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transportation device used to move goods or people vertically. In British English and other Commonwealth Englishes, elevators are known more commonly as lifts, although the word elevator is familiar from American movies and television shows.
Elevators began as simple rope or chain hoists. An elevator is a hoist contained within an elevator well. An elevator consists of a cab (also "cage" or "car") or platform, the ropes or cables required to raise and lower it using pulleys, and machinery to move the rope. Later refinements included steam power and hydraulic power.
In 1853, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke, and on March 23, 1857 his first elevator was installed at 488 Broadway in New York City. The first elevator shaft preceded the first elevator by four years. Construction for Peter Cooper's Cooper Union building in New York began in 1853. An elevator shaft was included in the design for Cooper Union, because Cooper was utterly confident a safe passenger elevator would soon be invented: the shaft however was circular because Cooper felt it was the most efficient design. Later Otis designed a special elevator for the school. Today the Otis Elevator Company, now a subsidiary of United Technologies Corporation, is the world's largest manufacturer of vertical transportation systems.
The first electric elevator was built by Werner von Siemens in 1880. The safety and speed of electric elevators were significantly enhanced by Frank Sprague.
The development of elevators allowed easy access to the upper storeys of tall buildings and skyscrapers.
In some locations, the shaft and parts of the cab are made of transparent material. This allows riders to see outside the cab as they travel on an elevator. It allows people to watch the elevator cab as it travels between floors. Other locations have elevators that are located along the outside wall of buildings. This allows riders to see the outdoor enviornment as the cab runs along the side of the buildings.
Today, most elevators are computer-controlled. This allows the elevator system to place cabs where they are most needed, and allow for the smooth running of the system. It also permits greater access control to various floors of a building after hours and on weekends. Methods of access control include card readers, keys, and typing access codes into the control panel of the elevator.
Elevators are usually installed in a building during construction. Further renovations upgrade the cab instead of replacing it, but in a few cases the entire cab is replaced as well.
In general, there are three types of elevators:
A special type of elevator is the paternoster, a constantly moving chain of boxes. A similar concept moves only a small platform, which the rider mounts while using a handhold and was once seen in multi-story industrial plants.
The simple algorithm by which a single elevator can decide where to stop is:
The elevator algorithm has found an application in computer operating systems as an algorithm for scheduling hard disk requests.
Modern elevators use more complex heuristic algorithms to decide which request to service next.
In areas with large populations of observant Jews, one may find a "Sabbath Elevator" which will stop automatically at every floor in turn. This allows people to step on and off without pressing buttons to summon the elevator or indicate the desired floor and thus (in the view of some Jews) violating the Sabbath prohibition against doing work.
In general, elevator call buttons are numbered one-by-one to indicate the floors or landings that they cause the car to move to. However, there are some conventions to be aware of. The most important are:
The convention that higher floors have their buttons placed higher may help resolve ambiguities, but many elevators have enough buttons that they are grouped in rows of two or even three.
A small box elevator designed for the carriage of goods only is called a dumb waiter (or dumbwaiter).
A different kind of elevator is used to transport material. It generally consists of an inclined plane on which a conveyor belt runs. The conveyor often includes partitions to prevent the material from sliding backwards. These elevators are often used in industrial and agricultural applications.
When such mechanisms (or spiral screws or pneumatic transport) are used to elevate grain for storage in large vertical silos, the entire structure is called a grain elevator,
The elevator in the new city hall in Hannover is a technical rarity, and unique in Europe, as the elevator starts straight up, but then changes its angle by 15 degrees to follow the contour of the dome of the new city hall in Hannover. The cabin therefore tilts 15 degrees during the ride. The elevator travels a height of 43 meters. The new city hall was built in 1913. The elevator was destroyed in 1943 and rebuilt in 1954.
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