. The Street railway journal . 20 FIG. 60 80 100 120 COMMERCIAL, H. P. RATING OF MOTOR -MOTOR CAPACITY, 60 DEGS. C. RISE (FRICTIONCURVE A) 200 values at this high maximum speed, the degree of error cannotbe determined and in any case should not exceed more than apossible maximum of 15 per cent. Figs. 7 and 8 are plotted for60 degs. also, but using friction curves B and C, so that bymeans of Figs. 6, 7 and 8 it is possible to determine the capacityof motor required for any maximum speed and any weight oftrain; while from Figs. 2, 3 and 4 the possible schedule speedand energy consumption can
. The Street railway journal . 20 FIG. 60 80 100 120 COMMERCIAL, H. P. RATING OF MOTOR -MOTOR CAPACITY, 60 DEGS. C. RISE (FRICTIONCURVE A) 200 values at this high maximum speed, the degree of error cannotbe determined and in any case should not exceed more than apossible maximum of 15 per cent. Figs. 7 and 8 are plotted for60 degs. also, but using friction curves B and C, so that bymeans of Figs. 6, 7 and 8 it is possible to determine the capacityof motor required for any maximum speed and any weight oftrain; while from Figs. 2, 3 and 4 the possible schedule speedand energy consumption can be obtained for any maximum I s I 3 3 M. 4 5 M 60 - 75 .H. 1 ! 60 SO 1C0 120 140 COMMERCIAL H. P. RATING OF MOTOR FIG 7—MOTOR CAPACITY, GO DEGS. C. RISE (FRICTIONCURVE B). 100 120 140 OF MOTOR -MOTOR CAPACITY, 60 DEGS. C. RISE (FRICTIONCURVE C) miles to five stops per mile. It is thus sufficient to associate agiven motor and gear ratio with a definite car weight which itcan operate with a given temperature rise, and with anyschedule speed which the number of stops per mile will at once affords a means of comparing motors of differentcapacity by means of the tons per motor which is permittedfor, say, 60 degs. rise and a given maximum speed presenting the curves in Fig. 6, the results of a large num-ber of experiments and calculations are incorporated on motorsof similar design, giving the relation between the commercialone-hour rating of the motor and the number of tons which thatmotor will carry at maximum speeds of 30 m. p. h., 4^ m. p. m. p. h. and 75 m. p. h. The curves of 30 m. p. h. and 45m. p. h. arc probably accurate, those at 60 m. p. h. may be opento the criticism of being conservative, and at 75 m. p. h.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
