. Electrical world. nnels. The two types of electric dredges which have been used securethe soil by either lifting it through centrifugal pumps or by anendless chain of buckets. The latter system seems to be the mostfavorable. A boat is built in a pit where it is to be operated, andthe necessary machinery placed aboard. The pit is then filled withwater to a depth of from 25 to 40 ft. The boats are fed by a cableabout 500 ft. long, which runs from the shore to the boat. Generallythese cables are arranged for three-phase, 60-cycle current standardlow voltage, but one or two of the boats are fed
. Electrical world. nnels. The two types of electric dredges which have been used securethe soil by either lifting it through centrifugal pumps or by anendless chain of buckets. The latter system seems to be the mostfavorable. A boat is built in a pit where it is to be operated, andthe necessary machinery placed aboard. The pit is then filled withwater to a depth of from 25 to 40 ft. The boats are fed by a cableabout 500 ft. long, which runs from the shore to the boat. Generallythese cables are arranged for three-phase, 60-cycle current standardlow voltage, but one or two of the boats are fed by a 4,000-volt,four-wire cable, which is carried directly to the boat and the oretransformers placed on the boat. The lower voltage cables are rubberinsulated and triple-braid water-proof. The 4,000-volt cables areleaded and armored. The transformers are sometimes placed on theboat and sometimes on a pole near the boat. Usually the latterarrangement. The dredger digs its own channel ahead of it, depositing the soil. FIG. I.—DREDGE HEAD OX. which has been worked behind it. The soil is elevated into a grizzlyor similar screening device where the rocks are w-ashed from thesoil, the rocks being delivered to the carrier that deposits them outof the way behind the dredger. The soil is then washed throughshakers and riffles, leaving the gold deposited on saving tables to betaken up with quicksilver, and the worked-over soil is run out atthe stern of the boat. The General Electric Company, Schenectady,N. Y., has developed electric equipments for such machinery of allkinds, and the electrically-operated dredges recently equipped bythat company are splendid examples of successful engineering en-terprise. A typical outfit recently sold to the Western Engineering & Con-struction Company for the Central Gold Dredging Company, ofOroville, consists of the following induction motors: One 50-hpmotor, with controller and resistance for driving the bucket line; oneiS-hp motor, with controller
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
