. A manual of the principles and practice of road-making : comprising the location, consruction, and improvement of roads (common, macadam, paved, plank, etc.) and railroads . For these longitudinalbearings, chairs are un-necessary, and peculiarlyshaped rails are favorite form is thatshown in Fig. 136, whichhas been made to weighfrom 35 to 60 lbs. per is fastened by screws, 4 inches long, the heads of whichare countersunk on the inner side, so as to be out of theway of the flange of the wheel. At the joints, four screwsare employed. Sometimes the rails are fastened by spik
. A manual of the principles and practice of road-making : comprising the location, consruction, and improvement of roads (common, macadam, paved, plank, etc.) and railroads . For these longitudinalbearings, chairs are un-necessary, and peculiarlyshaped rails are favorite form is thatshown in Fig. 136, whichhas been made to weighfrom 35 to 60 lbs. per is fastened by screws, 4 inches long, the heads of whichare countersunk on the inner side, so as to be out of theway of the flange of the wheel. At the joints, four screwsare employed. Sometimes the rails are fastened by spikes with bentheads, driven just outside of them, and clasping themirmly. The greater difficulty of packing the gravel around CONTINUOUS SUPPORT. 307. such longitudinal sleepers, and of removing and replacingthem, is the chief cause of the general preference of cross-ties, or transverse sleepers. Triangular sleepers have Fig. 137. been employed, with a railforked at bottom, as in thefigure. The rail can thusbe very firmly attached tothe sleeper, the shape ofwhich gives it much sta- ■<<<$$$;bility. Evans method of fastening is warmly recommended byProfessor Vignoles. The rails are rolled with a slit, orgroove, of a dove-tailed shape, (in its cross-section) run-ning on their under side for their whole length. The boltshave heads of corresponding shape, and are slipped intothe end of the groove, passed along it, and dropped throughholes made at proper intervals in the longitudinal lower ends of the bolts are cut into screws, andwashers and nuts draw the rails close down to the tim-bers. They are easily tightened, and not exposed to in-jury, while spikes and screws get loose, and their headsare in the way. Upon th
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectrailroa, bookyear1853
