History
of the Elevator
Although hoists and primitive
elevators operated by human and animal power or by water wheels were in use as
early as the 3rd century BC, the modern power elevator is largely a product of
the 19th century. Most elevators of the 19th century were powered by steam
engines, either directly or through some form of hydraulic drive.
In the early 19th century, hydraulic plunger elevators were used in some
European factories. In this type, later used to some extent in the United States
and more extensively elsewhere, the car is mounted on a hollow steel plunger
that drops into a cylinder sunk into the ground. Water forced into the cylinder
under pressure raises the plunger and car, which fall by gravity when water is
released. In early installations the main valve controlling the flow of water
was operated by hand by means of ropes running vertically through the car; lever
control and pilot valves regulating acceleration and deceleration were later
improvements.
A forerunner of the modern traction elevator was in use in Great Britain in
1835. In this case the hoisting rope passed over a belt-driven sheave, or
pulley, to a counterweight traveling in guides. The downward pull of the two
weights held the rope tight against its sheave, creating sufficient adhesive
friction, or traction, between the two so that the turning sheave pulled the
rope along.
Glossary of Common Elevator Terms
ADA (Americans with Disabilities Act) —
The Americans with Disabilities Act of 1990 was signed into
law by President Bush on July 26, 1990. The ADA is designed to give civil rights
protection to people with disabilities, similar to those granted by the Civil
Rights Act.
Balustrade — the side of an escalator extending above
the steps. It includes skirt panels, interior panels, decks and handrails.
Brake — an electro-mechanical device used to prevent
the elevator from moving when the car is at rest and no power is applied to the
hoist motor. On some types of control, it also stops the elevator when power is
removed from the hoist motor.
Brake shoe — moving member(s) of a brake, lined with
friction material which, when in contact with the brake drum, holds the elevator
at floor level. On some types of control, it will stop the elevator when power
is removed from the hoist motor.
Brush — a device, usually of carbon or graphite
composition, used to connect a circuit with the rotating or moving portion of a
DC motor, generator or other electrical device. It carries current to and from
the non-moving parts of connections.
Callback — in contract service, a customer request
which requires a check of an elevator other than the regularly scheduled
maintenance.
Car (elevator) — the load-carrying unit, including
its platform, frame, enclosure, and car door or gate.
Car counterweight — a set of weights roped directly
to the elevator car of a winding-drum type installation. In practice, this
weight is equal to approximately 70 percent of the car weight.
Car operating station — a panel mounted in the car
containing the car operating controls, such as call register buttons, door open
and close, alarm emergency stop and whatever other buttons or key switches are
required for operation.
Car top inspection station — a control panel on top
of an elevator car which, when activated, removes the car from normal service
and allows the car to run at inspection speed from the car top station only.
Code — a system of regulations pertaining to the
design, manufacture, installation and maintenance of elevators, dumbwaiters,
escalators and moving walks. The most widely recognized and used is ANSI A-17.1,
sponsored by the National Bureau of Standards, the American Institute of
Architects, The American Society of Mechanical Engineers, and published by ASME.
It has been adopted by many states. Some states and cities have written their
own codes, most of which are based on the ANSI A-17.1.
Controller — a device, or group of devices, which
serves to control, in a predetermined manner, the apparatus to which it is
connected.
Counterweight — a weight which counterbalances the
weight of an elevator car plus approximately 40 percent of the capacity load.
Cylinder — the outermost lining of a hydraulic jack.
Direct current (DC) — an electric current flowing in
one direction only and substantially constant in value.
Door lock — any type of mechanical lock designed to
prevent the opening of a hoistway door from the landing side.
Door operator — a motor-driven device mounted on the
car which opens and closes the car doors.
Drive machine — the power unit which applies the
energy necessary to raise and lower an elevator, material lift, or dumb waiter
car or to drive an escalator, an inclined lift or a moving walk.
Drive sheave — the grooved wheel of a traction-type
hoisting machine over which the hoist ropes pass, and by which motion is
imparted to the car and counterweight by the hoist ropes.
Escalator — a power-driven, inclined, continuous
stairway used for raising or lowering passengers.
Firefighter's service — a device or group of devices
which provide: (1) a signal for immediate recall to a designated landing in
order to remove cars from normal use, and (2) to permit special operation for
firefighters or other authorized emergency personnel.
Geared traction machine — a traction machine in which
the power from the motor is transmitted to the drive sheave through reduction
gears.
Gearless traction machine — a type of elevator
hoisting machine on which the hoist ropes pass over a traction drive sheave
which is an integral part of the armature. Called gearless because no geared
reduction unit is utilized.
Generator — an electromechanical device that converts
mechanical energy to electrical energy (usually direct current).
Governor — (1) a mechanical speed control mechanism.
For elevator, it is a wire-rope driven centrifugal device used to stop and hold
the movement of its driving rope. This initiates the activation of the car
safety device. It opens a switch which cuts off power to the drive motor and
brake if the car travels at a preset overspeed in the down direction. Some types
of governors will also open the governor switch and cut off power to the drive
motor and brake if the car overspeeds in the up direction. (2) on escalators, a
direct-driven centrifugal device which, when activated by overspeed, cuts off
power to the drive motor and service brake.
Governor rope — a wire rope attached to an elevator
car frame that drives the governor and, when stopped by the governor, initiates
setting of the car safety.
Guide rails — steel T-section with machined guiding
surfaces installed vertically in a hoistway to guide and direct the course of
travel of an elevator car and elevator counterweights.
Hall lantern — a corridor mounted signal light
indicating than an elevator car is approaching that landing and the direction in
which the car is to travel.
Handrail — (1) the moving handhold provided for
escalator passengers which moves over the top of the balustrade and newels; (2)
a railing serving as a support.
Handrail guard — a guard, usually made of rubber,
that fits over the outside of the handrail at a point where the handrail enters
or leaves the balustrade; it is designed to keep a person's fingers out of the
handrail opening.
Hoistway — a shaftway for the travel of one or more
elevators, dumbwaiters or material lifts. It includes the pit and terminates at
the underside of the overhead machinery space floor or grating, or at the
underside of the roof where the hoistway does not penetrate the roof.
Hydraulic elevator — a power elevator where the
energy is applied, by means of a liquid under pressure, in a cylinder equipped
with a plunger or piston.
Layout — a scaled mechanical drawing showing
dimensioned plan views and elevations of an elevator hoistway and machine room
to indicate space conditions, pertinent dimensions, sizes and location of
components of the installation.
Leveling — the movement of an elevator toward the
landing sill when it is within the leveling zone. When the word leveling is
used, the inference is that the process of attaining a level or stop position
(the platform level with the landing sill) is performed completely
automatically.
Machine room — the space in which the driving machine
for an elevator or group of elevators, dumbwaiter, escalator or group of
escalators is located.
Main (car) guide rails — steel T-sections with
machined guarding surfaces installed vertically in a hoistway to guide and
direct the course of travel of an elevator car.
Overspeed governor switch — a part of an escalator
machine. It is actuated by centrifugal force and trips a switch when the motor
speed has increased 20 percent over its rated name plate speed.
Preventive maintenance — inspections, tests,
adjustments, cleaning and similar activities carried out on elevator and
escalator equipment with the intention of preventing malfunctions from occurring
during operation. It is designed to keep equipment in proper operating order and
is done on a schedule basis. It is also referred to as schedule maintenance.
Relay — an electric device that is designed to
interpret input conditions in a prescribed manner and after specified conditions
are met, to respond and cause contact operation or create change in associated
electric control circuits.
Roller guides — guide shoes which use rollers that
rotate on guide rails rather than sliding on the rails.
Sheave — a wheel mounted in bearings and having one
or more grooves over which a rope or ropes may pass.
Specifications — a detailed itemized description of
the plans, materials, dimensions and all other requirements proposed for the
installation of the equipment.
Step — the moving platform on which an escalator
passenger rides.
Top-of-car inspection station — controls on the top
of the car used by an elevator constructor to operate the car at inspection
speed. It provides a means of operating an elevator from on top of the car at
slow speed during adjustment, inspection, maintenance and repair.
Traction machine — an electric machine in which the
friction between the hoist ropes and the machine sheave is used to move the
elevator car.
Traveling cable — a cable made up of electric
conductors which provides electrical connection between an elevator or
dumbwaiter car, or material lift, and a fixed outlet in the hoistway or machine
room.
