Abstract: The system provides a railroad switch for use in un-signaled (dark) territory. In particular, the system includes a plurality of audio messages maintained on a discrete audio board, where a DTMF signal is validated, initializes the control of a switch, and triggers an audio board to report a correspondence condition, where the output of the audio board is checked by a relay status.

Abstract: A device for detecting an occupied or available status of a track segment has a transmitter for feeding in a transmitted signal into the travel rails of the track segment and at least one receiver for receiving a received signal generated by transmitting the transmitted signal via the travel rails of the track segment. In order to simplify commissioning, the device is implemented for varying the frequency of the transmitted signal, for determining a resonant frequency of the transmitted signal, and for adjusting the frequency of the transmitted signal to the determined resonant frequency. A method for operating the device for detecting the occupied or available status of a rail segment is further discussed.

Abstract: A low profile double impedance bond for placement between a pair of rails and for electrical connection to opposite sides of a pair of insulated breaks on the pair of rails, the impedance bond comprising a rectangular enclosure attachable to ties supporting the pair of rails, the enclosure having a pair of ends and a pair of sides, each side for alignment parallel to one of the rails, the impedance bond having four coils each formed of a strip of copper foil with two ends wound in a spiral configuration about a core, the impedance bond having a terminal connection array formed of a plurality of copper conductors, the conductors, cores, and coils are arranged in a low profile manner on a single platform allowing quick installation inbetween rails.

Abstract: A low profile double impedance bond for placement between a pair of rails and for electrical connection to opposite sides of a pair of insulated breaks on the pair of rails, the impedance bond comprising a rectangular enclosure attachable to ties supporting the pair of rails, the enclosure having a pair of ends and a pair of sides, each side for alignment parallel to one of the rails, the impedance bond having four coils each formed of a strip of copper foil with two ends wound in a spiral configuration about a core, the impedance bond having a terminal connection array formed of a plurality of copper conductors, the conductors, cores, and coils are arranged in a low profile manner on a single platform allowing quick installation inbetween rails.

Abstract: Broken rail detection in a block of track without the need or expense of conventional signalling uses a chain of transmitters and receivers connected to the rails and defining sections of the block between the ends of the block. Either cyclically at a predetermined code rate or upon command of an external unit; an alternating current (AC) signal is launched from one end of the block and is repeated at different frequencies in each of the sections. When received at the end of the block, an indication of the absence of a broken rail condition is given either (a) by way of pole line or radio communication to a central control or dispatcher point and thence back to the trains, or (b) signals at the ends of the block are flashed at the code rate. The detected signal at the code rate may be used to modulate a direct current which is transmitted along the rails in the block to a signal at the opposite end of the block which also flashes at the code rate to indicate a safe condition.

Abstract: A center-fed track circuit arrangement for an electrified section of railroad track. A first and a second remotely located insulated joint defining the limits of the track circuit. A first impedance bond connected across the rails of the railroad track in the vicinity of the first remotely located insulated joint. A second impedance bond connected across the rails of the railroad track in the vicinity of the second remotely located insulated joint. A third impedance bond connected across the rails of the railroad tracks intermediate the first and second remotely located insulated joints. Each of the first and second impedance bonds includes a center tapped winding for accommodating propulsion current. A pair of tuned windings for accommodating at least two train detection signals having different frequencies. An untuned winding for exhibiting a low impedance at the frequency of a cab signal so as to mitigate leakage current across a broken-down insulated joint.

Abstract: An impedance bond for use in an electrified railway to provide a path for traction current includes a housing and a core positioned within the housing. The core is formed of a band of silicon steel wound into a closed loop construction which is then severed to form a cap and a U-shaped body. A pair of coils are positioned each upon a leg of the U-shaped core prior to repositioning the cap upon the core. Each of the coils is substantially identical in electrical resistance and each is formed of a flat copper sheet, identical in length, and wound into coils identical in configuration. There are terminal straps attached to the coil which extend outwardly from the housing. The terminal straps are preferably cast copper.

Abstract: A track circuit receiver is driven by the signal across an impedance bond and operates a relay to disconnect the signal so causing the relay to cycle. In series with the receiver input is a signal from the center tap of the impedance bond, which is normally at earth potential and does not affect the relay cycling. In the event of a rail break a significant output is obtained from the center tap, which either cancels or replaces the original receiver input signal but on a permanent basis uncontrolled by the relay. The relay therefore ceases to cycle in either event and thus provides a break indication.

Abstract: A track circuit signalling system for an electrified rapid transit system using significantly fewer components is provided. Instead of a transmitter and receiver at each track circuit boundary, alternate boundaries have transmitters only; and the intermediate boundaries have two receivers. The coupling units for the two receivers are more economical than the prior art coupling unit for coupling the transmitter-receiver combination. The transmitters on each side of a receiver pair transmit signals on different carrier frequencies. Each transmitter transmits in both directions from its location. Of the two receivers at a given boundary, one is tuned to respond to signals from the transmitter on one side, while the other receiver of the pair is tuned to respond to signals from the transmitter on the other side. For special applications using overlapping track circuits, selected transmitters may be omitted and a single receiver used on each side of the omitted transmitter.

Abstract: A stretch of railway track, has a high frequency track circuit transmitter and receiver and a cab signal transmitter coupled across track rails at each of several locations marking the ends of track sections along a stretch of railway track. Each location has an impedance bond having a primary winding connected across the track rails and having toroid secondary windings tuned to assigned distinctive high frequencies for coupling a track transmitter and a track receiver to the track rails. A loop circuit is also provided at each location, including a tuned loop, for inductively coupling a cab signal code transmitter to the track rails independent of the impedance bond. The tuned toroid coils and the loop circuit are connected in series to one end of a two wire line circuit, which, at its other end, is connected to a track circuit high frequency transmitteer, a track circuit receiver, and a cab signal transmitter connected in multiple.

Abstract: Alternating current track circuit energy for train detection and cab signals is coupled to the exit end of an insulated, dual gage track section between the common rail and the other two rails connected in parallel. The track relay is connected at the entrance end in a similar manner. Impedance bonds for direct current propulsion are also connected between the common rail and the other two rails at each end. In all forms, the propulsion return current is sufficiently balanced between the three rails to eliminate cab signal interference in either gage. In a first arrangement, a direct wire connection multiples the two other rails at each end. Impedance bond taps to complete the return circuit provide a two to one turn ratio from the common rail end of the bond winding to equalize the propulsion current ampere turns on each side of the tap and thus balance the flux generated.

Abstract: A detective circuit for railway points composed of three track sections connected together at a junction or for a railway crossing composed of four track sections connected together at a junction.