. Railway mechanical engineer . hub aroundthe crosshead pin. The same weakness developed in cross-heads of similar general design among locomotives of threeor four different classes. The defects which proved commonto these different crossheads are shown in Fig. 2. By breaking up these crossheads in order to investigate the nature of the metal, it was found that in most cases eachfracture had its origin in a shrinkage crack. The metal inmost of the broken crossheads was found to be porous and tocontain blowholes or gas holes, or shrinkage cracks, coldshuts or pipes. In some cases all of these d
. Railway mechanical engineer . hub aroundthe crosshead pin. The same weakness developed in cross-heads of similar general design among locomotives of threeor four different classes. The defects which proved commonto these different crossheads are shown in Fig. 2. By breaking up these crossheads in order to investigate the nature of the metal, it was found that in most cases eachfracture had its origin in a shrinkage crack. The metal inmost of the broken crossheads was found to be porous and tocontain blowholes or gas holes, or shrinkage cracks, coldshuts or pipes. In some cases all of these defects werepresent. Fig. 2 shows very clearly the difference in cross-section ofthe metal at and near the break. This difference is no doubtlargely responsible for the defects in the metal which havecaused an epidemic of failures. Crossheads of this generaldesign have been used for many years, and as it appearsimpossible to modify the shape to advantage, the question,then, is whether foundries can adjust their practices to cast. PaH-iallij Hidden hrinkage Crack CcldShui Fig. 2—Location and Nature of Defects In a Poorly Cast Crosshead such irregular sections without blowholes, shrinkage cracksand other defects. This is one of the opportunities for manu-facturers of material to co-operate with the locomotivedesigner. Driving Wheels Another irregular section which causes shrinkage cracks isthe cast-steel driving-wheel center. Rims and spokes are ofmuch lighter section than the hub and counterbalance, andshrinkage cracks are not unusual at the juncture of theselight and heavy sections. Foundries which cast locomotiveparts have these conditions to meet and it is believed thatfoundry practices can be adjusted to meet them. Crosshead Pins In the development of locomotive construction within re-cent years the union link of outside valve gears has beenconnected direct to the crosshead pin. This reduces weightby eliminating the crosshead arm and by shortening thelength of the combinati
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
