- This article is about the transportation device. For other meanings of the word, see Elevator (disambiguation).
 A modern elevator has buttons to allow passengers to select the desired floor. An elevator is a 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, just as some Americans are aware of lift from imported entertainment. Other languages, such as Cantonese use a word sounding similar to lift for the device.
History
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.
Elisha Otis's elevator patent drawing, 01/15/1861. 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 the elevator. Some locations take advantage of this transparent material by placing the elevators along the walls of their building. This allows riders to see the outdoor environment 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.
Uses of elevators
Passenger service
A passenger elevator is designed to carry people. Some residential elevators may be small enough for one person; some are large enough for more than a dozen. Wheelchair lifts, a specialized type of elevator designed to move a wheelchair short distances, often can accomodate just one person in a wheelchair at a time.
Freight elevators
A freight elevator is a large elevator designed to carry goods, rather than passengers. (Passengers often accompany the freight, however.) It will typically be much larger and capable of carrying much heavier loads than a passenger elevator. A small freight-only elevator is often called a dumb waiter (see next section). A specialized type of freight elevator is a car elevator, used to move automobiles around a parking garage or other facility.
Dumb waiter
A small box elevator designed for the carriage of goods only is called a dumb waiter (or dumbwaiter). Often they are used in restaurants to bring food from the kitchen to the dining area, hence the name.
Material handling belts
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,
Types of elevator hoist mechanisms
In general, there are three means of moving an elevator:
Traction Elevators
- Geared and Gearless Traction Elevators - Cables attached to a hitch plate on top of the cab move the elevator. A counterweight attached to the opposite end of the cables reduces the amount of power needed to move the cab. The cables are pulled by a sheave which is either attached directly to a motor (gearless) or to a gearbox attached to a motor (geared).
Hydraulic type
- Conventional Hydraulic Elevators - These are quite common for low and medium rise buildings.(2-5 Stories) They use a hydraulically powered plunger to push the elevator upwards. On some, the hydraulic piston (plunger) consists of telescoping concentric tubes, allowing a shallow tube to contain the mechanism below the lowest floor. On others, the piston requires a deeper hole below the bottom landing, usually with a PVC casing for protection.
Roped Hydraulic.
Twin Post Hydrauilc
Holeless Hydrauilc.
Paternoster
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.
Controlling elevators
General controls
A typical modern passenger elevator will have:
- Call buttons to choose a floor. Some of these may be key switches (to control access). In some elevators, certain floors are inaccessable unless one swipes a security card or enters a passcode (or both).
- Door open and door close buttons to instruct the elevator to close immediately or remain open longer. In some elevators, holding the door open for too long will trigger an audiable alarm.
- A stop switch to halt the elevator (often used to hold an elevator open while freight is loaded). Keeping an elevator stopped for too long may trigger an alarm. Often, this will be a key switch.
- An alarm button or switch, which passengers can use to signal that they have been trapped in the elevator
Some elevators may have one or more of the following:
- An elevator telephone, which can be used (in addition to the alarm) by a trapped passenger to call for help.
- A fireman's key switch, which places the elevator in a special operating mode designed to aid firefighters
- A medical emergency key switch, which places the elevator in a special operating mode designed to aid medical personnel
Other controls, which are generally inaccessible to the public (either because they are key switches, or because they are kept behind a locked panel, include:
- Switches to control the lights and ventilation fans in the elevator
- An inspector's switch, which places the elevator in inspection mode
- An independent service switch, which selects whether the elevator's operation will be coordinated with other elevators in an elevator bank.
- Up and down buttons, to move the car up and down without selecting a specific floor. Some older elevators can only be operated this way.
Controls in early elevators
- Some older freight elevators are controlled by switches operated by pulling on adjacent ropes. Safety interlocks ensure that the inner and outer doors are closed before the elevator is allowed to move.
- Early elevators had no automatic landing positioning. Elevators were operated by elevator operators using a motor controller. The controller was contained within a cylindrical container about the size and shape of a cake container and this was operated via aprojecting handle. This allowed some control over the energy supplied to the motor (located at the top of the elevator shaft) and so enabled the elevator to be accurately positioned — if the operator was sufficiently skilled. More typically the operator would have to "jog" the control to get the elevator reasonably close to the landing point and then direct the outgoing and incoming passengers to "watch the step". Such elevators did not contain inner doors, as the landing had to be visible for proper positioning of the cab. After stopping at the landing the operator would reach over and pull an attached lever to open the landing doors. Manually operated elevators were generally refitted or the cabs replaced by automatic equipment by the 1950's.
- Large buildings with multiple elevators of this type would also have an elevator dispatcher stationed in the lobby to direct passengers and to signal the operator to leave with the use of a mechanical "cricket" noisemaker.
- Some elevators still in operation have pushbutton manual controls; an example is in a thumbnail on this page.
Manual pushbutton elevator controls.
Floor numbering
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 differences in floor numbering between different cultures, such as the numbering system used by the USA and in China as compared with the conventions set by the British.
- Floor numbers considered unlucky may be skipped; the example, the floor above 12 may be numbered 14.
- The top level may be PH for Penthouse or, where applicable, R for Roof or O for Observation Deck.
- The ground floor may be G for Ground, M for Main, L for Lobby, or simply 1 (if it is also the first floor) or 0 (if not). As an aid to the visually impaired, there is often an embossed * beside the button.
- Below the ground floor is commonly B for Basement or P for Parking, sometimes L or LL for Lower Level.
- Below the basement may be SB for Sub-Basement. Numbered levels below ground, such as B1 or P1, are also common; the numbers may run either way, but B2 is usually below B1. Negative numbers (-1 for the first floor below ground, then -2, etc.) are also used, especially when the ground floor is numbered 0.
- Some buildings are just idiosyncratic; at one hotel in Toronto, the first six floors are labeled A, M, MM, C, H, and 1 (for Arcade, Main, Main Mezzanine, Convention, Health Club, and 1st floor).
- Floor designations sometimes vary between different banks of elevators in a building (due to its layout), or even between buttons and indicators in the same elevator (due to careless installation).
- Some elevators, especially in buildings with complex floor plans, have both front and rear doors that can open at the same floor; a second button with R appended to the floor abbreviation (e.g. GR or 2R) then requests a stop there with the rear door opening.
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.
In order to comply with laws regarding handicapped access, such as the Americans with Disabilities Act (ADA), a secondary button panel may be installed which is located at a height that can be reached by a person in a wheelchair. In this case the buttons may be arranged in a horizontal fashion.
On the elevator's position indicator, you may see the letters EZ. This is used to represent an Express Zone which is a long section of travel where the elevator makes no stops. Typically these are found in elevators that serve the upper reaches of tall buildings, thus bypassing several of the lower floors on the way.
The Elevator Algorithm
The simple algorithm by which a single elevator can decide where to stop is:
- Continue travelling in the same direction while there are remaining requests in that same direction.
- If there are no further requests in that direction, then stop and become idle, or change direction if there are requests in the opposite direction.
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.
Special operating modes
In areas with large populations of observant Jews, one may find a "Sabbath Elevator". In this mode, an elevator will stop automatically at every floor, allowing people to step on and off without having to press any buttons. Regenerative braking is also disabled if it is normally used, shunting energy collected from downward travel, and thus the gravitational potential energy of passengers, into a resistor network. This prevents violation of the Sabbath prohibition against doing useful work.
Unique Elevator Systems
Elevator in the new city hall, Hannover
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.
The Gateway Arch
Main Article: Gateway Arch
The Gateway Arch in Saint Louis, Missouri has a unique elevator system which carries passengers from the visitors center underneath the Arch to the observation deck at the top of structure.
The interior of one of the tramway cars. Called a tram or tramway, people enter this unique tramway much as one would enter an ordinary elevator, through double doors. Passing through the doors the passengers in small groups enter a horizontal cylindrical compartment containing seats on each side and a flat floor. A number of these compartments are linked to form a train. These compartments each individually retain an appropriate level orientation by tiliting while the entire train follows curved tracks up one leg of the arch.
There are two tramways within the Arch, one at the north end, and the other at the south end. The entry doors have windows, so people traveling within the Arch are able to see the interior structure of the Arch during the ride to and from the observation deck.
Fourth Street Elevator
Main Article: Fourth Street Elevator
The Fourth Street Elevator is located in Dubuque, Iowa. Also known as the Fenelon Place Elevator, it is the shortest and steepest railroad in the world. This elevator carries passengers from the bottom of one of the major bluffs in Dubuque to the top and back. The elevator is listed in the National Register of Historic Places.
The elevator is 296 feet long, with a vertical elevation of 189 feet. The elevator is funicular in design. There are two cars that always start out opposite each other, and pass each other at the mid-point of the elevator. The two cars in the cable-driven railway are powered by an engine in the station house at the top of the hill. The engine only needs to overcome inertia and compensate for the varying weight of the passengers in the cars. Because the design is funicular, the cars counterbalance each other, and it's the weight of the two cars that does much of the work in moving them back and forth. The weight of the car going down the bluff helps pull the other car at the bottom up to the top.
Local businessman J.K. Graves built an elevator in 1882 to carry him from his home at the top of the bluff to his office at the bottom. This saved a considerable amount of time - during the 19th century it took at least half an hour to get from one end of the bluff to the other. Eventually Graves gave his neighbors rides on the elevator. In 1884 the first elevator was destroyed by fire. Graves rebuilt the elevator, opened it to the public and charged admission. The second elevator lasted until 1893, when it was destroyed by fire. Graves was unable to rebuild the elevator, so a number of his neighbors banded together and formed the Fenlon Place Elevator Company. They built the present elevator, which is still in service today.
Even though the elevator is no longer daily necessity for neighbors since the rise of the automobile, it is still a popular tourist attraction and a unique part of the city. Downtown Dubuque can be seen from the observation deck, as well as the Mississippi River, and the states of Illinois and Wisconsin.
 Sketch of the elevator at the new city hall, Hannover, showing the cabin both at the bottom and the top
 View up the shaft of the elevator at the new city hall, HannoverSee also
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