. Electric railway review . orcracked wheels, to say nothing of irregular control of trains? Would it not be better to call for a modification in the fric-tional properties of the composition-filled shoe, because thereappears to be ample retardation secured with the cast-iron-bodied shoes of everyday practice in switching and servicework? In emergency stops at high speeds there may appearsome merit in the shoes of high frictional qualities as com-pared with cast-iron shoes in freight service; but will notthe cast iron wheels suffer here also? We have yet to hearof any complaints against the sh
. Electric railway review . orcracked wheels, to say nothing of irregular control of trains? Would it not be better to call for a modification in the fric-tional properties of the composition-filled shoe, because thereappears to be ample retardation secured with the cast-iron-bodied shoes of everyday practice in switching and servicework? In emergency stops at high speeds there may appearsome merit in the shoes of high frictional qualities as com-pared with cast-iron shoes in freight service; but will notthe cast iron wheels suffer here also? We have yet to hearof any complaints against the shoes of cast iron on the scoreof holding qualities, and a change in brakeshoe practice atthe expense of the wheel is poor economy. Fig. 2 shows graphically the results of brakeshoe testson steel-tired wheels; all the shoes tested fully meeting thespecified mean coefficient friction, as in Fig. 1. It will beseen that there is a wide variation in the retarding effect ofthe various shoes. The shoe in general use on steel-tired. aaOS 4-J50 6B40 /.cad on S/7oe. ir? PoundsFig. 1—The M. C. B. Brakeshoe Tests of 1906. wheels in passenger equipment, engine truck and tenders, arethe plain cast iron, the Diamond S, the U and the Streeter,all of which with the increase of load tend towards a commoncoefficient of friction at some point around 12;000 appears also that the Pittsburg shoe with the composi-tion filling tends to follow the general inclination and fallsrapidly in frictional effect with increase in the rate of heat-ing. Note the record of the 1905 report, shown by dottedline, also the record of the Diamond S shoe, of the 1905brakeshoe report, and the general trend of the curves to ameeting-point at about 12,000 pounds load, a condition notuncommon in the case of high-speed brake in heavy passen-ger service. It does not appear advisable to revise thespecification for the steel-tired wheel, at least the minimumlimit, for there is an urgent call for more life to the shoes,
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectstreetr, bookyear1906
