Patent US2528981A successfully refreshed from Google Patents.
US2528981A
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US
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Formation testing apparatus
Assignee: Reed Roller Bit Co
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Filing: 1948-10-15
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Granted: 1950-11-07
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Expires: 1968-10-15
Abstract
No abstract record available.
Inventors
- 👤 John C Stokes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:36
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/08; E21B49/081; E21B49/0815; E21B49/083
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) | 1953-11-06 | 1954-05-08 | 1954-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-11-06 | 1958-05-08 | 1958-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-11-06 | 1962-05-08 | 1962-11-07 | $7700.00 | Window Closed / Lapsed |