Escalators are one of the largest, most expensive machines people use on a regular basis, but they’re also one of the simplest.
At its most basic level, an escalator is just a simple variation on the conveyer belt. A pair of rotating chain loops pulls a series of stairs in a constant cycle, moving a lot of people a short distance at a good speed.
The core of an escalator is a pair of chains, looped around two pairs of gears. An electric motor turns the drive gears at the top, which rotate the chain loops. A typical escalator uses a 100 horsepower motor to rotate the gears. The motor and chain system are housed inside the truss, a metal structure extending between two floors.
Instead of moving a flat surface, as in a conveyer belt, the chain loops move a series of steps. The coolest thing about an escalator is the way these steps move. As the chains move, the steps always stay level. At the top and bottom of the escalator, the steps collapse on each other, creating a flat platform. This makes it easier to get on and off the escalator. In the diagram below, you can see how the escalator does all of this.
Each step in the escalator has two sets of wheels, which roll along two separate tracks. The upper set (the wheels near the top of the step) are connected to the rotating chains, and so are pulled by the drive gear at the top of the escalator. The other set of wheels simply glides along its track, following behind the first set.
Picture Credit : Google