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我的答案：Elevator, with the high-rise building construction and developed a kind of vertical transport. Multi-plant and multi-storey warehouses need to have freight elevators; the need for high-rise residential housing ladder; department stores and hotels need to have passenger elevators, escalators and so on. In modern society, elevator, like cars, boats, become an indispensable means of transport of mankind. According to statistics, the United States take the elevator trips per day than other modes of transport as set by the number of people. Today's world, the use of elevators has become one of the landmarks to measure the degree of modernization. Trace the history of the lift such a lifting device is said that it originated in the year 236 BC, ancient Greece. At that time a man named Archimedes who design - human-powered reel-type hoist. In 1858 the steam engine-powered passenger elevators in the United States appear, then, there is water pressure in the UK ladder. 1889, the United States, Otis Elevator Company as the first to use electric motors powered lift This elevator appeared genuine, and to lift tends to practical use. In 1900 there was also the first escalators. Appeared in 1949 elevator group control, the first 4 to 6 sets of elevator group control of the United Nations building in New York, to be used. Appeared in 1955, a small computer (vacuum tube) to control the lift. 1962 United States emerged in speeds of up to 8 m / s ultra-high speed elevators. Some of the advanced industrial countries in 1963, only to become a non-contact semiconductor logic control elevators. SCR 1967, applied to the lift, so that cylinder of the elevator drive system performance to improve. 1971 IC is applied to the lift. NC elevator appeared the following year. Microprocessor in 1976, started for the elevator, so that the elevator electrical control has entered a new period of development. |
