. The Street railway journal . bars constituting the frame are subjected to tensileand compressive strains only. It is evident from the abovethat the form of frame shown as B in Fig. 9 is not suitablefor the high accelerations and quick stops which are therule in interurban work. It was assumed above for the purpose of argument, thatthe swinging bolster was an essential feature in the designof a successful high-speed truck. It is not likely that any- one in the present time will question the assumption; stillit is desirable to examine the principles of its action. shows usual swing moti
. The Street railway journal . bars constituting the frame are subjected to tensileand compressive strains only. It is evident from the abovethat the form of frame shown as B in Fig. 9 is not suitablefor the high accelerations and quick stops which are therule in interurban work. It was assumed above for the purpose of argument, thatthe swinging bolster was an essential feature in the designof a successful high-speed truck. It is not likely that any- one in the present time will question the assumption; stillit is desirable to examine the principles of its action. shows usual swing motion and the principles demon-strated from it will apply to all others. The bolster, con-fined m the direction of locomotion between the transoms,is supported on the spring plank, and with it free to movelaterally. Lateral movement is permitted the spring plankby the swing of the links d, d, which support it, pivotedto the transoms at a, a, and to the spring plank at b, is the function of this swinging support to accomplish. FIG. 9.—TYPES OF M. C. B. FRAMES the same result in the horizontal plane that the springs doin the vertical, namely, to enable the body to conform to theirregularities and curvatures of the track more graduallythan do the wheels and truck frame. From inspection of Fig. 10 it is evident that the swingingmechanism is practically a double pendulum, and will con-form to its law, or the greater the length a, b, of the links,the slower will it swing. Again it is evident that when thebolster swings either way from the central position, it, to-gether with the car body it carries, is actually raised, andwhen the force required to raise the body equals the forcewhich swings it from its central position, the lateral move-ment will stop. If the links are made very short a veryshort lateral movement is required to raise the body suffi-ciently to offset the force tending to push it sideways, andthe swinging motion becomes quick and jerky. If thelinks are very long t
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
