Escalators

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Escalators
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Defintion

• An escalator is a moving staircase a conveyor
  transport device for carrying people between
  floors of a building.

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History

• In 1889, Leamon Souder successfully patented the
  "stairway", an escalator-type device that
  featured a "series of steps and links jointed to
  each other". No model was ever built.
• In November, 1898, Piat installed its "stepless"
  escalator in Harrods Knightsbridge store in
  England.

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Benefits

• The capacity to move large numbers of people.
• Can be placed in the same physical space as one
  might install a staircase.
• No waiting interval (except during very heavy
  traffic).
• They can be used to guide people toward main
  exits or special exhibits.

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Concept
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Main components

• Landing Platforms.
• Truss.
• Steps and Tracks.
• Handrail.
• Wheel track step chain.
• Driving control unit.

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Landing Platforms
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Landing Platforms

• The top platform contains the motor assembly and
  the main drive gear.
• Each platform contains a floor plate and a
  combplate.
• The floor plate provides a place for the
  passengers to stand before they step onto the
  moving stairs.
• The combplate is the piece between the stationary
  floor plate and the moving step.

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Truss
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Truss

• Assembly of structural steel that supports the
  weight and load of an escalator.
• A Control Panel, Drive Units for Steps and Moving
  Handrails and other components are housed inside
  the structure.
• Main parts
• - Top Machine Room/Bottom Machine
  Room.
• - Main Track.
• - Trailing Track.
• - Moving Handrail Drive Unit.

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Truss
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Top Machine Room/Bottom Machine Room

• 1) Control Panel Controls stop/start operation
  and also supplies electric power to the Drive
  Unit.
• 2) Drive Unit A unit to drive the escalator,
  comprised of electric motor, decelerator,
  electromagnetic brake, V belt, Sprocket, and
  other components.
• 3) Drive Chain A chain that transmits the Drive
  Unit's power to the drive wheel (Sprocket).
• 4) Sprocket (top/bottom) Drive wheels installed
  at top and bottom to drive the Steps. The top
  Sprocket drives the moving Steps, while the
  bottom sprocket turns the Steps.

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Steps Tracks

• The track system is built into the truss to guide
  the step chain, which continuously pulls the
  steps from the bottom up and the other way
  around.
• Every step has 4 wheels 2 step-wheels and 2
  trailing-wheels.
• For both type of wheels theres a separate track
  the step-wheel track (on the outer side) for the
  step wheels and the trailing wheel track (on the
  inner side) for the trailing wheels.

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Steps Tracks
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Steps Tracks

•  The wheels on the step-wheel track are the ones
  that are connected to the rotating step chain and
  so are pulled by the main drive gear at the top
  of the escalator. The other set of wheels just
  glide along its track, following the other ones.

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Steps Tracks

• The steps themselves are solid, one piece,
  die-cast aluminum or steel.
• Yellow demarcation lines may be added to clearly
  indicate their edges.

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Step Chain

• A chain, located on both sides of an escalator,
  connecting the Steps and driven by the Step Chain
  Sprocket.

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Handrails

• The handrail provides a convenient handhold for
  passengers while they are riding the escalator.
• Moves along the top of the Balustrade in
  synchronization with the Steps.

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Handrail Driver

• The handrail drive system is directly driven by
  the step drive system by adding an extra belt
  around the main drive gear that also drives the
  steps.
• Like this, both the steps and the handrail move
  at the same speed, making the ride for the
  passengers on the escalator more comfortable.

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Driving Unit

• The motor is a three phase squirrel cage AC
  induction motor specifically developed for
  escalator service.
• High starting torque.
• Minimal vibration.
• Reversing Type.

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Motor starting

• Direct-on-line.
• Star-Delta starter.
• Soft-starter(variable source voltage).
• VVVF Control (Variable Voltage, Variable
  Frequency)

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VVVF energy optimizer Controller

• Its soft starting feature also lowers excessive
  starting current and prevents wearing of
  mechanical gears, chains, belts etc. So it
  prevents mechanical shocks.
• Reduces losses in AC induction motors by way of
  voltage reduction and soft starting capability.
• It provides the required motor operating voltage
  to suit various loading conditions, resulting in
  higher power factor (i.e. better power
  efficiency) and reduced motor losses.

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On demand operation
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Braking

• An intelligent braking system would require a
  brake that can be proportionally controlled.
• The most widely used brake types on escalators
  are either hydraulic or electromagnetic.

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Electromagnetic Braking

• 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.

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Hydraulic Braking

• Hydraulic brakes on the other hand can be
  controlled by varying the oil pressure that acts
  against the springs.
• So modern escalators and intelligent braking
  systems use hydraulic brakes.

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Hydraulic Braking

• 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.

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Hydraulic Braking

• 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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Case Study

• Swafyyeh Mall (Avenue)

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General Specifications
Model 08JSB35-141
Speed0.5M/sec
Capacity1000 P/H
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Motor Specifications
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Motor Specifications
7.5 KW 380V 15A
50Hz 1450 rpm 78 Kg
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Brake
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Brake
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Brake
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Brake
140 N.m 200 V DC 0.3 A
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Main Wheel
Main Chain
Step chain
Main Wheel
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References

• Wikipedia.
• www.mitsubishielectric.com
• www.howstuffworks.com
• buckylab.blogspot.com
• Intelligent Braking Systems for Public Service
  Escalators by Dr. Lutfi Al-Sharif.

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• Thanks for your attention.
• Done by
• Ahmad Alammouri
• 0094295