Patent US2672222A successfully refreshed from Google Patents.
US2672222A
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Fluid pressure control apparatus for rotary well drilling equipment
Assignee: Westinghouse Air Brake Co
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Filing: 1948-06-05
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Granted: 1954-03-16
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Expires: 1968-06-05
Abstract
No abstract record available.
Inventors
- 👤 Roy R Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:51
CPC Classifications
E; E21; E21B; E21B19/00; E21B19/08; E21B19/086
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US1197693A
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US2109297A
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US2117078A
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US2187969A
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US2211890A
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US2282615A
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US2275255A
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US2366310A
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US2366608A
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US2515946A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-03-15 | 1957-09-14 | 1958-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-03-15 | 1961-09-14 | 1962-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-03-15 | 1965-09-14 | 1966-03-16 | $7700.00 | Window Closed / Lapsed |