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In horology, the anchor escapement is a type of escapement used in pendulum clocks. The escapement is a mechanism in a mechanical clock that maintains the swing of the pendulum by giving it a small push each swing, and allows the clock's wheels to advance a fixed amount with each swing, moving the clock's hands forward. The anchor escapement was so named because one of its principal parts is shaped vaguely like a ship's anchor. The anchor escapement was probably invented by British scientist Robert Hooke〔 p.146〕 around 1657, although some references credit clockmaker William Clement〔 who popularized the anchor in his invention of the longcase or grandfather clock around 1680, and disputed credit for the escapement with Hooke.〔 The earliest known anchor clock is Wadham College Clock, a tower clock built at Wadham College, Oxford, in 1670, probably by clockmaker Joseph Knibb. The anchor became the standard escapement used in almost all pendulum clocks. A variation without recoil called the deadbeat escapement was invented by Richard Towneley around 1675 and introduced by British clockmaker George Graham around 1715. This gradually superseded the recoil escapement and is used in virtually all modern pendulum clocks with anchor escapements. ==How it works== The anchor escapement consists of two parts; the ''escape wheel'', which is a vertical wheel with pointed teeth on it rather like saw teeth, and the ''anchor'', shaped vaguely like a ship's anchor, which swings back and forth on a pivot just above the escape wheel. On the two arms of the anchor are curved flat faces which the teeth of the escape wheel push against, called ''pallets''. The central shaft of the anchor is attached to a fork pushed by the pendulum, so the anchor swings back and forth, with the pallets alternately catching and releasing an escape wheel tooth on each side. Each time one pallet moves away from the escape wheel, releasing a tooth, the wheel turns and a tooth on the other side catches on the other pallet, which is moving toward the wheel. The momentum of the pendulum continues to move the second pallet toward the wheel, pushing the escape wheel backwards for a distance, until the pendulum reverses direction and the pallet begins to move away from the wheel, with the tooth sliding along its surface, pushing it. Then the tooth slides off the end of the pallet, beginning the cycle again. Neither the anchor escapement nor the deadbeat form, below, are self-starting. The pendulum must be given a swing to get them going. 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「Anchor escapement」の詳細全文を読む スポンサード リンク
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