This is the question which might have crossed your mind at some or the other moment in time. Well, nothing wrong with it as elevators are a serious piece of machinery which requires its fair share of respect and adulation.
In order to understand how the elevators or lifts actually work, we must first understand how many types of elevators are there actually. Well broadly and commonly speaking an elevator is classified on the basis of propulsion system or the powering mechanism used for its operation.
There are four types of the mechanism used for powering an elevator or a lift and this also forms the basis of their nomenclature:
Traction elevators are of two types geared and gearless. Geared traction elevators are used with an electric motor. These motors can either be AC or DC type. They use worm gears for mechanical control, basically, they control the elevator movement by using a steel rope over an drive shaft connected to a gearbox, this gearbox is eventually connected to the high-speed motor.
AC motors were widely in use owing to their low cost and economic feasibility. These motors serve the purpose perfectly where the low-speed application is desired. However, as the height of buildings increased there was a need for faster elevators as having a low-speed option was no longer viable. Hence the practice of using DC motors for driving the elevators came in to picture. These motors were typically powered by a stand-alone device called an MG set or a motor generator set which has the capability to operate in both AC and DC mode. It also powered other systems of the elevator hence separating the power supply to the elevator from that of the building. This also meant that there would be no power spikes in the building due to the operation of the elevator.
Gearless traction elevators typically use a DC motor at low RPM but producing high torque. It means that the motor used here would be larger in power capacity. They are not connected to any gearbox but are directly attached to the shaft. This type of elevator has the speed advantage and has brakes attached to it as a safety option. In case of power failure, the breaks would engage bringing it to a halt.
Hydraulic elevators are of three type:
- Rope type.
Conventional hydraulic elevator: They are powered by an underground hydraulic cylinder and have a typical speed of 1m/s. Ideal for condos having 4 to 5 floors, for higher buildings a larger cylinder might be used.
Holeless hydraulic elevator: In this type, the hydraulic cylinder is installed on the ground and is an economical option for a building having 2 to 3 floors.
Roped hydraulic Elevator: They have a set of both above and below the ground cylinders and cater for larger buildings.
With miniaturization of components used in a traction elevator, the hydraulic elevators are constantly losing market share as its losing economic viability.
Electromagnetic propulsion elevator:
These types are a great innovation in the field of elevators. Electromagnetic propulsion elevators do not have cables and ropes and can move both horizontally and vertically. They do so by using the properties of electromagnetics and varying magnetic fields.
These types are self-propelled and find their use in structures like towers or under-construction buildings. It is used mainly by maintenance crews and typically carries one person with equipment.
It uses pneumatic pressure for its operation. The pressure differential decides whether the elevator will go up or down.
General working of elevators :
If you know how a pulley works then chances are you already know how a common elevator works. In theory, it’s just a sophisticated pulley which can transport humans. A very strong steel rope is used to suspend the passenger car which goes up and down a sheave. Counterweights are employed to control the rate of ascent and descent along with powerful motors. Guided rails are also present and the car is also fitted with breaks which would bring the elevator to a halt in case of emergency. As a secondary safety measure a very strong and powerful spring is also installed at the bottom of the elevator shaft. This spring can break a direct fall keeping the elevator car safe.