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A train whistle or air whistle (originally referred to as a steam trumpet) is an audible signaling device on a steam locomotive used to warn that the train is approaching, and to communicate with rail workers. The older steam whistles were almost always actuated with a pull cord (or sometimes a lever) that permitted proportional (tracker) action, so that some form of "expression" could be put into the sound. Many locomotive operators would have their own style of blowing the whistle, and it was often apparent who was operating the locomotive by the sound. Modern locomotives often make use of a pushbutton switch, which takes away the fine control over the way the whistle is sounded. Because trains generally have extremely high mass and relatively low braking friction, they are inherently difficult to stop at normal speeds. Some way of warning others of the approach of a train from a distance is necessary. Since train whistles were extremely inexpensive to institute compared to other more effective warning devices, the use of loud and distinct train whistles became the preferred solution for railway operators. ==History== John Holliday describes the history of train whistles as originating in 1832, by way of a stationmaster at the Leicester and Swannington Railway opening, who suggested that the trains should have an audible signaling device. A local musical instrument builder was commissioned to provide a steam-powered whistle, then known as a "steam trumpet". The article also describes a train collision with a cart, wherein the train used a horn blown by the driver (as steam whistles had not yet been invented). One account states that Weatherburn, the engine driver, had "mouthblown his horn" at the crossing in an attempt to prevent the accident, but that no attention had been paid to this audible warning, perhaps because it had not been heard. Although nobody was injured, the accident was deemed serious enough to warrant George Stephenson’s personal intervention. Stephenson subsequently called a meeting of directors and accepted the suggestion of the company manager, Ashlin Bagster, that a horn or whistle which could be activated by steam should be constructed and fixed to the locomotives. Stephenson later visited a musical instrument maker in Duke Street in Leicester, who, on Stephenson's instructions, constructed a "steam trumpet", which was tested in the presence of the Board of Directors ten days later. Stephenson mounted the whistle on the top of the boiler's steam dome, which delivers dry steam to the cylinders for locomotion. The device was apparently about high and had an ever-widening trumpet shape with a diameter at its top or mouth. The company went on to mount similar devices on its other locomotives. There is another account that sets the invention of the steam whistle against the actual opening of the line in 1832, rather than associating it with a specific incident. North American steam locomotive whistles have different sounds from one another. They come in many forms, from tiny little single-note shriekers (called "banshees" on the Pennsylvania Railroad) to larger plain whistles with deeper tones (a deep, plain train whistle is the "hooter" of the Norfolk & Western, used on their A- and Y-class Mallet locomotives). Even more well known were the multi-chime train whistles. Nathan of New York copied and improved Casey Jones's boiler-tube chime whistle by casting the six chambers into a single bell, with open "steps" on top to save on casting. This whistle is still considered the "king of train whistles". It is the most copied train whistle in the United States, and many railroads' shops cast their own version of it. Another very popular American train whistle was, again, a Nathan product. This was a five-note whistle, with a much shorter bell, and therefore, much higher in pitch. This whistle produced a bright G-major 6th chord (GBDEG) and, again, was heavily imitated, copies being made by many different railroads. The most popular American chime train whistle was the three-note version. These were either commercially made (Crosby, Lunkenheimer, Star Brass, Hancock Inspirator Co. among others) or shop-made by the railroads themselves. Some famous and very melodious shop-made train whistles were Pennsy's passenger chimes and the Baltimore and Ohio's step-top three chimes. But the most beloved of all three-chime train whistles to the public and railroaders alike were the deep-chorded "steamboat minor" long-bells. A well known commercially made chime was Hancock Inspirator Company's three-note step top. These found use on almost every American railroad. Some railroads copied these also, examples being found on the old St. Louis–San Francisco Railway and Illinois Central. The Southern Railway made three-chime train whistles. These were all distinctive, having top-mounted levers. They had short-bell three-chimes as well as their (highly copied) long-bell three-chimes on passenger engines, especially their PS4 engines, one of which resides today at the Smithsonian Institution. Two-note and four-note train whistles never caught on with North American railroads, with one exception: Canadian National Railway created a large four-chime step-top whistle for limited use on some of their locomotives. These were not common and only a few survive today in the hands of collectors. Otherwise, North American train whistles were of the single-note, three-note, five-note and six-note varieties. These are a few American railroads with whistles valued by collectors: * Southern Pacific – six-chimes * Union Pacific – Hancock "steamboat" three-chimes * Reading Railroad – high-pitched passenger six-chimes and 'hooter' freight whistles * Chicago, Burlington and Quincy Railroad – five-chimes and three-chimes * Baltimore and Ohio – three-chime step-tops and six-chimes * Grand Trunk – shop-made six-chimes (Nathan copies) * New York Central – shop-made six-chimes * Norfolk and Western – low pitched, distinctive sounding 'hooter' whistles * Pennsylvania Railroad - medium-pitched three-chimes and high-pitched 'Banshees' 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「Train whistle」の詳細全文を読む スポンサード リンク
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