File:Factory and industrial management (1891) (14761931774).jpg

Identifier: factoryindustria15newy (find matches)
Title: Factory and industrial management
Year: 1891 (1890s)
Authors:
Subjects: Engineering Factory management Industrial efficiency
Publisher: New York (etc.) McGraw-Hill (etc.)
Contributing Library: Engineering - University of Toronto
Digitizing Sponsor: University of Toronto

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tate the penetration of the leaves of the bucket. Near Vicksburg, in soft material, four yard bucket machines movedabout 3,000 cubic yards per 24 hours, digging in 40 feet of water,—not half of that amount when compact sand was encountered. Like the scoop, this dredge recjuires the use of scows, and cannotbe economically handled with attached conveyors. The loss of timedue to repairs, handling scows, etc., is the same. Increased size ofbucket and power of machinery adds little to its efficiency or economy,and for the purpose of dredging the Mississippi crossings it wouldgive but mediocre results. In the endless chain or bucket ladder machine much the samefaults obtain. Bucket ladder dredges with self-contained hoppers areout of the ((uestion in this shoal river. Conveyors are successfiillyattached to these machines, and could be arranged on j)ontoonsdiminishing in height, but the distance of gravity conveyance wouldnecessarily be small. The bucket ladder dredge used by the writer on
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466 DREDGING ON THE MISSISSIPPI. the Mississippi, like the single bucket machines, did considerably lesswork on encountering sand, possibly because of faulty construction ofthe particular machine used. This type of dredge could be used onthe Mississippi bars, as it is in other portions of the world, in connec-tion with a hydraulic conveyor, but it would not be as economical asthe pump dredge, owing to the waste of power in raising to the top ofthe ladder material needed only at the elevation of the discharge hopperon deck. Webster says that the horse power required to raise the samematerial varies with the square root of the height from top of tumblerto surface of cut. The additional force exerted in a 300 yard-per-hour machine would be, therefore, about 15 h. p. The difficulty of applying economically the above-mentioneddredges on the bars of the Mississippi lies not so much in their inade- iWi t-4^

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