Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 110 views

    So How Do Elevators or Lifts Work

    Uploaded by

    Ayesha MAhmood
    The document discusses the working of elevators. It describes the main parts of an elevator including the counterweight, doors, electronic systems, and safety mechanisms. The counterweight helps reduce the amount of energy needed to lift the elevator car. Doors use a motor, arms, and rails to open and close automatically. Electronic systems control the elevator's movements. As for safety, early Otis elevators had ratchet systems as backups in case of cable failure. The document also discusses how different types of elevators work, including hydraulic elevators using fluid pressure, pneumatic elevators using air pressure, and traction elevators using cables and counterweights.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd

    So How Do Elevators or Lifts Work

    Uploaded by

    Ayesha MAhmood
    110 views12 pages
    The document discusses the working of elevators. It describes the main parts of an elevator including the counterweight, doors, electronic systems, and safety mechanisms. The counterweight helps reduce the amount of energy needed to lift the elevator car. Doors use a motor, arms, and rails to open and close automatically. Electronic systems control the elevator's movements. As for safety, early Otis elevators had ratchet systems as backups in case of cable failure. The document also discusses how different types of elevators work, including hydraulic elevators using fluid pressure, pneumatic elevators using air pressure, and traction elevators using cables and counterweights.

    Original Description:

    Original Title

    So how do elevators or lifts work

    Copyright

    © © All Rights Reserved

    Available Formats

    DOCX, PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    The document discusses the working of elevators. It describes the main parts of an elevator including the counterweight, doors, electronic systems, and safety mechanisms. The counterweight helps reduce the amount of energy needed to lift the elevator car. Doors use a motor, arms, and rails to open and close automatically. Electronic systems control the elevator's movements. As for safety, early Otis elevators had ratchet systems as backups in case of cable failure. The document also discusses how different types of elevators work, including hydraulic elevators using fluid pressure, pneumatic elevators using air pressure, and traction elevators using cables and counterweights.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    110 views12 pages

    So How Do Elevators or Lifts Work

    Uploaded by

    Ayesha MAhmood
    The document discusses the working of elevators. It describes the main parts of an elevator including the counterweight, doors, electronic systems, and safety mechanisms. The counterweight helps reduce the amount of energy needed to lift the elevator car. Doors use a motor, arms, and rails to open and close automatically. Electronic systems control the elevator's movements. As for safety, early Otis elevators had ratchet systems as backups in case of cable failure. The document also discusses how different types of elevators work, including hydraulic elevators using fluid pressure, pneumatic elevators using air pressure, and traction elevators using cables and counterweights.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 12

    WORKING OF ELEVATORS &

    ESCLATORS
    BUILDING SERVICES & SYSTEM 3

    Ayesha mahmood
    ELEVATORS
    The car is connected to a pulley system through steel or metal cables. The
    electric motor drives the pulley which pulls up or down the car(now we
    will see changes in the design as it was just rough idea).
    We will see one by one parts of a lift (called in British language) along
    with their contributions in working.

    The basic
    main parts of an Elevator.

    Counterweight :-
    You must have observed this one. You can see this thing on ground floor
    whenever an elevator is at the top floor. When the lift starts coming
    down, the counterweight starts moving upside & vice versa. But why do
    we need it ?Imagine the lift has to go up on 10th floor now being on
    ground floor & it will require 1000 KJ of energy. What these smartass’s
    have done –  they have joined a counterweight on the other end of the
    cables. Now what happens, the electric motor above require less energy to
    lift you because our friend –  Mr Counterweight is already helping us by
    pulling us up. Which means instead of 1000 KJ, this time you would need
    less amount of energy like 500 KJ thereby consuming less power.   There
    you go.
    The counterweight makes it easier for the motor to raise and lower the car
    just as sitting on a see-saw makes it much easier to lift someone’s weight
    compared to lifting them in your arms. Also a heavy loaded elevator car
    would be hard to pull up but will race down to the ground while coming
    down. All thanks to counterweight, which makes it easier to control the
    car. A counterweight weighs almost half of a fully loaded car.

    Doors :-
    The automatic doors of the car are essential & are very convenient to
    handicapped people. A typical automatic door systems consist of a motor
    which is connected to an arm which is again connected to a long metal
    arm which is attached to the door. The door then can slide back & forth
    on the metal rail.
    When the motor turns the wheel, it rotates the first arm which results in
    rotation of second long metal arm too which closes or opens the door.The
    door is made up of two panels which close in on when the door opens &
    extend when they close. You can visit this  link to see the animation.
    Also many elevators have a motion or ultrasonic sensor which keeps the
    doors from closing if somebody is between them.  

    Electronic systems :-
    Basically what they call is the “elevator algorithm” is fed into the lift’s
    computer system – to stop at floors to which the buttons represent, alarms
    etc.

    Safety :-
    Making the cables from steel strands doesn’t assure a 100% guarantee of
    safety. So Otis elevator(Otis -the one who designed it) had a ratchet
    system as a backup. Each car ran between two vertical guides with sturdy
    teeth all the way to the top. If the cables broke, a spring loaded
    mechanism with hooks sprung outside engaging into the metal teeth. So
    now you are somewhere stuck in between the floors but you are SAFE.
    These mechanisms were used on Otis elevators & only few of them have
    it today.

    How Do Elevator Works and Its Circuit Diagram?

    Due to the improved control structures, hardware and other  automation


    systems in traction elevator systems, most of the manufacturers are
    producing energy-efficient elevators. Regenerative drive system in
    elevator is a remarkable advancement in these energy efficient elevators.
    For mid and high-rise buildings, traction or cable-driven type of elevators
    are perfectly suitable compared with the electromechanical relays-based
    elevators and hydraulic elevators. This article is not intended to give an
    advanced concept about this topic, but to give an idea of ‘how elevators
    work’.

    Types of Elevators

    An Elevator is a vertical transport system that carries people or goods


    between the floors of building safely and efficiently. There are different
    types of elevators:

    1. Hydraulic Elevators

    2. Pneumatic Elevators

    3. Cable driven or traction Elevators

    Types of Elevators

    In an elevator, car is raised or lowered within several floors of a


    commercial and residential building. Depending on the load and the area
    of application, these elevators are installed with rated capacity. Hydraulic
    elevators are simple and effective in which the force required to move the
    car is low compared to the other elevators, but still their use is limited
    for certain stories high buildings such as 4 to 5 owing to the working
    ability of these elevators.

    Compared to traditional elevators, pneumatic-vacuum elevators are


    environmental friendly, easy to maintain, install and operate. And,
    compared to hydraulic elevators, pneumatic vacuum elevators require
    high pressure to move the car- and, in addition, their usage too is limited
    for a limited number of storied building. These elevators that run based
    on air pressure are safe and popular over the past several years for two to
    three-storied buildings.

    Nowadays buildings are constructed to greater heights and with the


    invention of traction electric elevators – they are commonly used in such
    buildings. Top speed, smooth ride quality and better elevation are the
    basic characteristics of these elevators. Let us see in brief about ‘how an
    elevator works’.

    How Hydraulic Elevators Work?

    The below figure shows the working of a hydraulic elevator wherein


    hydraulic fluid with a pumping system moves the elevator car up and
    down. In this type of elevator, a tank or fluid reservoir supplies hydraulic
    oil and the pump forces this oil through a least resistance path and
    returns it to the reservoir when the valve is opened. So when the valve is
    closed, the pressurized oil created by the pump pushes the piston upside
    so that the car moves in the upward direction. And when the valve is
    opened, the fluid returns back to the tank, and hence the piston moves
    downwards.

    Hydraulic Elevators

    If the elevator reaches the correct floor, the elevator-control system sends
    the signals to a motor driver,  which stops the motor , and then the
    pumping of fluid is halted at that position. While lowering, the car stays
    on exact floor by controlling the signals to the valve mechanism to open
    or close the valve. This is how the hydraulic system is operated for lifting
    and lowering the elevator car.
    Due to a special type of fluid in this system, the force required to push
    the piston is very less. This is an advantage of it, but, in order to elevate
    the car, the piston length required should be more. In other words, if the
    building height is more, the piston length required should also be longer.
    This requires an in-depth buried structure for high-storied buildings
    that’s why these are limited for high-storied buildings. Different types of
    hydraulic elevators are shown in the below figure.

    Different Types of Hydraulic Elevators

    How Pneumatic Elevators Work?

    Pneumatic Elevators

    This type of elevator consists of exterior cylinder which is transparent


    self-supporting tube consisting of modular sections, which can be easily
    fitted into one another. The roof of this tube is made up of steel that
    ensures air-tight closures with suction inlets and valves. An elevator car
    runs inside this cylinder, and the head unit on the top cylinder contains
    turbines, valves and controllers to control the movements of this elevator.

    How a Cable Driven or Traction Elevator Works?

    Cable Driven or Traction Elevator

    This is a typical and most popular type of elevator consisting of a few


    numbers of hoisting ropes or steel cables which run over a pulley
    connected to an electric motor. This elevator can be a geared or gearless-
    traction elevator. In this type of elevator, five to eight wire cables or
    hoisting cables are attached to the top of the elevator car by wrapping
    around it on sheaves at one end, and the other end is attached to a counter
    weight that moves up and down on its guiderails. This counter weight is
    equal to the weight of the car plus half of the maximum passenger load in
    that car. This means, during the lifting operation, it needs power for the
    extra passengers in the car, and, the rest of the weight is balanced by the
    counter weight.

    Whenever  the control system  attached to the elevator drives the motor in
    the forward direction, the sheaves also turn around causing to move the
    car elevator upwards, and then stopping in the desired floor wherein the
    car is balanced by the counter weight. For the downward movement of the
    car, reverse happens through a rotating motor via a control mechanism.
    Some of the elevators use  motors with four-quadrant operation  to save the
    energy in regenerative mode. Due to high speeds and high-rise
    capabilities, these types of elevators are found in many of the
    applications of lifts and escalators.

    Elevator Circuit Diagram

    For a better understanding of an elevator operation, a simple practical


    circuit is illustrated here using a microcontroller for the readers who are
    interested in developing  microcontroller projects . In the below circuit,
    switches are connected to the various ports of the microcontroller on
    three floors and also in the car elevator. Each floor’s display is depicted
    in seven-segment displays which are interfaced to the microcontroller
    unit.

    Elevator Circuit Diagram

    The indications of the upward and downward directions of the elevator


    are indicated using  Light Emitting Diodes . For moving the elevator, a
    motor is driven through a transistor which is not given in the circuit.
    The Microcontroller is programmed  logically in such a way that for the
    corresponding input switch, it rotates the motor and also drives  the
    seven-segment display  and LED display.
    This is how elevators work based on hydraulic, pneumatic and traction
    electric principles. Thanks for your keen attention on reading this article
    and we believe that the given content might have offered you some
    interesting insights while reading it. You can also write to us in the
    comment section for any doubts about this topic, particularly in the
    circuit demonstrated at last.
    Black colored teeth
    pointing upwards in Otis Elevator.
    What if the teeth or hook breaks or bends & the car doesn’t stop ?
    So, as a second backup, there are giant hydraulics or gas spring buffer
    located at the bottom to absorb the impact of collision. So don’t worry
    you are safe.

    Some quick facts:-

     The first safety elevator was designed by Elisha Graves Otis.


     The Taipei 101 tower in Taipei, Taiwan has the fastest elevator
    having a stunning & mind-boggling speed of  60 km/hr(37.7
    mph) !!!!! The elevators even has pressurized cylinders to prevent
    ear popping!

    How does a hydraulic elevator work?


    Hydraulic elevator with two linked rams and a counterweight.
    Artwork: A hydraulic elevator with an energy-saving counterweight. In this design, the
    passenger car (1) is supported by a direct-acting hydraulic ram (2), connected through a
    hydraulic pump (3) operated by a motor (4) connected to a second hydraulic ram (5) that
    operates a counterweight (6). As the elevator car falls, the pump transfers hydraulic fluid
    from one ram (2) to the other (5), so avoiding the need for a fluid reservoir. My drawing
    is based on a design by Otis described in US Patent 5,975,246: Hydraulically balanced
    elevator by Renzo Toschi, Otis Elevator Company, patented November 2, 1999.
    Elevators that work with cables and wheels are sometimes called traction elevators,
    because they involve a motor pulling on the car and counterweight. Not all elevators
    work this way, however. In small buildings, it's quite common to find hydraulic elevators
    that raise and lower a single car using a hydraulic ram (a fluid-filled piston similar to the
    ones that operate construction machines like bulldozers and cranes). Hydraulic elevators
    are mechanically simpler and therefore cheaper to install, but since they typically don't
    use counterweights, they consume more power raising and lowering the car. Sometimes
    the hydraulic ram is installed directly underneath the car and pushes it up and down (a
    design known as direct-acting) . Alternatively, if there isn't room to do that, the ram can
    be mounted to the side of the lift shaft, operating the car using a system of ropes and
    sheaves (in a design known as indirect-acting). More complex elevators, like the one
    shown here, use multiple hydraulic cylinders and counterweights.

    ESCLATORS
    I think every one of us must have seen and used an escalator. At its core,
    an escalator is a very simple machine. It is designed  for facilitating
    humans and at times goods from a lower point to higher point or vice
    versa. Today we will see how an escalator actually works.

    Escalator although a simple piece of machinery is also an expensive one. It has to be


    durable and has sufficient work stamina. It is just like a conveyor belt, only with steps on
    it. Now again terming it just a conveyor belt would not be doing justice to this machine.
    At a first glance, it looks like a moving staircase which in fact it is. Only a very robust
    one.

    Interior consists of a pair of chains which are wrapped around two gears. These gears are
    driven by a powerful electric motor. It is very common to see escalators with 100 HP
    motors. The chains, gears, and the motor are enclosed in a structure called the truss. Truss
    runs along the floors that the escalator is supposed to service.
    These chains of the escalator move a series of metallic steps. Every step in the escalator
    assembly has its own two sets of wheels which move on separate tracks. The upper
    wheels are the one which moves with the chain whereas the lower wheels ensure that the
    level of the step is maintained at any given moment of operation. As every one of us must
    have observed, every step in the escalator is collapsible. It collapses to a flat surface at
    the beginning and at the end of the escalator. It accounts for the safe and smooth ride for
    the user.

    You might also like