Patent US2491908A successfully refreshed from Google Patents.
US2491908A
Expired / Lapsed
US
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Earth drilling device
Assignee: Individual
•
Filing: 1945-08-11
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Granted: 1949-12-20
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Expires: 1965-08-11
Abstract
No abstract record available.
Inventors
- 👤 James E Roberts
- 👤 Albert O Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:12
CPC Classifications
E; E21; E21B; E21B7/00; E21B7/003; E21B7/005; E21B7/002
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US588929A
Cited
US1419068A
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US852833A
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US1374867A
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US1391626A
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US1523629A
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US1726049A
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US1696576A
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US1988414A
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US2090355A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-12-19 | 1953-06-20 | 1953-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-12-19 | 1957-06-20 | 1957-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-12-19 | 1961-06-20 | 1961-12-20 | $7700.00 | Window Closed / Lapsed |