Railway switches and signals – Electric automatic highway signals – mine doors – and gates – Normally closed track circuit
Patent
1979-08-17
1982-12-28
Groody, James J.
Railway switches and signals
Electric automatic highway signals, mine doors, and gates
Normally closed track circuit
246 34CT, 246125, 246128, 307260, 324 76R, 330107, B61L 102, B61L 112, B61L 2106
Patent
active
043657770
ABSTRACT:
A train approach detector uses frequencies in the audio spectrum to activate grade crossing protection devices in advance of and during the presence of railroad trains at grade crossings. The detector is completely solid state, and includes one transmitter and one receiver each connected to the tracks so that transmitted and received track signals, which are partially pulse modulated for optimum filtering and signal coupling and minimum third harmonic radiation, appear on opposite sides of the crossing. The section of track between the transmitter and receiver is designated as a crossing island and sections of rail outside of the island are known as approaches. In addition to its basic train movement detection function, the detector contains additional features that are designed to provide operation under a variety of application conditions, including automatic ballast compensation, loss of shunt, low signal/low gain condition, high signal/broken rail condition, delayed pick-up, delayed drop-out and reverse switch override, and bi-directional motion detection.
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Groody James J.
Modern Industries Signal Equipment, Inc.
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