. Railway age . the running surface of the head and extending downwardthrough the rail. The flow of the metal under wheel pressures Is one of the mo«tImportant of the causes of fractures. Whatever may be done tostrengthen the rail in other respect?, the fact still remains thatthe load is applied on a very limited surface of contact. Thl»obstacle Is Insuperable and Imposes a limit on the size of concen-trated wheel loads. The Influences enumerated tend to develop fractures Id railsstructurally sound and with good physical properties, but It Is recog-nized that rails are not always free from str
. Railway age . the running surface of the head and extending downwardthrough the rail. The flow of the metal under wheel pressures Is one of the mo«tImportant of the causes of fractures. Whatever may be done tostrengthen the rail in other respect?, the fact still remains thatthe load is applied on a very limited surface of contact. Thl»obstacle Is Insuperable and Imposes a limit on the size of concen-trated wheel loads. The Influences enumerated tend to develop fractures Id railsstructurally sound and with good physical properties, but It Is recog-nized that rails are not always free from structural defects, althoughthey may have satisfactory tensile properties. Some of these defectsare serious and apparently have led to a considerable number offractures in recent years. It has been found In a number of railsexamined that longitudinal streaks are present in both the headand in the base, streaks of a different color from the adjacentmetal as they appear when etched with tincture of Iodine. Some of. Fig. 1—Portion of the Shop Where Tests Were from Is the old Emirv Ustiiiu machine of Ihs ..>,.... ■(„ 7/..,. ..v „ /../(,..,/ . •>. (/.. «,«, „n,m{,c,l for a lot h„ MAll! II 27, ]908. THE RAILROAD GAZETTE. 441 the streaks are several feet long, others a few inches or only a frac-tion of an incli in length. They are of different widths, from a fewhundredths of an inch to upwards of an eighth of an inch, and notinfrequently have a fine hair line or crack along the middle. are commonly short, less than an inch, and in depth pene-trating the metal but a few hundredths of an inch. They are, insome rails, quite numerous, and in planing the metal away for ex-amination new hair lines appear in succession as those first in view-are planed away. The steel fractures without elongation when rup-tured by stresses applied at right angles to the direction of thecracks. That the streaks represent lines of weakness tliere is
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Keywords: ., bookcentury1800, bookdecade1870, bookidrailwayage44, bookyear1870
