Escalator and moving walk

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University of Jordan Electrical engineering
department Electric drive
Escalator and moving walk
Prof. Mohammad Zeki KhedHer
Done by amr quedan 0086264
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Definition
Escalator is a moving staircase a conveyor
transport device for carrying people between
floors of a building. The device consists of
a motor -driven chain of individual, linked steps
that move up or down on tracks, allowing the step
treads to remain horizontal.
Moving walk way is a slow moving conveyor
mechanism that transports people across a
horizontal or inclined plane over a short to
medium distance. Moving walkways can be used by
standing or walking on them. 
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Escalator
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Moving walk
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Escalator parts
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Drive systems
1- Step Drive System
2- Handrail Drive System.
The variation on how these two systems are
combined is dependent upon the type of escalator.
The Drive Machine used to drive the pinion gear
or the main drive chain may directly or
indirectly drive the Handrail Drive System.
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External Drive Systems
The Drive machine is located outside the truss.
The main drive machine is located in the upper
pit area or in a separate machine room located
below the upper section of the escalator. An
external drive located in the upper pit area may
employ a direct motor to gearbox drive, or a
motor to gear reducer with a chain drive. An
external drive escalator with the drive unit
located within a machine room beneath the upper
landing will normally employ a motor/gearbox with
a chain drive extending to the upper landing.
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Internal Drive Systems
The Drive machine is located at the upper landing
within the truss between the step bands
The main drive machine is located at the upper
landing within the truss, between the step bands
of the escalator. It employs a motor to gearbox
drive with a direct drive axle connection. A
separate dual drive machine within the step band
is not uncommon with one machine used to directly
drive the step chains located a few feet below
the upper incline and one above the lower
incline.
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Modular Drive Systems
The Drive machine is located within the incline
of the truss between the step bands.
The main drive is located within the incline of
the truss within the step band. The motor may be
directly connected to the gearbox or it may
transfer power through a belt drive. The gearbox
will have a direct connection to the drive axle.
A modular escalator may have a single drive or a
multiple drive depending on the overall length of
the escalator.
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Drive Machine
The Drive machine provides the torque to drive
the step band at a constant speed.
The drive motor shall be integrally mounted, A.C.
squirrel cage, three phase induction motor of
continuous rating, reversible type with high
starting torque and low starting current and
specially designed for escalator application.
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It is either directly or flexibly coupled to the
reduction gear. The motor is usually protected
by thermal and/or electro-magnetic overload
devices as well as thermistors in the motor
winding.
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Motor Control
Todays drive systems incorporate a solid-state
soft-start controller These new types of power
control offer the ability to adjust the motor
power to match the load. Modular soft-starters
allow for gradual smooth starting of three-phase
squirrel cage motors. Unlike conventional (older)
electromechanical starting systems, these devices
allow precise adjustment of motor starting
torque, eliminating mechanical shocks to the
systems components.
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Motor Gear Reducer
The drive motor, together with the gear reducer,
deliver the necessary torque.
The Main Drive Gear or gear reducer assembly may
be a single-stage type gear reducer. This is an
enclosed, mechanical device that takes the drive
motor torque and transmits this torque to the
bull gear through a gearbox shaft (pinion) or the
main drive chain. The gear reducer assembly
contains a steel worm gear that is coupled or
directly sleeved onto the motor shaft and it
meshes with the pinion (bronze) gear.
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Steps Overview
When looking up the escalator you are facing the
riser of the step. The length of the step is
measured from both ends of the step tread (front
and rear) and the width is from both sides of the
step. The step frames, treads, and riser
excluding their attachment or inserts (yellow
demarcations) are a die-cast aluminum design and
form the Step Unit Assembly.
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Step
Each step in the escalator has two sets of
wheels, which roll along two separate tracks. The
upper set (the wheels near the top of the step)
are connected to the rotating chains, and so are
pulled by the drive gear at the top of the
escalator. The other set of wheels simply glides
along its track, following behind the first set.
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The tracks are spaced apart in such a way that
each step will always remain level. At the top
and bottom of the escalator, the tracks level off
to a horizontal position, flattening the
stairway. Each step has a series of grooves in
it, so it will fit together with the steps behind
it and in front of it during this flattening
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Step Chain Drive
The Step Chains are endless links connected with
link pins to make a complete loop and are
attached to an axle on each side of the steps
forming a loop which runs for the whole escalator
length.
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Step Chain Drive
The step motion is achieved by a direct step
assembly connection to the step chains.
Two-step chains one for each side of the
escalator are directly coupled to the Main Drive
axle, the bull gear shaft, through the step chain
sprockets. The step chain form a loop for the
length of the truss, from the step chain
sprockets at the upper end down to the tension
carriage gear or turnaround (depending on the
manufacturer) at the lower end or the lower
reversing station.
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Step Chain Drive
The Main Drive Axle is driven by the motor and
reducer assembly. Sprockets or bull gears
(depending on the manufacturer). On both ends of
the Main Drive Axle transfer power to the Step
Drive System. These sprockets or bull gears
drive two step chains, one each for the right and
left sides of the escalator, which are connected
at the lower end of the escalator to the step
chain sprockets of the Tension Carriage.
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Escalator step widths and energy usage
Size Width (between balustrade panels) Single-step capacity Applications Energy consumption
Very small 400 mm (16 in) One passenger, with feet together A rare historic design found mostly in older department stores 3.7 kW (5.0 hp)
Small 600 mm (24 in) One passenger Low-volume sites, uppermost levels of department stores, when space is limited 3.7 kW (5.0 hp)
Medium 800 mm (31 in) One passenger one package or one piece of luggage Shopping malls, department stores, smaller airports 7.5 kW (10.1 hp)
Large 1,000 mm (39 in) Two passengers one may walk past another Mainstay of metro systems, larger airports, train stations, some retail usage 7.5 kW (10.1 hp)
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Circle Tracks (Crab Tracks)
The Circle Tracks provide smooth step travel at
the end of the tracks. The Chain Wheel is used to
maintain proper tracking of the step chain. Most
of the outer circle tracks have access windows
for easy step removal.
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Handrail Overview
The Handrail provides a convenient handhold for
passengers.
The Handrail is constructed of four distinct
sections. At the center of the handrail is a
"slider. The next layer, known as the tension
member consists of either steel cable or flat
steel tape. On top of the tension member are the
inner construction components. Finally, the outer
layer, which is a blend of synthetic polymers and
rubber.
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Handrail Overview
The system uses a drive wheel with an uphill and
downhill side.
The escalator handrail is wrapped around a
portion of the drive wheel and two pressure
rollers. The escalator handrail is driven by the
drive wheel with the assistance of the uphill
pressure roller and the downhill pressure roller
applying pressure to the handrail as it passes
through each of the first and second nips. There
are also guide rollers with at least one
positioned adjacent to the downhill and the
uphill sides of the drive wheel.
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Handrail Overview
There are a the mechanical link between the dual
toothed drive chain sprockets. The drive chain
sprockets and handrail drive chain coming to
transfer power from the bull gear shaft to the
handrail drive sheave. The Handrail drive chain
has an adjustable take-up sprocket to keep the
drive chain snug. The handrail drive chain
receives lubrication from an enclosed bath
system. 
The Handrail Take-Up Devices are located directly
downhill from the handrail drive sheaves. The
handrail take-up devices remove slack in the
handrail to provide the proper amount of slack in
the handrail required to drive the handrail.
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Auto-Lubrication System
The Automatic Lubrication System supplies oil to
lubricate the main drive chain, step chain, and
the handrail drive chains. Oil flow rate is
adjustable by setting the automatic timer control
off and on periods to supply more or less
lubrication. The system dispenses pre-determined
amounts of oil to the distribution network which
delivers this oil to the bearing points.
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Braking Systems
Brakes in lift and escalator applications have to
be fail-safe. For this reason, they are
invariably spring applied and power lifted
(either hydraulically or electromagnetically).  Th
e most widely used brake types on escalators are
either hydraulic or electromagnetic (i.e.,
solenoid). An intelligent braking system would
require a brake than can be proportionally
controlled.
Hydraulic brakes are more amenable to
proportional control than electromagnetic brakes.
The problem with electromagnetic brakes is that
they can either be set in the on or off
positions, and it is not possible to keep them in
intermediate positions in order to vary the
pressure. Hydraulic brakes on the other hand can
be controlled by varying the oil pressure that
acts against the springs. So the decision was
made to use hydraulic brakes for the intelligent
braking system.
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The pressure applied by the hydraulic brake is
the result of the interaction between the spring
force (trying to apply the brake pads on the
disk) and hydraulic pressure (trying to keep the
brake pads off the disk). The spring pressure is
constant and cannot be varied, as it is a
characteristic of the spring. By controlling the
hydraulic pressure, the exact braking effort can
be applied. The hydraulic pressure is varied by
controlling the valves that control the flow of
the oil. Such a control can be done via two
methods    Proportional valves.  Pulse width
modulation (PWM) control of on/off valves.
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The second method of PWM is the one used in this
system. Although the switching is not
proportional (i.e., only on and off), the duty
cycle of the on/off proportions is varied such
that a 50  duty cycle leads to no change in
pressure, while a duty cycle in excess of 50 
(i.e., with the valve feeding the oil staying
open longer than 50 ) leads to an increase in
pressure and reduction in braking (and vice
versa). This requirement to increase or decrease
the braking depends on the comparison between the
reference ideal speed profile and the actual
measured speed profile.  
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Escalator speed
Escalator speeds vary from about 90 feet per
minute to 180 feet per minute (27 to 55 meters
per minute). An escalator moving 145 feet (44 m)
per minute can carry more than 10,000 people an
hour -- many more people than a standard elevator.
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-Step widths 600, 800 1000 mm min. step or
tread length 400mm - Inclination usually at
angle 30 . 35 if rise lt 6 m speed lt 0.5 m/s
-Escalator handling capacity
 
 
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Modes of operation
- Continuous operation is the optimal mode for
the commercial sector in which customers are to
be transported efficiently to the upper floors of
the store.
- Stop--go operation is recommended for the
intermittent arrival of passengers or for
sporadic use outside peak times. Typical
applications include movie theaters, airports,
subway stations and railway stations. The unit
remains ready for operation when there are no
passengers, as signaled by a direction indicator.
The Schindler entrance monitoring system detects
approaching passengers and sets the
escalator/moving walk into motion whenever
required.
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- continuous operation with crawling the
escalator/moving walk continues to crawl along at
0.1 m/s in the absence of passengers, using a
frequency converter. Unlike conventional
stop--go operation, mechanical wear is
considerably lower, and in this operating mode
the readiness for operation and the direction of
travel are indicated by the slowly moving steps.
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Levytator
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References
www.schindler.com www.wikipedia.org www.mtisubishi
.com www.lift-report.de Transit
Elevator/Escalator Consortium www.youtube.com