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Great Floating Derrick "atlas," At The Champ Shu'vard, Philadelphia, Pa.

at. all times automatically keeps a similar position on the opposite arm.

Probably the best exemplification of the possibilities of these adjuncts of twentieth century shipbuilding is afforded at the Cramp plant at Philadelphia, where there are several of these cranes, all driven by electricity. F.ach crane is mounted on a steel trestle of special design and construction, about 600 feet long, and of sufficient height to bring the under side of the crane-girder 105 feet above the ground. One of these cranes, which may be considered as representative of its class, is 102 feet long from end to end of girders, with 190 feet effective travel of trolley. It will lift 30.000 pounds at 60 feet either side of the center, and 9.000 pounds at either end of bridge. A single electric motor operates all functions of the crane at the following speeds:

Hoisting a full load of 30,000 pounds—125 feet per minute.

Trolley across cantilever—400 to 800 feet per minute.

Entire crane along trestle, on track of 20foot gauge—400 to 700 feet per minute, depending on load and wind-pressure. The minimum of 400 feet is with full load and against a wind pressure of ,30 miles per hour.

Recently this crane placed in position on shipboard, a battleship sternpost weighing eighteen tons, and, with the assistance of but a few men, conveyed it from the cars at the opposite end of the yard, an operation never accomplished under the old plan in less than two or three days nor without a large force of workmen engaged.

Derricks

Ranking with the cantilever cranes for marvelous achievement are the monster derricks to be found at several American shipyards. The best example is afforded by the "Atlas" at the Cramp yard—the largest and most powerful floating derrick in the world. The pontoon of the structure is 73 feet in length, 62 feet in width, and 13 feet deep. When carrying the maximum load of 125 tons at the boom end, and with water ballast aft sufficient to bring her to an even keel, the "Atlas" has a freeboard of 16 inches and a displacement of 1,563 tons. The cone has a diameter of 40 feet at the base; the length of boom from the axis is 58'/. feet; and the boom swings 36 feet clear of the pontoon. The height from deck to masthead is 116 feet; and from deck to boom, 65 feet. The maximum hoisting height is 50 feet. The pontoon is of iron, while the boom, mast,

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plating so heavy that to draw it up requires rivets too large to be properly driven by hand. From an economical standpoint, the power riveters perform wonders. In deck and tank topwork, for instance, three men and a heater boy will drive from 800 to 1,000 rivets a day. Not only is the whole operation of driving a rivet completed much more quickly than by hand, but it is done so expeditiously that the rivet has not lost its heat ere completion, and consequently there is gained the benefit of the resulting contraction, which, as the rivet cools, draws everything together with firmness.

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Lakes, where pneumatic machinery of this class is used very extensively, the saving on an ordinary lake steamer of 4,000 tons is from $4,000 to $5,000. One machine will not infrequently drive 450 ^-inch rivets in a single day. At the regular hand-work rate, this would involve an outlay of $15.75; whereas, with the machine, the cost is but $5.50, including the wages of operatives and the cost of power.

Another class of pneumatic tools in use in shipyards consists of chipping, calking, and bending hammers, machines which range in weight from 7 to 11 pounds and which have a stroke of from one to four inches at speeds varying from 3,400 to 2,200 strokes per minute according to size. These hammers require 20 feet of free air per minute, and work at a pressure of from 70 to 80 pounds. The heavy chipping hammers weigh fifteen pounds, and attain a speed of 1.200 blows per minute for the 7-inch stroke. Most powerful of all the hammers is what is known as the "9-inch stroke riveting hammer," which has a speed of ooo strokes per minute. A pneumatic holderon is in use in many shipyards, instead of the ordinary bar, for holding up the head of the rivet. It can readily be put

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Pneumatic Drill In Operation.

furnished in most instances by a 2j4inch main; and an air pressure of at least no pounds is carried, supplied by an air compressor capable of delivering, say, 5,000 cubic feet of air per minute.

Machine and Brass Shops

The machine and brass shops and other under-cover portions of modern American shipyards have within the past few years shown vast improvement in equipment and arrangement. An ideal structure of this kind—the newest shop at the Cramp plant—is 335 by 143 feet, and of steel-skeleton framework construction. The floor load in the second story is 400 pounds per square foot, while the third floor is designed for a load of 350 pounds per square foot. The structure has a main central traveling-crane runway, served by two 50-ton electric cranes, with a span of about 57 feet, center to center of supporting girders. On either side of the main central portion are galleries 42 feet wide. The floor space in the lower story of both wings is served by electric cranes of from 10 to 30 tons' capacity.

Some idea of the magnitude of a present-day shipyard of the first class, may be gained from the fact that the Cramp yard at Philadelphia represents an expenditure of more than $7,000,000; and the great shipyard at Newport News, Ya., on Hampton Roads, involved an even greater outlay. In the laying out of all our big shipbuilding plants, heavy expenditure has been made to secure convenience, speed, and economy in the conduct of operations—a continuous, unretarded movement forward of the material from the time it enters the yard in raw state until it is ready to leave as part of a completed ship. To this end, buildings have been grouped—at the Cramp plant, joiner, pattern, machine, and erecting shops are combined within the shelter of one immense structure 1,164 feet m length—and all material is conveyed by short hauls.

Use of Electric Power In conclusion, a word should be said regarding the extent to which electrical energy is displacing steam power in the operations of the more important shipyards. Not only are almost all the cranes, large and small, electrically operated, but almost every one of the big machine tools is impelled by an individual motor, thus insuring a great saving, since the power need be turned on only when actually needed. The electrical outfit which at the Newport News yard furnishes power for running all the machines in the shops and also supplies current for the 2,500 incandescent and 150 arc lights in the plant, consists of three 600-K. W. generators driven by three compound engines; two 125-K. YV. generators driven by one horizontal-compound engine; and two 75-K. W. generators driven by simple engines.

The Machinery of Modern Warfare

No. II. Ingenious Devices that Increase the Efficiency of Peacemakers

By RUTLEDGE RUTHERFORD

THIS IS AN AGE of new machines of war. In the last issue of The Technical World were described several of the new weapons and methods of destruction that were making their appearance in the Japanese-Russian war. But these are not all. The fever to invent devices that will destroy life and property in the quickest and most wholesale manner, is catching; and nations seem to vie with one another in their efforts to produce the most deadly weapons. Indications are that the next decade will witness radical changes in the features and methods of manufacture of all war materials.

The new era of fighting devices through which we are now passing, seems to have had its birth in the recent South African war. That stubborn struggle not only tested the courage and en

durance of the English, but incited the Englishman's wits, awakened his latent mechanical genius, and brought forth new inventions that have surprised the world. In Thibet the British are now testing for the first time several marvelous new contrivances that had their inception in ideas originating in South Africa.

The Hyposcope

The very newest of these contrivances, and one that has a most promising future, is a new rifle-sight that enables a soldier to shoot at the enemy while the marksman hides behind a rock or tree or otherwise completely obscures himself. This is regarded as war's masterpiece of protective mechanism, and is causing a great amount of comment in Europe. The sight is called the "Hyposcope." The pictures of the rifle with the new arrange

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