Steam locomotive lighting
When night operations of the steam locomotive began, railway companies in some countries equipped their locomotives with lights to allow the driver to see what lay ahead of the train or to enable others to see the locomotive.
Steam locomotive original headlights were oil or acetylene lamps, but when electric arc lamps became available in the late 1880s, they quickly replaced the older types.
Britain did not adopt bright headlights as they would affect night-adapted vision and so could mask the low-intensity oil lamps used in the semaphore signals and at each end of trains, increasing the danger of missing signals especially on busy tracks.
In any case, trains' stopping distances were normally much greater than the range of headlights, and the railways were well-signaled and fully fenced to prevent livestock and people from straying onto them.
In some countries heritage steam operation continues on the national network. Some railway authorities have mandated powerful headlights on at all times, including during daylight. This was to further inform the public or track workers of any active trains.
Steam locomotives used bells and steam whistles from earliest days. In the United States, India and Canada bells warned of a train in motion. In Britain, where all lines are by law fenced throughout, bells were only a requirement on railways running on a road which was not fenced off, for example a tramway along the side of the road or in a dockyard.
Consequently only a minority of locomotives in the UK carried bells. Whistles are used to signal personnel and give warnings. Depending on the terrain the locomotive was being used in the whistle could be designed for long distance warning of impending arrival, or more for localized use.
Early bells and whistles were sounded through pull-string cords and levers. Automatic bell ringers came into widespread use in the U.S. after 1910.
From early in the 20th century operating companies in such countries as Germany and Britain began to fit locomotives with in-cab signaling which automatically applied the brakes when a signal was passed at "caution". In Britain these became mandatory in 1956.
In the United States and Australia the trailing truck was often equipped with an auxiliary steam engine which provided extra power for starting. This booster engine was set to cut out automatically at a certain speed.
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