A device which carries people or objects from one level to another in a building with several floors. The elevator car is moved by a system of cables and pulleys, which link the car to a counterweight, the power usually being generated by electricity (earlier lifting systems had used a variety of methods, such as animal, steam, and water power). The invention of the elevator fostered the development of the skyscraper in modern cities. Following the invention of a safety device by Otis in 1852, the first (steam-powered) passenger elevator was introduced in New York City in 1857. Later improvements have included increased speeds, noise reduction, safety features (such as lighting and alarm systems), the automatic operation of groups of elevators, and two-deck cars (serving two levels simultaneously).
An elevator is a transport device used to move goods or people vertically.
Design
Elevators began as simple rope or chain hoists. An elevator is essentially a platform that is either pulled or pushed up by a mechanical means. A modern day elevator consists of a cab (also called a "cage" or "car") mounted on a platform within an enclosed space called a shaft, or in Commonwealth English called a "hoistway". In the past elevator drive mechanisms were powered by steam and water hydraulic pistons.
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 friction between the ropes and the pulley furnishes the traction which gives this type of elevator its name.
Hydraulic elevators use the principal of hydraulics to pressurize an above ground or in-ground piston to raise and lower the car. Hydraulic elevators are usually slower than traction elevators.
In 1853, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. It consists of knurled roller(s) that lock the elevator to its guides should the elevator descend at an excessive speed, which is monitored by a governor device.
On March 23, 1857 the first Otis elevator was installed at 488 Broadway in New York City. The first elevator shaft preceded the first elevator by four years. An elevator shaft was included in the design for Cooper Union, because Cooper was utterly confident a safe passenger elevator would soon be invented; 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 transport systems, followed by Schindler, Thyssen-Krupp and Kone, in order.
The first electric elevator was built by Werner von Siemens in 1880.
The development of elevators was led by the need for movement of large amounts of raw materials including coal and lumber from hillsides.
In October 11, 1887 Alexander Miles, an African American inventor, patented a method which permitted elevator doors to open and close safely.
In 1929, Clarence Conrad Crispen, with Inclinator Company of America, created the first residential elevator.
Modern elevator construction
Today, elevators are built under strict supervision of the Building Codes.
Elevators are generally sold in prepackaged components which are inherently non-proprietary. In the case of renovations, the use of non-proprietary controls has become a large part of that business because it allows the owner to offer the maintenance contract to multiple bidders rather than accept a single manufacturer for the life of the elevator which can be more than 30 years. Non-proprietary systems generally have a higher up front cost, but may be offset by allowing the owner to control the long term costs over the life of the elevator.
In some locations, the shaft and parts of the cab are made of transparent material for specialized "Scenic elevators." This allows riders to see outside the cab as they travel on the elevator.
Today, all new elevators are computer-controlled and microprocessor based. This allows the elevator system to place cabs where they are most needed in the interest of smooth running, with behavior based on analysis of building use called "Traffic Studies." Traffic Studies are done by professional elevator consultants who use specialized tools to determine the optimum size, speed and number of elevators for a building based on its peak use periods. Methods of access control include card readers, keys, and access codes entered into the control panel of the elevator.
Elevators are usually installed in a building during construction.
Elevator safety
Elevators are characterized as being extremely safe. A certain number of passengers do die every year in elevator related incidents. "Statistically, it's a safe ride", says Ray Lapierre, executive director of the Elevator Escalator Safety Foundation.
Past problems with hydraulic elevators meant such elevators built prior to a code change in 1972 were subject to possible catastrophic failure. in the event of a breach of the cylinder, an uncontrolled fall of the elevator might result.
In addition to the safety concerns for older hydraulic elevators, there is risk of leaking hydraulic oil into the aquifer and causing potential environmental contamination.
In the past decade, recent innovations called machine room-less elevators first developed by Kone called the EcoSpace , have reduced the amount of overhead machinery required (the main disadvantage of the traction elevator) are gradually making hydraulic elevators obsolete. Today, MRL elevator models include the Kone EcoSpace, Mitsubishi ELENESSA, Otis Gen2, Fujitec Talon, ThyssenKrupp ISIS 2 and the Schindler 400A models. In Hong Kong, few hydraulic elevators remain and most companies only install hydraulic elevators as a special order.
Uses of elevators
Passenger service
A Passenger lift is designed to ferry people from point A to Point B vertically.
Passenger elevators capacity is related to the available floor space.
Sometimes passenger elevators used as a city transport along with funiculars. For example, there is a 3-station underground public elevator in Yalta, Ukraine, which takes passengers from the top of a hill above the Black Sea on which hotels are pirched, to a tunnel located on the beach below.
Types of passenger elevators
Passenger elevators may be specialized for the service they perform, including: Hospital emergency (Code blue), front and rear entrances, double decker, and other uses.
Entrapment
The concern for entrapping passengers requires all elevators to have communication connection to an outside 24 hour emergency service, automatic recall capability in a fire emergency, and special access for fire fighters' use in a fire. Numerous building codes requires signs near the elevator to state "USE STAIRS IN CASE OF FIRE".
Capacity
Residential elevators may be small enough for one person while some are large enough for more than a dozen. Wheelchair, or platform lifts, a specialized type of elevator designed to move a wheelchair 6 ft (2 m) or less, often can accommodate just one person in a wheelchair at a time with a maximum load of 750 lb (340 kg).
Freight elevators
A freight elevator (or goods lift) is an elevator designed to carry goods, rather than passengers. Freight elevators or service elevators (goods or service lifts) may be exempt from some of the requirements for fire service. Freight elevators are generally required to display a written notice in the car that the use by passengers is prohibited, though certain freight elevators allow dual use through the use of an inconspicuous riser. Freight elevators are typically larger and capable of carrying heavier loads than a passenger elevator, generally from 2,300 to 4,500 kg. Although hydraulic freight elevators exist, electric elevators are more energy efficient for the work of freight lifting.
Vehicle elevators
A car lift is installed where ramps are considered space-inconservative for smaller buildings (usually in apartment buildings where frequent access is not an issue).
In spite of the sheer size of the car platform and its perceived "passenger capacity", there are huge passenger and freight lifts that can accommodate more than the rated capacity of the car lift.
Aircraft elevators
On aircraft carriers, elevators carry airplanes and helicopters from the flight deck to the hangar deck and vice versa for operations or for repairs. These elevators are designed for much greater capacity than any other elevator ever built, designed to carry up and down up to 200,000 pounds of tactical aircraft and equipment at a time.
Dumbwaiter
A small freight elevator is often called a dumbwaiter, often used for the moving of small items such as dishes in a 2-story kitchen or books in a multi-story rack assembly.
Material handling belts and belt elevators
A different kind of elevator is used to transport material. 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 elevatorsGeared Traction machines are driven by AC or DC electric motors. Geared machines use worm gears to control mechanically movement of elevator cars by "rolling" steel hoist ropes over a drive sheave which is attached to a gearbox driven by a high speed motor. A brake is mounted between the motor and drive sheave (or gearbox) to hold the elevator stationary at a floor. a power failure will cause the brake to engage and prevent the elevator from falling (see inherent safety and safety engineering). This action is powered by the traction machine which is directed by the controller, typically a relay logic or computerized device that directs starting, acceleration, deceleration and stopping of the elevator cab. The weight of the counterweight is typically equal to the weight of the elevator cab plus 40-50% of the capacity of the elevator. This is a separate set of cables or a chain attached to the bottom of the counterweight and the bottom of the elevator cab. This makes it easier to control the elevator because the weight will fluctuate less over the entire system. If the elevator cab is at the top of the hoist-way, there is a short length of hoist cable above the car and a long length of compensating cable below the car and vice versa for the counterweight. If the compensation system uses cables, there will be an additional sheave in the pit below the elevator, to guide the cables.
Hydraulic type Conventional Hydraulic elevators were first developed by Dover Elevator (now ThyssenKrupp Elevator). They are quite common for low and medium rise buildings (2-7 floors) and use a hydraulically powered plunger to push the elevator upwards. In most designs, the cab is lifted by a pair of hydraulic jacks, one on each side of the elevator. Climbing elevatorA climbing elevator is a self-ascending elevator with its own propulsion.
PaternosterA special type of elevator is the paternoster, a constantly moving chain of boxes.
Controlling elevators
General controls
A typical modern passenger elevator will have:
Call buttons to choose a floor. In the United States and other countries, call button text and icons are raised to allow blind users to operate the elevator; 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 audible alarm (This alarm might confuse some people to think that the elevator is overloaded or otherwise broken). A stop switch (this is not allowed under British regulations) 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. 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. Cancel floor: On some elevator models, the building owner can enable a feature so that "double-clicking" a floor button will de-select it.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 (this may be situated on top of the elevator) An independent service switch, which selects whether the elevator's operation will be coordinated with other elevators in an elevator bank.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. Elevators were operated by elevator operators using a motor controller. This allowed some control over the energy supplied to the motor (located at the top of the elevator shaft or beside the bottom 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".Floor numbering
The elevator algorithm
The elevator algorithm, a simple algorithm by which a single elevator can decide where to stop, is summarized as follows:
Continue travelling in the same direction while there are remaining requests in that same direction.The elevator algorithm has found an application in computer operating systems as an algorithm for scheduling hard disk requests.
Computer dispatched
Efficiencies of multiple elevators installed in an office building may increase if a central dispatcher is used to group passengers going to the same floor to the same elevator. In buildings with these computer-dispatched elevator system, passengers key in their destination floor in a central dispatch panel located at the building lobby. The dispatch panel will then tell the passenger which elevator to use. Inside the elevator there is no call button to push (or the buttons are there but they cannot be pushed, they only indicate stopping floors). The system was first pioneered by Schindler Elevator as the Miconic 10. The dispatching algorithm is usually unable to completely cater for the variation, and late comers may find the elevator they are assigned to is already full.
Destination Elevators
Destination elevators are computer controlled for maximum efficiency of the system. The system then directs the passenger to an elevator that will be stopping at their floor. There are no floor buttons inside a destination elevator.
Special operating modes
Up peak
During Up Peak mode, elevator cars in a group are recalled to the lobby to provide expeditious service to passengers arriving at the building, most typically in the morning as people arrive for work or at the conclusion of a lunch-time period. The next elevator to be dispatched usually has its hall lantern or a "this car leaving next" sign illuminated to encourage passengers to make maximum use of the available elevator system capacity.
The commencement of Up Peak may be triggered by a time clock, by the departure of a certain number of fully loaded cars leaving the lobby within a given time period, or by a switch manually operated by a building attendant.
Down peak
During Down Peak mode, elevator cars in a group are sent away from the lobby towards the highest floor served, after which they commence running down the floors in response to hall calls placed by passengers wishing to leave the building. This allows the elevator system to provide maximum passenger handling capacity for people leaving the building.
The commencement of Down peak may be triggered by a time clock, by the arrival of a certain number of fully loaded cars at the lobby within a given time period, or by a switch manually operated by a building attendant.
Sabbath service
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.
Independent service
Independent service is a special service mode found on most elevators. It is activated by a key switch either inside the elevator itself or on a centralised control panel. When an elevator is placed on independent service, it will no longer respond to hall calls. (In a bank of elevators, traffic would be rerouted to the other elevators, while in a single elevator, the hall buttons will be disabled). The elevator will remain parked on a floor with its doors open until a floor is selected and the door close button is held until the elevator starts to travel.
Inspect mode
Inspect mode is a mode that is activated only by a key switch that is usually located inside the elevator on the COP (control operating panel). When activated, the elevator will no longer respond to calls and comes immediately to a halt. The elevator car will continue to remain idle until given a command from a corresponding access key switch. This enables the Elevator Mechanic to gain access to the pit of the elevator or the car top. Since this key allows entry into the hoist way of the elevator, this key is not given out and is restricted only for use by qualified Elevator Mechanics.
Fire service mode
Depending on the location of the elevator, fire service code will vary state to state and country to country. Phase One and Phase Two are separate modes that the elevator can go into. Once an alarm has been activated, the elevator will automatically go into phase one. The elevator will wait an amount of time, then proceed to go into nudging mode to tell everyone the elevator is leaving the floor. Once the elevator has left the floor, depending on where the alarm was set off, the elevator will go to the Fire Recall Floor. However, if the alarm was activated on the fire recall floor the elevator will have an alternate floor to recall to. When the elevator is recalled, it proceeds to the recall floor and stops with its doors open. The elevator will no longer respond to calls or move in any direction. The only way to return the elevator to normal service is to switch it to bypass after the alarms have reset.
Phase two mode can only be activated by a key switch located inside the elevator on the centralized control panel. Once the elevator gets to the desired floor it will not open its doors unless the firefighter holds the door open button. If for any reason the firefighter wishes to leave the elevator, they will use the hold position on the key switch to make sure the elevator remains at that floor.
Standards
The mechanical, electrical and operational design of elevators are dictated according to various standards (aka elevator codes), which may typically be international, national, state, regional or city based. Where once many standards were prescriptive, specifying exact criteria which must be complied with, there has been a shift towards more performance-based standards where the onus falls on the designer to ensure that the elevator meets or exceeds the standard.
Some of the national elevator standards include:
Australia - AS1735 Canada - CAN/CSA B44 Europe - EN 81 series (EN 81-1, EN 81-2, EN 81-28, EN 81-70, EN 12015, EN 12016, EN 13015, etc.) USA - ASME A17Because an elevator is part of a building, it must also comply with standards relating to earthquake resilience, fire standards, electrical wiring rules and so forth.
US and Canadian elevator standard specifics
Passenger elevators are required to conform to the American Society of Mechanical Engineer's Standard A17.1 Safety Code for Elevators and Escalators in most US and Canadian jurisdictions (In Canada the document is the CAN/CSA B44 Safety Standard which was harmonized with the US version in the 2000 edition.) In addition passenger elevators may be required to conform to the requirements of A17.3 for existing elevators where referenced by the local jurisdiction.
Passenger elevators must also conform to many ancillary building codes including the Local or State building code, National Fire Protection Association standards for Electrical, Fire Sprinklers and Fire Alarms, Plumbing codes, and HVAC codes.
Residential elevators are required to conform to ASME A17.1.
Most elevators have a location in which the permit for the building owner to operate the elevator is displayed. While some jurisdictions require the permit to be displayed in the elevator cab, other jurisdictions allow for the operating permit to be kept on file elsewhere - such as the maintenance office - and to be made available for inspection on demand. In such cases instead of the permit being displayed in the elevator cab, often a notice is posted in its place informing riders of where the actual permits are kept.
Notable Elevator Installations, by Location
Eiffel TowerThe Eiffel Tower has double-deck elevators built into the legs of the tower, serving the ground level to the first and second levels.
There are four elevator cars of the traditional design that run from the second level to the third level. The cars are connected to their opposite pairs (opposite in the elevator landing/hall) and use each other as the counterweight.
Taipei 101It is worth noting that Taipei 101 uses double-deck elevators to service the main building tenants, although it is not the first of such implementations.
The observation deck elevators are the fastest in the world.
The Gateway ArchThe Gateway Arch in St. 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 the structure.
Called a tram or tramway, people enter this unique tramway much as one would enter an ordinary elevator, through double doors.
New city hall, Hanover, GermanyThe elevator in the new city hall in Hanover, Germany 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 hall. The elevator travels a height of 43 meters. The elevator was destroyed in 1943 and rebuilt in 1954.
Luxor Inclinator ElevatorIn Las Vegas, Nevada, at the Luxor Casino, is the Inclinator. Therefore, the elevator travels up the side of the pyramid at a 39 degree angle.
Twilight Zone Tower of TerrorMain Article: Twilight Zone Tower of Terror
The Twilight Zone Tower of Terror is the common name for a series of a free-fall elevator attractions at the Disney-MGM Studios park in Orlando, Disney's California Adventure park in Anaheim, the Walt Disney Studios Park in Paris and the Tokyo DisneySea park in Tokyo. The central element of this attraction is the unique free-fall experience achieved through the use of a state-of-the-art elevator system. Unlike most traction elevators, the elevator car and counterweight are joined using a cable system in a continuous loop running through both the top and the bottom of the drop shaft. This allows the drive motor to pull down on the elevator car from underneath, a feature which is used to raise passengers out of their seats early in the drop sequence by applying downward acceleration in addition to that of gravity. Furthermore, the uniquely fast and powerful drive motor allows the elevator to ascend to the top in mere seconds.
Finally, the passenger cab is mechanically removed from the main elevator car so that the elevator shaft can efficiently be used continuously while the passenger cabs can alternatingly be removed to permit passenger boarding. All of the attraction buildings feature multiple elevator shafts to further improve throughput.
"Top of the Rock" elevatorsGuests ascending to the 67th, 69th, and 70th level observation decks (dubbed "Top of the Rock") atop the GE Building at Rockefeller Center in New York City ride a high-speed glass-top elevator. When entering the cab, it appears to be any normal elevator ride.
Apple Store, New York CityOtis has recently installed an elevator that takes Apple customers from the 32 foot ground floor cube to the basement store. The elevator, except for the floor, is made completely of glass.
Examples:
Bad Schandau Elevator in Bad Schandau, Germany Hammetschwand Elevator in Bürgenstock, SwitzerlandElevator accidents
Maintenance is crucial for the safety of an elevator since they usually operate more than 20-30 years before replacement or modernization. As the elevator rose past the 29/F, the elevator suddenly moved up and down through the span of the shaft (between G/F and 40/F). The elevator was reported to have jerked up and down several stories 3 times and shook violently laterally. It just so happened that Ms Au, a woman waiting for an elevator in the lobby, saw the hall position indicator flash nonsense - one moment it showed "40/F" and just seconds later it would show "30/F". The elevator doors suddenly opened and the passengers fled the elevator. The elevators, as with all government Housing Authority elevators in public estates, are maintained by their original manufacturer (in this case, Schindler). The elevator was inspected and the only explanation given was one from a mechanic who said that "it was normal for an elevator to grind to a halt if it detects an abnormality, and then carry out its learning mode where it detects and 'learns' its position by travelling to the top and bottom of the shaft". Fanling, January 2002 - 11 year old boy killed involving Schindler elevator. Elevator ascended with the doors still open. (Chinese newspaper documents the Japanese incident and relates it to the 2002 Hong Kong incident - pictures on the left are the 'deadly elevators' in Hong Kong) Japan Hachioji, Tokyo, August 30, 2006 - A carpenter doing interior design work in a building in the Tokyo city of Hachioji plunged to his death after stepping into an empty elevator shaft, mistakenly thinking that the elevator had arrived, police said. The elevator involved was installed by Hitachi (not confirmed yet). Source: Mainichi Shinbun Kyoto, August 29, 2006 - In the Kyoto prefecture, in a distribution centre under construction, an installation subcontractor, while doing some cleaning work being on top of the elevator car, fell down by 10 meters through the 1-meter gap [between the elevator] and the shaft wall. Yokohama Elevator had entrusted the subcontractor with the installation of the elevator. Source: Kyoto Shinbun Tokyo, August 24, 2006 - On the evening of August 24, in the Tokyo-based headquarters of Tostem --a large building materials company-- a male technician who was performing the periodical maintenance got sandwiched for about 3 hours between an elevator car and the [shaft] wall. The accident elevator has been manufactured by Toshiba and is maintained by Toshiba Elevators. Source: NHK (TV) Minato-ku, Tokyo, Japan, July 12 2006 - The Schindler Elevator installed right next to the one in Minato Ward that killed 16 year old Ichikawa Hirosuke trapped a woman and a Schindler engineer riding along for 30 minutes. Source: Chiba Prefecture, Japan, June 2006 -Similar to Minato Ward incident although with no fatalities also involving Schindler elevator. This incident lead to Schindler admitting to computer programming errors that dated back to 1991, which allowed the doors to re-open even if the elevator has already started travelling. Minato-ku, Tokyo, Japan, June 2006 - a 16-year old high school student was killed as he was backing out of an elevator with his bicycle when the elevator suddenly rose with the doors still open, crushing his skull. Using a special key, the victim opened the 1-floor landing door while the elevator was not in the first floor. This case involved a Hitachi Elevator installed in 1974 and maintained by Hitachi. This case involved a Toshiba Elevator installed in 1993. Source: Japanese Elevator Association. Canada Toronto - five people receive broken ankles and other minor injuries, as an Otis parking garage hydraulic elevator in a National Life building on University Avenue plummets five floors. Fatality involving malfunction of Schindler freight elevator. Decapitation of doctor in old Otis made elevator. Kone, Inc., which had recently been servicing the elevator was later dismissed. Fatality involving malfunction of elevator at the Kenner Regional Medical Center. Woman age 56 on gurney became lodged between elevator car and shaft wall and dragged four floors. Runaway elevator in office building decapitated 55-year-old James Chenault as he tried to help fellow passengers out of a malfunctioning car. Explosion in pit of a Kone elevator during modernization in a Post Office injures 2 elevator workers. A student at The Ohio State University was killed while riding an elevator in a dormitory. The elevator began to descend while the doors were still open, and he became pinned between the building and the car while trying to exit the crowded elevator, causing asphyxiation. Brake tests were run on the elevator, which involves loading the car with 125% of it's rated load capacity. The elevator in question (as well as many others on campus) failed this test. A teenager vacationing with his family at the hotel Royal Solaris in Cancun fell to his death in an elevator shaft. An eight-month-old baby died when an elevator in an apartment building fell six stories. The elevator in question was not installed by a major elevator manufacturer. (Source: Nowosti)
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