The technical challenge of the lock gates was in their mechanical engineering, in the design and manufacture of all the devices needed to make them open, close, shut, and lock. So basic an “accessory” item as a hinge assembly called for specifications unlike any previously prepared for a manufacturer. Flawless, precision hardware had to be cast of special steels in pieces that weighed several thousand pounds and that could withstand a strain of several million pounds. The yoke assembly used to fasten the tops of the gates to the lock walls weighed seven tons and looked not unlike the metal creations of some latter-day sculptors.
The gates were opened and closed by a simple, very powerful mechanism devised by Edward Schildhauer. The leaves of the gates were connected by steel arms, or struts, to enormous horizontal “bull wheels” concealed within the lock walls. These wheels, nearly twenty feet in diameter, were each geared to a big electric motor; and wheel and strut worked like the driving wheel and connecting rod on a locomotive, only here the action was reversed since the power was being delivered from the wheel. To open or close a gate, the wheel revolved about 200 degrees.
In the design of such a fundamental piece of apparatus the young engineer had had no established model to go by. Available data “were at variance,” as he wrote, and he had to reckon with such forces as mechanical friction, acceleration, wind resistance, and the effect of different water levels on the two sides of a gate. The extreme test would be the opening and closing of the heaviest gates in a dry chamber. But in recalling the first of such “dry lock” tests, Bishop wrote that the gates swung to and fro “as easily and steadily as one would open an ordinary door.”
But as resourceful as Schildhauer had been in this and other designs, as notably as he and Goldmark succeeded in everything they undertook, the end results were, above all, a stunning demonstration of how very far industrial technology had advanced. Among the more fascinating facts about the Panama Canal, for example, is that all hardware for the lock gates–the lifting mechanisms for the stem valves, the special bearings, gears, and struts for the gate machines, all ninety-two bull wheels–was made by a single manufacturer in Wheeling, West Virginia. In 1878, only thirty-five years before, the Quaker ironmaster Daniel J. Morrell had marveled at certain relatively simple steel castings displayed by the French at their Universal Exposition in Paris. Most of what he had seen was quite beyond the most advanced work at Pittsburgh then or at his own mills in Johnstown. now a comparatively small organization, the Wheeling Mold and Foundry Company, in a comparatively small industrial center, could produce castings in sizes and quantities unimagined in 1878, and of alloy steels formerly used in small quantities only for fine tools and cutlery. Carbon steel, nickel steel, vanadium steel, steels of exceptional strength and high resistance to corrosion, were being developed for naval armament before the turn of the century, but it was the advent of the automobile that spurred their real production. Vanadium steel, for instance, had been adopted by the Ford Motor Company for use in its engines in 1904, and it was of vanadium steel that the most important casting in the lock gates was made, the huge plate upon which the base of each gate leaf turned, a plate that had not only to bear the weight of the gate, but withstand constant immersion in water.
The most obvious and frequently emphasized differences between the French and American efforts at Panama, between failure and success at Panama, were in the application of modern medical science, the methods of financing, and the size of the excavation equipment used. But it should also be understood that the canal that was built was very different from what could have been built by anyone thirty years earlier. It was not only a much larger canal than it would have been (the locks were nearly twice as large as those designed by Eiffel, which measured 59 by 590 feet); it was constructed differently and of different materials. And its means of operation and control were altogether different. “Strongly as the Panama Canal appeals to the imagination as the carrying out of an ideal,” wrote one astute editor, “it is above all things a practical, mechanical, and industrial achievement.”
Nowhere was this more apparent than in the city of Pittsburgh, where some fifty different mills, foundries, machine shops, and specialty fabricators were involved in the canal, making rivets, bolts, nuts (in the millions), steel girders, steel plates, steel forms for the lock walls, special collapsible steel tubes by which the main culverts were formed, steel roller bearings (18,794 steel roller bearings) for the stem valves and spillway gates. The building of the gates themselves had been entrusted to McClintic-Marshall, a Pittsburgh contracting firm that specialized in heavy steel bridge construction.
The giant cranes in use on the Pacific locks traced their structural lineage to the Eiffel Tower. The steel rope–wire cable–used in the cableways and on the cranes, used in fact on every steam shovel and dipper dredge, had its origins in the Brooklyn Bridge, and indeed most of the cable had been manufactured by John A. Roebling Sons.
Cranes, cableways, rock crushers, cement mixers, all ran by electricity. The canal’s own motive power, its entire nervous system, was electrical, and an all-electric canal was something quite new under the sun and something that would have been altogether impossible even ten years earlier.
Operation of the locks would depend on no less than 1,500 electric motors. All controls were electrical. The most important part played by any one manufacturer was that of the General Electric Company, which produced approximately half the electrical apparatus needed during construction and virtually all the motors, relays, switches, wiring, and generating equipment that was installed permanently, in addition to the towing locomotives and all the lighting.
Besides the ninety-two motors used to swing the lock gates, there were forty-six small motors to run a miter forcing “mechanisms that locked the gate leaves once they were in the closed position. On top of every gate was a footwalk with a handrail, so attendants could go back and forth from one side of the lock to the other whenever the gates were closed. With the gates open, the handrail would be in the way, so it too was raised or lowered by an electric motor.
There were more than a hundred 40-horsepower motors to operate the big stem valves in the main culverts, while the largest motors installed, motors of 70 and 150 horsepower, similar to those being developed for heavy duty in steel mills, were needed for Two “extraordinary precautions” taken to safeguard the lock gates from damage.
As a ship approached the entrance to the locks, its path would be blocked by a tremendous iron “fender” chain stretched between the walls. The chain would be lowered (into a special groove in the channel floor) only if all was proceeding properly–that is, if the ship was in proper position and in control of the towing locomotives. If the ship was out of control and struck the chain, then the chain would be payed out slowly by an automatic release until the ship was brought to a stop, short of the lock gates. (A 10,000-ton ship moving at five knots could be checked Within seventy feet.) The length of the chain was more than four hundred feet and its ends were attached to big hydraulic pistons housed in the lock walls. There were pumps to supply water for the pistons and more electric motors to run the pumps.
If by some very remote chance a ship were to smash Through the fender chain, the safety gates would still stand in the path, the apex of their leaves pointed toward the ship. To break through the safety gates would take a colossal force, and it was almost inconceivable that the forward motion of any ship could be that great, having just encountered the fender chain. But in the event that this too occurred, there was still one further safeguard.
The most serious threat to the locks would be from a ship out of control as it approached the upper gates, a ship, that is, about to go down through the locks and out of the canal. For if the upper gates were destroyed, then the lake would come plunging through the locks.
So on the side walls at the entrance of each upper lock, between the fender chain and the guard gates, stood a big steel apparatus that looked like a cantilever railroad bridge. This was the emergen
cy dam. It was mounted on a pivot and in a crisis it could be swung–turned electrically–across the lock entrance in about two minutes’ time. From its underside a series of wicket girders would descend, their ends dropping into iron pockets in the concrete channel floor. The girders would form runways down which huge steel plates would be dropped, one after another, until the channel was sealed off. It was an ungainly contraption, but it worked most effectively.
The likelihood of a ship even hitting the chain was extremely small. The chance of a ship hitting the chain and breaking it was reckoned at perhaps one in ten thousand.*
Under normal procedure a ship would be controlled by the towing locomotives all the way through the locks, with four locomotives to the average-sized ship, two forward pulling, two aft holding the ship steady. At no time in the locks would a ship move under its own power.
Like nearly every detail of the locks, the towing locomotives were the first of a kind. Presently they would become one of the most familiar features of the canal. They were designed by Schildhauer to work back and forth on tracks built into the top of the lock walls and to move a ship from point to point at about two miles an hour or less. But they also had to negotiate the 45-degree incline between the locks.
Built at Schenectady, the early model cost $13,000. The first order was for forty. Each machine was a little more than thirty feet long, weighed forty-three tons, and had identical cabs at either end, duplicate controls and driving engines, so that it could run in either direction without being turned around. The key feature, however, was a big independently powered, center-mounted windlass that handled some eight hundred feet of steel cable. With the windlass the loco motive could control a ship without even moving. Line could be payed out or reeled in at rapid speed and with loads On the line of as much as twenty-five thousand pounds.
For the still young, still comparatively small General Electric Company the successful performance of all such apparatus, indeed the perfect efficiency of the entire electrical system, was of the utmost importance. This was not merely a very large government contract, the company’s first large government contract, but one that would attract worldwide attention. It was a chance like none other to display the virtues of electric power, to bring to bear the creative resources of the electrical engineer. The canal, declared one technical journal, would be a “monument to the electrical art.” It had been less than a year since the first factory in the United States had been electrified.
In the broader context, the arrangement was also a historic forerunner: a large, novel, technological objective was to be obtained in abnormally little time and according to the most stringent standards through the combined efforts of the federal government and a specialized industry. (It is, to be sure, a very long way from the electrical installations at Panama to the Manhattan Project, but the lineage is plain.) Furthermore, the outstanding success of the arrangement, the most original and important piece of work to come out of the con tract, was that for which the spirit of government-industry cooperation was the most pronounced.
The advantages of electrical power were many: it could be transmitted over long distances; in complicated installations each different machine or mechanism could have its own motor drive (exactly as in the locks), instead of the power being transmitted here and there from one central source by an elaborate system of drive shafts, belts, and pulleys (as in a conventional steam-driven factory). The motors themselves were relatively small, compact, watertight; they turned at constant speeds irrespective of the loads put upon them; they required a minimum of attention; they would not blow up.
But the chief virtue of electricity was in the degree of control it afforded. Things could be made to happen–stop, start, open, close– with the mere press of a button or the turning of a few simple switches on a central control board. And so it was to be at Panama, and with one other extremely important feature. In this operation, things could be made to happen only as they were supposed to, in exactly the prescribed sequence.
Though the fundamental principles were much like those developed for railroad switchboards, no comparable control system had been produced heretofore. Again credit for the basic conception belongs to Edward Schildhauer, but otherwise it was a wholly joint effort. “No specifications could have been more exacting or explicit as to the results to be accomplished,” wrote one of the engineers at Schenectady, “or have given a wider range as to the method of their accomplishment. . . . It was the single aim of all concerned to produce something better, safer and more reliable than anything before undertaken.” A special department was set up at the General Electric works, wherein picked employees concentrated solely on the Panama project. Company engineers were sent to the Isthmus to become thoroughly familiar with all aspects of the problem; Schildhauer and members of his staff came to Schenectady. The result was an unqualified success.
The operation of each flight of locks was to be run from the second floor of a large control house built on the center wall of the uppermost lock. From there, with an unobstructed view of the entire flight, one man at one control board could run every operation in the passage of a ship except the movement of the towing locomotives.
Each control board was a long, flat, waist-high bench, or counter, upon which the locks were represented in miniature–a complete working reproduction. The board at Gatun was sixty-four feet in length and about five feet wide. There were little aluminum fender chains that would actually rise in place or sink back out of sight on the board as a switch was turned. The lock chambers were represented by slabs of blue marble. There were aluminum pointers placed in the same relative positions as the lock gates and these opened or closed as the actual lock gates opened and closed. There were upright indicators showing the positions of the rising stem valves, and there were still taller upright indexes showing the level of the water in the chambers to within half an inch.
Everything that happened in the locks–the rise and fall of the fender chains, the opening and closing of the gates–happened on the board in the appropriate place and at precisely the same time. So the situation in the locks could be read in an instant on the board at any stage of the lockage.
In addition, the switches to work the fender chains, lock gates, stem valves, all the switches for every mechanism in the system, were located beside the representation of that device on the board. To lift a 40,000-ton ship twenty-one feet in a lock chamber, one had only to turn a small aluminum handle about like that on an ordinary faucet.
The genius of the system, however, was in the elaborate racks of interlocking bars concealed from view beneath the board. For not only was the operator able to see the entire lockage process in miniature and in operation on the board before him, but the switches were interlocking–mechanically. Each had to be turned in proper sequence, other-wise it would not turn. It was impossible therefore to do anything out of order or to forget to take any crucial step in the necessary order. For example, the switch to lower the fender chain would not operate until the switch to open the lock gates had been thrown into the opening position. Thus no one at the control board could inadvertently lower the chain for a ship to proceed and not have the gates open for the ship to enter the locks. Nor could the same gates be closed once the ship was in the lock without first turning the switch to raise the fender chain again, thus assuring that the chain would always be in the up position to protect the gates whenever the gates were closed.
The gate switch was further interlocked with the switch for the miter-forcing machine (to open the gates the operator had first to unlock the miter-forcing machine). when the stem valves in the culverts were to be opened, to raise the water and lift the ship to the next level, it was possible to open only the correct valves. At Gatun, for example, this would mean that an operator could not possibly flood the lower locks in the flight by opening the valves for the middle and upper chambers at once.
Only with a system run by electricity could the locks have been controlled from a central point. In some ins
tances the distance from an individual motor in the system to the control board was as much as half a mile.
More than half a century later the same control panels would still be in use, functioning exactly as intended, everything as the engineers originally devised. “They were very smart people,” a latter-day engineer at Miraflores would remark. “After twenty-one years here I am still amazed at what they did. “
Once, just before the canal was completed, the Commission of Fine Arts sent the sculptor Daniel Chester French and the landscape architect Frederick Olmsted, Jr., son of the famous creator of New York’s Central Park, to suggest ways in which the appearance of the locks and other components might be dressed up or improved upon. The Two men reported:
The canal itself and all the structures connected with it impress one with a sense of their having been built with a view strictly to their utility. There is an entire absence of ornament and no evidence that the aesthetic has been considered except in a few instances. . . . Because of this very fact there is little to find fault with from the artist’s point of view. The canal, like the Pyramids or some imposing object in natural scenery, is impressive from its scale and simplicity and directness. One feels that anything done merely for the purpose of beautifying it would not only fail to accomplish that purpose, but would be an impertinence.
Consequently nothing was changed or added. The canal would look as its builders intended, nothing less or more.
II
For all practical purposes the canal was finished when the locks were. And so efficiently had construction of the locks been organized that they were finished nearly a year earlier than anticipated. Had it not been for the slides in the Cut, adding more than 25,000,000 cubic yards to the total amount of excavation, the canal might have opened in 1913.
The locks on the Pacific side were finished first, the single flight at Pedro Miguel in 1911, Miraflores in May 1913. Morale was at an all-time high. Asked by a journalist what the secret of success had been, Goethals answered, “The pride everyone feels in the work.”
David McCullough Library E-book Box Set Page 398