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elevators An elevator is a transport device used to move goods or people vertically. In Commonwealth English, elevators are more commonly called lifts. Other languages may have loanwords based on either elevator (e.g. Japanese) or lift (e.g. Cantonese). Because of wheelchair access laws, elevators are often a requirement in new buildings with multiple floors.  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. elevators 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 with a counterweight. Sometimes two elevators move always synchronizedly in opposite direction, and they are each other's counterweight. The friction between the ropes and the pulley furnishes the traction which gives this type of elevator its name.  For more details on this topic, see #Traction elevators. Hydraulic elevators use the principal of hydraulics to pressurize an above ground or in-ground piston to raise and lower the car. Roped Hydraulics use a combination elevators of both ropes and hydraulic power to raise and lower cars. Recent innovations include permanent earth magnet motors, machine room-less rail mounted gearless machines, and microprocessor controls. For more details on this topic, see #Hydraulic type. Which technology is 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 elevators very high lift hoistways. For buildings of much over seven stories, traction elevators must be employed instead. Hydraulic elevators are usually slower than traction elevators. [edit] History Elisha Otis's elevator patent drawing, 15 January 1861.In 1823, an "ascending room" made its debut in London. [1] In 1853, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. The design of the OTIS safety is somewhat similar to one type still elevators used today. 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. Construction for Peter Cooper's Cooper Union building in New York began in 1853. An elevator shaft was included in the design for elevators 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 transport systems, followed by Schindler, Thyssen-Krupp and Kone, in order. The first electric elevator was built by Werner von elevators Siemens in 1880. The safety and speed of electric elevators were significantly enhanced by Frank Sprague. The development of elevators was led by the need for movement of large amounts 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 need for the passenger and freight elevators we use today. In October 11, 1887 Alexander Miles, elevators an African American inventor, patented a method which permitted elevator doors to open and close safely. In 1929, Clarence Conrad Crispen, with Inclinator elevators Company of America, created the first residential elevator. Crispen also invented the first inclined stair lift. [edit] Modern elevator construction Today, elevators are built under strict supervision of the Building Codes. Model Codes which are the standard in most US jurisdictions require compliance with the American elevators Society of Mechanical Engineers' (ASME) standards for the installation, maintenance, and inspection of elevators. In Canada, the governing authority is the CSA (Canadian Standards Association). In addition other related standards are likely required to be complied with as specified by Local Authorities Having Jurisdiction. Elevators are generally sold in prepackaged components which are inherently non-proprietary. All of the four major manufacturers sell proprietary microprocessor controls. elevators Each manufacturer provides similar product designs, with differing emphasis on quality, price,or reliablility. 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. In some large campus type properties, the use of non-proprietary equipment in new elevators construction has replaced the standard prepackaged product. 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. A scenic elevator in action.In some locations, the shaft and parts of the cab are made of transparent material for specialized "Scenic elevators." This allows riders to see elevators 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. Some examples of this are the CN Tower in Toronto, Canada and Galtier Plaza in Saint Paul, Minnesota. 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 elevators 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. Computer control also permits greater control of access to various floors of a building after hours and on weekends. 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. Renovations (mostly referred to as Modernizations in the industry) may consist of replacements for hoistway (floor landing) doors, car doors, interior cab finishes, controls, all hoistway wiring and cab wiring, hoist machines, governors, elevators hydraulic pistons and hall fixtures. At times renovations may also include replacement of the entire cab itself. In many instances the upgrading of components may require additional code compliance. [edit] Elevator safety Elevators are characterized as being extremely safe. Indeed, their safety record, that of moving millions of passengers every day, with extremely low rate of incident, is unsurpassed elevators by any other vehicle system, although fatalities due to malfunction [1] have been known to occur on occasion.[2] A certain number of passengers do die every year in elevator related incidents.[3] In 1998, in the United States, it was reported that of the estimated 120 billion rides per year in the approximately 600,000 elevators in the U.S., 10,000 people wound up in the emergency room.[4] because of elevator-related accidents. "Statistically, it's a safe ride", says Ray Lapierre, executive director of the Elevator Escalator Safety Foundation.[4] Past problems with hydraulic elevators meant such elevators built prior to a code change in 1972 were subject to possible catastrophic failure. The code had previously elevators required only single-bottom hydraulic cylinders; in the event of a breach of the cylinder, an uncontrolled fall of the elevator might result. Because it is impossible to verify the system completely without a pressurized casing (as described below), it is necessary to remove the piston to inspect it. The cost of removing the piston is such that it makes no economic sense to re-install the old cylinder, and therefore it is necessary to replace the cylinder and install a new piston.[citation needed] 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. This has led to the introduction of PVC liners (casings) around hydraulic cylinders which can be monitored for integrity. In the past decade, recent innovations called elevators machine room-less elevators first developed by Kone called the EcoSpace [5], 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 elevators hydraulic elevators as a special order. While the new machine room-less have proved good for space, a few companies have experienced major problems with quality control, such as limited travel to 300 feet with 40 floors, and engineering design when it comes to maintenance and replacement parts.[citation needed] Uses of elevators Passenger service A Passenger lift is designed to ferry people from point A to Point B vertically. The modern passenger lift is a simple means of transport within a building. This apparent simplicity belies a complex and sophisticated mechanical, electrical and microelectronic system. Passenger elevators capacity is related to the available floor space. Generally passenger elevators are available in typical capacities from 2,000 to 5,000 lb (455 to 2,720 kg) in 500 lb (230 kg) increments. Generally passenger elevators in buildings eight floors or less are hydraulic. In buildings up to ten floors, electric elevators are likely to have speeds up to 500 ft/min (2.5 m/s), and above ten floors speeds begin at 500 ft/min (2.5 m/s) up to about 2000ft/min (10 m/s). 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. Hydraulic type elevators 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. On some, the hydraulic piston (plunger) elevators 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 (also known as a caisson) for protection. A paternoster in Berlin from the 1970sRoped elevators hydraulic elevators use a combination of ropes and hydraulics. Twin post hydraulic Holeless hydraulic elevators do not require holes to be dug for the hydraulic cylinder. In most designs, the cab is lifted by a pair of hydraulic jacks, one on each side of the elevator. Climbing elevator A climbing elevator is a self-ascending elevator with its own propulsion. The propulsion can be done by an electric or a combustion engine. Climbing elevators are used in guyed masts or towers, in order to make easy access to parts of these constructions, such as flight safety lamps for maintenance. An example would be the Moonlight Towers in Austin, Texas, where the lift holds only one person and equipment for elevators maintenance. 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 elevators and was once seen in multi-story industrial plants. Controlling ELEVATORS General controls North American Elevator Buttons: A modern elevator has buttons to allow passengers to select the desired floor. Asian Elevator Buttons: Car operating panel of a modern freight elevator.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 inaccessible unless one swipes a security card or enters a elevators passcode (or both). In the United States and other countries, call button text and icons are raised to allow blind users to operate the elevator; many have Braille text besides. 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 elevators 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 elevators 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 elevators 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. Security controls: Elevators in modern buildings incorporate security features to control / prevent unauthorized floor access. One method is to use RFID card access in which call buttons don't register until an authorized card is detected. Another method is to require the passenger to enter a code, either on a separate elevators keypad or the call buttons themselves, followed by the desired floor number. Hold button: Larger elevators used for freight and hospital beds have an appropriately named button that "holds" the door open longer. Cancel floor: On some elevator models, the building owner elevators 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. Up and down buttons, to move the car up and down elevators without selecting a specific floor. Some older elevators can only be operated this way. [edit] Controls in early elevators Manual pushbutton elevator controls.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 a projecting handle. This allowed some elevators 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 elevators "watch the step". After stopping at the landing the operator would open the door/doors. Manually operated elevators were generally refitted or the cabs replaced by automatic equipment by the 1950s. 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 elevators of a mechanical "cricket" noisemaker. Some elevators still in operation have pushbutton manual controls. Floor numbering Further information: 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 elevators 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. [edit] 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. Regenerative braking is also disabled if it is elevators normally used, shunting energy collected elevators 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.[2] [edit] 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 elevators 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 elevators doors open until a floor is selected and the door close button is held until the elevator starts to travel. Independent service is useful when transporting large goods or moving groups of people between certain floors. [edit] 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. In theory, this mode could be used as a way to stop the car in mid flight if one did not have a stop switch key. The elevator car will continue to remain idle until given a command from a corresponding access key switch. Key switches for access are usually located at the bottom floor and top floor. This enables the Elevator Mechanic to elevators gain access to the pit of the elevator or the car top. The access key switch will bypass the door lock circuit for the floor it is located on and allow the car to move at Inspection Speed. This speed can range from anywhere up to 60% of contract speed on most controllers. 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. Another type of inspect is called Car Top Inspection mode. Most modern elevators have a car top inspect station on the top of the car that will isolate the landing and car push stations (LOP and COP). There are three main control elevators buttons fitted to the station that consists of an UP button, DOWN button and RUN button, all work as dead man buttons i.e. no pressure on the buttons means no car movement. The run button has to be elevators activated along with a direction button. This test station usually has a Light, Alarm Button, Stop Button and close access to the door operating control. The speed that a car on inspection is defined by local code. [edit] Fire service mode Depending on the location of the elevator, fire service code will vary state to state and country to country. Fire service is usually split up into two modes. Phase One and Phase Two are elevators separate modes that the elevator can go into. |