. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . rill of this type is given in The drills are operated in parallel; three wires lead fromthe two drill-coils to the generator, comprising two distinctcircuits, each circuit including similar coils in the these two circuits electrical impulses are sent in alter-nation. One impulse moves the iron bar or plunger back,and the next moves it forward; thus the drills all move to-gether and in synchronism
. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . rill of this type is given in The drills are operated in parallel; three wires lead fromthe two drill-coils to the generator, comprising two distinctcircuits, each circuit including similar coils in the these two circuits electrical impulses are sent in alter-nation. One impulse moves the iron bar or plunger back,and the next moves it forward; thus the drills all move to-gether and in synchronism with the generator. The drillmakes about 000 strokes per minute, and the stroke of theplunger is from 3 to 4i in. The heaviest single parts of thedrill are the tripod-weights, which are about 100 lbs. to these in order of weight are the two coils, which weigh about GO lbs. each. Thelargest piece in the entire drill is the cylindrical casing, which is 38 in. long by about 7 in. indiameter. The Van Depoele Electric Percussion Rock-Drill consists of two or more coils of copper•wire inclosed in an iron tube, and a wrought-iron core moving within them. To one end of. Fio. —Electric rock-drill.
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Keywords: ., bookcentury1800, bookdecade189, booksubjectmechanicalengineering
