Elevator

An elevator (US and Canada) or lift (UK, Ireland and Australia) is a type of vertical transportation device that moves people or goods between floors (levels, decks) of a building, vessel, or other structure. Elevators are typically powered by electric motors that drive traction cables and counterweight systems like a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack. In agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or silos. Several types exist, such as the chain and bucket elevator, grain auger screw conveyor using the principle of Archimedes' screw, or the chain and paddles or forks of hay elevators. Languages other than English may have loanwords based on either elevator or lift. Because of wheelchair access laws, elevators are often a legal requirement in new multistory buildings, especially where wheelchair ramps would be impractical. There are also some elevators which can go sideways in addition to the usual up-and-down motion. The earliest known reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes (c. 287 BC – c. 212 BC) built his first elevator probably in 236 BC. Some sources from later historical periods mention elevators as cabs on a hemp rope powered by hand or by animals. In 1000, the Book of Secrets by al-Muradi in Islamic Spain described the use of an elevator-like lifting device, in order to raise a large battering ram to destroy a fortress. In the 17th century the prototypes of elevators were located in the palace buildings of England and France. Louis XV of France had a so-called 'flying chair' built for one of his mistresses at the Chateau de Versailles in 1743. Ancient and medieval elevators used drive systems based on hoists or windlasses. The invention of a system based on the screw drive was perhaps the most important step in elevator technology since ancient times, leading to the creation of modern passenger elevators. The first screw drive elevator was built by Ivan Kulibin and installed in the Winter Palace in 1793. Several years later another of Kulibin's elevators was installed in the Arkhangelskoye near Moscow. The development of elevators was led by the need for movement of raw materials including coal and lumber from hillsides. The technology developed by these industries and the introduction of steel beam construction worked together to provide the passenger and freight elevators in use today.