US2638536A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Four-indication signal control system embodying polar biased code following and polarized line relays
Assignee: Westinghouse Air Brake Co
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Filing: 1947-04-05
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Granted: 1953-05-12
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Expires: 1967-04-05
Abstract
No abstract record available.
Inventors
- 👤 Jr Thomas W Tizzard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:30
CPC Classifications
B; B61; B61L; B61L1/00; B61L1/18; B61L1/181; B61L1/185
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1709907A
Cited
US2096832A
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US2076930A
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US2105260A
Cited
US2133306A
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US2221726A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-05-11 | 1956-11-10 | 1957-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-05-11 | 1960-11-10 | 1961-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-05-11 | 1964-11-10 | 1965-05-12 | $7700.00 | Window Closed / Lapsed |