Patent US2991852A successfully refreshed from Google Patents.
US2991852A
Expired / Lapsed
US
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Drilling rig and method of extending an upper section of the mast thereof
Assignee: C N HOUSH
•
Filing: 1956-11-29
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Granted: 1961-07-11
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Expires: 1976-11-29
Abstract
No abstract record available.
Inventors
- 👤 Harold D Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:53
CPC Classifications
E; E21; E21B; E21B15/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US1000842A
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US1119734A
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US1586424A
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US2470998A
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US2463841A
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US2692031A
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US2781108A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-07-10 | 1965-01-09 | 1965-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-07-10 | 1969-01-09 | 1969-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-07-10 | 1973-01-09 | 1973-07-11 | $7700.00 | Window Closed / Lapsed |