OF THE FRANKLIN INSTITUTE OF THE State of Pennsylvania, AND AMERICAN REPERTORY OF MECHANICAL AND PHYSICAL SCIENCE, AND OF AMERICAN AND OTHER PATENTED INVENTIONS. EDITED BY THOMAS P. JONES, M. D., Mem of the Am. Philos. Soc.; of the Acad. of Nat. Sci., Philad.; the Am. Acad. of Arts and Sci., Mass. PUBLISHED BY THE FRANKLIN INSTITUTE, AT THEIR HALL. 1843 JOURNAL OF THE FRANKLIN INSTITUTE OF THE State of Pennsylvania, AND AMERICAN REPERTORY. JULY, 1843. Civil Engineering. FOR THE JOURNAL OF THE FRANKLIN INSTITUTE. On Cast and Rolled Iron Rails for Railways. By JOHN C. TRAUTWINE, Civil Engineer and Architect. Although this subject has recently been much discussed, it does not appear to me that all the facts bearing upon it have been taken into consideration; or that all those which have been examined, have received that degree of attention which is requisite to a satisfactory solution of the question, which of these two materials is the more eligible for common railroad purposes? It is not my intention here to enter upon an examination of all the various points of inquiry necessarily involved in a detailed investigation of this important question; but merely to draw attention to one or two matters connected with it, which have, as I conceive, either been overlooked by those who have hitherto had the subject under consideration, or have been deemed by them of less moment than I suppose them to be. It is my opinion that injury has resulted from the fact that those gentlemen who have been most active in discussing the question, have, in too unqualified a manner, expressed themselves in favor of one material, or the other, as preferable in all cases, to the entire exclusion of the other: or, in other words, I conceive the question to be not an abstract one, but one dependent upon contingent circumstances, by which it becomes so modified as to render the one material preferable, in some cases; and the other, in others. I have myself recommended the adoption of a heavy cast-iron U-rail, on a VOL. VI, 3RD SERIES.-No. 1.-JULY, 1843. 1 railroad nearly one hundred miles in length, under my charge, from considerations of economy of original outlay, which attended that particular instance, and which happened to be, in that case, one of vital importance; combined with the peculiar difficulty that would necessarily be encountered in fabricating a rolled rail, in a section of country where it would be nearly impossible to obtain, or rather to retain, a sufficient number of experienced workmen for conducting an extensive rolling establishment uninterruptedly. Those who have embarked in such undertakings, under similar circumstances, can testify from experience how much importance is to be attached to this consideration. Added to these reasons, it was my intention to employ engines with much less weight upon their drivers than is usual on most of our railroads; a point which, as I hope to show further on, has much to do in deciding the question of a choice between cast and rolled rails. Those who advocate the future rejection of rolled rails "in toto," and the consequent adoption of cast-iron, urge, as the chief argument in support of their views, the splitting, or lamination, as it is more generally termed, which experience has shown to take place, to a very serious extent, in the rolled rails used on all our railroads. Instead of lasting from forty, to one hundred years, which was the term of duration originally predicted for the rolled rail, the supposition being based upon the probable rate of wear, or diminution of material, as deduced from some limited experiments, it has, in fact, on most of our roads doing a heavy business, needed partial replacements within some six or eight years, with a prospect of requiring much more extensive renewals within a few years more. I conceive, however, that this defect in the rolled rail is not one inherent in the nature of the material, but one admitting of remedies of easy application; and I will proceed to point out in what particulars I think changes should be made in the manufacture of the rolled rail, in order to diminish, if not entirely to remove, its liability to split. In the manufacture of this rail, as is well known, the process of piling is necessarily employed; that is, a number of short, flat, pieces of iron are piled on top of each other, and the pile is placed in a heating furnace, where it is subjected to a temperature sufficient to bring the several pieces of which it is composed, to the welding point. When the pile has attained this point, it is withdrawn from the furnace, and, without loss of time, is rapidly passed through the successive rolls, by which its pieces are at the same time welded together, elongated, and shaped to the required section of the rail. But, from want of proper attention on the part of the workmen, the pile is occasionally taken from the furnace before it has reached the welding point; and the consequence is, that the process of rolling does not always unite, or weld together, the several pieces into one mass, so effectually as is necessary for a good rail; and we therefore see that the weight of the engines afterwards separates them, or splits the rail. I say the weight of the engines, because I am perfectly convinced, from close observation, that it is the great weight borne by their driving wheels, that does most of the injury. I have seen comparatively very little of this lamination in either edge-rails, or the common flat-bar, of an inch thick, where horses are used for the motive power, drawing cars having no greater loads than 11⁄2 tons to a wheel; on the contrary, I have seen the five-eighths flat-bar laid even immediately upon continuous granite sills, (on which the splitting is more apt to occur than in any other situation,) which have for nearly ten years endured the passage of a very heavy traffic, not drawn by locomotives, without the splitting of a single bar; while the edge-rails on the adjoining parts of the road, over which precisely the same transportation has passed, drawn by locomotives, are split to a very serious extent. Fig. 2. During a personal examination of most of the railroads in the United States, this matter has, among others, received my close attention; and I feel confident that this lamination may be almost, if not entirely, prevented; 1st, (and principally,) by more care in the application of the welding heat;-2d, by so passing the pile through the rolls, that the finished rail shall always consist of laminæ lying parallel to the top and bottom of the rail, as in fig. 1, instead of perpendicular Fig. 1. to them, as in fig. 2; and, 3d, by rounding off more boldly the edges of the upper table, or top of the rail. Of the first precaution, we have already spoken. As to the second, it appears to me that the arrangement of the lamina indicated in the first figure, must, for reasons too evident to require explanation, present more resistance to splitting (though probably less to exfoliation) than that exhibited in the second figure; and this supposition is sustained by the fact, that the splitting does almost invariably occur in lines approaching to the vertical. From this fact, the deduction very naturally follows, that a different disposition of the lamina would produce a different result; and it is perhaps owing, in a great measure, to the frequent occurrence (probably accidental) of a horizontal disposition of them, that we have not much more splitting than actually does occur. I have, it is true, in some rare instances, seen splitting occur in lines forming nearly a semi-circle, transversely of the rail; but these, I am inclined to believe, may be fairly ascribed to a very bad condition of the welding. The necessity of the third precaution, or that of giving a bolder curvature to the upper edges of the rails, has also been impressed upon me by extensive observation. It is plain that a great weight acting on a rail, the edges of whose top table are comparatively sharp, as in this figure, (3,) has a tendency to split them off; and when it happens, as it frequently does, that the line of welding of two of the original pieces of the pile lies near either of these edges, experience has shown that, if the welding be at all defective, such a splitting actually does take place. Fig. 3. |