. Railway mechanical engineer . design a bolster, it is essential not only to know the maxi-mum reaction to which it will be subjected, but also to knowwhat per cent of tliis reaction will be due to vertical oscil-lation. If the reaction at each end of the bolster were re-corded simultaneously, then it would be possible to deter-mine the exact relation between the vertical oscillation andthe horizontal force, both as regards the amount and alsothe time of action, but until such experimental data is ob-tained, it is necessary to assume some such relation. Sincethe system of loading which deals
. Railway mechanical engineer . design a bolster, it is essential not only to know the maxi-mum reaction to which it will be subjected, but also to knowwhat per cent of tliis reaction will be due to vertical oscil-lation. If the reaction at each end of the bolster were re-corded simultaneously, then it would be possible to deter-mine the exact relation between the vertical oscillation andthe horizontal force, both as regards the amount and alsothe time of action, but until such experimental data is ob-tained, it is necessary to assume some such relation. Sincethe system of loading which deals with a comljination ofcenter plate load of 7o,000 lb. and a horizontal force equalto of the center plate load or 29,000 lb., acting throughan arm of 46 in., sets up reactions which approximate thoseof Prof. Endsleys experiments, we have, in view of thisfact, constructed section modulus diagram. Fig. 10, whichis the same general type as Fig. 9. In determining the sec-tion moduli, the values for the bending moments of Fig. .^. Fig. 12—Bending IVIoment Diagram Shown at 9, Fig. 5 were used and diagrams developed for the three side bear-ing spacings, the numbers 9, 10, 11 referring to the bendingmoment curves of Fig. S of the same number. As was the case in constructing the diagrams of Fig. 9,which were based upon an assumed iibre stress which wouldprovide for a section modulus at the center of the bolsterapproximating the same as that obtained by use of the for-mula used in plotting diagram 8, a tibre stress was assumedin order to plot 9, 10 and 11 of Fig. 10. It was found that with a tibre stress of 14,000 lb. per sq. in., the sectionmoduli at the center of the bolster were , for the three side bearing spacings as compared by the formula in which a 12,500 lb. stress was reaction for the subjected to the combined action)f a direct center plate load of 7,5,000 lb. and a horizontalforce equal in amount to of this load and whose
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
