Brake Tests

180 390. The load on the tender was observed for each test, and due allowance was made for this in calculating the per cent, braking power based on the actual brake cylinder pressure obtained for the entire train. Comparison of Individual Stops at Actual Per Cent, of BRAKING Power. 391. Figs. 101 to 108 show the length of all the emergency stops made with the various air brake equipments, plotted against the corre- sponding actual percentage of braking power realized in each test. 392. The stops obtained with the locomotive from speeds of 30, 60 and 80 m.p.h. are shown in Fig. 109. These stops are the results from the breakaway tests and from the tests made with the locomotive only. 393. The decrease in stop with the increase in braking power pro- vided by the by-pass valve feature is pronounced at 60 and 80 m.p.h. speeds. The weight of the locomotive and tender varied from 195 to 220 tons on these tests. 394. From the records of all the comparative tests, curves have been drawn through the average of points so plotted. These curves mdicate the effect on the length of the stop of a change in percentage of braking power. 395. Figs. 110 to 112 show curves of the train stops which may be expected from various speeds with electro-pneumatic equipment, with the standard single shoe, No. 1 and No. 2 clasp brakes. These curves are drawn for a braking power on the cars of 90, 125, 150 and 180 per cent. For a given weight of locomotive and tender the braking power is assumed to be constant regardless of the braking power of the cars (Par. 322), and therefore, in making up these curves the loco- motive and tender are taken as half loaded and for the various per- centages of braking power of the cars the corresponding braking power on the train as a whole is computed. Using this braking power the corresponding stop is taken from the curves shown in Fig. 104. 396. Fig. 114 shows the stops which may be expected with standard (single shoe) brake and flange shoes and has been made up from the curves in Fig. 108. 397. The curves shown for train stops from various speeds with the No. 3 clasp brake (Fig. 113), have been derived from the single car stops by assuming that the same ratio exists between the single car and train stops with the No. 3 clasp brake as was found to exist between the single car and train stops of the No. 2 clasp brake. Comparison of Stops, No. 2 AND No. 3 Clasp Brakes. 398. In Fig. 115 curves have been plotted from the data of all single car breakaway stops made from 60 m.p.h. with the various percentages of braking power employed. The solid lines represent the fairest