. Electric railway journal . 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 wit
. Electric railway journal . 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. < a m 00 3050 2540 20M 1520 1010 / : _J I I \ 1 I i i_L i L 0 t0 JO 100 Electrx Ey- Journal Fig. 2—Speed-Time and Current Curves with Two Gear Ratios speed gearing thus shows a saving in energy consumptionbesides greatly reducing the temperature of the advantage will be much more pronounced with theshort runs and low schedule speed of the city service andwill also prove of far greater advantage on the long, steepgrades. The most common error in the selection of gearing hasbeen to gear for high speed when the service gave noopportunity for using it to advantage. This improperselection of gear ratios alone has caused a loss of hundredsof thousands of dollars due to overloads and consequent Weight of train, including equipment and live load 19 tons Average motor voltage 500 volts Length of run 300 m and 400 m Length of stop 2(1 seconds Schedule of speed 13 kw ( miles) per hour Initial acceleration kw miles) per hour per second Braki
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkmcgrawhillp
