. Electric railway journal . s. The electrical conduct-ance of the joint is equal to that of an equal length ofthe unbroken contact rail, the conductance of this railbeing about one-seventh that of annealed copper. The accompanying illustrations show the steps in theinstallation of this bond. The surfaces of the rail which are to come in contact with the bond are first ground toremove the scale and rust and give a bright, clean con-tact surface. An electrically driven hand grinder isused for this purpose, the operation being done by oneman in about twenty minutes. A carbon mold is thenplaced a
. Electric railway journal . s. The electrical conduct-ance of the joint is equal to that of an equal length ofthe unbroken contact rail, the conductance of this railbeing about one-seventh that of annealed copper. The accompanying illustrations show the steps in theinstallation of this bond. The surfaces of the rail which are to come in contact with the bond are first ground toremove the scale and rust and give a bright, clean con-tact surface. An electrically driven hand grinder isused for this purpose, the operation being done by oneman in about twenty minutes. A carbon mold is thenplaced around the joint and held in position by two ironclamps, care being taken that the rails are in perfectalignment. After the mold has been placed, the cracksbetween it and the rail are filled with plaster of man can place the mold and make it ready to re-ceive the molten copper in about ten minutes. Insteadof filling the cracks between the mold and the rail with plaster of Paris, alater practice hasbeen to use a sand. bon lining. As soonas the mold is ready,the copper which ismelted by a specialfurnace is pouredinto the mold, andafter it has cooledfor a few minutesthe clamps and the third-rail bonding—completed mold are copper bond Heavy lugs on each side of the bondproper are cast simultaneously with the bond itselfand are for the purpose of heating the rail sufficientlyto insure a perfect weld between the copper and therail. That this is obtained is shown by the presenceof a considerable amount of iron in the bonds thathave been removed. After the joints have cooled, theselugs and other superfluous metal are cleaned off, andthe bond is trimmed to the proper dimensions. The in-
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkmcgrawhillp
