Robert M. Vogel

“ While the 200-foot height of the viaduct’s two greatest piers was not startling even at that period, the studies proved that piers of far greater height were entirely feasible in iron construction. This led to the design of a 395-foot pier, which, although never incorporated into a bridge, may be said to have been the direct basis for the Eiffel Tower.
Preliminary studies for a 300-meter tower were made with the 1889 fair immediately in mind. With an assurance born of positive knowledge, Eiffel in June of 1886 approached the Exposition commissioners with the project. ”

“ By the last quarter of the century, a continuous series of improvements in the valving, control systems, and safety features of the steam machine had made possible an elevator able to compete with the subsequently appearing hydraulic systems for freight and low-rise passenger service insofar as smoothness, control, and lifting power were concerned. However, steam machinery began to fail in this competition as the increasing height of buildings rapidly extended the demands of speed and length of rise. ”

“ Although highly efficient and of unquestionable security, this safety device was considered an insufficient safeguard by Eiffel, who, speaking in the name of the Commission, demanded the application of a device known as the rack and pinion safety that was used to some extent on European cog railways. The commissioners not only considered this system more reliable but felt that one of its features was a necessity: a device that permitted the car to be lowered by hand, even after failure of all the hoisting cables. ”

“ The Commission discarded the whole scheme about the middle of 1888, giving two reasons for its action: (1) the novelty of the system and the attendant possibility of stoppages which might seriously interrupt the “exploitation of the Tower,” and (2) fear that the rollers running around the tracks would cause excessive noise and vibration. Both reasons seem quite incredible when the Backmann system is compared to one of those actually used—the Roux, described below—which obviously must have been subject to identical failings, and on a far greater scale. ”

“ To transport people to the second platform was an altogether different problem. Since there was to be a single run from the ground, it would have been necessary to form the elevator guides either with a constant curvature, approximating that of the legs, or with a series of straight chords connected by short segmental curves of small radius. Eiffel planned initially to use the first method, but the second was adopted ultimately, probably as being the simpler because only two straight lengths of run were found to be necessary. ”

“ The American Elevator Company, the European branch of Otis Brothers & Company, did submit a proposal through its Paris office, Otis Ascenseur Cie., but the Commission was compelled to reject it because a clause in the fair’s charter prohibited the use of any foreign material in the construction of the Tower. Furthermore, there was a strong prejudice against foreign contractors, which, because of the general background of disfavor surrounding the project during its early stages, was an element worth serious consideration by the Commission. ”

“ The above Engraving illustrates a very superior Hoisting Machine, designed for Store and Warehouse Hoisting. It is very simple in its construction, compact, durable, and not liable to get out of order. An examination of the Engraving will convince any one who has any knowledge of Machinery, that the screw is the only safe principle on which to construct a Hoisting Machine or Elevator. ”

“ In the decade following the Civil War, tall buildings had just begun to emerge; and, although the skylines of the world’s great cities were still dominated by church spires, there was increasing activity in the development of elevator apparatus adapted to the transportation of people as well as of merchandise. ”

“ The disagreement threatened to halt the entire project. In common with all elevators in which the car hangs by cables, the prime consideration here was a means of arresting the cabin should the cables fail. As originally presented to Eiffel, the plans indicated an elaborate modification of the standard Otis safety device—itself a direct derivative of E. G. Otis’ original.
If any one of the six hoisting cables broke or stretched unduly, or if their tension slackened for any reason, powerful leaf springs were released causing brake shoes to grip the rails. ”

“ Not until the beginning of the 20th century, when hydraulic systems were forced into competition with electrical systems, was the direct plunger elevator improved in America to the extent of being practically capable of high rises and speeds. Another reason for its early disfavor in the United States was the necessity for drilling an expensive plunger well equal in length to the rise. [14]
As mentioned, the most serious problem confronting Edoux was the extremely high rise of 525 feet. The Trocadero elevator, then the highest plunger machine in the world, traveled only about 230 feet. ”

“ In 1900, after the customary 11-year period, Paris again prepared for an international exposition, about 5 years too early to take advantage of the great progress made by the electric elevator. When the Roux machines, the weakest element in the Eiffel Tower system, were replaced at this time, it was by other hydraulics. Built by the well known French engineering organization of Fives-Lilles, the new machines were the ultimate in power, control, and general excellence of operation. As in the Otis system, the cars ran all the way to the second platform. ”

“ Since the only practical way in which the power of a steam engine could be applied to the haulage of elevator cables was through a rotational system, the [Pg 10] cables invariably were wound on a drum. The travel or rise of the car was therefore limited by the cable capacity of the winding drum. As building heights increased, drums became necessarily longer and larger until they grew so cumbersome as to impose a serious limitation upon further upward growth. A drum machine rarely could be used for a lift of more than 150 feet. ”

“ The section of the Tower presenting the least difficulty to elevator installation was that above the juncture of the four legs—from the second platform to the third, or observation, enclosure. There was no question that French equipment could perform this service. The run being perfectly straight and vertical, the only unusual demand upon contemporary elevator technology was the length of rise—525 feet. ”

“ The first complete elevator machine in the United States, constructed in 1855, was a complex and inefficient contrivance built around an oscillating-cylinder steam engine. The advantages of an elevator system independent of the mill drive quickly became apparent, and by 1860 improved steam elevator machines were being produced in some quantity, but almost exclusively for freight service. It is not clear when the first elevator was installed explicitly for passenger service, but it was probably in 1857, when Otis placed one in a store on Broadway at Broome Street in New York. ”

“ Pertinent is the one nearly successful attempt which was made to approach the high-rise problem electrically. In 1888, Charles R. Pratt, an elevator engineer of Montclair, New Jersey, invented a machine based on the horizontal cylinder rope-geared hydraulic elevator, in which the two sets of sheaves were drawn apart by a screw and traveling nut. The screw was revolved directly by a Sprague motor, the system being known as the Sprague-Pratt. While a number of installations were made, the machine was subject to several serious mechanical faults and passed out of use around 1900. ”

“ The curvature of the Tower’s legs imposed a problem unique in elevator design, and it caused great annoyance to Eiffel, the fair’s Commission, and all others concerned. Since a vertical shaftway anywhere within the open area beneath the first platform was esthetically unthinkable, the elevators could be placed only in the inclined legs. ”

“ Operators of hotels and stores gradually became aware of the commercial advantages to be gained by elevating their patrons even one or two floors above the ground, by machinery. The steam engine formed the foundation of the early elevator industry, but as building heights increased it was gradually replaced by hydraulic, and ultimately by electrical, systems. ”

“ To study the elevator problem, Eiffel retained a man named Backmann who was considered an expert on the subject. Apparently Backmann originally was to design the complete system, but he was to prove inadequate to the task. As his few schemes are [Pg 21] studied it becomes increasingly difficult to imagine by what qualifications he was regarded as either an elevator expert or designer by Eiffel and the Commission. ”

“ Absence of a drum enabled the car to be carried by a number of cables rather than by one or two, and rendered overtravel impossible. It was fast. Control devices had received probably the most attention by engineers and were as perfect and sensitive as was [Pg 13] possible with mechanical means. Cars with lever control could be run at the high speeds required for high buildings, yet they could be stopped with a smoothness and precision unattainable earlier with systems in which the valves were controlled by an endless rope, worked by the operator. ”

“ Hale eventually abandoned it and became the western agent for Otis—by this time prominent in the field—and subsequently was influential in development of the hydraulic elevator.
The rope-geared system of hydraulic elevator operation was so basically simple that by 1880 it had been embraced by virtually all manufacturers. However, for years most builders continued to maintain a line of steam and belt driven machines for freight service. Inspired by the rapid increase of taller and taller buildings, there was a concentrated effort, heightened by severe competition, to refine the basic system. ”

“ It employed water not under pressure but simply as mass under the influence of gravity. The elevator car’s supporting cables ran over sheaves at the top of the shaft to a large iron bucket, which traveled in a closed tube or well adjacent to and the same length as the shaft. To raise the car, the operator caused a valve to open, filling the bucket with water from a roof tank. When the weight of water was sufficient to overbalance the loaded car, the bucket descended, raising the car. ”

“ The double car, traveling at 400 feet per minute, carried 40 persons, all seated because of the change of inclination. The main valve or distributor that controlled the flow of water to and from the driving cylinder was operated from the car by cables. The hydraulic head necessary to produce pressure within the cylinder was obtained from a large open reservoir on the second platform. After being exhausted from the cylinder, the water was pumped back up by two Girard pumps (fig. 31) in the engine room at the base of the Tower’s south leg. ”

“ The comparative position of American practice, which will be demonstrated farther on, is indicated by the fact that Otis Brothers and other large elevator concerns in the United States were able to establish offices in many of the major cities of Europe and compete very successfully with local firms in spite of the higher costs due to shipment. ”

“ In the plan as first presented, a ground-based steam engine drove the frames and rollers through an endless fly rope—traveling at high speed presumably to permit it to be of small diameter and still transmit a reasonable amount of power—which engaged pulleys on the cars. The design was remarkably similar to that of the Miller Patent Screw Hoisting Machine, which had had a brief life in the United States around 1865. ”

“ It was almost completely silent, and when the cylinder was placed vertically in a well near the shaft, practically no valuable floor space was occupied. But most important, the length of rise was unlimited because no drum was used. As greater rises were required, the multiplication of the ropes and sheaves was simply increased, raising the piston-car travel ratio and permitting the cylinder to remain of manageable length. The ratio was often as high as 10 or 12 to 1, the car moving 10 or 12 feet to the piston’s 1. ”

“ Another organic difficulty existing in drum machines was the dangerous possibility of the car—or the counterweight, whose cables often wound on the drum—being drawn past the normal top limit and into the upper supporting works. ”

“ If higher speeds were used, an impractically long express run would be necessary for starting and stopping in order to prevent an acceleration so rapid as to be uncomfortable to passengers and a strain on the equipment. ”

“ Jacques, the Dôme des Invalides, the Arc de Triomphe, humiliating these monuments by an act of madness. [1]
Further, a prediction was made that the entire city would become dishonored by the odious shadow of the odious column of bolted sheet iron. ”

“ Upon reaching the top, the operator was able to open a valve in the bucket, now at the bottom of its travel, and discharge its contents into a basement tank, to be pumped back to the roof. No longer counterbalanced, the car could descend, its speed controlled solely by the brake. ”

“ To permit the upper car to descend under the first condition, the plungers were made sufficiently heavy, by the addition of cast iron at their lower ends, to overbalance the weight of a capacity load in the lower car. ”