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per round trip has been averaged for hours at a time. If the filling, handling, and hooking-on of buckets be done with reasonable dispatch, a single machine will readily transfer 400 gross tons of ore per day of ten hours. The cost of handling coal and ore by this means varies from seven-tenths of a cent to two cents per gross ton.

The first bridge tramway plants were erected on the iron ore unloading docks at Cleveland, Ohio, about twenty-five years ago, and the new machines were for a time confined in their sphere of usefulness to the empire of the Great Lakes. Gradually, however, they secured general

Grab Buckets

During the early history of the bridge tramway plants, there was universal employment of tubs or buckets which, although self-dumping, had to be filled by hand. As an improvement upon these, there have been introduced various types of self-filling and automatic dumping buckets which will handle from twothirds to four-fifths of a cargo or consignment of the bulk material without hand-shoveling. The most primitive forms of these self-filling buckets were "shovel" buckets of five tons' capacity, which scooped up their load through being dragged against the slope of the

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FOUR HULETT AUTOMATIC ORE UNLOADERS TAKING ORE FROM A LAKE VESSEL.

adoption, particularly for coal handling; and they are now to be found, not only on the Atlantic and Pacific coasts, but in Germany, Austria, Russia, Sweden, Egypt, and other foreign countries. Perhaps the best exemplification of the possibilities of this Yankee invention for coal handling, is afforded at the coaling stations of the United States Navy at Key West, Dry Tortugas, Mare Island, Cal., and New London, Conn., where, by means of bridge tramways such as have been described, fuel is transferred directly from storage buildings (having a capacity of 10.000 tons each) to the holds of United States war vessels.

coal or ore pile. Then came the "grab" buckets, descending with open jaws, which, closing, took from the ore or coal pile a "bite" of one ton or more and held the material securely until released at any desired point of discharge. This class of buckets were introduced, not only in connection with the familiar bridge tramways, but also in conjunction with wirerope cableways. The latter have been utilized to some extent for coal and ore handling, in locations where the span necessitated was greater than could be successfully covered by a suspension structure of the weight of a bridge tram

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a height of 55 feet. It consists primarily of a foundation trestle, which is mounted upon wheels and which can be moved along the dock, the rails carrying the forward end of the trestle being directly on the brink of the dock, as in the case of the bridge tramways. Moving backward and forward on this foundation span, at right angles to the dock, is a heavy walking beam, attached to the outer end of which is the depending leg or mast that carries the clam-shell bucket used in dipping out the ore. The parallel motion keeps the leg always in a vertical position; and the weight of the end of the walking beam from which the bucket is suspended is counterbalanced by means of a hydraulic accumulator located at the opposite end.

the bucket has been closed by hydraulic power, it is lifted from the boat and run back over the dock, where its contents can, if desired, be discharged directly into the railroad cars which are to convey the ore to the blast furnaces. Only three men are required in order to operate one of these machines, which has a capacity of 250 tons per hour.

The world's record for the rapid handling of an ore cargo was made a short time ago at the port of Conneaut, Ohio, when four of these machines, in a total working time of 4 hours 43 minutes, removed from the steamer James H. Hoyt a cargo of 5,300 tons of ore. All the cargo was taken out by the machines, no cleaning up whatever by hand labor being necessary.

Furnace Hoists

The usefulness of new marvels for handling bulk materials is by no means confined to the transfer of coal and iron ore to and from ships, railroad cars, and stock piles, but is demonstrated in scarcely a less striking manner at blast furnaces and iron and steel making plants in general. Foremost among the utilities in this field is the furnace hoist and stockdistributer, which has done away entirely with the old-time dangerous and unsatisfactory method of feeding blast furnaces, and, by automatically charging the furnaces, dispenses entirely with the employment of top-fillers.

This hoist consists, in the main, of an inclined steel-trussed bridge starting from a pit and reaching to the top of the shell of the furnace, where it terminates in an extension over the top of the bell and hopper. A skip car with a capacity of from 2,000 to 6,000 pounds is arranged to run on this track, the hoist rope passing over the top sheave and back to the drum of the hoisting engine near the incline. When the skip car, loaded with iron ore, coke, or limestone, as the case may be, arrives at the top of the furnace, the car is automatically tipped, and the load is dumped into the great receptacle, from which the bell has been automatically lifted for the purpose.

At all blast furnaces the transfer of iron ore from stock or storage piles to the furnace as the raw material is required for consumption, constitutes a handling problem of some complexity. In this work there are employed steam shovels, locomotive derricks equipped with grab buckets, and, finally, various modifications of the bridge tramway. Some of the bridges thus employed have a clear span of about 250 feet over storage yard and railroad tracks, thus enabling the ore to be handled directly from railroad cars to furnaces, or from the stock piles where the surplus supply is held.

Car-Dumping Machines

Yet another form of apparatus which is being employed in handling both coal and iron ore, is the car-dumping machine. At the furnaces these dumpers are utilized in some instances to transfer the contents of standard-sized railroad cars to smaller cars which carry the material

to the furnaces; but the true province of this type of apparatus is in transferring coal (for water shipment) from cars to colliers. In this field they have found extensive utilization.

There are in existence many different designs of car-dumping machines; but the most efficient styles are those which pick up and completely overturn the loaded car, transferring its contents to the hold of the vessel to be loaded. The earliest forms of car dumpers, while entirely satisfactory in the rapidity with which they handled material, were considered deficient in that they entailed a serious breakage of the coal. This, how

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A MODERN CAR-DUMPING MACHINE.

ever, was finally remedied by modifications whereby the coal is dumped into pans connected with chutes leading to the vessel, which not only enable the fuel to be handled with far less breakage than formerly, but also make it possible to direct the influx to any portion of the hold desired.

The fundamental feature of the average car-dumping machine is a car-tipping device or cradle into which the car is run and then clamped, and which turns over with the car and discharges its contents. In some machines the receiving pan is automatically tilted at an angle proportionate to that of the car-tipping device, so that the coal slides gradually instead. of pouring or falling; and in certain machines the coal is not sent into the vessel hold through a chute, but is transferred from the car, as it is dumped, to transfer tubs or to steel buckets arranged on the endless-chain plan, which convey

it to the cargo space by easy stages and with practically no breakage. Some of these car-dumping machines will handle. upward of 200 loaded cars in an ordinary working day, not only actually transferring the coal, but handling the loaded and empty cars to and from the machine, and obviating all necessity for the employment of a shifting engine and train

crew.

Coal-Loading Machines

An ingenious type of coal-loading machine is found at Fairport on the south shore of Lake Erie, and at several other points in the United States. By its operation the coal to be loaded on a boat is dumped from the hopper-bottomed railroad cars into a large receiving hopper underneath the car. From this hop

per the fuel is delivered to a carrier of the continuous type, which hoists it up to an incline spout down which it passes into a telescope spout and thus directly into the boat. This telescope spout is drawn out to its full length at the commencement of operations, and is then gradually taken up or shortened as the boat is filled. By this means the spout is kept constantly full of coal, and the breakage of the fuel is reduced to a minimum. It requires but two men to operate such a machine, which is driven by a 50-horse-power engine. The cost of an installation of this kind is much less than in the case of some of the other types of coal-handling machinery, and yet such a machine is capable of loading from 600 to 900 tons of coal per hour.

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A Quarter-Century of American
Central Station Engineering

The Marvelously Rapid Progress in Electrical Engineering which has
Revolutionized Industrial Conditions

Part III.

T

By R. F. SCHUCHARDT, B. S. Testing Laboratory, Chicago Edison Company

Consolidation of Plants HE NEXT STEP in the development was one of consolidation.

Many cities had been liberal in granting franchises to lighting companies, and as a result there were built within the same city many systems of various excellence and stability. To the engineers of the consolidated company was then presented the problem of unifying the systems; but the changes to the new sys

tem had to be made without sacrificing the value of the investment represented by the generating apparatus and lines of the existing stations. Such a change, naturally, was made step by step, and thus required several years. In addition to providing for the existing load, the new system had to be designed for the future; and the probable development in the line of various classes of electrical apparatus had to be considered.

In our larger American cities, the load

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