. The Street railway journal . .—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 carri
. The Street railway journal . .—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 the correspondingly long lateral move-. FIG. 10.—M. C. B. ARRANGEMENT OF LINKS AND SPRINGPLANK ment results in the bolster striking the side frames, unlessexcessive space is allowed at the ends for clearance. To obtain at the same time the advantage of the slowswing of the long link and the short travel of the shortone the plan shown in Fig. 10 is used of spreading the linksfurther apart at the bottom than at the .top. The advan-tages of this arrangement are double. First, as the pin b ofthe link on the end toward which the swing takes place willrise farther for a given lateral displacement than that of thelink at the other end will fall. Second, shorter lateral dis-placement is necessary to raise the car far enough to 520 STREET RAILWAY JOURNAL. [Vol. XX. No. 14. counter-balance the displacing force, and this is accom-plished without the quick, jerky motion that results fromthe use of short links. Third, the link toward which theswing takes place raises its side of the car, and thus tendsto
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
