. Electric railway journal . onds and brakes to standstill at80 seconds. The time of coasting is so chosen that thedistance traveled and time consumed are the same as inFig. r. The broken lines in Fig. 2 show the outlines ofthe principal curves of Fig. 1, and it is at once evident thatthe power consumption has been greatly reduced. The track and bearing friction area has, of course, beeneliminated, rheostat losses are slightly reduced due toquicker acceleration; motor losses and windage are bothmaterially reduced on account of the shorter time whichpower is supplied at high speed, and power fo
. Electric railway journal . onds and brakes to standstill at80 seconds. The time of coasting is so chosen that thedistance traveled and time consumed are the same as inFig. r. The broken lines in Fig. 2 show the outlines ofthe principal curves of Fig. 1, and it is at once evident thatthe power consumption has been greatly reduced. The track and bearing friction area has, of course, beeneliminated, rheostat losses are slightly reduced due toquicker acceleration; motor losses and windage are bothmaterially reduced on account of the shorter time whichpower is supplied at high speed, and power for accelerationis reduced most of all on account of the lower speedreached. This latter quantity is reduced as the square ofthe speed. The results are given in Table II, comparedwith the results from Fig. 1 : TABLE II. , Watt-hours. ^ Reduction. Fig. 1. Fig. 2. Percent. Rheostat losses 157 136 Motor losses j. 285 195 Track and bearing friction 158 0 Windage 57 29 Acceleration 993 83J 1,650 1,195 Ily. J», Fig. 2—Energy Consumption of 41-Ton Car, ExcludingTrack and Bearing Friction It thus appears that by eliminating a friction consumingonly per cent of the power supplied we can effect asaving of per cent in power required. This result isobtained in a case which was purposely chosen as repre-senting an extreme case of frequent-stop service, in whichthe possible saving due to reducing bearing friction is theleast. A further study of the curves of Figs. 1 and 2 will ex-plain the above apparently anomalous result. In Fig. 1 the areas F and G show the energy expendedin windage and track and bearing friction after power isshut off, and area H shows the energy dissipated in brak-ing. It is interesting to observe that this latter reachesthe formidable figure of 370 kw. The energy representedby the curves F and G has to be supplied from that storedup in the car during acceleration. This causes the slopeof the speed-lime curve during the coastin
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