File:The Street railway journal (1906) (14572342079).jpg

Identifier:streetrailwayj271906newy (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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SING OVER TREADLE divided up into sections to correspond with the sectionscontrolled by each signal. Simple direct-working relaysare placed across the track rails at one end of eachsection, and the current is fed in at the opposite endof each section, at a pressure varying from 3 volts to 7volts. This current is supplied from a 100-volt generator,and the pressure is reduced by lamp resistances between the100-volt main and the track rails. To guard against anyirregular operation of the track relays by stray currents, a nal to the section or sections in the rear. That is, the func-tion of the track relay is to drop its armature, putting thesignal to danger by opening the local signalling circuit whenany pair of wheels enters the section it controls. Once thesignal has gone to danger, it remains locked there by a stopwhich falls into place by gravity, and can only be removedwhen the train has passed the corresponding treadle in ad-vance. It will be observed that should a train become de-
Text Appearing After Image:
SWITCH AND BOLT LOCK DETECTORS railed, or divided and leave a portion behind—a remote pos-sibility on modern electric railways with air brakes runningfrom end to end of the train—or should a single car be de-railed in such manner that its wheels are free of the run-ning rails, and the track relay being thus clear, the treadlecontrol would still be there to protect the block, and pro-vide an additional safeguard. The diagram shows a train which, having entered a section,has placed the starter at danger, and the train treadle brush 3<M STREET RAILWAY JOURNAL. (Vol. XXVII. No. 9. in the act of clearing the lock on inner home signal in therear. All the signals drop to danger should the 100-volt cir-cuit fail. If the 500-volt circuit should fail, the passing ofthe train over a treadle will not energize the treadle, and,consequently, although the signal drops to red immediatelybehind the train, as it should, the signal controlling the sec-tion further in the rear also remains at red.

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