With apologies in advance to electrical engineers who may read this, the Interurban ran on electricity. More specifically, it ran on direct current.
The power to weight ratio measures the power output generated by a system as it relates to the weight of the vehicle. The power to weight ratio is greater for electric trains is greater than that of steam or diesel trains, primarily because electric trains are not required to carry fuel as the other trains must do. Because its weight is less as it relates to the power of the motor, the acceleration of an electric train is better. Typically, streetcars in the US run on 600 to 750 volts of power. In the early to mid 1900s the industry standard was 600 volts. The Texas Electric Railway trains ran on 1200 volts on their longer runs, such as Dallas to Waco and 600 volts in the urban areas.
Electricity was supplied to the Interurban cars via overhead trolley wires that the cars touched by means of a trolley pole or pantograph. There was a trolley pole at each end of each car. Contemporary systems instead use an electrified third rail rather than the pantograph.
Current was supplied by converter stations placed 8 to 10 miles apart for a 600 volt line. Twice that distance could be used for a 1200 volt line. The overhead copper cables were thick in order to reduce the resistance as the current traveled through the line. The trolley wire made contact with the cable by touching it and was kept in contact by being spring loaded. There was a pantograph at each end of each car. The current was delivered to the wheel assembly containing the electric motors which propelled the cars. The circuit was completed as the current traveled from the cable, through the cars and finally to the rails. It would be considered an environmentally friendly system today, although the rotary converters in the converter stations gave off a considerable amount of heat. Though the cars themselves had no air conditioning system during the hot Texas summers, they were fitted with electric heaters in the winter.
Though the system has been updated, contemporary electric rail systems daily use all over the world still function according the same basic technological principles, though considerably refined.
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