Elevator
An elevator or lift is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems such as a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack.
Elevators are used in agriculture and manufacturing to lift materials. There are various types, like chain and bucket elevators, grain augers, and hay elevators. Modern buildings often have elevators to ensure accessibility, especially where ramps aren't feasible. High-speed elevators are common in skyscrapers. Some elevators can even move horizontally. Smart elevators enable multi-elevator coordination, enhancing the riding experience while reducing costs.
History
Pre-industrial era
The earliest known reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes built his first elevator probably in 236 BC. Sources from later periods mention elevators as cabs on a hemp rope, powered by people or animals.The Roman Colosseum, completed in 80 AD, had roughly 25 elevators that were used for raising animals up to the floor. Each elevator could carry about up when powered by up to eight men. In 1000, the Book of Secrets by Ibn Khalaf al-Muradi in Islamic Spain described the use of an elevator-like lifting device to raise a large battering ram to destroy a fortress.
In the 17th century, prototypes of elevators were installed 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 Château de Versailles in 1743.
Ancient and medieval elevators used drive systems based on hoists and 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, although there may have been an earlier design by Leonardo da Vinci. Several years later, another of Kulibin's elevators was installed in the Arkhangelskoye near Moscow.
Industrial Era
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. Starting in coal mines, elevators in the mid-19th century operated with steam power, and were used for moving goods in bulk in mines and factories. These devices were soon applied to a diverse set of purposes. In 1823, Burton and Homer, two architects in London, built and operated a novel tourist attraction which they called the "ascending room", which elevated customers to a considerable height in the center of London, providing a panoramic view.Early, crude steam-driven elevators were refined in the ensuing decade. In 1835, an innovative elevator, the Teagle, was developed by the company Frost and Stutt in England. It was belt-driven and used a counterweight for extra lifting ability.
In 1845, Neapolitan architect Gaetano Genovese installed the "Flying chair", an elevator ahead of its time in the Royal Palace of Caserta. It was covered with chestnut wood outside and with maple wood inside. It included a light, two benches, and a hand-operated signal, and could be activated from the outside, without any effort by the occupants. Traction was controlled by a motor mechanic utilizing a system of toothed wheels. A safety system was designed to take effect if the cords broke, consisting of a beam pushed outwards by a steel spring.
The hydraulic crane was invented by Sir William Armstrong in 1846, primarily for use at the Tyneside docks for loading cargo. They quickly supplanted the earlier steam-driven elevators, exploiting Pascal's law to provide much greater force. A water pump supplied a variable level of water pressure to a plunger encased inside a vertical cylinder, allowing the platform, carrying a heavy load, to be raised and lowered. Counterweights and balances were also used to increase lifting power.
File:Elisha OTIS 1854.jpg|thumb|Elisha Otis demonstrating his safety system, at the New York Crystal Palace, 1853
Henry Waterman of New York is credited with inventing the "standing rope control" for an elevator in 1850.
In 1852, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. He demonstrated it at the New York exposition in the Crystal Palace in a dramatic, death-defying presentation in 1854, and the first such passenger elevator was installed at 488 Broadway in New York City on 23 March 1857.
The first elevator shaft preceded the first elevator by four years. Construction for Peter Cooper's Cooper Union Foundation building in New York began in 1853. An elevator shaft was included in the design because Cooper was confident that a safe passenger elevator would soon be invented. The shaft was cylindrical because Cooper thought it was the most efficient design. Otis later designed a special elevator for the building.
Peter Ellis, an English architect, installed the first elevators that could be described as paternoster elevators in Oriel Chambers in Liverpool in 1868.
The Equitable Life Building, completed in 1870 in New York City, is thought to be the first office building with passenger elevators.
In 1872, American inventor James Wayland patented a novel method of securing elevator shafts with doors that are automatically opened and closed as the elevator car approaches and leaves them.
In 1874, J. W. Meaker patented a method permitting elevator doors to open and close safely.
The first electric elevator was built by Werner von Siemens in 1880 in Germany. Inventor Anton Freissler further developed von Siemens' ideas and created a successful elevator enterprise in Austria-Hungary. The safety and speed of electric elevators were significantly enhanced by Frank Sprague, who added floor control, automatic operation, acceleration control, and further safety devices. His elevator ran faster and with larger loads than hydraulic or steam elevators. 584 of Sprague's elevators were installed before he sold his company to the Otis Elevator Company in 1895. Sprague also developed the idea and technology for multiple elevators in a single shaft.
In 1871, when hydraulic power was a well established technology, Edward B. Ellington founded Wharves and Warehouses Steam Power and Hydraulic Pressure Company, which became the London Hydraulic Power Company in 1883. It constructed a network of high-pressure mains on both sides of the Thames which ultimately extended and powered some 8,000 machines, predominantly elevators and cranes.
Schuyler Wheeler patented his electric elevator design in 1883.
In 1884, American inventor D. Humphreys of Norfolk, Virginia, patented an elevator with automatic doors that closed off the elevator shaft when the car was not being entered or exited. In 1887, American inventor Alexander Miles of Duluth, Minnesota, patented an elevator with automatic doors that closed off the elevator shaft when the car was not being entered or exited.
In 1891, American inventors Joseph Kelly and William L. Woods co-patented a novel way to guard elevator shafts against accident, by way of hatches that would automatically open and close as the car passed through them.
The first elevator in India was installed at the Government House in Calcutta by Otis in 1892.
By 1900, completely automated elevators were available, but passengers were reluctant to use them. Their adoption was aided by a 1945 elevator operator strike in New York City, and the addition of an emergency stop button, emergency telephone, and a soothing explanatory automated voice.
Modern elevators era
In 2000, the first vacuum elevator was offered commercially in Argentina.Green elevators achieve kinetic and potential energy recovery, along with more durable technology. For example, more efficient coordination between different elevators.
In Asia, screens in elevators are commonplace to help passengers pass the time during their journey and can generate additional revenue.
Some cruise ships have been updated with smart elevators since 2020s to avoid traffic congestion.
Design
Some people argue that elevators began as simple rope or chain hoists. An elevator is essentially a platform that is either pulled or pushed up by mechanical means. A modern-day elevator consists of a cab mounted on a platform within an enclosed space called a shaft or sometimes a "hoistway". In the past, elevator drive mechanisms were powered by steam and water hydraulic pistons or by hand. In a "traction" elevator, cars are pulled up by means of rolling steel ropes over a deeply grooved pulley, commonly called a sheave in the industry. The weight of the car is balanced by a counterweight. Often two elevators are built so that their cars always move synchronously in opposite directions, and are each other's counterweight.The friction between the ropes and the pulley furnishes the traction which gives this type of elevator its name.
Hydraulic elevators use the principles of hydraulics to pressurize an above-ground or in-ground piston to raise and lower the car. Roped hydraulics use a combination of both ropes and hydraulic power to raise and lower cars. Recent innovations include permanent magnet motors, machine room-less rail mounted gearless machines, and microprocessor controls.
The technology used in new installations depends on a variety of factors. Hydraulic elevators are cheaper, but installing cylinders greater than a certain length becomes impractical for very-high lift hoistways. For buildings of much over seven floors, traction elevators must be employed instead. Hydraulic elevators are usually slower than traction elevators.
Elevators are a candidate for mass customization. There are economies to be made from mass production of the components, but each building comes with its own requirements like different number of floors, dimensions of the well and usage patterns.