Elevator refers to the permanent transportation equipment that serves a number of specific floors in the building, and its car runs on at least two columns of e68a84e8a2ade79fa5e9819331333366303139 rigid track movement that is perpendicular to the horizontal plane or inclined at an angle of less than 15 ° to the vertical. There are also steps, with treads installed on the crawlers to run continuously, commonly known as escalators or moving walkways. Fixed lifting equipment serving the specified floors. A vertical elevator has a car that runs between at least two rows of vertical or rigid guide rails with a tilt angle of less than 15 °.Safe Elevators Manufacturers

The size and structure of the car are convenient for passengers to enter or load cargo. It is customary to use elevators as the general term for vertical transportation in buildings regardless of their driving method. According to the speed, it can be divided into low-speed elevators (below 4 meters / second), fast elevators (4-12 meters / second) and high-speed elevators (above 12 meters / second). Hydraulic elevators began to appear in the mid-19th century and are still used in low-rise buildings to this day. In 1852, E.G. Otis of the United States developed a safety elevator for lifting steel wire ropes. In the 1980s, the driving device was further improved, such as the motor driving the winding drum through the worm drive, and using a balance weight. At the end of the 19th century, friction wheel transmission was used to greatly increase the lifting height of the elevator.