. The Street railway journal . t they may be upset while hot. These are notdeemed necessary, however, and are not generally used, as it hasbeen found sufficient to simply weld the base and web of the molds are then backed up with sand. The crucible, which is set September 30, 1905.] STREET RAILWAY JOURNAL. 573 on a tripod, is next placed over the molds, with the tapping holedirectly over the gate in the mold. A tapping rod is then placedin the hole, which is then stopped up by means of a couple of asbes-tos washers, a small iron disc, and finally a little refractory charge o
. The Street railway journal . t they may be upset while hot. These are notdeemed necessary, however, and are not generally used, as it hasbeen found sufficient to simply weld the base and web of the molds are then backed up with sand. The crucible, which is set September 30, 1905.] STREET RAILWAY JOURNAL. 573 on a tripod, is next placed over the molds, with the tapping holedirectly over the gate in the mold. A tapping rod is then placedin the hole, which is then stopped up by means of a couple of asbes-tos washers, a small iron disc, and finally a little refractory charge of thermit is then added and a little of the ignitionpowder placed on top, which is set off with an ordinary stormmatch. The reaction when once started proceeds rapidly, usuallytaking about 10 seconds, the molten mass boiling furiously. Atthe end of about 20 seconds more the boiling has ceased and theiron is separated from the slag. The crucible is then tapped andthe metal flows into the molds, followed by the slag, and in less. TAPPING CRUCIBLE than a minute the joint is made. The joint is then allowed tocool about 15 minutes before the molds are taken off. This can bedone three or four minutes after pouring, if necessary, as whenwelding while the cars are running. Two or three taps of a ham-mer will separate the slag from the joint, and the work is com-pleted, no chipping or grinding being necessary except when weld-ing old rails where the joints are battered, when, of course, therails have to be ground down to an even surface. In case thetwo rails do not come together closely, a shim of steel may be in-serted and welded in, completely filling the gap. The writer hasmade many joints in this manner with perfect success. Four men constitute a welding gang, and eighteen or twenty
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
