. The street railway review . they maydeteriorate by exposure to the atmosphere. The ironclad porcelaininsulator is strong, durable and cheap. There can be no hesitationabout its use. The insulators should be vertical, so that they maynot ofifer the chance for the accumulation of dirt, which can easilyhappen with one horizontally placed. Assuming a vertical ironclad porcelain insulator, the method of May 15, 1901.] STREET RAILWAY REVIEW. 285 attaching it to the conduit construction becomes important, thedepth of the tube being somewhat dependent upon this. For thesake of simphcity they should
. The street railway review . they maydeteriorate by exposure to the atmosphere. The ironclad porcelaininsulator is strong, durable and cheap. There can be no hesitationabout its use. The insulators should be vertical, so that they maynot ofifer the chance for the accumulation of dirt, which can easilyhappen with one horizontally placed. Assuming a vertical ironclad porcelain insulator, the method of May 15, 1901.] STREET RAILWAY REVIEW. 285 attaching it to the conduit construction becomes important, thedepth of the tube being somewhat dependent upon this. For thesake of simphcity they should be fastened to the metallic structure,which has the further advantage of keeping the conductor-bars atthe same distance from the wheel-rails, except in the special caseof a center-slot conduit where the yoke construction does notpermit the carrying of the wheel rails. The extreme positions ofthe insulators are, first, with the upper surface of the insulator asnear the street surface as it can be for mechanical protection, and. secondly, with the upper surface of the cast-iron insulator coverbolted directly to the bottom flange of the slot-rail. If the insulators are carried close to the street level they mustbe protected by metallic covers, which in Europe are consideredobjectionable, and in some cases they are absolutely forbidden bythe authorities, as in Paris. Therefore, the second method is theonly one that can be used in such cases. Perhaps it should be saidthat the insulators are protected by metallic covers in the secondcase; but these are paved over, so that the street surface is in noway altered in appearance by their use. The limiting conduit depth is often a vitally important matteron account of the crossing of immovable sub-surface construc-tions. The conductor-bar carrying height is arrived at by addingthe depth of yoke-seat and the air-gap to the height of is possible that the height so arrived at will not give thenecessary distance for a vertically h
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
