Patent US1938690A successfully refreshed from Google Patents.
US1938690A
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US
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Well drilling apparatus
Assignee: VICTOR I ZELOV
•
Filing: 1931-11-16
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Granted: 1933-12-12
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Expires: 1951-11-16
Abstract
No abstract record available.
Inventors
- 👤 John G Burmist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:38
CPC Classifications
E; E21; E21B; E21B19/00; E21B19/08; E21B19/086; Y; Y10; Y10T; Y10T137/00; Y10T137/7722; Y10T137/7781; Y10T137/7793
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) | 1936-12-11 | 1937-06-12 | 1937-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1940-12-11 | 1941-06-12 | 1941-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1944-12-11 | 1945-06-12 | 1945-12-12 | $7700.00 | Window Closed / Lapsed |