Escalator
The escalator is a continuous moving staircase that carries people from one level or floor to another. A series of steps are pulled by chains along two sets of tracks, powered by an electric motor.
The first United States patent for an escalator was issued in 1859, but the invention wasn't used. The practical escalator was the result of independent inventions in the early 1890s by two Americans, Jesse Reno and Charles Seeberger. Reno invented an inclined belt with a grooved tread for steady footing. Seeberger produced a flat-step design with side entrance. A problem with both designs, however, was the stationary handrail.
During the 189Os, the Otis Elevator Company acquired rights to these two designs. Otis put several escalators into operation at its factory in Yonkers, New York, in 1899. The first public installations of an escalator were at the 1900 Paris Exposition and in the New York City elevated railroad. Otis made other early installations in Chicago, Illinois, and Philadelphia, Pennsylvania, department stores.
Around 1920 the Reno and Seeberger designs were combined and the result was the modern escalator. The word escalator, derived from a Latin word meaning "ladder," was originally an Otis Elevator Company trademark. The term lost trademark status in 1949 because of its widely popular use.
Modern escalators are powered by electric motors that move their steps at a fairly slow 100 feet per minute. All standard-use escalators carry their passengers upwards at a 30-degree angle. They are used in many multistoried public buildings, especially in malls and department stores where people move continuously between connecting floors. Viewed in cross-section or from the side, an escalator is seen as an endless belt. When its stairs reach the top, they fold flat and go around a large wheel to make a return trip to the stairway bottom. There, the stairs or steps go around another wheel that rolls them back up, and they reappear. Many of the moving sidewalks or walkways appearing in increasingly spread-out airports are essentially a flat type of escalator. The world's tallest bank of escalators are in London, England. In 1993 in Hong Kong, a 2,600-fot (800-meter) Hillside Escalator Link opened and was able to move about 27,000 people a day. The Link is a series of moving sidewalks and escalators -- all covered -- that move residents from one part of town to another. It has 20 exits and entrances, takes about 20 minutes to run end-to-end, and reverses itself for the afternoon rush hour.
By the end of the 1990s, the newest escalator designs stress slimmer, sleeker profiles and major safety enhancements such as a gap of only 1/16th of an inch between the escalator steps and the skirt (side) panels. This provides a greater measure of user safety, especially for small childern and slow-moving seniors. The newest models will also feature a totally enclosed and quieter drive system instead of a chain drive.
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