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In horology, a movement, also known as a caliber, is the 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 clockwork 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 inserted 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 select movement and case individually. 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. ==Mechanical movements== 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 of the following components:〔 〕 ;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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Movement (clockwork)」の詳細全文を読む スポンサード リンク
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