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THE BOX THAT OTIS BUILT
By TOM SOTER
from CITY LEGACY, 1996
He was an unlikely visionary, a man who tinkered and toiled with various inventions in his lifetime. And although he died long before the first skyscraper was built, Elisha Graves Otis is the spiritual architect of modern New York. In fact, the city as we know it, owes its existence to the little box that Otis built.
We’re talking about elevators, the world’s most frequently used and perhaps most underappreciated mechanical mode of transportation. There are large elevators and small ones, ornate elevators and mundane ones. There are hydraulic and electric, glass and wood. In Manhattan alone, there are about 56,000 cabs, with the fastest (in the Met Life building) traveling at 1600 feet a minute (the fastest in the world is in Tokyo, operating at 2,000 feet per minute), and the slowest -- well, who knows?
"Elevators are the safest mode of transportation per capita per mile," notes one elevator repair technician. "They're safer than walking, than running, than using the stairs." The Buildings Department reports few deaths in elevators, and those are ususlly caused by human error, not mechanical failure.
Elisha Graves Otis didn't invent the elevator -- there had been horse-drawn hoisting devices as far back as the pyramids in 2600 B.C. -- but he did make it workable by creating the first "safety elevator." No wonder, too: Otis was a natural tinkerer. Born in 1811 as the youngest of six children, he abandoned his father's farm to become a master builder in Albany. Between 1834 and 1850, he went through a succession of jobs that were all tied together by a single thread: the need to invent.
"He possessed no ordinary genius as an inventor," his son Charles wrote in 1911. "He could invent, design, and construct a perfect working machine or improve anything to which he gave his mind, without recourse to any of the modern drafting room methods. He needed no assistance, asked no advice, consulted with no one, and never made much use of pen or pencil in designing his various machines...the desired result was reached by him more as an inspiration than by a process of slow, laborious reasoning and experiment."
Otis built a grist mill run by water power and worked at a carriage manufacturing plant and then a sawmill. He was hired as a master mechanic and soon devised a number of labor-saving machines. In 1850, he invented a set of safety brakes for a train company and that led him to the safety elevator. In 1852, Otis was asked to build a freight elevator for his employer, the Bedstead Manufacturing Company. Previous elevators all had a fatal flaw: when the rope broke, the cab fell. That created a widespread fear of the lifts that was hard to overcome. Even in the 1890s, when elevators were more common, many people still considered them unsafe, and some insurance policies even excluded coverage for elevator deaths.
Otis's innovations changed that. Accompanied by the motto, "Safe Enough for Grandma to Ride In," the new Otis elevator employed a brake. The inventor put a wagon spring on top of the hoist bar and ratchet bars attached to the guide rails on both sides of the hoistway. According to an account by the Otis Elevator Company, "the lifting rope was attached to the wagon spring in such a way that the weight of the hoist platform alone exerted enough tension on the spring to keep it from touching the ratchet bars. But, if the cable snapped, the tension would be released from the wagon spring, and each end would immediately engage the ratchet bars, securely locking the hoist platform in place and preventing it from falling."
The safety device was a success and the forerunner of present-day devices. Further development saw a speed governor in the control room, connected to the elevator by a rope. If the elevator goes too fast, the governor pulls on the rope, which slows or stops the elevator by released the spring-loaded wedges under the cab. These shoot out, grab onto rails in the shaft and stop the cab from falling.
The method is so surefire, in fact, that its most noteworthy failure is also its most extraordinary. In 1945, a low-flying airplane crashed into the side of the Empire State Building and sheared the elevator's cable and the safety rope. When the cab fell, the saftey wedges were not activated.
By 1854, Otis was exhibiting a working model of his invention at the Crystal Palace Exhibition in New York. When his rising platform, reached the top, 40 feet above the assembled crowds below, he had an assistant dramatically cut the hoist rope and, like a good showman, bow to the gasps of the onlookers when the elevator did not fall. The New York Tribune called the demonstration "sensational" (labeling Otis, "Mr. Safety Elevator Man"). In 1856, Otis erected what many consider the nation’s first regularly used passenger elevator in the new five-story E.V. Haughwought & Co. store at the northeast corner of Broome Street and Broadway. By 1861, when he died of diphtheria, Otis was doing a brisk business creating elevators for manufacturing companies. (And his legend was beginning to grow, as well, with his son claiming that his father was, improbably, a Civil War veteran and “without doubt a lineal descendant of the most distinguished family known to history, Adam and Eve.” )
The evolution of the elevator might have stalled there, restricted to manufacturing uses, had it not been for steel-frame building construction. In 1885, W.L. Jenney designed the 10-story Home Insurance Building in Chicago. At the time, making buildings higher than six storys was impractical because of the huge brick foundations necessary. Jenney's "skyscraper" employed an iron frame to support the weight of the structure. The elevator allowed the hi-rise to be conceived. Soon, skyscrapers began rising with rapidity: the 22-story World Building in 1890; the 20-story Flatiron Building in 1903; the 41-story Singer Building in 1906; the 52-story Metropolitan Life Building in 1908; the 60-story Woolworth Building in 1912. Out of 800,000 buildings in New York, the buildings department reports that roughly 8,400 have elevators, mostly concentrated in Manhattan.
By 1929, as the Depression came down, more hi-rises seemed to be going up. Between 1929 and 1931, four of the tallest buildings in the world arose: the 71-story Bank of Manhattan (927 feet); the 66-story Wall Tower (950 feet); the 77-story Chrysler Building (1,046 feet); and the 102-story Empire State Building (1,250 feet).
As they were created, so were new laws governing the manufacture and safety of elevators. By the 1920s, there were two types of elevator in operation. The older models were generally either plunger or roped hydraulic elevators. The plunger style featured a cab built directly on a hollow piston that was moved in and out of a large cylinder by varying fluid pressures. In a roped model, ropes were linked to the elevator car and powered by a separate hydraulic piston and cylinder. Water from the water main and later under high pressure pumped by steam forced the plunger up and carried the elevator up. The relaxation of pressure allowed the plunger to sink, carrying the elevator down. (Modern hydraulic elevators use oil pumped by electricity.)
A quarter of the elevators currently in the city are hydraulic, usually found in such low-rise buildings as lofts. Hydraulic elevators were prominent at the turn-of-the-century, but controlling them was a little tricky: the water pressure could fluctuate and the elevator would bounce at the floor landing.
Traction elevators, employing electricity and counter weights, were introduced in 1889. They allowed for more precision in stopping and starting the cab, and also, eventually, greater speeds. According to the Otis Elevator Company: "The principle is similar to the operation of a locomotive pulling a train as the result of traction between the steel wheels of the locomotive and the rails. With an elevator, six to eight lengths of wire cable are attached to the top of the elevator and wrapped around the drive sheave in special grooves. The other end of the cables is attached to a counterweight that slides up and down in the shaftway on its own guide rails. The result of this arrangement is that with the weight of the elevator car on one end of the cable, and the total mass of the counterweight on the other, it presses the cables down on the grooves of the drive sheave. When the motor turns the sheave, it moves the cables with almost no slippage. The weight of the car and about half its passenger load is balanced out by the counterweight, which is [traveling] down as the car is going up. It supplies the necessary traction."
Electricity brought further modifications: the elevator relays were programmed to make multiple decisions, doors with interlocks were mandated, and door operation refined to provide safe automatic opening and closing. The last two were the biggest steps towards complete automation of elevators. In the 1890s, a number of residential buildings had self-service passenger cabs. These featured a shaftway door, and, in the elevator, a gate that the passenger would open and close himself. Locks were devised to prevent the hoistway doors from being opened if the elevator wasn't there or preventing the elevator from running if the door wasn't locked. When the inner gate was transformed into an automatic inner door in the early 20th century, safety edges were developed and added to reopen the door if anyone was in its path.
By the 1920s and '30s, fancy hi-rise apartment buildings started turning up – and with them, elevators. "American architecture as an independent school began its existence with the invention and adaptation of the elevator," observed one 19th century writer. "The architectural features of New York City are passing through a transitional period because of the demand for every possible square foot of enclosed space that can be had anywhere on Manhattan Island. The amount of business to be transacted will steadily increase, and with it the demand for more room in which to transact that business."
Since then, elevators have essentially remained the same – except for becoming sleeker, faster, and computerized. Every major elevator manufacturing company has introduced microprocessor technology for elevator buildings with large and complex traffic patterns. Computers, Westinghouse Elevator noted in a sales brochure, have become so sophisticated that "every potential corridor call in the building is preassigned to an elevator before the call is actually entered. These preassignments are reevaluated and redefined twice a second. In effect, the system is predicting, every half second, which car will be in the best position to answer any call that may be entered in the next half second, minimizing the response time of the elevator system when a call has been registered. Registered calls are instantly assigned and the system is scanned 10 times a second for new calls being entered."
As for the future, the only major difference in the box that Otis built will probably be aesthetics: glass or gold-plated, chrome or wood, plastic or formica. But the basic concept will not change much: a box hooked to a cable running over a pulley. And why should it? Simple yet brilliant, Otis’ “Magnificent Moving Machine” has helped New York City grow and prosper. Mr. Elevator Safety Man would be pleased.