Patent US3538469A successfully refreshed from Google Patents.
US3538469A
Expired / Lapsed
US
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Viscous damper using magnetic ferrofluid
Assignee: Avco Corp
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Filing: 1967-09-22
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Granted: 1970-11-03
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Expires: 1987-09-22
Abstract
No abstract record available.
Inventors
- 👤 Rudolph Litte
- 👤 Leo Beltracchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:34
CPC Classifications
F; F16; F16D; F16D37/00; F16D37/02; F16F; F16F15/00; F16F15/10; F16F15/16; F16F9/00; F16F9/32; F16F9/53; F16F9/535; F16D2037/005
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) | 1973-11-02 | 1974-05-04 | 1974-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-11-02 | 1978-05-04 | 1978-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-11-02 | 1982-05-04 | 1982-11-03 | $7700.00 | Window Closed / Lapsed |