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: Means for differentiating between traction current and signal current in an electrified railroad includes a first input transformer providing an input signal of the same frequency and phase as the track signal current. A second input transformer is connected to the track to provide a track signal. There are means for comparing the phase and frequency of the input signal and the track signal and means responsive to an output from the comparison means indicating a correct comparison for providing a relay driving signal.

Abstract: A railroad signal circuit includes a transmitter and a receiver which have a common connection to the track rails at one end of a signal block. There will be a similar transmitter and receiver at the opposite end of the signal block. A transmit/receive switch is connected in circuit with the transmitter and there is a code following element connecting the receiver to the transmit/receive switch and transmitter. The code following element comprises a Hall effect cell whose output is connected to the receiver.

Abstract: A railroad signal system includes an A type transmitter and receiver for sending and receiving signal messages in one direction and a B type transmitter and receiver for sending and receiving signal messages in the opposite direction. The A transmitter and the B receiver are located at one end of a signal block and the B transmitter and A receiver are located at the opposite end. The A transmitter provides an A type DC message and the B transmitter provides a B type DC message. The A receiver is responsive to only an A type message and the B receiver is responsive to only a B type message.