![]() The third function, that of handling the scows, is accomplished by three wires attached to the scows and lead to capstans or to hoisting engines on the deck of the dredge. They are raised by hoisting engines and, when released, penetrate into the river bottom by virtue of their own weight, thus anchoring the hull and holding it in position while digging. Spuds are long timbers of heavy section suspended from tall masts or so-called gallows-frames and running vertically through openings in or pockets attached to the hull. The position and local movement of the dredge is controlled by spuds, by anchors, or a combination of both. It is hung from the end of the boom by two wires or chains by means of which it is raised, lowered, opened and closed and by which also the boom is swung. It will be discussed in detail subsequently. The bucket is a very important machine in itself, and its proper design is most essential to the efficiency of the dredge. The first requires a derrick, comprising boom, “A” frame and back legs and the requisite hoisting machinery, consisting of a double cylinder, double drum engine with boiler, auxiliaries and appurtenances. To control the position and local movement of the dredge itself.The operation of the bucket is but one of three principal functions of the grapple necessary to the complete business of “mud-digging.” They are: This, however, is merely a makeshift, and by no means constitutes a dredge. Any derrick lighter may perform the operation of dredging by simply attaching a grab bucket to its fall. General Description.-A grapple dredge is, in principle, a derrick mounted on a float and swinging a grab bucket.
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