Escalator

Invented by : Nathan Ames

Invented in year : 1859

Escalator is a stairway which consists of steps attached to a continuously circulating belt. It is a conveyor type transport device in which motor-driven set of stairs are arranged like an endless belt that ascend or descend continuously. It is used as means of transportation between floors or levels in subways, buildings and other mass pedestrian areas. It is also known as ‘Moving Staircase’ as the stairway is constantly in motion. The typical angle of inclination of an escalator to the horizontal floor level is 30 degrees with a standard rise up to about 60 feet (18 m). Most of the Escalators have moving handrails that keep pace with the movement of the steps. The direction of movement (up or down) can be configured to automatic, permanently directed or controlled by a person. The system is programmed in such a way that the direction cannot be reversed while a passenger is on the escalator. These are mostly setup in airports, convention centres, hotels, department stores, public buildings, shopping malls and transit systems.

Escalators have 3 typical Configuration Options:

1. Parallel Configuration – This type of configuration is often installed in metro stations and multilevel motion picture theatres. These can be setup in - Up and Down Escalation side by side format or separated by a distance.
2. Criss-Cross Configuration - This type of configuration is often installed in department stores or shopping centres. In such system escalators are stacked over one another and move in one direction.
3. Multiple Parallel Configuration - This type of configuration is often installed at airports, railways stations or places where a lot of commutation occurs. In such a system 2 or more escalators travel together in one direction next to 1 or 2 escalators in the same bank that travel in the other direction.

Components of an Escalator:

Landing platforms - The 2 platforms house the curved sections of the tracks, as well as the gears and motors that drive the stairs. The top platform contains the motor assembly and the main drive gear, while the bottom holds the step return idler sprockets. These sections also anchor the ends of the escalator truss.

Truss - The truss is a hollow metal structure that bridges the lower and upper landings. It is composed of 2 side sections joined together with cross braces across the bottom and just below the top. The ends of the truss are attached to the top and bottom landing platforms via steel or concrete supports. The truss carries all the straight track sections connecting the upper and lower sections.

Tracks - The track system is built into the truss to guide the step chain, which continuously pulls the steps from the bottom platform and back to the top in an endless loop. There are actually 2 tracks: 1 for the front wheels of the steps (called the step-wheel track) and 2nd for the back wheels of the steps (called the trailer-wheel track). The relative positions of these tracks cause the steps to form a staircase as they move.

Steps - The steps are made up of one piece, die-cast aluminium or steel. Yellow demarcation lines may be added to clearly indicate their edges. In most escalator models manufactured after 1950, both the riser and the tread of each step is cleated (given a ribbed appearance) with comb like protrusions.

Handrail - The handrail provides a convenient handhold for passengers while they are riding the escalator. In an escalator, the handrail is pulled along its track by a chain that is connected to the main drive gear by a series of pulleys.

It is constructed of 4 distinct sections:

1. Slider Layer (glider ply) – It is a layer of a cotton or synthetic textile. It allows the handrail to move smoothly along its track.
2. Tension Member – It is a layer of steel cable or flat steel tape. It provides the handrail with tensile strength and flexibility.
3. Inner Construction Components – It is a layer of chemically treated rubber designed to prevent the layers from separating. This layer lies on the top of 2nd layer.
4. Outer Layer - It is a layer of synthetic polymers and rubber which is the cover of the handrail. It provides resistance against various types of degradation.

How Escalators Work?

An escalator system consists of a pair of Rotating Chain Loops pulling a series of stairs in a constant cycle. This pair of chains is looped around 2 pairs of Gears. An electric motor turns the drive gears at the top, which rotate the chain loops which further move a series of steps. 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.  Truss hides the machinery of an escalator beneath its steps. At the top of the escalator, housed in the truss, is an electric motor. All escalators have 4 gears run by a motor -  2 drive gears on either side at the top and 2 return gears on either side at the bottom. These gears have chains that loop around the gears and run down on each side of the escalator. Each step is connected to these chains which helps the steps to make their way up, or down, the escalator.

The handrails are connected to the 2 drive gears at the top of the escalator and powered by the same electric motor that powers the steps.  Each escalator step has 4 wheels below the step — 2 each on either side. The 2 wheels that are closest to the top of the step, connect the steps to the 2 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 2 wheels that are closest to the bottom of the step roll along a rail within the truss providing  stability. The grooves in the steps of escalators help with alignment.

Escalator History

The Invention of the ‘First Escalator’ began as a Design which had no working model. Nathan Ames, a Patent Solicitor from Saugus, Massachusetts, was granted the patent (#25,076) on  August 9, 1859 for the ‘First Escalator’, which he called ‘Revolving Stairs’. His idea lacked details, he was not sure of possible power source (manual, steam or hydraulic) for his machine and it wasn’t viable to use wood and chains for its creation. In his view, the machine could benefit the sick or weak person within a household.

In 1889, Leamon Souder, an amateur scientist developed and improved the concept further. His design was a series of steps and links jointed to each other powered hydraulically or manually. He also suggested that the use of steel or aluminium stairs would be better than wooden ones. He called his idea, 'The Stairway'. Souder received the 1st of at least 4 Escalator-style patents, including 2 for spiral designs (U. S. Patent Nos. 723,325 and 792,623). Yet, no model was built.

During the early 1890s, American - Jesse Wilfred Reno,  invented ‘The First Working Model of the Escalator’. His model was an inclined belt with cast-iron slats or cleats on the surface for traction, and travelled along a 25° incline. Initially it had stationary Horizontal steps, but an improved version was introduced the same year. Because of its incline, it was known as 'Inclined Elevator', ‘ Endless Conveyor’ or ‘Elevator’. On March 15 1892, Jesse Reno patented his invention. In 1895, he created a new novelty ride at Coney Island from his patented design, a moving stairway that elevated passengers on a conveyor belt at a 25 degree angle. His device was used briefly at the Brooklyn Bridge. However, his invention was more of an amusement and rather than mean of practical transport. At the same time (1892), George A. Wheeler came up with idea of an escalator-type apparatus. His patented idea was more recognizable even though it was never built.

Charles Seeberger, an American inventor, bought Wheeler’s patent and used a similar pattern of design developed by Wheeler. It was in May 1895, that Seeberger, came up with the idea of practical transport and the precursor to the ‘Modern Escalators’. His device actually consisted of flat, moving stairs, similar to the escalators of today. The step surface of his device was smooth, with no comb effect to safely guide the rider's feet off at the ends. Instead, the passenger had to step off sideways. To facilitate this, at the top or bottom of the escalator the steps continued moving horizontally beyond the end of the handrail (like a miniature moving side walk) until they disappeared under a triangular Divider which guided the passenger to either side. In 1897, Seeberger created the name 'Escalator' from the word 'Scala', which is Latin for ‘Steps’ and the word 'Elevator'. Seeberger teamed with Otis Elevator Company in 1899 and Company produced the ‘First Commercial Escalator’ at the Otis factory in Yonkers, N.Y. This escalator also won the first prize at the Paris 1900 Exposition Universelle in France.

In 1902, Jesse Reno founded the Reno Electric Stairways and Conveyors company. By 1910, Charles Seeberger sold his patent rights to the Otis Elevator Company, who also bought Jesse Reno's escalator patent in 1911. Otis dominated escalator production and combined and improved the various designs of escalators.

Development in the Invention of the Escalator

Seeberger's model, bought by Otis, clearly became the ‘First Step-Type’ Escalator. It was known so because of its visual likeness to steps on a regular staircase. Later on, the company, combined the best aspects of ‘Guiding Slats’ and ‘Flat Steps’ invention, to produce the ‘L-Type Escalator’ in 1921. These were succeeded by the ‘M-type’, the ‘O-type’ and the prevalent ‘NCE-Type’ escalator made by OTIS.

During the mid 1980s, Mitsubishi Electric Corporation further developed ‘Spiral Escalators’ which follow smooth curving path to its destination. Spiral Escalators take much less horizontal floor space than traditional units, which frequently house large machine rooms underneath the truss.

Role of the Invention of the Escalator in the Improvement of Human Life

• Escalators enabled the smooth flow of pedestrian traffic.
• They have been essentially beneficial where elevators are impractical.
• They have no waiting interval, except during very heavy traffic.
• They guide people toward main exits or special exhibits and are of great help to the sick and the old.