US3781541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fail-safe railroad-highway grade crossing protection system
Assignee: Trane US Inc
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Filing: 1972-09-07
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Granted: 1973-12-25
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Expires: 1992-09-07
Abstract
Abstract This disclosure relates to a fail-safe electronic system for protecting a railroad-highway grade crossing. The system includes a solid state transmitter for applying a constant current to the track and a solid-state receiver for obtaining a voltage signal from the track. A differentiating circuit senses any differential change between the track voltage and an opposing voltage in order to distinguish an approaching train from a receding train so as to appropriately control the warning apparatus. The integrity of the system is constantly monitored by modulating the track voltage signal so that the absence of the modulating signal activates the warning apparatus to ensure the highest degree of safety to pedestrians and motorists.
Inventors
- 👤 J Darrow
- 👤 T Vaughn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:23
CPC Classifications
B; B61; B61L; B61L29/00; B61L29/24; B61L29/28; B61L29/286
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
175 words
A fail-safe electronic system for protecting a railroadhighway grade crossing comprising, transmitter means for applying a constant current signal to the track, receiver means for receiving a voltage signal from the track, means coupled to said receiver means for producing a voltage potential which is in bucking relationship with said track voltage signal, means coupled to said receiver means for modulating said track voltage signal, differentiator means coupled to said receiving means for producing an output signal substantially proportional to the rate of change of the input signal, oscillator means coupled to said differentiator means, a track circuit coupled to the track and encompassing the grade crossing, and means coupled to said oscillator and said track circuit and responsive to the condition of said oscillator and said track circuit for actuating a protective warning when a train is approaching the grade crossing and is outside the limits of said track circuit or when a traiN is within the limits of said track circuit or when a critical circuit or component failure occurs within the system.
Claim 2
Dependent Claim
175 words
A fail-safe electronic system for protecting a railroadhighway grade crossing comprising, transmitter means for applying a constant current signal to the track, receiver means for receiving a voltage signal from the track, means coupled to said receiver means for producing a voltage potential which is in bucking relationship with said track voltage signal, means coupled to said receiver means for modulating said track voltage signal, differentiator means coupled to said receiving means for producing an output signal substantially proportional to the rate of change of the input signal, oscillator means coupled to said differentiator means, a track circuit coupled to the track and encompassing the grade crossing, and means coupled to said oscillator and said track circuit and responsive to the condition of said oscillator and said track circuit for actuating a protective warning when a train is approaching the grade crossing and is outside the limits of said track circuit or when a traiN is within the limits of said track circuit or when a critical circuit or component failure occurs within the system.
Claim 3
Dependent Claim
20 words
A fail-safe electronic system as defined in claim 1, wherein a transformer provides said bucking voltage to said receiver means.
Claim 4
Dependent Claim
20 words
A fail-safe electronic system as defined in claim 1, wherein said modulating means is transformer coupled to said receiver means.
Claim 5
Dependent Claim
46 words
A fail-safe electronic system as defined in claim 1, wherein said differentiator means is coupled to the power supply of said oscillator means so that the power supply voltage is opposed by voltage supplied by said differentiator means when a train is approaching the grade crossing.
Claim 6
Dependent Claim
47 words
A fail-safe electronic system as defined in claim 1, wherein said differentiator means is coupled to the power supply of said oscillator means so that the power supply voltage is enhanced by voltage supplied by said differentiator means when a train is receding from the grade crossing.
Claim 7
Dependent Claim
45 words
A fail-safe electronic system as defined in claim 1, wherein said responsive means includes a first AND logic gate having two inputs and an output in which one input is connected to said oscillator means and the other input is connected to the track circuit.
Claim 8
Dependent Claim
44 words
A fail-safe electronic system as defined in claim 6, wherein said output of said first AND logic gate is connected to a modulation detector for detecting the modulated signal of said modulating means, to a modulating amplifier and to a second AND logic circuit.
Claim 9
Dependent Claim
41 words
A fail-safe electronic circuit as defined in claim 6, wherein said second AND logic gate requires an input signal to be applied from said first AND logic gate and an input from said modulation amplifier in order to produce an output.
Claim 10
Dependent Claim
48 words
A fail-safe electronic system as defined in claim 1, wherein said track circuit is an island circuit having a transmitter means connected to the track on one side of the grade crossing and a receiver means connected to the track on the other side of the grade crossing.
Claim 11
Dependent Claim
38 words
A fail-safe electronic system as defined in claim 6, wherein said track circuit includes a receiver means the output of which is amplified and rectified and then is applied to the other input of said first AND gate.
Claim 12
Dependent Claim
23 words
A fail-safe electronic system as defined in claim 1, wherein said transmitter means is connected to the track through a tuned resonant circuit.
Claim 13
Dependent Claim
21 words
A fail-safe electronic system as defined in claim 11, wherein said tuned resonant circuit includes the primary winding of a transformer.
Claim 14
Dependent Claim
32 words
A fail-safe electronic system as defined in claim 12, wherein said transformer includes a secondary winding which is connected to said receiver means and into which is induced said bucking voltage potential.
Claim 15
Dependent Claim
66 words
A fail-safe electronic system as defined in claim 1, wherein said differentiator means opposes the power supply of said oscillator means when a train approaches the grade crossing so that said oscillator means assumes a non-oscillatory condition and said differentiator means enhances the power supply of said oscillator means when a train recedes from the grade crossing so that said oscillator means assumes an oscillatory condition.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |