allow it to be wound up, which includes a ratchet to prevent it from unwinding. The barrel or pulley has gear teeth on it which drives the center wheel.
- Wheel train: a gear train that transmits the force of the power source to the escapement. Large gears known as wheels mesh with small gears known as pinions. The wheels in a typical going train are the centre wheel, third wheel, and fourth wheel. A separate set of wheels, the motion work, divides the motion of the minute hand by 12 to move the hour hand, and in watches another set, the keyless work, allows the hands to be set.
- Escapement: a mechanism that allows the wheel train to advance or 'escape' a fixed amount with each swing of the balance wheel or pendulum. It consists of a gear called an escape wheel, which is released one tooth at a time by a lever that rocks back and forth. Each time the escape wheel moves forward it also gives the pendulum or balance wheel a push to keep it moving.
- Oscillator: the timekeeping element, either a pendulum or a balance wheel. It swings back and forth, with a precisely constant time interval between each swing, called the beat. A pendulum movement has a pendulum hangar usually attached to a sturdy support on the back, from which the pendulum is suspended, and a 'fork' which gives the pendulum impulses. The oscillator always has some means for adjusting the rate of the clock. Pendulums usually have an adjustment nut under the bob, while balance wheels have a regulator lever on the balance spring.
Mechanical watch movements
Watch movements come in various shapes to fit different case styles, such as round, tonneau, rectangular, rectangular with cut corners, oval and baguette, and are measured in "lignes", or in millimeters. Each specific watch movement is called a caliber. (see a listing of the main Swiss calibers: [1] ). The movement parts are separated into two main categories: those belonging to the ébauches and those belonging to the assortments.[2]
In watch movements the wheels and other moving parts are mounted between two plates, which are held a small distance apart with pillars to make a rigid framework for the movement. One of these plates, the front plate just behind the face, is always circular, or the same shape and dimensions as the movement. The back plate had various shapes:
- Full plate movement - In this design, used in the earliest pocketwatches until the 1700s, the back plate was also circular. The balance wheel was mounted on the outside of the back plate, held by a bracket called the 'balance cock'.
- Three-quarter plate movement - In the 1700s, to make movements thinner, part of the back plate was cut away to make room for the balance and balance cock.
- Bridge movement - In modern watch movements, the back plate is replaced with a series of plates or bars, called bridges. This makes servicing the movement easier, since individual bridges and the wheels they support can be removed and installed without disturbing the rest of the movement. The first bridge movements, in Swiss pocketwatches from around 1900, had three parallel bar bridges to support the three wheels of the going train. This style is called a 'three finger' or 'Geneva' movement.
Moreover, Mechanical Watch Movement has 2 types: Manual and Automatic.
- Manual or Hand winding movement is a watch movement needs the wearer to turn the crown regularly in order to wind the mainspring.
- Automatic watch movement is a watch movement can wind the mainspring automatically when the wearer swings the watch that is being worn.
See also
References
- ^ "Clock Services and Repairs". Grandfather Clock Manufacturers and Antique Clock Repairs. Affordable Clocks. 2008. http://www.affordableclocks.co.za/clocks_services_and_repairs.html. Retrieved 2008-07-09.
- ^ a b "Glossary". Federation of the Swiss Watch Industry. 2008. http://www.fhs.ch/en/glossary.php. Retrieved 2008-07-09.
External links
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