Escalators work in much the same way that conveyor belts do, and in most cases the moving stairs are actually on a belt that rotates around a set of gears at a certain fixed speed. The gears tend to be large, and typically sit just below the steps. They are electrically powered and, as they turn, the steps move. In most cases the stairs themselves are just grooved metal that lies flat as it travels down the backside, beneath the floor, and back around again. In most cases this same system controls handrail motion, though this is an additional moving part. These machines often look really imposing, but from a mechanical perspective they tend to be pretty straightforward. Repairs are also usually pretty easy, though they can take a lot of time since they involve, in most cases, major moving parts. Accessibility is often the hardest part about servicing gears and other internal parts.
The core machinery for these large appliances is usually hidden beneath the steps in what is called a truss. At the top of the machine, housed in the truss, is an electric motor that runs the four primary gears all models have — two drive gears on either side at the top, and two return gears on either side at the bottom. Chains loop around the gears and run down each side. These chains are connected to each step and help each make their way up or down at a speed that is set by the motor, often through an electronic control panel..
The way the steps flatten out at the tops and bottoms has to do with how each step is constructed as a unit. In most cases, the stairs themselves are little more than flattened metal with four wheels attached to the underside, two each on the top and bottom. The two wheels that are closest to the top of the step connect to the two chains that loop around the gears. The horizontal positioning of that chain at the top and bottom causes the steps, in turn, to flatten out. The two wheels that are closest to the bottom of the step roll along a rail within the truss for stability. The grooves in the steps aren’t really essential, though they’re thought to help with alignment and can also improve balance and stability for people riding.
The handrails that riders use for balance and safety on their ride up or down are usually powered by the same system that powers the steps. The handrails are essentially long rubber loops connected to the two drive gears at the top and powered by the same electric motor that powers the steps. Their speed is usually controlled automatically by the drive gears so that they are in perfect synch with the steps.
The concept of the modern escalator has been around for a long time. In 1859, the American entrepreneur Nathan Ames was granted a patent for his model, and the American inventor Leamon Souder was later granted more patents for several of his own versions. Neither, however, ever succeeded in building a functioning version. In the early 1890s, another American, Jesse Reno, was granted a patent for his version, which was slightly different, and he was actually able to produce a working model. It debuted as an amusement park ride at Coney Island in New York. A commercial model wasn't produced until 1899, when the American inventor Charles Seeberger built one. Seeberger was actually the first of these inventors to use the term “escalator.”
The first commercial versions were installed primarily in multi-story department stores such as Bloomingdale's in New York City. Both Seeberger and Reno sold their patent rights to the Otis Elevator Company in 1910, which proceeded to dominate the industry.
Common Risks and Problems
Escalators are generally considered safe, though depending on how tightly the steps close in on themselves and how much of a gap there is between the belt’s retraction at the top or base and the metal footplate, things can sometimes get stuck. Riding in the center is usually just fine. Problems come most often at either end. Long, drapey clothing can sometimes become entangled with the steps as they retract, and thin shoes like flip-flops can sometimes get stuck if they fit in the gap between the top casing and the stairway belt. When this happens, the machine usually needs to be shut off and a mechanic will usually have to reverse the belt to free the jammed item.
Mechanical repairs are usually somewhat simple, though they can be inconvenient as they usually require the whole machine to be powered off. Repair personnel can usually remove the steps individually to reveal the gear chamber, and most parts are relatively easy to access through these panels. They often require a mechanic to physically get inside the inner chamber, though.