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US2680581A
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Elevator control ratio changer
Assignee: Northrop Grumman Corp
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Filing: 1951-08-03
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Granted: 1954-06-08
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Expires: 1971-08-03
Abstract
No abstract record available.
Inventors
- 👤 John D Mckellar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:44
CPC Classifications
B; B64; B64C; B64C9/00; Y; Y10; Y10T; Y10T74/00; Y10T74/20; Y10T74/20576; Y10T74/20582; Y10T74/206
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-06-07 | 1957-12-07 | 1958-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-06-07 | 1961-12-07 | 1962-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-06-07 | 1965-12-07 | 1966-06-08 | $7700.00 | Window Closed / Lapsed |