During the 1977 power blackout in New York City, the business and commercial life of the world’s busiest metropolis came to a complete halt for an entire day. Though buses were still running to take people to work and many offices had sufficient natural lighting to make some work possible, the blackout shut off one electrical device without which the modern city is completely helpless: the elevator.
With thousands of offices vacant for the lack of a means of reaching them and hundreds of thousands of people stranded in high-rise apartment buildings, the importance of the elevator in today’s city was drawn sharply into focus. There can be no doubt that the invention of the elevator has had a great deal to do with shaping our urban geography. But the question arises, did the need for taller buildings spur the invention of the elevator, or did the invention of the elevator produce higher office and apartment buildings?
No one can prove that the paucity of high buildings before the modern era was due solely to the lack of a means to reach the upper floors. It could more easily be argued that the demands for utilizing urban space were never so great as to make the high-rise a necessity and that once the demand was there, human ingenuity rose to the job of inventing an efficient elevator. But one thing is certain: the idea of vertical transportation, if not the means, has been with us for well over 2,000 years. Which brings us to the History of Elevators.
Ruins from a number of ancient civilizations contain shafts; some archaeologists believe that these shafts were actually hoist ways in which goods and perhaps people were lifted. But no mention of an elevator-like device appears in any ancient writings until the first century B.C. when the Roman architect engineer Vitruvius described lifting platforms that utilized pulleys and human, animal, or water power. The Roman Coliseum, built in 80 A.D., used crude lifting platforms to raise gladiators and wild animals to the arena level.
Many medieval monasteries were built atop steep cliffs or surrounded by high walls, and some of the more unsociable cloisters depended upon a device known as the basket elevator for entry and exit. A basket elevator was just that, a basket in which the passenger was lifted or lowered by rope along the outside of the monastery walls. Not the most gracious entry, perhaps, but unwanted guests certainly posed little problem.
In 17th century France, a device known as the “flying chair” occasionally brought passengers to the upper floors of higher buildings. Similar to hoists used by stablemen to lift bales of hay to a loft, the flying chair was operated by a rope running around a wheel at the top of the building exterior. One end of the rope was attached to the chair, the other end to a counterweight. To rise, a passenger threw off a sandbag attached to the chair, the counterweight would then descend and the much lighter chair and passenger would rise. Not a very pleasant ride, as you might imagine. Even so, at the end of the upward journey, the passenger had to climb in through the window.
In a sense the flying chair was similar in operation to the dumb waiter, a pulley and counterweight device used chiefly to lift food from kitchen to dining room. An apocryphal story credits Thomas Jefferson with the invention of the dumbwaiter; we do know that Jefferson used one of the world’s first dumbwaiters in his Virginia home to deliver food from a basement kitchen to the dining room. The dumbwaiter was later used in this country to deliver garbage to the basement of many apartment buildings.
In the early 19th century, the hydraulic elevator became popular for moving goods in factories and warehouses. The platform of a hydraulic elevator was mounted atop a plunger that rose or fell in a hollow cylinder according to the amount of water in the cylinder. A steam engine pumped water into the cylinder to lift the plunger; valves released the water to lower the plunger and car. But the hydraulic elevator had one serious disadvantage: since the length of the plunger had to be equivalent to the height of the shaft, the cylinder in which the plunger sank had to be buried to a depth equal to the height of the shaft. Thus the heights to which an elevator could go were severely limited.
The problem was partially solved by an American, Cyrus Baldwin, who designed a new kind of hydraulic elevator, in which a much shorter plunger turned wheels at the top of the shaft. Ropes wrapped around the wheels actually raised and lowered the platform. These later models did away with the need for extensive excavation for the cylinder, and allowed some platforms to attain the blinding speed of 600 feet per minute, about seven miles an hour. The hydraulic elevator is still used in some warehouses and parking garages where speed is less important than strength.
The first successful non-hydraulic elevator was built by Henry Waterman in New York City in 1850, and was installed in a Manhattan warehouse to hoist barrels to the upper floor. Waterman’s elevator was a crude platform lifted by a cable that wound around a cylindrical drum known as the windlass. The windlass was turned by steam power in one direction to lift the platform; then turned in the other direction to lower it. But these devices also limited the height of an elevator shaft, since the drum afforded only so much room to safely accept the winding rope.
Like the hydraulic elevator, windlass elevators were used only for hauling freight. Why not passengers as well? Well, for one thing, few people at the time were ready to trust their lives to the hemp ropes then used as cables.
Then, along came Elisha Graves Otis. Though Otis is often called the inventor of the elevator, he initially contributed only one major innovation to elevator design. But that innovation was significant enough to make him, in effect, the father of the passenger elevator.
Vermont-born Otis was working in a furniture factory when he was asked to design a machine for lifting lumber and other materials from floor to floor. Otis’s invention made its debut at the 1853 Crystal Palace Exposition in New York, where it was billed as “An elevator, or machine for hoisting goods.”
Otis’s elevator was a simple platform that moved between two guide rails, with a steam-powered windlass at the top of the shaft to raise or lower the cable. The innovation was a safety device that could stop the fall of the elevator in the event the cable broke. The simple device consisted of two metal hooks and a spring, attached to the cable where it met the platform. If tension in the hoist rope was relaxed, in the event of a cable break, for instance, the hooks immediately sprang to a horizontal position, where their ends would catch in teeth cut into the guide rails and stop the elevator’s descent. Sounds a bit shaky? Well, it’s basically the safety device modern elevators rely on today, and it’s totally reliable.
According to some accounts Otis demonstrated the safety of his invention by holding regular cable-breaking exhibitions at the exposition. Spectators would watch in amazement as Otis climbed on the platform, rose to the top of the shaft, and then cut the cable! His expected fall would be checked by the safety hooks.
By 1857, Otis had installed the world’s first commercial passenger elevator in the Haughwout Department Store in New York. A steam driven lift, the elevator rose five stories at a speed of forty feet per minute, barely faster than a stairway. At first, shoppers were reluctant to risk their lives on the newfangled device, but as more and more people took the, plunge, it soon became clear that the passenger elevator was here to stay.
Early steam-driven elevators required a large space for the steam engine, and often spewed thick smoke into the shaft. The next step was obvious: an electric elevator. In 1880, a German named Werner Siemens built a crude electric elevator, with a motor under the platform turning cogwheels that fit into notches in the guide rails.
In 1887, William Baxter built an unsuccessful electric machine in Baltimore. The world’s first successful electric elevator was installed two years later by the Otis Elevator Company in the Demarest Building in New York, and was in continual use until the building was demolished in 1920.
The Demarest Building elevator’s 30 year life span pales next to the endurance record of the world’s oldest operating elevators, three hydraulic machines installed in a Grammercy Park, Manhattan apartment building in 1883, and still operating after more than ninety years of service.
In 1895, the Englishmen Frost and Strutt invented a device called the teagle that offered a marked improvement over the windlass. Instead of a drum at the top of the shaft, the teagle employed a pulley wheel and counterweight; with the cable pressed so tightly against the wheel that it turned with the pulley. The teagle eliminated the cable-length limitations of the earlier windlass elevators, now buildings could rise toward the sky.
By the turn of the century, the problems of speed, safety, and height limitation had been successfully challenged. There remained only improvements in convenience and economy. The push-button elevator, introduced in 1894, was both more reliable and cheaper to operate than the hand-operated manned elevator you can still find in the moldiest of city buildings. Automatic leveling, which brings the car to rest precisely at floor level, made its debut in 1915, but the cry of “watch your step” will live on forever. By the middle of this century, automation had rendered the elevator operator nearly extinct.
The Otis Elevator Company, the world’s largest manufacturer of elevators, now installs from 20,000 to 25,000 new elevators and escalators each year, and services an estimated 400,000 Otis elevators functioning around the world. Otis was exporting elevator equipment to thirty-one countries as early as the 1890′s. Nowadays, Otis operates twenty-nine plants worldwide, with over 44,000 employees.
Modern elevators are “gearless traction” machines. An electric motor turns a wheel, called the traction sheave, at the top of the shaft. The cable runs over the traction sheave, around a smaller wheel below the traction sheave, back around the traction sheave, and down the shaft. One end of the cable is attached to the car, the other to the counterweight. Another cable, called the compensating cable, stretches from the bottom of the car to the bottom of the counterweight, after first passing over an idler wheel at the bottom of the shaft. The compensating cable is needed to, yep, compensate for the unequal distribution of cable weight when the car is near the top or bottom of the shaft.
The earliest electric elevators with push-button controls simply carried a passenger from point A to point B without stops, no matter how many people on intermediate floors impatiently watched the car glide by. A modern elevator answers all calls in one direction, then responds to calls waiting in the other direction. Large office buildings with many elevators use group control systems, which keep the cars correctly spaced and send only the closest elevator to answer a call.
Thanks to Otis, elevators are now almost 100 percent, five times safer than a staircase, according to the elevator industry. Cable failure is extremely rare, for each of a modern machine’s eight woven steel cables can support a load eight times the capacity of the car. Safety devices similar to Otis’s assure that even if the cable does break, the car won’t fall very far in the shaft. And a device at the bottom of the shaft, called the buffer, will break the fall of an errant elevator in the unlikely event the car does plummet.
An airplane once crashed into a New York office building and struck directly into the elevator shaft, destroying the cables. The car plunged 17 floors, but the buffer saved the life of the elevator’s lone passenger!
Modern elevators travel at many times the speed of the earliest machines, with express elevators in some taller buildings speeding along at 1,200 feet per minute, fast enough to -require machinery to adjust changing air pressures in the car. And newer elevators, such as those in the Sears Tower and the John Hancock Building in Chicago, travel at speeds of up to 1,800 feet per minute!
One of the largest elevators in the world, a hydraulic model, raises, lowers, and revolves the stage at New York’s Radio City Music Hall. But the largest commercial elevator on record was constructed to raise and lower a full swimming pool on the stage of the Hippodrome Theater in New York. The device had a capacity of 250,000 pounds, that’s equal in weight to 35 hippopotami, and moved at a speed of 12 feet per minute, slower than the most sluggish hippopotamus!
A second means of vertical transportation, the escalator, was developed while the electric elevator was still in its infancy. A patent for an escalator was issued in 1859, but the first working escalator, a stepless conveyor belt with cleats for traction, was installed by Jesse Reno in 1896 on a pier in Coney Island, New York. About the same time, Charles Seeburger constructed a similar conveyor with horizontal steps. Seeburger coined the word “escalator” for his invention, combining the Latin Scala (“steps”) with the first letter and ending of “elevator.” Seeburger’s device forced riders to step on and off to one side, at their own risk. The Otis Elevator Company acquired both inventions. By 1921, Otis had developed the kind of horizontal-step escalator in use today.
Escalators eliminated both the need for an elevator operator and, more important, long waits for an elevator car. Escalators were installed extensively in deep subway stations, transporting a steady stream of riders and thereby eliminating bottlenecks at elevator doors. In fact, the longest escalator in the world can be found in the Leningrad subway, with a vertical rise of 195 feet.
The steps of an escalator are moved by an endless chain powered by electricity, usually at speeds of about 100 feet per minute. The underside of each step is triangular in shape, and mounted on four wheels running in tracks under the steps. When the step begins its ascent, the rear wheels rise to keep the top of the step horizontal.
As anyone who’s had to climb to the 8th floor of a department store via seven escalators is well aware, the escalator will never replace the elevator for long distances. As buildings rise higher and increase in floor area, engineers have had to keep pace with constant innovation. The major problem faced by the engineers is how to minimize the space taken up by elevator shafts when many elevators are needed for a building. One answer is the dual elevator, two cars running in one shaft. The first dual elevator was placed in service in Pittsburgh in 1931, with the upper car running as an express, the lower car as a local. Another development, the double-deck car, was introduced in 1932, with two attached cars that stop one floor above the other.
The designers of the 110-story World Trade Center in New York arrived at another solution for minimizing elevator shaft space. In each of the two towers, express elevators speed passengers to “sky lobbies” on the 44th and 78th floors. Local elevators run only between one lobby and another. Thus three local cars can run in the same shaft, each serving one-third of the tower, and the amount of floor space occupied by elevator shafts is cut by almost two-thirds!
Round elevator cars serve a Johnson Wax Company building in Racine, Wisconsin, designed by renowned architect Frank Lloyd Wright. Another Wright creation, the Price Tower in Oklahoma, is served by hexagonally shaped elevator cars.
And who says an elevator can go only straight up? The Eiffel Tower boasts elevators that move along dizzily inclined tracks, as does the George Washington Masonic Monument in Virginia. And the outdoor elevator is now coming into vogue, as demonstrated by the new Hyatt Regency Hotel in Atlanta, served by glass-cab elevators running in rails on the outside of the building.
Beats a flying chair, doesn’t it?