Elevator is nothing but one or more cars which are metal boxes which rise up and down for vertical transport of people or goods.

Parts:

• Car(metal boxes)
• Counterweight
• Electric motor ,Braking system
• Strong metal cables and pulleys
• Control System
• Switches and Sensors
• Safety system

It uses motor for hoisting the car. For vertical movement it uses strong metal cables and pulleys. There are different types of elevators based upon different factors like technologies used,application,speed,hoist mechanism used,whether it carries people or good ,control system used,etc. Two types of elevators that are most commonly used in residential and commercial buildings are: Traction elevators and Hydraulic elevators.For high speed and high rising modern buildings,traction elevators are used.Traction elevators are also energy efficient because it uses counterweights to balance cars weight so requires less energy as compared to hydraulic elevators.At every floor there is display system which is showing the current direction of elevator and floor number at which the elevator is. In hospital like places where there can be an emergency for transport,we can implement elevator control system which will respond immediately when emergency switch is pressed. When emergency switch will be pressed,the elevator comes to requested floor and serves the request as interrupt.

Function of each part:

CAR  –  It is a type of vertical transport equipment that efficiently moves people or goods between floors of building.It is mounted on shaft.It can be of passenger service type or goods service type. Inside car there is keypad user interface for selecting destination floor.

There are two sets of elevator doors- Doors on the car and doors opening in elevator shaft.The car doors have clutch mechanism which will unlock the outer door to open. So outer door can open only when there is elevator at that floor.This avoids opening of outer doors in empty elevator shaft.There are main 2 types of doors manual and automatic.In automatic type doors it can be center opening door or double opening door.

COUNTERWEIGHT – Counterweight is used for balancing the weight of car.Car is pulled up by steel ropes in traction elevators.Sometimes one car is used as counterweight for another car i.e. balancing weights of each other.Using counterweight,there will be less force required for pulling the car hence less strain on cables.

ELECTRIC MOTOR BRAKING SYSTEM- Depending upon type of elevator we can use any actuator .Latest design use 3 phase induction motor with variable frequency drive electric control.For hoisting of a car it is placed above top floor of the building. There are two types of brakes for elevator system.One is for stopping the elevator at required floor and another one is for emergency like power failure or cable break-down or malfunctioning.Braking system uses combination of electrical and mechanical switches.

CONTROL SYSTEM – There are main two types of control -Manual control i.e. switches operated by pulling respective ropes.Relay-controlled elevator system was common until 1980’s.But now a days microprocessor based elevator systems are industry standards.

There are 3 types elevator controls can be implemented:

• Selective Collective operation
• Constant pressure operation
• Non-Selective Collective operation
• In selective collective operation,elevator responds to the requests along same path. Requests along opposite path will be added to the list .It reverses the direction and then serves the requests along opposite path. In constant pressure operation, the button must have pressure maintained for movement of elevator. Once pressure is removed,elevator will stop at that point. In non-selective collective operation, the elevator will respond to the calls sequentially i.e.order in which it comes.

SWITCHES AND SENSORS – Inside car there is a keypad for selecting the floor number .There is a floor button at every floor for requesting the elevator service.User can call the elevator by pressing the floor button. There are arrival sensors places at the top and bottom of car. Arrival sensors consist of reed switches which are electromagnetic switches activated my magnet.Magnet is placed at every floor and metal rods are connected to car. Respective reed switches get activated when comes near magnet and this sensors output is given to controller by which we will get to know the status of elevator i.e. at which floor elevator is. More sensors used in elevator are: Overload sensor for overload protection,current sensor,limit switches,level sensor etc.In elevator doors, infrared sensors are used for detecting obstacle between doors.

SAFETY SYSTEM-  Elevators are designed with several safety systems that keep them in position.If elevator control system detects that car is speeding downwards or upwards,it jams the metal brake from underneath the car into the guide rails on shaft. In case of power failure,electro-mechanical brakes will get activated.

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