Patent US2581527A successfully refreshed from Google Patents.
US2581527A
Expired / Lapsed
US
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Track circuit apparatus
Assignee: Westinghouse Air Brake Co
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Filing: 1948-04-06
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Granted: 1952-01-08
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Expires: 1968-04-06
Abstract
No abstract record available.
Inventors
- 👤 Robert M Gilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:01
CPC Classifications
B; B61; B61L; B61L3/00; B61L3/16; B61L3/22; B61L3/221
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2045992A
Cited
US2465691A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1955-01-07 | 1955-07-09 | 1956-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1959-01-07 | 1959-07-09 | 1960-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1963-01-07 | 1963-07-09 | 1964-01-08 | $7700.00 | Window Closed / Lapsed |