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US2969846A
Expired / Lapsed
US
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Percussive drill bit for use in reverse flow flushing in soft rock drilling
Assignee: Thor Power Tool Co
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Filing: 1958-12-16
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Granted: 1961-01-31
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Expires: 1978-12-16
Abstract
No abstract record available.
Inventors
- 👤 Robert L Sandvig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:00
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/16
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2733943A
Cited
US1941289A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-01-31 | 1964-08-01 | 1965-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-01-31 | 1968-08-01 | 1969-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-01-31 | 1972-08-01 | 1973-01-31 | $7700.00 | Window Closed / Lapsed |