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What is an Elevator?

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Basics of an Elevator

Elevator or Lift is a Mechanical or Electromechanical equipment which is used to transport Man, Material, etc Vertically to different floor levels in a Structure made for such Movement.

In most Modern Elevators Such vertical movement is Powered by a Electrical Motor which converts the Electrical energy to Vertical Motion with the help of Wire ropes, Pulleys to move the carriage, Brakes coupled to the Motor or Gearbox are used to hold the Carriage in Position generally at a floor level of a building and control systems for the carriage to travel to the desired floor level and ensure safety while doing so.

History and Evolution of an Elevator

Earliest recorded Elevator design used Man or Animals to Pull on the Ropes to move the Cage up. According to Wikipedia, the Roman Colosseum had upto 25 Elevators each designed to carry upto 270 Kgs. These Elevators were used to carry Animals to the Floors roughly 23m in height and were powered by eight Men.

The Elevator was Powered using Various Sources and with the change is use of materials and availability of various energy Sources to drive the Elevator, many different types of Elevators were invented including the Screw Type, the Hydraulic Powered, The Hoist Type, etc.

Once the Vertical Transportation was possible, Safety was a prerequisite, without safety it would be difficult to trust the system and adopt it for day to day use at such large scale. The basic Safety Mechanism was invented by Otis and introduced to the world in 1852, he made a grand dramatic display of the safety mechanism that would prevent fall of the Elevator if the cable broke and even today Most of the Elevators, if not all use a similar type or a modified version of that safety Mechanism.

Once safety was in place the Elevators were improved upon to have higher reliability, better ride quality, higher Speeds, more travel height, Remote Monitoring Systems, etc. This was made possible with improvement in technology and integration of various Mechanical, Electrical and Electronic Science and Technologies.

There was improvement of the Elevators in various ways including Controllers to stop at a floor level, automated doors, soothing music, Intercom for communication, etc. A great deal of effort was put in to make sure that the general public were accepting of the elevator. The Fully Automated elevator was available by 1900 but the passengers were reluctant to use them and the adoption was aided by elevator operators going on strike, Emergency Stop Buttons, Telephones and Automated Explanatory Voices in the Lift Cabin.

Since 1900 not much has changed in the elevator, it has become faster, smoother, quieter, more friendly, etc. However, the basic design remains the same. However, Future of the Elevators seems like sci-fi movies where the elevators could go vertically and horizontally through a building and this is also made possible by Linear Motors. More on this Later in a Separate post.

Modern Elevator

Most Modern Elevators generally consists of a cabin to carry passengers, a Gearless Motor for moving the Cabin using Steel Wire Ropes having a counter weight to counter balance the load in the cabin, speed governor continuously check the speed of the lift in down and / or in up direction and a highly efficient controllers using IGBT to ensure right Power Delivery to the Motor to output the right amount of Torque and Speed providing a comfortable ride experience while keeping a continuous check on all the safeties.

There also are Elevators Powered using Hydraulics, Pneumatic and ball Screw. Though in very small Number, the Hydraulics are more frequently used than the other two types. Hydraulics are generally used for elevators in low height buildings or home Elevator. Hydraulics are also used in car Elevators. Generally hydraulic elevators are very slow as compared to the elevators using Geared or Gearless Motors and are not capable achieving high speeds and heights that Geared or Gearless Motors can be used to Achieve.

Components in a Modern Elevator

Elevator Consists of Mechanical and Electrical Components, We will list out the main components below and also explain its role in functioning of the elevator.

  1. Traction Machine
  2. Control Panel
  3. Wire Rope
  4. Car Frame and Counter Weight Frame
  5. Cabin
  6. Speed Governor
  7. Counter Weights
  8. Car Operating Panel & Landing Operating Panel
  9. Cables and Wires

Let us Explain below the Role and the Function of the Components mentioned above

Traction Machine

Traction Machine consists of a Motor Attached to the Pulley / Sheave and Brake/s, Gearbox may be used in which can the gearbox is coupled to the Pulley. Let us discuss both type of traction Machine. The Traction machine uses 3 Phase Power Supply from the Variable Frequency drives which are used for Speed and Torque control.

Geared Traction Machine : In a Geared traction machine a reduction Gearbox is used, generally Gear type is worm wheel with 90 degrees output Shaft, this is because of its inherent capability of the worm wheel gearbox to handle high loads.

Gearless Traction Machine : The Modern Elevators generally use a Gearless Traction Machine (Without Gearbox) for better efficiency. With High Torque Permanent Magnet motors, it is possible to remove the gearbox from the Assembly and Mount the sheave directly on to the motor bring the overall efficiency of the motor close to 90%.

Brakes on the Traction Machine : Both Gearless and Geared Machines use Electromagentic Fail to safe Brakes. The Fail to safe brakes here signify that in case of power failure or failure of the electromagnetic Coil, the brakes will applied and the lift will be brought to a halt. Brake Switches on the Brake Mechanism are used to provide feedback to the controller if the brakes are open or closed.

Control Panel

Simplistically, a Modern Elevator Control Panel have a Mother Board, a Variable Frequency Variable Voltage Drive (VFD) and Switch Gear.

Mother Board : Mother board receives all the sensor inputs and inputs from the other devices from the various points and Provides Outputs to the various devices based on the inputs and requirements. The input generaly cosists of the position of the Elevator, the speed of the elevator, Status of the Safety, Door Position, Door Obstruction, Direction of Motor Rotation, Machine Brake Position, Total weight in the cabin, Switch Gear Status, VFD Status, etc. Based on these inputs the controller takes action.

Variable Voltage Variable Frequency Drive (VFD) : The VFD is used to drive and control the motor so that the motor generates right amount Speed as instructed by the Controller in Mother Board, while doing so it also ensures motor delivers right amount of torque at the given speed. Variable Frequency drives use IGBT Modules which convert the incoming Three Phase Power Supply into DC and then use the high frequency IGBT’s to convert the DC back to modulated AC using PWM to output the Required Frequency and Current as Required by the Motor. Use this Wikipedia Link for know more about VFD.

Switch Gear : All Control Panel use Switch Gear like Circuit Breakers, Fuses, Relays, Contactors, etc. These Switch Gear is used to Switch high voltage and current as per the instruction from the Mother Board, it is also used to Protect the equipment from short circuits or overload events. Depending upon the logic of the controller and the safety systems and control philosophy undertaken by the manufacturer, Switch gear used for multiple Purposes right from receiving power to supply power to the motor or any other device in the elevator system.

Wire Ropes

Wire Ropes are used to hold the cabin and the counter weight and are held by the Traction Machine using the Pulley. The Wire Ropes Sits in the Groove in the traction machine. The number of Wire Ropes used for any elevator depends on the speed and the carrying capacity of the Elevator. The Traction is created using the wire Ropes the Pulley due to the Loads on each Side of the Ropes. When the Pulleys move in one direction, the Ropes are moved from one side to another and the Car moves up or down depending on the direction of Rotation of the Pulley.

The Wires Ropes used are Single Tensile or dual Tensile based on the type of Elevator, the Carrying Capacity, Speed, Travel Height of the Elevator. If the ropes of higher tensile strength is used, the Pulleys will wear out faster and also the bending radius is more. Lower Tensile Strength will have a small bending radius but also will ware out faster due to its friction with the Pulleys. Some Prefer The Dual Tensile rope due to this reason, the Dual tensile rope will have strands of two tensile strength and the outer strands contacting the Pulley will have lower tensile strength, this helps increase the life of the rope and the Pulley.

Wire Rope Types : Many Wire Rope Types exist for lift application with different types of construction including Filler Core, Seale, Warrington and Combined.

Wire Rope Termination : The Wire Ropes are terminated using a thimble and an I Bolt which is Connected either to the Car/ Counter Weight Frame (in a 1:1 Roping Style) or to a hitch plate in the Machine Room (in 2:1 Roping Style). At the Termination, U clamps or Rope Clips are used to Tighten the Ropes together.

Type of Roping : The Type of Roping is a Type of Gearing in which a Combination of Pulley are placed so that Load is distributed and the required speed is achieved. Following are the Types of Roping

  • 1 : 1 Roping
  • 2 : 1 Roping
  • 4 : 1 Roping

In 1:1 Roping the Amount of Roped moved by the Motor will result in the same amount of distance travelled by the elevator. Also in this case the Load of the Lift Cabin and the Counter weight is taken totally by the Traction Machine

In 2:1 Roping the distance travelled by the Elevator will be half the rope moved by the Main Pulley. Also, the Traction Machine Shares the Load of the Lift with the Building Structure and Carries half the load, this means a load twice the size can be moved with this roping type but at half the speed as compare to 1:1 Roping.

In 4:1 Roping the Distance travelled by the elevator will be Quarter (1/4th) of the Rope moved by the main pulley. Also the Traction Machine carries about one fourth of the load of the lift cabin and the counter weight. This helps a smaller machine carry a much larger load but at a slow speed. This is generally used in Goods lift and Car Lifts.

Car and Counter Weight Frame

Car Frame or Sling is a structural Frame which is used to hold and carry the cabin. The Counter Weight frame is a structural frame which is used to hold and carry the counter weight.

The wire ropes are also attached to the Car Frame and Counter Weight Frame (in 1:1 Roping) or is passed though the pulley attached to the Car and counter weight frame (in 2:1 and 4:1 Roping).

The Car and Counter Weight Frames are generally made of Structural Steel (Channels and Angles) or Steel Plates Bent to Form a Strong Structure. The Various Parts of the Car and Counter weight frame are held together using a combination of welding and nut bolts to ensure ease of packaging, transportation and also assembly at site.


Elevator cabin is used for movement of the load from one floor to another. The cabin Consists of a Floor, Side Walls and Ceiling.

The Flooring is generally made of Steel Plate or Wooden Ply as the base and then may be covered with Steel Chequered Plate, PVC Flooring or Marble Flooring depending on the Requirement of the end user.

The Side walls are made of Steel Panels Generally Mild Steel or Stainless Steel. Various Finishes may be used including Painted Finish for Mild Steel, Brushed Finish or Designer Finish for Stainless Steel. Steel of Different grades may be used.

The Cabin may have a ceiling and also a false Ceiling, the ceiling of the cabin is generally made from Mild Steel and used by the technicians to stand on top of the lift. The cieling is generally made to carry load of atleast two persons. Ceiling is used to carry car top box which has controls to move the lift during inspection and maintenance. Most of the cables carrying sensors are terminated at the box on the ceiling and All the Wiring for the Cabin is generally done from the Ceiling. The Car Top is fitted with Barricade to safeguard the technicians when using the elevator. The false ceiling gives a great look inside the cabin and is used to hold the Lighting, Fan Etc.

Speed Governor

Speed Governor is a safety device which works on the principle of centrifugal force. Each Speed Governor is manufactured for a rated speed and also has a tripping speed. The Speed Governor comes into action when the Speed of the Elevator Exceeds the Tripping Speed.

The Speed Governor has two Parts the Top Pulley and the Bottom or Pit Pulley. The Top Pulley is Fixed at the Machine Level at the top of the Lift Shaft and the Pit Pulley is Fixed at the bottom of the lift shaft in the Pit. A Rope is Connected to the safety Mechanism in the car frame and Passes through the Top Pulley going all the way down and passes through the pit pulley and finally returning to the safety Mechanism in the car frame.

When the Speed of the lift meets or exceeds the tripping speed of the speed governor, the governor is tripped mechanically and Electrically. Mechanically the Pulley stops Rotating while the lift is still moving resulting in the activation of safety mechanism in the car frame. This way the safety gear in the car frame holds on to the Guide Rails. Electrically the safety switch is activated and cuts off power to the safety subsystem in the control panel resulting in immediate stopping of the lift.

Counter Weight

These are weights made from Cast Iron or Mild Steel Plates or Iron Ore Filled in a Form. These Weights are used to counter Balance the Elevator Cabin. The Weight of the The Counter weight along with the Counter weight frame is equal to Weight of the car frame and the cabin plus about 50% (Generally between 40 to 60%) the weight of the carrying capacity of the lift.

Car and Landing Operating Panel

Car and landing Operating Panels are Human Machine interface device which act as an input for the controller to know that the passenger wishes to board the elevator and which floor the passenger wishes to travel to.

Landing Operating panel is called a hall call button because it is used to call the lift to the floor level in order to enter the lift cabin. The Landing operating Panel has buttons indicating the direction in which the passenger want to travel, a Digital indicator to indicate where the lift is and which direction it is travelling to. The Display may also show some other details such as the mode of the elevator or error code if the lift under breakdown due to some error.

Car Operating panel (COP) is used to move the lift to the desired floor where the passenger wishes to alight the elevator. COP may have many other buttons like door close, door open, Attendant mode, non stop, fan switch, Fire mode Switch, etc. The COP has a display to indicate the direction of travel, the Position of the lift, etc.

Cables and Wires

The Elevator will in general have 3 Types of Cables or Cables that are used for 3 purposes, the Travelling cable to carry the Power and signals from control panel to cabin and back, the Communication cable to carry the Power and Signals from Landing Operating Panel and Back and the third one is for carrying power and signal in the lift shaft for various sensors and switches. Other than these cable there are cables that run from motor to control Panel for Power, Encoder Feed Back etc.

The travelling cable is the cable which hangs from below the cabin and is connected to the control Panel. The Travelling cable consists of multiple number of cores of individual wires and sometimes even different types of Wires. It may contact Signal Wire for Communication, Coaxial Cable for CCTv Connection, etc. It also sometime contains a pair of Steel Wire Ropes for carrying the weights of the cable.

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