Elevator

From Wikinfo

An elevator is a transportation device used to move goods or people vertically. In British English and Australian English, 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 ("cage") 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 is the world's largest manufacturer of vertical transportation systems.

The first electric elevator was built by Werner von Siemens in 1880.

The development of elevators allowed easy access to the upper storeys of tall buildings and skyscrapers.

In general, there are two types of elevators:

• Cable/traction Elevators - Operate using a counterweight that allows the elevator to easily be pulled up or down using cables attached to the roof of the elevator car.
• Hydraulic Elevators - These are quite common. They use a hydraulically powered plunger to push the elevator upwards.

A special type of elevator is the paternoster.

In areas with large populations of observants 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 violating the Sabbath prohibition against doing work.

In general, elevator buttons are numbered one-by-one to indicate the floors that they take you to. However, there are some exceptions. The most common are:

• Lobby = L
• Parking = P
• Ground floor = G
• Thirteenth floor = 14

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.

Elevators are also control surfaces, usually at the rear of aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. An increased angle of attack will cause a greater lift to be produced by the profile of the wing, and (if no power is added or available), a slowing of the aircraft. A decreased angle of attack will produce an increase in speed (a dive). In some aircraft the elevator is in the front of the aircraft, ahead of the wing. (This type of configuration is called a "canard", the french word for duck.) The Wright Brothers' early aircraft was of this type. The canard type is more efficient, since the forward surface produces upward lift. The main wing is also less likely to stall, as the forward control surface is configured to stall before the wing, causing a pitch down and reducing the angle of attack of the wing. The elevator may be the only pitch control surface present or it may be hinged to a fixed or adjustable surface called a stabilizer.

See also: Grain elevator, Elevator music, Space elevator

References

• Adapted from the Wikipedia article, "Elevator" http://en.wikipedia.org/wiki/Elevator, used under the GNU Free Documentation License