Elevators and escalators are the machines that carry people between the floors of a building. In India, an elevator is usually called a lift. A lift is a cabin that moves up and down a shaft. Steel ropes or belts, running over a wheel turned by a motor, pull it up and lower it down. An escalator is a moving staircase. It is used where many people move between a few floors, such as in malls and metro stations.
A lift is sold once, but it must be maintained for as long as the building stands, often 25 years or more. In India, the owner usually pays the lift's maker for an annual maintenance contract (AMC). A comprehensive AMC includes spare parts. A non-comprehensive AMC covers only the visits, and the owner pays for parts separately. Most states also require every lift to be licensed and inspected by a state lift inspector. For the maker, this service work brings in money for decades after the sale. The industry calls this aftermarket services.
Modern lifts report their own condition. The lift's controller, the computer that runs the motor, the brakes and the doors, records every trip, every door movement and every fault. A small connected box sends these records to the maker's remote monitoring centre over a mobile network. This is an example of the industrial Internet of Things (IIoT).
Here is a typical case. A hospital in Lucknow has eight lifts. Two of them carry patients on stretchers between the wards and the operation theatres. On a Tuesday, the records from one stretcher lift show that its doors failed to close at the first attempt 40 times that day, against the usual two or three. Nothing has broken yet. But the pattern matches a worn door roller. The maker's software flags the lift, and its field service management (FSM) system books a technician for the next morning, with the right part in his van. He replaces the ₹2,500 roller in under an hour. Without the warning, the doors might have jammed with a patient inside. Finding a fault from data before it causes a breakdown is called predictive maintenance.
The lift also shares its status with the building automation system (BAS). So the building's engineers can see which lifts are running. During a fire alarm, the BAS sends every lift to the ground floor. Many lifts in India also have an automatic rescue device. When the power fails, it moves the cabin on battery power to the nearest floor and opens the doors, so that nobody is trapped while the standby generator starts.
Some new office towers use destination dispatch. You enter your floor on a keypad in the lobby before you step in. The system tells you which lift to take, and it puts people going to nearby floors in the same cabin. So each lift makes fewer stops, and people wait less in the morning rush.