The use of mechanical devices for lifting loads dates back at least to the time of the ancient Romans, who used platforms attached to pulleys in constructing buildings. In the 17th century, a crude passenger elevator known as the "flying chair" was invented. These early elevators were operated by human, animal, or waterpower.
By the early 19th century, steam was used to power machines that raised elevators. For about the first half of the century, elevators were almost always used for lifting freight. This was because the hemp ropes that supported and hauled the elevators were not strong enough to be safe for passenger use. In 1852, Elisha G. Otis designed and installed the first elevator with a safety device that prevented it from falling if the rope broke. Five years later, Otis's first safety elevator for carrying passengers was put into use in a store in New York City, and it was immediately declared a success.
Steam-powered elevators were used until the 1880s, when elevators powered by electricity were introduced. Subsequent design changes brought a series of improvements such as pushbutton operation, taller shafts, and faster speeds, so that the elevators could be used even in skyscrapers, and power doors and automatic operation, which made elevators more economical than they had been when human operators were necessary. Today's elevators often are controlled electronically, and the fastest elevators in the world can move up and down at 4,000 feet per minute.
Jesse W. Reno invented the escalator, or moving stairway, in 1891. Early escalators, like modern ones, were electrically powered and resembled an inclined endless belt held in position by two tracks. Moving sidewalks and ramps are based on the same principle.
Almost as long as these machines have been in use in buildings to move people and their belongings, there has been a need for workers who specialize in assembling, installing, and maintaining them.
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