US2491583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shaft sinking apparatus
Assignee: Individual
•
Filing: 1948-02-17
•
Granted: 1949-12-20
•
Expires: 1968-02-17
Abstract
No abstract record available.
Inventors
- 👤 Riddell Paul Alexander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:37
CPC Classifications
E; E21; E21D; E21D1/00; E21D1/03; E21D1/04; Y; Y10; Y10S; Y10S414/00; Y10S414/129
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-12-19 | 1953-06-20 | 1953-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-12-19 | 1957-06-20 | 1957-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-12-19 | 1961-06-20 | 1961-12-20 | $7700.00 | Window Closed / Lapsed |