File:The Street railway journal (1899) (14572695527).jpg

Identifier: streetrailwayjo151899newy (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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on theplatforms. The cars are alsowired for conductors signal,with buzzers on each plat-form and push buttons in thewindow pilasters. The weight of the car bodyis 9000 lbs., and it will be mounted on Moore electric trucks with9-ft. wheel base, equipped with Price power brakes. A Resistance Detector The accompanying diagram shows a differential resistance de-tector recently invented by John C. Henry, of Denver, Col., fordetermining slight differences of resistance. Fig. i shows its ap-plication to track joint testing. The indicating needle is normallyheld at zero by a permanent magnet. One-half an amp. is takenthrough the instrument from trolley to ground. This current di-vides between the solenoidal coils within the instrument, de-pending upon the resistance of the joint which is being measured,and moves the needle proportionately. The coil surrounding thepermanent magnet is placed in shunt with the rail, the spaces de-pending upon the weight of the rail, and it is intended to balance
Text Appearing After Image:
RESISTANCE DETECTOR the variation in the resistance of the joint, which is caused by fluc-tuations of the current. For other purposes, when it is desired tocompensate for drop in voltage, the coil can be connected in shuntwith one of the lamps. Where the tests are made at night, whenthe cars are not running, the compensating coil need not be used.Where there are two bonds, one of which is in good conditionand the other not, or where the current can be shunted aroundthe bond through a cross connection, the instrument, of course,would not show the defect, but this is also true of most other de-tectors. Fig. 2 shows the connections used to compare the relative con-ductivity of the track and water mains. In this case the deflectionof the needle also indicates the direction of any current and volt-age between the conductors. Fig. 3 shows the method of usingthe instrument to test controller connections. In this case thecontroller is then turned a notch at a time, and the indicationsnoted on

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