File:The Street railway journal (1902) (14574434627).jpg

Identifier: streetrailwayjo201902newy (find matches)
Title: The Street railway journal
Year: 1884 (1880s)
Authors:
Subjects: Street-railroads Electric railroads Transportation
Publisher: New York : McGraw Pub. Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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lOh 35 30 MinutesStmt OiUway J^mai IN ZOSSEN TESTS FIG. 3—SPEED, CURRENT, VOLTAGE AND POWER OF CAR car, which is assumed to be con The resistance of thestant, then becomes W = p (M + R) = 0.033 X 10,090 = 333 kg.For 1 ton of train load he then findsw = 3.6 kg. He says that this value seems small, if compared with the value calculated by one of the usual resistance formulas. From the formula mentioned before v2 Mgw = (2.5 h ) ■ 1300 IOOO he gets w = S 4 kg which is 50 per cent greater than the above value 3.6. Inthis resistance formula the figure 2.5 may be assumed to be
Text Appearing After Image:
August 2, 1902.) STREET RAILWAY JOURNAL. 149 correct, and the discrepance can only be due to the secondv- Mg term . The discrepancy may be explained when 1300 1000 one considers that the car is very heavy and that the air v2 resistance (to which the term mainly refers) depends 1300 less upon the weight than upon the volume of the car. Thevolume is the determining factor and should be taken intoaccount in calculating the resistance. It has been knownbefore that the above formula gives too high values forhigh-speed trains with heavy cars. TOTAL POWER CONSUMPTION Very careful measurements of the power consumptionwere made on the motor cars, as well as in the centralstation. The latter were more reliable, as, in the readingsof the instruments on the cars, there could be errors dueto the vibrations. In starting with an acceleration between0.1 and 0.2 meter (0.3 to 0.7 feet) per second per second,the power consumption in the car was between 400 kw or544 hp and 740 kw or 1000 hp. In runs at

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