US3663809A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detection of end zones in alternating track circuits
Assignee: SPX Technologies Inc
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Filing: 1970-05-04
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Granted: 1972-05-16
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Expires: 1990-05-04
Abstract
Abstract A continuous rail track circuit apparatus having termination shunts at each end detects the presence of a railroad vehicle shunt across the rails and indicates vehicle presence. Shunt means near one end of the track circuit periodically introduces a test shunt across the track, and receiver means coupled to the rails near the other end of the track circuit is sensitive to changes in track circuit parameters occasioned by the test shunt and respondingly introduces a reply test shunt in accordance with the period of the shunt means. Means at the first end of the circuit sensitive to changes in track circuit parameters occasioned by the reply test shunt provides indication of vehicle presence when the change in track circuit parameters ceases.
Inventors
- 👤 Henry C Sibley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:01
CPC Classifications
B; B61; B61L; B61L1/00; B61L1/18; B61L1/181; B61L1/187
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
123 words
A continuous rail track circuit apparatus having termination shunts at each end for detecting the presence of a railroad vehicle shunt across the rails indicative of vehicle presence comprising: a. shunt means near one end of the circuit for periodically introducing a test shunt across the tracks; b. receiver means coupled to the rails near the other end of the circuit sensitive to change in circuit parameters occasioned by said test shunt for respondingly introducing a reply test shunt in accordance with the period of the shunt means; and c. means at the first end of the circuit sensitive to change in circuit parameters occasioned by said reply test shunt for providing indication of vehicle presence when said change in circuit parameters ceases.
Claim 2
Dependent Claim
123 words
A continuous rail track circuit apparatus having termination shunts at each end for detecting the presence of a railroad vehicle shunt across the rails indicative of vehicle presence comprising: a. shunt means near one end of the circuit for periodically introducing a test shunt across the tracks; b. receiver means coupled to the rails near the other end of the circuit sensitive to change in circuit parameters occasioned by said test shunt for respondingly introducing a reply test shunt in accordance with the period of the shunt means; and c. means at the first end of the circuit sensitive to change in circuit parameters occasioned by said reply test shunt for providing indication of vehicle presence when said change in circuit parameters ceases.
Claim 3
Dependent Claim
71 words
The track circuit apparatus of claim 1 wherein the shunt means includes: a. driver means at the first end for shunting the rails in the vicinity of the termination shunt; b. transmitter means coupled to the rails at the first end for feeding the rails with a carrier signal; and c. shift means responsive to an increase in track current occasioned by the test shunt for shifting the frequency carrier signal.
Claim 4
Dependent Claim
51 words
The track circuit apparatus of claim 2 wherein said test shunt means comprises: a. an Impedance coupled to a rail calibrated in accordance with a preselected value; and b. switch means serially connected with said impedance operative when actuated by said drive means for shunting said track with the calibrated impedance.
Claim 5
Dependent Claim
26 words
The track circuit apparatus of claim 3 wherein said driver means includes a pulse generator for providing periodic pulses of energy for actuating said switch means.
Claim 6
Dependent Claim
100 words
The track circuit apparatus of claim 2 wherein said receiver means includes: a. reply test shunt means at the second end for shunting the rails in the vicinity of the termination shunt; b. frequency responsive means coupled to the rails at the second end for introducing the reply test shunt in response to the shifted carrier frequency; c. second transmitter means at the second end for feeding the circuit with a second carrier signal; and d. second shift means responsive to an increase in track current occasioned by the reply test shunt for shifting the frequency of the transmitted signal.
Claim 7
Dependent Claim
115 words
The track circuit apparatus of claim 3 wherein the means at the first end sensitive to the change in circuit parameters includes: a. a capture receiver coupled to the rails responsive for generating a signal in accordance with the occurrence of the second frequency shift carrier; and b. output logic means responsive to the period of the first shunt means and the capture receiver signal for providing an output signal as long as the period of the first shunt means agrees with the occurrence of the second shifted carrier signal, said output indication of a clear track circuit and ceasing the output upon occurrence of disagreement of the signals thereby providing indication of vehicle presence.
Claim 8
Dependent Claim
102 words
The track circuit of claim 4 wherein said output logic means comprises: a. a switching means for changing conductance state in accordance with each state of said capture receiver and said driver means; b. gate means responsive to positive and negative conductance states of the capture receiver and driver means respectively for generating an output when said conductance states are in phase correspondence and clearing said output for indicating vehicle presence when said correspondence ceases, thereby providing synchronism of the ends of the track circuits such that spurious signals are substantially ineffective to actuate said output logic means to an unsafe condition.
Claim 9
Dependent Claim
143 words
A continuous rail track circuit apparatus having termination shunts at each end for detecting the presence of a railroad vehicle shunt across the rails indicative of vehicle presence comprising: a. train simulation means near one end of the circuit for periodically introducing a fixed impedance across the rails commensurate with an ideal vehicle shunt at a selected distance from the end of the track circuit, b. receiver means coupled to the rails near the other end of the circuit sensitive to change in circuit parameters occasioned by said test shunt for respondingly introducing a reply train simulation shunt in accordance with the period of the train simulator means, c. means at the first end of the circuit sensitive to change in circuit parameters occasioned by said reply train simulation shunt for providing indication of vehicle presence when said change in circuit parameters ceases.
Claim 10
Dependent Claim
143 words
A continuous rail track circuit apparatus having termination shunts at each end for detecting the presence of a railroad vehicle shunt across the rails indicative of vehicle presence comprising: a. train simulation means near one end of the circuit for periodically introducing a fixed impedance across the rails commensurate with an ideal vehicle shunt at a selected distance from the end of the track circuit, b. receiver means coupled to the rails near the other end of the circuit sensitive to change in circuit parameters occasioned by said test shunt for respondingly introducing a reply train simulation shunt in accordance with the period of the train simulator means, c. means at the first end of the circuit sensitive to change in circuit parameters occasioned by said reply train simulation shunt for providing indication of vehicle presence when said change in circuit parameters ceases.
Claim 11
Dependent Claim
28 words
The track circuit apparatus of claim 8 wherein said fixed impedance is a value indicative of a maximum allowable train shunt, typically on the order of 0.6 ohm.
References Cited (Backward Citations)
FR1036142A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |