Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc. . he latter run slower by the ratio 1 Thecar wheel is 33 inches in diameter. Assume that it requires 20 136 ELECTRIC RAILWAYS 41 pounds per ton, applied along the direction of motion, to overcomefriction. Determine with the aid of the curves the following items:(a) At what speed will
Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc. . he latter run slower by the ratio 1 Thecar wheel is 33 inches in diameter. Assume that it requires 20 136 ELECTRIC RAILWAYS 41 pounds per ton, applied along the direction of motion, to overcomefriction. Determine with the aid of the curves the following items:(a) At what speed will the car mount a 5 per cent grade? (b) Howmuch current will it draw from the line while climbing this grade? (c) How much mechanical power will each motor be developing? (d) How much electrical power will each motor be taking (thevoltage for which the speed curve was derived is 500) ? (e) Whatis the efficiency of the motors? Solution, (a) and (b). In Fig. 46 is represented the car onthe grade. To pull it up the grade will require a force made up oftwo components, (1) that required to overcome friction; and (2)that required to lift the car. The former is 20 pounds per ton, or400 pounds. The latter is 5 per cent* of the weight of the car, or2,000 pounds. The total force required is 2,400 pounds, which is. Fig. 46. Diagram of Car on Grade independent of the speed, the friction being assumed force is produced by two motors, hence each must produceone-half. To use the curves requires the transfer of this force toterms of torque. Each motor must deliver at the wheel tread atractive effort of 1,200 pounds. This means an axle torque of 16 5r=-— Xl,200 = 1,650 pound-feet or pounds at 1 foot radius. The motor torque is less than this—as the motor shaft runs faster than the car axle by the ratio of thenumber of gear teeth to pinion teeth — by the gear ratio. Or *For convenience it is to define the per cent grade of a track as the ratio ofthe lift to the dista
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Keywords: ., bookauthoramericantechnicalsoci, bookcentury1900, bookdecade1910
