Escalator

An escalator is a moving staircase which carries people between floors of a building or structure. It consists of a motor-driven chain of individually linked steps on a track which cycle on a pair of tracks which keep the step tread horizontal.

Escalators are often used around the world in places where lifts would be impractical, or they can be used in conjunction with them. Principal areas of usage include department stores, shopping malls, airports, transit systems (railway/railroad stations), convention centers, hotels, arenas, stadiums and public buildings.

Escalators have the capacity to move large numbers of people. They have no waiting interval (Except during mass foot traffic). They can be used to guide people toward main exits or special exhibits and may be weatherproofed for outdoor use. A non-functional escalator can function as a normal staircase, whereas many other methods of transport become useless when they break down or lose power.

History

Inventors and manufacturers

Nathan Ames, a patent attorney from Saugus, Massachusetts, is credited with patenting the first "escalator" in 1859, even though no working model of his design was ever built. His invention, the "revolving stairs", is largely speculative and the patent specifications indicate that he had no preference for materials or potential use (he noted that steps could be upholstered or made of wood, and suggested that the units might benefit the infirm within a household use). The suggested motive power was either manual or hydraulic.[1][2] "The object of the invention is to enable persons to ascend and descend from one story of a building to another" according to his 1859 patent, while also indicating that they can be "used in the ordinary way, when desired." It is implied that the normal way is identical to that of a stationary staircase.

In 1889, Leamon Souder successfully patented the "stairway", an analogous device that featured a "series of steps and links jointed to each other". No model was ever built.[3] This was the first of at least four escalator-style patents issued to Souder, including two for spiral designs.

Design

Design factors include innovative technology, physical requirements, location, traffic patterns, safety considerations, and aesthetics. Physical factors such as the distance to be spanned determine the length and pitch of the escalator, while factors such as the infrastructure's ability to provide support and power must be considered. How upward and downward traffic is separated and load/unload areas are other important considerations.

Temporal traffic patterns must be anticipated. Some escalators need only to move people from one floor to another, but others may have specific requirements, such as funneling visitors towards exits or exhibits. The visibility and accessibility of the escalator to traffic is relevant. Designers need to account for the projected traffic volumes. For example, a single-width escalator traveling at about 1+1/2 ft/s can move about 2000 people per hour, assuming that passengers ride single file. The carrying capacity of an escalator system is typically matched to the expected peak traffic demand. For example, escalators at transit stations must be designed to cater for the peak traffic flow discharged from a train, without excessive bunching at the escalator entrance. In this regard, escalators help manage the flow of people. For example, at many airports an unpaired escalator delivers passengers to an exit, with no means for anyone entering at the exit to access the concourse.

Escalators are often built next to or around staircases that allow alternative travel between the same two floors. Elevators are necessary for disability access to floors serviced by escalators.

Escalators typically rise at an angle of 30 or 35 degrees from the ground.[29] They move at 1 –, like moving walkways, and may traverse vertical distances in excess of 60 ft. Most modern escalators have single-piece aluminum

Safety

Safety is a major concern in escalator design, as escalators are powerful machines that can become entangled with clothing and other items. Such entanglements can injure or kill riders. In India many women wear saris, increasing the likelihood of entangling the clothing's loose end.[42] To prevent this, sari guards are built into most escalators in India.

Children wearing footwear such as Crocs and flip-flops are especially at risk of being caught in escalator mechanisms.[43][44] The softness of the shoe's material combined with the smaller size of children's feet makes this sort of accident especially common.[45]

Escalators sometimes include fire protection systems including automatic fire detection and suppression systems within the dust collection and engineer pit. To limit the danger caused by overheating, spaces that contain motors and gears typically include additional ventilation.

Legislation

In the 1930s, at least one suit was filed against a department store, alleging that its escalators posed an attractive nuisance, responsible for a child's injury.[50]

Despite their considerable scope, the two Congressional Acts regarding accessibility (the Rehabilitation Act of 1973 and the Americans with Disabilities Act of 1990 (ADA)) did not directly affect escalators or their public installations. Since Section 504 of the Rehabilitation Act included public transportation systems, for a few years, the United States Department of Transportation considered designs to retrofit existing escalators for wheelchair access. Nonetheless, Foster-Miller Associates' 1980 plan, Escalator Modification for the Handicapped was ultimately ignored in favor of increased elevator installations in subway systems. Likewise, the ADA provided more accessibility options, but expressly excluded escalators as "accessible means of egress", advocating neither their removal nor their retention in public structures.[51]

In the United States and Canada, new escalators must abide by ASME A17.1 standards,[52] and old/historic escalators must conform to the safety guidelines of ASME A17.3.

Etiquette

In most major countries, the expectation is that escalator users wishing to stand keep to one side to allow others to climb past them on the other. Due to historical design purposes,[54] riders in Canada, Germany, Hong Kong, Taiwan,[55] the United Kingdom,[56] France and the United States are expected to stand on the right and walk on the left.[57] However, in Australia and New Zealand, the opposite is the case.[58] Practice may differ from city to city within countries: in Osaka, riders stand on the right, whereas in Tokyo (and most other Japanese cities), riders stand on the left.[59]

External links

"Escalator, escalators, at Złote Tarasy Shopping Mall, Warsaw, Poland / Liukuportaat", Jun 21, 2007, by PomppuY on YouTube
Illustrated description of escalators on the London Underground and their advantages over lifts

References

{{patent|US|25076|Ames, N. Revolving Stairs August 9, 1859}}^
DA Cooper. The History of The Escalator liftescalatorlibrary.org, 1998, retrieved 26 September 2025^
{{patent|US|406314|Souder, Leamon. Stairway July 2, 1889}}^
{{Patent|US|723325}} {{Patent|US|792623}}^

Etymology

Authors and historians have offered multiple interpretations of the source of the word "escalator", and some degree of misinformation then proliferated. For reference, contradictory citations by seven separate individuals, including the Otis Elevator Company itself, are provided below.[22]

Seeberger trademarked the word "escalator" in 1900, to coincide with his device's debut at the Exposition universelle. According to his own account, in 1895, his legal counsel advised him to name his new invention, and he then set out to devise a title for it. As evidenced in Seeberger's handwritten documents, the inventor consulted "a Latin lexicon" and "adopted as the root of the new word, 'Scala'; as a prefix, 'E' and as a suffix, 'Tor.'"[23] His own rough translation of the word thus created was "means of traversing from", and he intended for the word to be pronounced. By 1906, Seeberger noted that the public had instead come to pronounce it .[24]

"Escalator" was not a combination of other French or Greek words, and was never a derivative of "elevator" in the original sense, which means "one who raises up, a deliverer" in Latin.[25] Similarly, the root word "scala" does not mean "a flight of steps", but is the singular form of the plural noun "scalae", which can denote any of: "a flight of steps or stairs, a staircase; a ladder, [or] a scaling-ladder."[25]

The alleged intended capitalization of "escalator" is likewise a topic of debate. Seeberger's trademark application lists the word not only with the "E", but also with all of the letters capitalized (in two different instances), and he specifies that "any other form and character of type may be employed... without altering in any essential manner the character of [the] trade-mark."[26] Otis Elevator Co. advertisements so frequently capitalized all of the letters in the word.

In 1950, the landmark case Haughton Elevator Co. v. Seeberger precipitated the end of Otis's exclusive reign over the word "escalator", and simultaneously created a cautionary study for companies and individuals interested in trademark retention.[27] Confirming the contention of the Examiner of Trademark Interferences, Assistant Commissioner of Patents Murphy's decision rejected Otis’ appeal to keep their trademark intact, and noted that "the term 'escalator' is recognized by the general public as the name for a moving stairway and not the source thereof", observing that Otis had "used the term as a generic descriptive term... in a number of patents which [had] been issued to them and... in their advertising matter."[28] All trademark protections were removed from the word "escalator", the term was officially genericized, and it fell into the public domain.

Components

Landing platforms are the two platforms (at the two ends) that house the curved sections of the tracks, as well as the gears and motors that drive the stairs. The top platform usually contains the motor assembly and the main drive gear, while the bottom holds the return gear. These sections also anchor the ends of the escalator truss. Each platform also has a floor and a comb bearer. The floor plate provides a place for the passengers to stand before they step onto the moving stairs, flush with the rest of the floor and are removable to allow easy engineer access, while the comb bearer sits between the stationary floor plate and the moving step, so named for the cleats on its edge which mesh with the matching cleats on each step (and resemble a comb). The comb plates, which bolt to the comb bearer (usually 4 or 5 depending on the width of the machine), help to minimize the gap between the stairs and landing, preventing objects or persons from becoming caught in it. The comb bearer, depending on the brand of the escalator, will push back and/or up and activate limit switches in the event of an impact if something jams through the combs (typically stones, screws & popcorn) as it could be someone's shoe/item loose clothing.

The truss is the hollow metal structure that bridges the lower and upper landings, composed of two side sections joined 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. It carries all the straight track sections connecting the upper and lower sections.

The balustrade is composed of handrails, balustrade panels, and skirt panels.[33]

The handrail provides a handhold for passengers while they are riding the escalator. The handrail is pulled along its own track by a chain that is connected to the main drive gear by a series of pulleys, keeping it at the same speed as the steps. Four distinct sections make up the rail: at its center is a "slider", also known as a "glider ply", which is a layer of a cotton or synthetic textile that allows the rail to move smoothly along its track. The "tension member" lies on the slider and consists of either steel cable or flat steel tape, providing the handrail with tensile strength and flexibility. The inner components, on top of the tension member, are made of chemically treated rubber designed to prevent the layers from separating. Finally, the outer layer—the part that passengers see—is the cover, typically a blend of synthetic polymers and rubber. Covers are designed to resist degradation from environmental conditions, mechanical wear and tear, and vandalism. In a factory, handrails are constructed by feeding rubber through an extrusion machine to produce layers of the required size and type in order to match specific orders. The component layers of fabric, rubber and steel are shaped by workers before being fed into the presses which fuse them together. In the mid-twentieth century, some handrail designs consisted of a rubber bellows, with rings of smooth metal cladding called "bracelets" between each coil. This gave the handrail a rigid yet flexible feel. Additionally, each bellows section was no more than around a metre long, so if part of the handrail was damaged, only the bad segment needed to be replaced. These forms of handrail have largely been replaced with fabric-and-rubber railings. Being made of either metal, sandwich panel, or glass, the balustrade panel supports the handrails of the escalator. It also provides additional protection for the handrail and passengers. Some escalators have direction arrows on the ends of the balustrade. Escalators' on/off buttons are frequently located at the ends of the balustrade. Moving walkways often use balustrades in the same way. The bottom of the balustrade is called a skirt panel. It is notorious in this art for being a frequent site of injuries and failures, due to the possible entrapment of materials (including body parts) in the machinery. Multiple solutions have been suggested for this issue, including coating with a low-friction material, employing bristles, and others.[33]

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. One track guides the front wheels of the steps (called the step-wheel track) and another guides 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 out from under the comb plate. Along the straight section of the truss the tracks are at their maximum distance apart. This configuration forces the back of one step to be at a 90-degree angle relative to the step behind it. This right angle forces the steps into a shape resembling a staircase. At the top and bottom of the escalator, the two tracks converge so that the front and back wheels of the steps are almost in a straight line. This causes the stairs to lay in a flat sheetlike arrangement, one after another, so they can easily travel around the bend in the curved section of track. The tracks carry the steps down along the underside of the truss until they reach the bottom landing, where they pass through another curved section of track before exiting the bottom landing. At this point, the tracks separate and the steps once again assume a staircase configuration. This cycle is repeated continually as the steps are pulled from bottom to top and back to the bottom again.

The steps themselves are solid, one piece, die-cast aluminium or steel. Yellow demarcation lines are sometimes added to 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 that mesh with the comb plates on the top and bottom platforms and the succeeding steps in the chain. Seeberger escalators featured flat treads and smooth risers; other escalator models have cleated treads and smooth risers. The steps are linked by a continuous metal chain that forms a closed loop. The front and back edges of the steps each have two wheels, the rear of which are set further apart and fit into the trailer-wheel track while the front set have narrower axles and fit the step-wheel track.

Alternative designs

Jesse Reno also designed the first escalators installed in any underground subway system in the form of a helical escalator at Holloway Road tube station in London in 1906. The experimental device never saw public use and its remains are now in the London Transport Museum's depot in Acton.[34][35]

Although the first fully operational spiral escalator, Reno's design was nonetheless only one in a series of similar proposed contraptions. Souder patented two helical designs, while Wheeler drafted helical stairway plans in 1905. Seeberger devised at least two helical designs between 1906 and 1911 (including an unrealized arrangement for the London Underground), and Gilbert Luna obtained West German, Japanese, and United States patents for his version of a spiral escalator by 1973. When interviewed for the Los Angeles Times that year, Luna was in the process of soliciting major firms for the acquisition of his patents and company, but statistics are unclear on the outcome of these endeavors.[36] Karl-Heinz Pahl received a European and a US patent for a spiral escalator in 1992.[37]