Railway switches and signals – Block-signal systems – Automatic
Patent
1976-12-09
1977-12-27
Kunin, Stephen G.
Railway switches and signals
Block-signal systems
Automatic
246 63C, B61L 2316
Patent
active
040650812
ABSTRACT:
Alternating current track circuits are provided for the several adjoining track sections of a stretch of railway track, each of the track circuits comprising an alternating current code transmitter and an alternating current code receiver connected to track rails at opposite ends of the associated section. Circuit apparatus including an alternating current line circuit extending along the stretch of railway track is provided for normally communicating alternating current from the line circuit through rails of the associated track sections, the alternating current being modulated at a selected rate code and current in any two adjoining track sections being of opposite instantaneous polarity for broken down joint protection. Phase sensing apparatus is provided at a receiving end of each track section including a comparator for comparing the rate code modulated alternating current communicated through the track rails with a steady reference source connected to the line circuit. A system including a flip-flop circuit and a low pass filter is provided for energizing a track relay only in response to a distinctive output of the comparator indicative of proper phase relationship of the current in the associated track section.
REFERENCES:
patent: 3270199 (1966-08-01), Smith
patent: 3339067 (1967-08-01), Reich
patent: 3986691 (1976-10-01), Ehrlich et al.
Huffman Jerry P.
LaForest John P.
Petit William A.
Smith James A.
General Signal Corporation
Kunin Stephen G.
Wynn Harold S.
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