Patent US2776817A successfully refreshed from Google Patents.
US2776817A
Expired / Lapsed
US
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Drilling apparatus
Assignee: Shell Development Co
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Filing: 1952-07-21
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Granted: 1957-01-08
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Expires: 1972-07-21
Abstract
No abstract record available.
Inventors
- 👤 James N Gregory
- 👤 Charles A Yeatman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:55
CPC Classifications
E; E21; E21B; E21B17/00; E21B17/02; E21B17/04; E21B17/07; E21B4/00; E21B4/18; E21B44/00; E21B44/005; E21B47/00; E21B47/09; E21B47/095
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) | 1960-01-08 | 1960-07-09 | 1961-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-01-08 | 1964-07-09 | 1965-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-01-08 | 1968-07-09 | 1969-01-08 | $7700.00 | Window Closed / Lapsed |