Patent US4236672A successfully refreshed from Google Patents.
Patent US1867833A successfully refreshed from Google Patents.
US1867833A
Expired / Lapsed
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Subcirculation oil well drilling apparatus with suction pumping
Assignee: Union Oil Company of California
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Filing: 1928-06-06
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Granted: 1932-07-19
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Expires: 1948-06-06
Abstract
No abstract record available.
Inventors
- 👤 Frank F Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:07
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/01
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1935-07-19 | 1936-01-18 | 1936-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1939-07-19 | 1940-01-18 | 1940-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1943-07-19 | 1944-01-18 | 1944-07-19 | $7700.00 | Window Closed / Lapsed |