Patent US3422913A successfully refreshed from Google Patents.
US3422913A
Expired / Lapsed
US
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Earth digging and conveying apparatus
Assignee: DU VAL DEV CORP
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Filing: 1966-11-10
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Granted: 1969-01-21
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Expires: 1986-11-10
Abstract
No abstract record available.
Inventors
- 👤 William O Young Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:40
CPC Classifications
E; E21; E21B; E21B17/00; E21B17/22; E21B7/00; E21B7/003; E21B7/005
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1850317A
Cited
US1931348A
Cited
US2041690A
Cited
US1985157A
Cited
US2182165A
Cited
US2197989A
Cited
US2250671A
Cited
US2730333A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-01-21 | 1972-07-22 | 1973-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-01-21 | 1976-07-22 | 1977-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-01-21 | 1980-07-22 | 1981-01-21 | $7700.00 | Window Closed / Lapsed |