. The Street railway journal . ont half of the wheeltire which is grasping the rail so much as to tend to flattenit. The curve, therefore, corresponds to the one for thestationary wheel, except that the branch on the right hasgreater radii of curvature, hence in general it resemblesthe rolling wheel. This is confirmed by Fig. 5, whichshows even better than Fig. 4 that the material in the railhead is pushed forward by the wheel which strongly com-presses it and forces the material to rise upward. Of course between the curves given there is a series ofvariations differing in accordance to the re
. The Street railway journal . ont half of the wheeltire which is grasping the rail so much as to tend to flattenit. The curve, therefore, corresponds to the one for thestationary wheel, except that the branch on the right hasgreater radii of curvature, hence in general it resemblesthe rolling wheel. This is confirmed by Fig. 5, whichshows even better than Fig. 4 that the material in the railhead is pushed forward by the wheel which strongly com-presses it and forces the material to rise upward. Of course between the curves given there is a series ofvariations differing in accordance to the relative propor- tion of rolling and sliding, but in general all of thesecurves are similar. For the sake of simplicity only the longitudinal distor-tion has been considered, but naturally the gripping depthof the wheel depends also on the width of the contact sur-faces, for the smaller the one factor the higher must bethe other. The impression made by the wheel on the railhead is elastic and changes its position with the FIG. 4.—ROLLING WHEEL Hence the rolling of a wheel over a rail originates on thehead a progressive wave movement, or, in other words,molecular vibrations are generated both transversely andlongitudinally. The first can last but a brief time, foreven at hollow spots in the rail the wheel load tends tocrush such spots and thus break up transverse movements,while the longitudinal movements continue for a longperiod as can easily be learned by placing ones hand on therail after a car has passed. These longitudinal vibrationsare the cause of the noise made by cars on both tangent andcurved track. Although this musical side of the theory of rolling fric-tion is of little interest here, the vibrations which causethe noise must be considered and have already been re-ferred to elsewhere. Those mentioned previously, how-ever, were intended to relate to causes independent of themutual action of the metals in contact. Both result in thesame reactions in the rail a
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
