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A point machine (also known as a point motor, switch machine or switch motor) is a device for operating railway turnouts especially at a distance. ==Overview== In the earliest times, railway turnouts were operated manually by simple levers. There are a number of different kinds of levers including throwover levers which stay in the last position thrown, and ball levers which revert to a standard position. Gradually the turnouts on main lines came to be operated at distances up to about 300 m by centralised levers in signal boxes, either by rods, or by double wire arrangements. Since the limitation of mechanical operation restricted the design of track layouts on the one hand, and tended to require more signal boxes, even lightly used ones, on the other hand, there has always been a desire of railway administrations to increase the distance that remote turnouts can be operated. This requires some kind of power operation of points and signals. The principal means of power operation include hydraulic, pneumatic and electric. More recently with the increase in weight of rail, and the introduction of high speed turnouts with finer angles requiring multiple drives, points have become stiffer and beyond the capability of mechanical drives, forcing the introduction of point machines if not already done so. 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「point machine」の詳細全文を読む スポンサード リンク
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