US2857138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Core barrel
Assignee: EJ Longyear Co
•
Filing: 1954-07-02
•
Granted: 1958-10-21
•
Expires: 1974-07-02
Abstract
No abstract record available.
Inventors
- 👤 Walter W Svendsen
- 👤 Jr John C C Blair
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:39
CPC Classifications
E; E21; E21B; E21B25/00; E21B25/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1883960A
Cited
US2182251A
Cited
US2167991A
Cited
US2159640A
Cited
US2260320A
Cited
US2612953A
Cited
US2532716A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-10-20 | 1962-04-21 | 1962-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-10-20 | 1966-04-21 | 1966-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-10-20 | 1970-04-21 | 1970-10-21 | $7700.00 | Window Closed / Lapsed |