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US2777978A
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Apparatus for regulating the number of revolutions of electric motors by means of ward-leonard control
Assignee: THOMAS B THRIDGE
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Filing: 1952-11-25
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Granted: 1957-01-15
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Expires: 1972-11-25
Abstract
No abstract record available.
Inventors
- 👤 Krabbe Ulrik Hindenburg
- 👤 Sphirensen Harald Mann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:43
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/34
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) | 1960-01-15 | 1960-07-16 | 1961-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-01-15 | 1964-07-16 | 1965-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-01-15 | 1968-07-16 | 1969-01-15 | $7700.00 | Window Closed / Lapsed |