. Electric railway journal . ter of the grades. We have taken the characteristiccurves of a standard 35-hp railway motor having an arm-ature speed of 575 when taking a current equal toits one-hour rating and have corrected these curves for gearratios of 1 . and 1 , assuming the diameter of thedriving wheels as 30 in. (750 mm) and the average voltageat the motor terminals as 500 volts. From these curves,shown in Fig. 1, we have worked out the speed-time andcurrent curves shown in Fig. 2 for runs on level tangenttrack at a schedule speed of 13 km per hour. Curve 1, Fig. 2, is the
. Electric railway journal . ter of the grades. We have taken the characteristiccurves of a standard 35-hp railway motor having an arm-ature speed of 575 when taking a current equal toits one-hour rating and have corrected these curves for gearratios of 1 . and 1 , assuming the diameter of thedriving wheels as 30 in. (750 mm) and the average voltageat the motor terminals as 500 volts. From these curves,shown in Fig. 1, we have worked out the speed-time andcurrent curves shown in Fig. 2 for runs on level tangenttrack at a schedule speed of 13 km per hour. Curve 1, Fig. 2, is the speed-time curve for a train with1 gearing running 300 m (984 ft.). Curve 2 is for atrain with 1 gearing running 300 m and curve 3 is fora train with 1 gearing running 400 m (1312 ft.).Curve 4 shows the current taken per motor with 1 gear-ing and curve 5 the current per motor with 1 gearing. Lb. Tractive Effort ^ - - j« Effort S Kilometers per Hour bpeed O M CO CD O W Miles per Hour Speed. Eer trie Hi/- Journal Fig. 1—Speed and Tractive Effort Curves for Two Gear Ratios These curves are calculated for the conditions shown inthe accompanying table. Curve 2 shows that a train equipped with the 1 gear-ing can make a schedule speed of 13 km an hour with atwenty-second stop every 300 meters and still have a rea-sonable margin for making up lost time, as the coasting- time for this run is 28 per cent of the total tune consumed. By comparing curves 4 and 5 it is found that the accelera-ting current per motor is 71 amp with 1 gearing, and 62amp with 1 gearing, and that the average current permotor for a run of 300 m, including stop, is amp withi gearing and amp with 1 gearing. The low- Specd-Time and Current CurvesCurves 1 & itov a Run of 303 Meters with 1:5,1 Gear RatioCurves 2 4 5 Cor a Run oi 300 Meters with 1:6,25 Gear RatioCurve 3 for a Run oi 400 Meters with 1:6,25 Gear Ratio
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