Crossing control unit

Claim 3

Crossing control apparatus for activating a warning when a train is approaching or present at a crossing, said apparatus comprising: a warning unit having at least one electrically operated warning device, means for generating a warning rate signal having a predetermined repetition rate, means for generating a safe status signal having a predetermined frequency different from the repetition rate of said warning rate signal, a driver connected with said unit for controlling the energization and deenergization of said device in response to said signals, and including circuit means having a normal condition in which said device is energized and an excited condition in which said device is deenergized, means responsive to an approaching or present train for delivering said warning rate signal to said driver, and for delivering said safe status signal thereto in the absence of a train, and said driver having frequency sensitive means responsive to said warning rate signal for causing said circuit means to alternate between said conditions thereof to operate said device at the warning rate, and responsive to said safe status signal for maintaining said circuit means in its excited condition to thereby maintain said device inoperative.

Claim 4

Crossing control apparatus for activating a warning when a train is approaching or present at a crossing, said apparatus comprising: a warning unit having at least one electrically operated warning device, means for generating a warning rate signal having a predetermined repetition rate, means for generating a safe status signal having a predetermined frequency different from the repetition rate of said warning rate signal, a driver connected with said unit for controlling the energization and deenergization of said device in response to said signals, and including circuit means having a normal condition in which said device is energized and an excited condition in which said device is deenergized, means responsive to an approaching or present train for delivering said warning rate signal to said driver, and for delivering said safe status signal thereto in the absence of a train, and said driver having frequency sensitive means responsive to said warning rate signal for causing said circuit means to alternate between said conditions thereof to operate said device at the warning rate, and responsive to said safe status signal for maintaining said circuit means in its excited condition to thereby maintain said device inoperative.

Claim 5

The apparatus as claimed in claim 2, wherein said circuit means includes an electrically responsive switching component normally in conduction, and wherein said frequency sensitive means delivers continuous control excitation to said component to render the same nonconductive in response to said safe status signal, and delivers said control excitation to said component intermittently at said warning rate in response to said warning rate signal.

Claim 6

The apparatus as claimed in claim 2, wherein the frequency of said safe status signal is substantially higher than the repetition rate of said warning rate signal.

Claim 7

The apparatus as claimed in claim 4, wherein said circuit means includes an electrically responsive switching component normally in conduction, and wherein said frequency sensitive means includes an RC network having a time constant causing continuous delivery of control excitation to said component to render the same nonconductive in response to said safe status signal, and intermittent delivery of said excitation at said warning rate in response to said warning rate signal.

Claim 8

Crossing control apparatus for activating a warning when a train is approaching or present at a crossing, said apparatus comprising: a warning unit having first and second electrically operated warning devices, means for generating a warning rate signal having a predetermined repetition rate, means for generating a safe status signal having a predetermined frequency different from the repetition rate of said warning rate signal, first and second drivers connected with corresponding devices for controlling the energization and deenergization of said devices in response to said signals, and each including circuit means having a normal condition in which the corresponding device is energized and an excited condition in which the device is deenergized, crossing status means responsive to an approaching or present train and including oscillator means having first and second output frequency components substantially higher than the frequencies of said warning rate and safe status signals, gate means connected with said oscillator means and responsive to said warning rate and safe status signals for alternating the output of said oscillator means between said first and second frequencies in synchronism with the signal that is indicative of the status of the crossing, whereby the output of said oscillator means provides a two-component control signal that alternates between said components at the warning rate when a train is approaching or present and alternates at the safe status signal frequency in the absence of a train, frequency responsive filter means interposed between the output of said oscillator means and said drivers for delivering the component of said control signal at said first frequency exclusively to said first driver and delivering the component of said control signal at said second frequency exclusively to said second driver, and each of said drivers having frequency sensitive means responsive to said warning rate for causing its circuit means to alternate between said conditions thereof to operate the corresponding device at the warning rate, and responsive to said safe status frequency for maintaining the circuit means in its excited condition to thereby maintain the corresponding device inoperative, whereby said first and second devices are alternately energized at the warning rate when a train is approaching or present at the crossing.

Claim 9

Crossing control apparatus for activating a warning when a train is approaching or present at a crossing, said apparatus comprising: a warning unit having first and second electrically operated warning devices, means for generating a warning rate signal having a predetermined repetition rate, means for generating a safe status signal having a predetermined frequency different from the repetition rate of said warning rate signal, first and second drivers connected with corresponding devices for controlling the energization and deenergization of said devices in response to said signals, and each including circuit means having a normal condition in which the corresponding device is energized and an excited condition in which the device is deenergized, crossing status means responsive to an approaching or present train and including oscillator means having first and second output frequency components substantially higher than the frequencies of said warning rate and safe status signals, gate means connected with said oscillator means and responsive to said warning rate and safe status signals for alternating the output of said oscillator means between said first and second frequencies in synchronism with the signal that is indicative of the status of the crossing, whereby the output of said oscillator means provides a two-component control signal that alternates between said components at the warning rate when a train is approaching or present and alternates at the safe status signal frequency in the absence of a train, frequency responsive filter means interposed between the output of said oscillator means and said drivers for delivering the component of said control signal at said first frequency exclusively to said first driver and delivering the component of said control signal at said second frequency exclusively to said second driver, and each of said drivers having frequency sensitive means responsive to said warning rate for causing its circuit means to alternate between said conditions thereof to operate the corresponding device at the warning rate, and responsive to said safe status frequency for maintaining the circuit means in its excited condition to thereby maintain the corresponding device inoperative, whereby said first and second devices are alternately energized at the warning rate when a train is approaching or present at the crossing.

Claim 10

The apparatus as claimed in claim 6, further comprising a current-carrying conductor terminating at said devices for supplying the same with energizing power, modulation means coupled between said oscillator means and said conductor for modulating the energizing current with said two-component control signal, and means connecting said filter means to said conductor adjacent said devices.

Claim 11

The apparatus as claimed in claim 6, wherein said circuit means of each driver includes an electrically responsive switching component normally in conduction, and wherein said frequency sensitive means of each driver delivers continuous control excitation to said component to render the same nonconductive in response to said safe status frequency, and delivers said control excitation to said component intermittently at said warning rate in response to said warning rate signal.

Claim 12

The apparatus as claimed in claim 6, wherein the frequency of said safe status signal is substantially higher than the repetition rate of said warning rate signal.

Claim 13

The apparatus as claimed in claim 9, wherein said circuit means of each driver includes an electrically responsive switching component normally in conduction, and wherein said frequency sensitive means thereof includes an RC network having a time constant causing continuous delivery of control excitation to said component to render the same nonconductive in response to said safe status frequency, and intermittent delivery of said excitation at said warning rate in response to said warning rate signal.