A wire-cage lift circa 1895
is a vertical
vehicle that efficiently moves
people or goods between floors of a building. They are generally
powered by electric motors that either drive traction cables and
counterweight systems, or pump hydraulic fluid to raise a
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 multi-story buildings, especially where
wheelchair ramps would be impractical.
Lifts began as simple rope or chain
. A lift is essentially a
platform that is either pulled or pushed up by a mechanical means.
A modern day lift consists of a cab (also called a "cage" or "car")
mounted on a platform within an enclosed space called a shaft or
sometimes a "hoistway". In the past, lift drive mechanisms were
powered by steam and water hydraulic pistons. In a "traction" lift,
cars are pulled up by means of rolling steel ropes over a deeply
, commonly called a sheave in
the industry. The weight of the car is balanced with a counterweight
. Sometimes two lifts always move
synchronously in opposite directions, and they are each other's
The friction between the ropes and the pulley furnishes the
traction which gives this type of lift its name.
Hydraulic lifts use the principles of hydraulics
(in the sense of hydraulic power
) 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 earth
magnet motors, machine room-less rail mounted gearless machines,
and microprocessor controls.
Which technology is used in new installations depends on a variety
of factors. Hydraulic lifts are cheaper, but installing cylinders
greater than a certain length becomes impractical for very high
lift hoistways. For buildings of much over seven stories, traction
lifts must be employed instead. Hydraulic lifts are usually slower
than traction lifts.
Lifts are a candidate for mass
.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.
Elevator doors protect riders from falling into the shaft. The most
common configuration is to have two panels that meet in the middle,
and slide open laterally. In a cascading configuration (potentially
allowing wider entryways within limited space), the doors run on
independent tracks so that while open, they are tucked behind one
another, and while closed, they form cascading layers on one
All elevators, whether traction or hydraulic, require a machine
room to store large electric motors (or hydraulic pumps) and a
controller cabinet. This room is located above the hoistway (or
below, for hydraulic elevators) and may contain machinery for a
single or a group of elevators. Modern day traction motors
drive can be more compact and efficient; electronic
microprocessors have replaced the mechanical relays. As a result,
traction elevators can be built without a dedicated room above the
shaft, saving valuable space in building planning.
The new lift design presents a departure from the traditional,
looped over-the-top traction rope routing of traction elevators.
The ends of the cables are fixed to the supporting structure, and
the length of the cable are connected to the car and counterweight
by means of a force-multiplying, energy saving compound pulley
system. Machine Room-less
elevators have become a welcome alternative to the older hydraulic
elevator for low to medium rise buildings.
Benefits from a Green Perspective
- creates more usable space
- uses less energy (70-80% less than hydraulic elevators)
- uses no oil
- all components are above ground
---this takes away the environmental concern that was created by
the hydraulic cylinder being stored underground
- much lower cost than other elevators
- ride quality is better due to gearless traction
- operates at faster speeds than hydraulics
The first reference to an elevator is in the works of the Roman
, who reported that
built his first elevator,
probably in 236 B.C. In some literary sources of later historical
periods, elevators were mentioned as cabs on a hemp rope and
powered by hand or by animals. It is supposed that elevators of
this type were installed in the Sinai monastery
of Egypt. In the 17th century the
prototypes of elevators were located in the palace buildings of
England and France.
the Book of Secrets by Arab inventor Ibn
Khalaf 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
Ivan Kulibin created an elevator with
the screw lifting mechanism for the Winter Palace of Saint Petersburg.
In 1816 an elevator was established in the
main building of sub Moscow village called Arkhangelskoye. In 1823,
an "ascending room" made its debut in London.
In the middle 1800's, there were many types of crude elevators that
carried freight. Most of them ran hydraulically. The first
hydraulic elevators used a plunger below the car to raise or lower
the elevator. A pump applied water pressure to a plunger, or steel
column, inside a vertical cylinder. Increasing the pressure allowed
the elevator to descend. The elevator also used a system of
counter-balancing so that the plunger did not have to lift the
entire weight of the elevator and its load. The plunger, however,
was not practical for tall buildings, because it required a pit as
deep below the building as the building was tall. Later a
rope-geared elevator with multiple pulleys was developed.
of New York is
credited with inventing the "standing rope control
" for an elevator
In 1852, Elisha Otis
safety elevator, which prevented the fall of the cab if the cable
broke. The design of the Otis safety elevator is somewhat similar
to one type still used today. A governor device engages knurled
roller(s), locking the elevator to its guides should the elevator
descend at excessive speed. He demonstrated it at the New York
exposition in the Crystal
23, 1857 the first Otis passenger elevator was installed at
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 confident that a
safe passenger elevator would soon be invented. The shaft was
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
, is the world's largest manufacturer
of vertical transport 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 was led by the need for movement of
raw materials including coal
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
In 1874, J.W. Meaker patented a method which permitted elevator
doors to open and close safely.
In 1882, when hydraulic power was a well established technology, a
company later named the London Hydraulic Power
was formed. It constructed a network of high pressure
mains on both sides of the Thames which, ultimately, extended to
184 miles and powered some 8,000 machines, predominantly lifts
(elevators) and cranes.
In 1929, Clarence Conrad Crispen, with Inclinator Company of
America, created the first residential elevator. Crispen also
invented the first inclined stairlift
Pneumatic Vacuum Elevators
Pneumatic or "Vacuum" elevators operate without cables and can be
installed more easily and quickly than their alternatives since
their housing comprises prefabricated sections which are
considerably narrower than conventional lift shafts. These sections
are often transparent and afford the passenger a near 360°
Statistically speaking, elevators are extremely safe. Their safety
record is unsurpassed by any other vehicle system. In 1998, it was
estimated that approximately eight 100-millionths of one percent
(10,000 in 120 billion) of elevator rides resulted in an anomaly,
and the vast majority of these were minor things such as the doors
failing to open. For all practical purposes, there are no cases of
elevators simply free-falling and killing the passengers inside; of
the 20 to 30 elevator-related deaths each year, most of them are
maintenance-related - for example, technicians leaning too far into
the shaft or getting caught between moving parts, and most of the
rest are attributed to easily avoidable accidents, such as people
stepping blindly through doors that open into empty shafts or being
strangled by scarves caught in the doors. In fact, prior to the
, the only known free-fall incident in a
modern cable-borne elevator happened in 1945 when a B-25 bomber struck the Empire
in fog, severing the cables of an elevator cab,
which fell from the 75th floor all the way to the bottom of the
building, seriously injuring (though not killing) the sole occupant
- the female elevator operator. While it is possible (though
extraordinarily unlikely) for an elevator's cable to snap, all
elevators in the modern era have been fitted with several safety
devices which prevent the elevator from simply free-falling and
crashing. An elevator cab is typically borne by six or eight hoist
cables, each of which is capable on its own of supporting the full
load of the elevator plus twenty-five per cent more weight. In
addition, there is a device which detects whether the elevator is
descending faster than its maximum designed speed; if this happens,
the device causes bronze brake shoes to clamp down along the
vertical rails in the shaft, stopping the elevator quickly, but not
so abruptly as to cause injury. In addition, a hydraulic buffer is
installed at the bottom of the shaft to cushion any impact
Past problems with early hydraulic elevators meant those built
prior to a code change in 1972 were subject to possible catastrophic failure
. The code had
previously required only single-bottom hydraulic cylinders
. In the event of a
cylinder breach, 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;
therefore it is necessary to replace the cylinder and install a new
piston. Another solution to protect against a cylinder blowout is
to install a "life jacket." This is a device which, in the event of
an excessive downward speed, clamps onto the cylinder and stops the
car. This device is also known as a Rupture Valve in some parts of
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
liners (casings) around
hydraulic cylinders which can be monitored for integrity.
In the past decade, recent innovations in inverted hydraulic jack
have eliminated the costly
process of drilling the ground to install a borehole jack. This
also eliminates the threat of corrosion to the system and increases
Safety testing of mine shaft
cables is routinely undertaken. The method involves destructive
testing of a segment of the cable. The ends of the segment are
frayed, then set in conical zinc molds
. Each end of the segment is then secured in a
large, hydraulic stretching machine. The segment is then placed
under increasing load to the point of failure. Data about
elasticity, load, and other factors is compiled and a report is
produced. The report is then analyzed to determine whether or not
the entire cable is safe to use.
Uses of elevators
A passenger elevator is designed to move people between a
Passenger elevators capacity is related to the available floor
space. Generally passenger elevators are available in capacities
from in 500 lb (230 kg) increments. Generally passenger
elevators in buildings eight floors or less are hydraulic or
electric, which can reach speeds up to 200 ft/min
(1.0 m/s) hydraulic and up to 500 ft/min electric. In
buildings up to ten floors, electric and gearless 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 2000 ft/min (10 m/s).
Sometimes passenger elevators are used as a city transport along
. 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 perched, to a tunnel located on the beach below.
At Casco Viejo station in the Bilbao
, the elevator that provides access to the station from a
hilltop neighbourhood doubles as city transportation: the station's
ticket barriers are set up in such a way that passengers can pay to
reach the elevator from the entrance in the lower city, or vice
versa. See also the Elevators for urban
Types of passenger elevators
elevators may be specialized for the service they perform,
including: hospital emergency (Code blue
front and rear entrances, double
, and other uses. Cars may be ornate in their interior
appearance, may have audio visual advertising, and may be provided
with specialized recorded voice instructions.
An express elevator
does not serve all floors. For
example, it moves between the ground floor and a skylobby
, or it moves from the ground floor or a
skylobby to a range of floors, skipping floors in between. These
are especially popular in eastern Asia.
All elevators are required to have communication connection to an
outside 24 hour emergency service, automatic recall capability in a
fire emergency, and special access for fire
' use in a fire. Elevators should not be used by the
public if there is a fire in or around the building, and numerous
require signs to this
effect be posted near the elevator. However, emergency evacuations
in some countries do allow the use of special 'fire
Residential elevators may be small enough to only accommodate 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 (1.8
m) or less, often can accommodate just one person in a wheelchair
at a time with a load of 1000 lb (450 kg).
A freight elevator, or goods lift, is an elevator designed to carry
goods, rather than passengers. 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. Freight elevators may have manually operated doors,
and often have rugged interior finishes to prevent damage while
loading and unloading. Although hydraulic freight elevators exist,
electric elevators are more energy efficient for the work of
Stage and orchestra lifts are specialized lifts for use in the
performing arts, and are often exempt from some requirements .
Local jurisdictions may govern their use, installation and testing;
however they are often left out of local code enforcement
provisions due to their infrequent installation.
In America when black people were denied equal rights, they had to
use the freight elevator as they were not allowed to use the proper
Vehicular elevators are used within buildings with limited space
(in lieu of ramps) to move cars into the parking garage. Geared
hydraulic chains (not unlike bicycle chains) generate lift for the
platform and there are no counterweights. To accommodate building
designs and improve accessibility, the platform may rotate so that
the driver only has to drive forward. Most vehicle elevators have a
weight capacity of 2 tons, while some are large enough for 20-ton
In some smaller canals, boats and small ships can pass between
different levels of a canal with a boat lift rather than through a
On aircraft carriers
carry aircraft between the flight deck and the hangar deck for
operations or repairs. These elevators are designed for much
greater capacity than any other elevator ever built, up to 200,000
pounds (90 tonnes
) of aircraft and equipment.
Smaller elevators lift munitions to the flight deck from magazines
deep inside the ship.
Upon some passenger double-deck
such as the Boeing 747
or other widebody aircraft
, lifts transport flight
attendants and food and beverage trolleys from lower deck galleys
to upper passenger carrying
The residential elevator is often permitted to be of lower cost and
complexity than full commercial elevators. They may have unique
design characteristics suited for home furnishings, such as hinged
wooden shaft-access doors rather than the typical metal sliding
doors of commercial elevators. Construction may be less robust than
in commercial designs with shorter maintenance periods, but safety
systems such as locks on shaft access doors, fall arrestors, and
emergency phones must still be present in the event of
Limited Use / Limited Application
The limited-use, limited-application (LU/LA) elevator is a special
purpose passenger elevator used infrequently, and which is exempt
from many commercial regulations and accommodations. For example, a
LU/LA potentially may not necessarily be handicapped accessible,
and there might only be room for a single standing passenger.
Dumbwaiters are small freight elevators that are intended to carry
food rather than passengers. They often link kitchens with rooms on
A special type of elevator is the paternoster, a constantly moving
chain of boxes. A similar concept, the humanlift
, moves only a small platform, which the
rider mounts while using a handhold and was once seen in
multi-story industrial plants.
Material handling belts and belt elevators
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
There have occasionally been lift belts for humans; these typically
have steps about every seven feet along the length of the belt,
which moves vertically, so that the passenger can stand on one step
and hold on to the one above. These belts are sometimes used, for
example, to carry the employees of parking garages, but are
considered too dangerous for public use.
Types of hoist mechanisms
There are at least four means of moving an elevator:
- Geared and gearless traction elevators
Geared traction machines are driven by AC
electric motors. Geared machines use worm
to control mechanical 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.
These machines are generally the best option for basement or
overhead traction use for speeds up to 500 ft/min (2.5 m/s).
Gearless traction machines are low speed (low RPM), high torque
electric motors powered either by AC or DC. In
this case, the drive sheave is directly attached to the end of the
motor. Gearless traction elevators can reach speeds of up to 2,000
ft/min (10 m/s), or even higher. A brake is mounted between the
motor and drive sheave (or gearbox) to hold the elevator stationary
at a floor. This brake is usually an external drum type
and is actuated by spring force and
held open electrically; a power failure will cause the brake to
engage and prevent the elevator from falling (see inherent safety
and safety engineering
In each case, cables are attached to a hitch plate on top of the
cab or may be "underslung" below a cab, and then looped over the
drive sheave to a counterweight
attached to the opposite end of the cables which reduces the amount
needed to move the cab. The
counterweight is located in the hoist-way and rides a separate rail
system; as the car goes up, the counterweight goes down, and vice
versa. 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
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. The
grooves in the drive sheave are specially designed to prevent the
cables from slipping. "Traction
" is provided to the ropes by
the grip of the grooves in the sheave, thereby the name. As the
ropes age and the traction grooves wear, some traction is lost and
the ropes must be replaced and the sheave repaired or
Elevators with more than 100' (30 m) of travel have a system called
compensation. 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, as it
compensates for the differing weight of cable between the hoist and
the cab. 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. If the compensation system uses chains, the chain is guided
by a bar mounted between the counterweight rails.
- Conventional hydraulic elevators. They use an
underground cylinder, are quite common for low level buildings with
2-7 floors, and have speeds of up to 200 feet/minute (1
- Holeless hydraulic elevators were developed in the
1970s, and use a pair of above ground cylinders, which makes it
practical for environmentally or cost sensitive buildings with 2,
3, or 4 floors.
- Roped hydraulic elevators use both above ground
cylinders and a rope system, which combines the versatility of
inground hydraulic with the reliability of holeless hydraulic, even
though they can serve up to 8-10 floors.
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
in Austin, Texas, where the elevator holds only one
person and equipment for maintenance.
Elevator air conditioning
Elevator air conditioning is fast becoming a popular concept around
the world. The primary reason for installing an elevator air conditioner
is the comfort that it
provides while travelling in the elevator. It stabilizes the
condition of the air inside the lift car. Some elevator air
conditioners can be used in countries with cold climates if a
thermostat is used to reverse the refrigeration cycle to warm the
One of the many benefits of installing an elevator air conditioner
is the clean air that it provides.
Air is sucked from the elevator’s hoist way straight into the car
using a motorised fan. The air sucked into the hoist way may be
filled with dust mites, germs and bacteria.
With an elevator air conditioner, air provided is much cleaner
because the cold air is the same air that comes from the car
itself. Not only that, the cold air that is produced from the air
conditioner also goes through a layer of filter. This filtration
removes particles that are harmful to the human body.
A poorly maintained air-conditioning system may promote the growth
and spread of microorganisms, but as long as the air conditioner is
kept clean these health hazards can be avoided.
Elevator airflow diagram
Elevator lobby air conditioning constantly leaks into the elevator
shaft due to elevator movements and elevator shaft ventilation
requirements, resulting in wasted energy. By using elevator air
conditioners, less energy is used because the air conditioner is
able to cool the inside of the elevator more effectively.
Heat generated from the cooling process is rejected into the
hoistway. The elevator cab (or car) is not air-tight, and some of
this heat will reenter the car and reduce the overall cooling
effect, which may be less than ideal.
Air conditioning poses a problem to elevators because of the
condensation that occurs. The condensed water produced has to be
disposed of; otherwise, it would create flooding in the elevator
car and hoistway.
Ways to remove condensed water
There are at least four ways to remove condensed water from the air
conditioner. However, each solution has its pros and cons.
Atomizing, also known as misting the condensed water, is another
way to dispose of the condensed water. Spraying ultra fine water
droplets on to the hot coils of the air conditioner would ensure
the condensed water evaporates quickly.
Though this is one of the best methods to dispose of the condensed
water, it is also one of the costliest because the nozzle that
atomizes the water easily gets choked. The majority of the cost
goes to maintaining the entire atomizing system.
Disposing of condensed water works by firstly collecting the
condensed water and then heating it to above boiling point. The
condensed water would eventually be evaporated thereby disposing
Consumers are reluctant to employ this system because of the high
rate of energy used just to dispose of this water.
The cascading method works by flowing the condensed water directly
onto the hot coils of the air conditioner. This would eventually
evaporate the condensed water.
The downside of this technology is that the coils have to be at
extremely high temperature for the condensed water to be
evaporated. There is a chance that the water might not evaporate
entirely and that would cause water to overflow on to the exterior
of the car.
Drainage system works by creating a sump to collect the condensed
water and using a pump to dispose it off through using a drainage
It is an efficient method, but it comes at a heavy price because
the cost of building the sump, and maintaining the pump to make
sure it operates, is very expensive. Moreover, the pipes used for
drainage would look ugly on the exterior. This system also cannot
be implemented on a built project.
An internal control panel
A typical modern passenger elevator will have:
- Space to stand in, guardrails, seating cushion (luxury)
- Electric fans or air conditioning units to enhance circulation
- 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 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
- A set of doors kept locked on each floor to prevent
unintentional access into the elevator shaft by the unsuspecting
individual. The door is unlocked and opened by a machine sitting on
the roof of the car, which also drives the doors that travel with
the car. Door controls are provided to close immediately or reopen
the doors. Objects in the path of the moving doors will either be
detected by sensors or physically activate a switch that reopens
the doors. Otherwise, the doors will close after a preset
- A stop switch (not allowed under British regulations) to halt
the elevator while in motion and 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
- Hold button: This button delays the door closing timer, useful
for loading freight and hospital beds.
- Call cancellation: A destination floor may be deselected by
- Access restriction by key switches, RFID reader, code keypad,
hotel room card, etc..
- One or more additional sets of doors that can serve different
floor plans. For example, in an elevated crosswalk setup, the front
doors may open on the street level, and the rear doors open on the
- Security camera
- Plain walls or mirrored walls giving the illusion of larger
- Glass windowpane providing a view of the building interior or
onto the streets.
Other controls, which are generally inaccessible to the public
(either because they are key switches
because they are kept behind a locked panel), include:
- Fireman's service, phase II key switch
- Switch to enable or disable the elevator.
- An inspector's switch, which places the elevator in
inspection mode (this may be situated on top of the elevator)
- Manual up/down controls for elevator technicians, to be used in
inspection mode, for example.
- An independent service/exclusive mode will
prevent the car from answering to hall calls and only arrive at
floors selected via the panel. The door should stay open while
parked on a floor. This mode may be used for temporarily
- Attendant service mode.
Controls in early elevators
Manual pushbutton elevator
- 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 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". After
stopping at the landing the operator would open the door/doors.
Some slightly later lifts though, had door(s) that could be
operated by the same control (so when the lever is moved in the
desired direction, between the idle and motion points there is a
trigger to close the doors. When the handle is moved to idle, the
doors open again.) This sort of arrangement was used sometimes in
subway stations. Manually operated elevators were generally
refitted or the cabs replaced by automatic equipment by the 1950s.
The major exception is freight elevators which today are just as
commonly operated manually as automatically, and even when equipped
with automatic controls, are often operated by an attendant to
- Early automatic elevators used relays as
logic gates to control them, which began
to be replaced by microprocessors in
the late 1980s.
- 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
An external control panel
Elevators are typically controlled from the outside by up and down
buttons at each stop. When pressed at a certain floor, the elevator
arrives to pick up more passengers. If the particular elevator is
currently serving traffic in a certain direction, it will only
answer hall calls in the same direction unless there are no more
calls beyond that floor.
In a group of two or more elevators, the call buttons may be linked
to a central dispatch computer, such that they illuminate and
cancel together. This is done to ensure that only one car is called
at one time.
Key switches may be installed on the ground floor so that the
elevator can be remotely switched on or off from the outside.
In sky lobby
elevator systems, one would
select the intended destination floor (in lieu of pressing "up")
and be notified which elevator is to serve that request.
The elevator algorithm
The elevator algorithm
, a simple
by which a single elevator can
decide where to stop, is summarized as follows:
- Continue traveling 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
The elevator algorithm has found an application in computer
as an algorithm
for scheduling hard disk
elevators use more complex heuristic algorithms
which request to service next.
Destination Control System
Some skyscraper buildings feature a destination operating panel
where a passenger would register their floor calls before entering
the car. The system would let them know which car to wait for,
instead of everyone boarding the next car. In this way, travel time
is reduced as the elevator makes fewer stops for individual
passengers, and the computer distributes adjacent stops to
different cars in the bank.
It can also improve accessibility, as a mobility-impaired passenger
can move to his or her designated car in advance.
Inside the elevator there is no call button to push, or the buttons
are there but they cannot be pushed – they only indicate stopping
The system was first pioneered by Schindler Elevator as the Miconic
10. Manufacturers of such systems claim that average traveling time
can be reduced by up to 30%.
There are some problems with the system, though, and it is subject
to gaming. Sometimes, one person enters the destination for a large
group of people going to the same floor. 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. Also, occasionally, one person may
press the floor multiple times. This is common with up/down buttons
when people believe this to be an effective way to hurry elevators.
However, this will make the computer think multiple people are
waiting and will allocate empty cars to serve this one
The same destination scheduling concept can also be applied to
public transit such as in group
Special operating modes
Anti-Crime Protection (ACP)
Anti-Crime Protection will force each car to stop at a pre-defined
landing and open its doors. This allows a security guard or a
receptionist at the landing to visually inspect the passengers. The
car stops at this landing as it passes to serve further
Up peak (MIT)
During Up Peak mode (also called Moderate Incoming Traffic),
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. Elevators are dispatched
one-by-one when they reach a pre-determined passenger load, or when
they have had their doors opened for a certain period of time. 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.
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
Sabbath service (SHO)
In areas with large populations of observant Jews
or in facilities catering to Jews, one may find a
". In this mode,
an elevator will stop automatically at every floor, allowing people
to step on and off without having to press any buttons. This
prevents violation of the Sabbath
prohibition against operating electrical devices when Sabbath is in
effect for those who observe this ritual.
However, Sabbath mode has the side effect of wasting considerable
amounts of energy, needlessly running the elevator car sequentially
up and down every floor of a building, repeatedly servicing floors
where it is not needed. For a tall building with many floors, the
car must move on a frequent enough basis so as to not cause undue
delay for potential users that will not touch the controls as it
opens the doors on every floor up the building.
Independent service (ISC)
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 centralized control panel in the lobby.
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. Independent service is useful when transporting
large goods or moving groups of people between certain
Inspection service (INS)
Inspection service is designed to provide access to the hoistway
and car top for inspection and maintenance purposes by qualified
elevator mechanics. It is first activated by a key switch on the
car operating panel usually labelled 'Inspection', 'Car Top',
'Access Enable' or 'HWENAB'. When this switch is activated the
elevator will come to a stop if moving, car calls will be cancelled
(and the buttons disabled), and hall calls will be assigned to
other elevator cars in the group (or cancelled in a single elevator
configuration). The elevator can now only be moved by the
corresponding 'Access' key switches, usually located at the
top-most (to access the top of the car) and bottom-most (to access
the elevator pit) landings. The access key switches will bypass the
door lock circuit for the floor it is located on and allow the car
to move at reduced inspection speed with the hoistway door open.
This speed can range from anywhere up to 60% of normal operating
speed on most controllers, and is usually defined by local safety
Elevators have a car top inspection station that allows the car to
be operated by a mechanic in order to move it through the hoistway.
Generally, there are three buttons - UP, RUN, and DOWN. Both the
RUN and a direction button must be held to move the car in that
direction, and the elevator will stop moving as soon as the buttons
are released. The inspection panel also has standard power outlets
for work lamps and powered tools.
Fire service mode (EFS)
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. These are
separate modes that the elevator can go into.
Phase one mode is activated by a corresponding smoke sensor or heat
sensor in the building. 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.
Located on the fire recall floor is a fire service key switch. The
fire service key switch has the ability to turn fire service off,
turn fire service on or to bypass fire service. 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. This mode was
created for firefighters so that they may rescue people from a
burning building. The phase two key switch located on the COP has
three positions: off, on, and hold. By turning phase two on, the
firefighter enables the car to move. However, like independent
service mode, the car will not respond to a car call unless the
firefighter manually pushes and holds the door close button. Once
the elevator gets to the desired floor it will not open its doors
unless the firefighter holds the door open button. This is in case
the floor is burning and the firefighter can feel the heat and
knows not to open the door. The firefighter must hold door open
until the door is completely opened. 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. If the firefighter wishes to return to the recall
floor, they simply turn the key off and close the doors.
Medical emergency/'Code Blue' service (EHS)
Commonly found in hospitals, Code Blue service allows an elevator
to be summoned to any floor for use in an emergency situation. Each
floor will have a 'Code Blue' recall key switch, and when
activated, the elevator system will immediately select the elevator
car that can respond the fastest, regardless of direction of travel
and passenger load. Passengers inside the elevator will be notified
with an alarm and indicator light to exit the elevator when the
Once the elevator arrives at the floor, it will park with its doors
open and the car buttons will be disabled to prevent a passenger
from taking control of the elevator. Medical personnel must then
activate the Code Blue key switch inside the car, select their
floor and close the doors with the door close button. The elevator
will then travel non-stop to the selected floor, and will remain in
Code Blue service until switched off in the car. Some hospital
elevators will feature a 'hold' position on the Code Blue key
switch (similar to fire service) which allows the elevator to
remain at a floor locked out of service until Code Blue is
Emergency power operation (EPR)
Many elevator installations now feature emergency power systems
which allow elevator use in blackout situations and prevent people
from becoming trapped in elevators.
When power is lost in a traction elevator system, all elevators
will initially come to a halt. One by one, each car in the group
will return to the lobby floor, open its doors and shut down.
People in the remaining elevators may see an indicator light or
hear a voice announcement informing them that the elevator will
return to the lobby shortly. Once all cars have successfully
returned, the system will then automatically select one or more
cars to be used for normal operations and these cars will return to
service. The car(s) selected to run under emergency power can be
manually overridden by a key or strip switch in the lobby. In order
to help prevent entrapment, when the system detects that it is
running low on power, it will bring the running cars to the lobby
or nearest floor, open the doors and shut down.
In hydraulic elevator systems, emergency power will lower the
elevators to the lowest landing and open the doors to allow
passengers to exit. The doors then close after an adjustable time
period and the car remains unusable until reset, usually by cycling
the elevator main power switch. Typically, due to the high current
draw when starting the pump motor, hydraulic elevators aren't run
using standard emergency power systems. Buildings like hospitals
and nursing homes usually size their emergency generators to
accommodate this draw. However, the increasing use of current
limiting motor starters, commonly known as "Soft-Start" contactors,
avoid much of this problem and the current draw of the pump motor
is less of a limiting concern.
Elevator convenience features
Elevator floor indicator
Elevators may feature talking devices as an accessibility aid for
the blind. In addition to floor arrival notifications, the computer
announces the direction of travel, and notifies the passengers
before the doors are to close.
In addition to the call buttons, elevators usually have floor
indicators (often illuminated by LED
direction lanterns. The former are almost universal in cab
interiors with more than two stops and may be found outside the
elevators as well on one or more of the floors. Floor indicators
can consist of a dial
with a rotating needle
, but the most common types are those with
successively illuminated floor indications or LCDs
. Likewise, a change of floors or
an arrival at a floor is indicated by a sound, depending on the
Direction lanterns are also found both inside and outside elevator
cars, but they should always be visible from outside because their
primary purpose is to help people decide whether or not to get on
the elevator. If somebody waiting for the elevator wants to go up,
but a car comes first that indicates that it is going down, then
the person may decide not to get on the elevator. If the person
waits, then one will still stop going up. Direction indicators are
sometimes etched with arrows or shaped like arrows and/or use the
convention that one that lights up red means "down" and green means
"up". Since the color convention is often undermined or overrided
by systems that do not invoke it, it is usually used only in
conjunction with other differentiating factors. An example of a place
whose elevators use only the color convention to differentiate
between directions is the Museum of
Contemporary Art in Chicago, where a single circle can be made to
light up green for "up" and red for "down."
directions must be inferred by the position of the indicators
relative to one another.
In addition to lanterns, most elevators have a chime to indicate if
the elevator is going up or down either before or after the doors
open, usually in conjunction with the lanterns lighting up.
Universally, one chime is for up, two is for down, and none
indicates an elevator that is 'free'.
Observatory service elevators often convey other facts of interest,
including elevator speed, stopwatch, and current position
(altitude), as with the case for Taipei 101's service
The mechanical and electrical design of elevators is dictated
according to various standards (aka elevator codes), which may be
international, national, state, regional or city based. Whereas
once many standards were prescriptive, specifying exact criteria
which must be complied with, there has recently been a shift
towards more performance-based standards where the onus falls on
the designer to ensure that the elevator meets or exceeds the
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 A17
Because 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.
The American National Elevator Standards Group (ANESG) sets an
elevator weight standard to be 2200 lbs.
Additional requirements relating to access by disabled persons, may
be mandated by laws or regulations such as the Americans with Disabilities
US and Canadian elevator standard specifics
In most US and Canadian jurisdictions, passenger elevators are
required to conform to the American Society of Mechanical
Engineers' Standard A17.1, Safety Code for Elevators and
Escalators. 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 are
tested using the ASME A17.2 Standard. The frequency of these tests
is mandated by the local jurisdiction, which may be a town, city,
state or provincial standard.
Passenger elevators must also conform to many ancillary building
codes including the Local or State building code, National Fire Protection
standards for Electrical, Fire Sprinklers and Fire
Alarms, Plumbing codes, and HVAC
passenger elevators are required to conform to the Americans with
Disabilities Act and other State and Federal civil rights
legislation regarding accessibility.
Residential elevators are required to conform to ASME A17.1.
Platform and Wheelchair lifts are required to comply with ASME
A18.1 in most US jurisdictions.
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
Unique elevator installations
January 2008, Italy is the
nation with the most elevators installed in the world, with 850,000
elevators installed that run more than one hundred million lifts
every day, followed by United States with 700,000 elevators installed and People's
Republic of China with 610,000 elevators installed since 1949.
The world's largest market for elevators is Italy with more than
1,629 million euros of sales and 1,224 million euros of internal
Tower has double-deck elevators built into the legs of
the tower, serving the ground level to the first and second
An elevator pulley in the Eiffel Tower.
Even though the shaft runs diagonally upwards with
the contour of the tower, both the upper and lower cars remain
horizontally level. The offset distance of the two cars changes
throughout the journey.
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
As one car ascends from level 2, the other descends from level 3.
The operations of these elevators are synchronized by a light
signal in the car.
deck elevators are used in the Taipei 101 office tower.
Tenants of even-numbered
floors first take an escalator (or an elevator from the parking
garage) to the 2nd level, where they will enter the upper deck and
arrive at their floors. The lower deck is turned off during
low-volume hours, and the upper deck can act as a single-level
elevator stopping at all adjacent floors. For example, the 85th
floor restaurants can be accessed from the 60th floor sky-lobby.
Restaurant customers must clear their reservations at the reception
counter on the 2nd floor. A bank of express elevators stop only on
the sky lobby levels (36 and 60, upper deck car), where tenants can
transfer to "local" elevators.
The high speed observation deck elevators accelerate to a
world-record certified speed of 1010 meters per minute
(60.6 km/h) in 16 seconds, and then it slows down for arrival
with subtle air pressure sensations. The door opens after 37
seconds from the 5th floor. Special features include aerodynamic
car and counterweights, and cabin pressure control to help
passengers adapt smoothly to pressure changes. The downwards
journey is completed at a reduced speed of 600 meters per minute,
with the doors opening at the 52nd second.
The Gateway Arch
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.
The interior of one of the Gateway
Arch tramway cars
Called a tram
, people enter this
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 tilting 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. At the
beginning of the trip the cars hang from the drive cables, but as
the angle of the shaft changes, they end up beside and then on top
of the cables.
View up the shaft of the elevator at
the new city hall, Hannover, Germany.
New City Hall, Hanover, Germany
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.
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.
Luxor Inclinator Elevator
Nevada, at the Luxor Hotel, is the Inclinator.
The shape of this casino
is a pyramid
. Therefore, the elevator
travels up the side of the pyramid at a 39 degree angle. Although
people refer to this "inclined elevator" as an inclinator, this is
Twilight Zone Tower of Terror
Twilight Zone Tower of Terror is the common name for a series of
elevator attractions at the Disney's Hollywood Studios park in Orlando, the 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 a simulated free-fall achieved through the use of a
high-speed elevator system. For safety reasons, passengers are
seated and secured in their seats rather than standing. 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, resulting in downward acceleration
greater than that of normal gravity. The high-speed drive motor is
used to rapidly lift the elevator as well.
The passenger cabs are mechanically separated from the lift
mechanism, thus allowing the elevator shafts to be used
continuously while passengers board and disembark from the cabs.
Multiple elevator shafts are used to further improve passenger
throughput. The doorways of the top few "floors" of the attraction
are open to the outdoor environment, thus allowing passengers to
look out from the top of the structure.
"Top of the Rock" elevators
ascending to the 67th, 69th, and 70th level observation decks
(dubbed "Top of the Rock") atop the
Building at Rockefeller
Center in New York
City ride a high-speed glass-top elevator.
entering the cab, it appears to be any normal elevator ride.
However, once the cab begins moving, the interior lights turn off
and a special blue light above the cab turns on. This lights the
entire shaft, so riders can see the moving cab through its glass
ceiling as it rises and lowers through the shaft. Music plays and
various animations are also displayed on the ceiling. The entire
ride takes about 60 seconds.
elevator located in the centre of the Apple
Store in London takes
passengers between the ground and first floors.
is operated by a hydraulic ram and made almost entirely of glass,
consisting of a glass shaft, containing a car with glass walls and
ceiling. The elevator, manufactured by Apex Lifts, is unique in a
number of ways: firstly, the car-top controls are removable, so
that whilst the lift is in normal service, there are no visible
mechanics on top of the glass box that is the car; secondly, there
are no lift position switches within the shaft, with the exception
of the top final-limit switch. Instead of these conventional
switches within the shaft, the lift employs a laser, which is aimed
from under the pit floor to a target on the car, and in this way
the exact height of the car can be obtained, enabling the car to
stop with an accuracy of 1 mm.
A similar elevator, installed by Otis
, takes Apple customers in the New
York City store from the 35-foot ground floor cube to the basement
store. This elevator too is made entirely of glass. On May 29,
2006, just a week after its opening, it made the news when it
trapped five passengers.
Disneyland, Anaheim, California
the Haunted Mansion attraction at
Disneyland in Anaheim, California, takes place on an elevator.
room" on the ride is actually an elevator that travels downwards,
giving access to a short underground tunnel which leads to the rest
of the attraction. The elevator has no ceiling and its shaft is
decorated to look like walls of a mansion. Because there is no
roof, passengers are able to see the walls of the shaft by looking
up, which gives the illusion of the room stretching.
Elevators for urban transport
In some towns, where terrain is difficult enough to justify,
elevators are used as part of the urban transport systems.
- Skyway in Nagasaki,
- Bad Schandau Elevator in Bad
- Barcelona, Spain - Elevator and cableway line connecting the
port terminal to Montjuic hill
- Bilbao - Casco
Viejo Bilbao Metro station (fare-paying
elevator connecting upper and lower neighbourhoods, as well as the
- Genoa, Italy -
ten public elevators
- Hammetschwand Elevator in Bürgenstock, Switzerland
- Katarina Elevator in Stockholm, Sweden
Elevator in Salvador,
- Marburg, Germany - some parts of the historic city core
built on higher ground (Uppertown, "Oberstadt" in German) are
accessible from the lower street level by elevators. These
elevators are unique in servicing also various buildings partially
embedded in the steep-sloping terrain.
- Monaco, seven
- Naples, Italy -
three public elevators
- Oregon City Municipal
Elevator in Oregon City, Oregon, United States
- Santa Justa Lift in Lisbon,
Cliff Lift in Shanklin, Isle of Wight
- Asansor, Izmir, Turkey
- Jersey City, New
Jersey elevator at Bergen Hudson Light Rail station at
9th Street and Palisade Avenue.
- The Elevator Museum, timeline
- The History of the Elevator - Elisha Otis
- Ralph Turvey, London Lifts and Hydraulic Power, Transactions of
the Newcomen Society, Vol. 65, 1993-94, PP.147-164
- source: ANIE Federazione (Federazione Nazionale
Industrie Elettrotecniche ed Elettroniche
- source: China's elevator market study, 2005-2006,
Publisher "Research in China"
- BSEE - Building Services and Environmental
Engineer: Liftstore Core to Apple Success
- Jobs' glass elevator locks in group customers -
- Manavalan, Theresa (30 October 2005). "Don't let them ride
alone". New Straits
Times, p. F2.