US4434968A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic jack
Assignee: Individual
•
Filing: 1981-09-28
•
Granted: 1984-03-06
•
Expires: 2001-09-28
Abstract
Abstract A magnetic jack comprising a body consisting of a series of slidably telescoped sections expandable along the jack axis, and a pair of electromagnets disposed between each successive pair of sections, each connected to one section, and having confronting poles of like polarity, so that they repel each other when electric current is supplied thereto, in order to extend the sections along the jack axis. The magnet pairs between successive pairs of body sections may be energized selectively, or the energizing current may be variably adjusted, in order to vary the height and force of the lift provided by the jack.
Inventors
- 👤 Raymond H. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:12
CPC Classifications
B; B66; B66F; B66F3/00; H; H01; H01F; H01F7/00; H01F7/06; H01F7/20; H01F7/206
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
144 words
A magnetic jack comprising: a. a body member consisting of a series of sections connected together for limited telescopic extension in a direction parallel to the lift axis of the jack, b. A pair of electromagnets carried between each successive pair of body sections, the magnets of said pair being affixed respectively to said related pair of body sections, being coaxial and having a magnetic axis parallel to the jack lift axis, and having confronting poles which are of like polarity when electric current is supplied thereto, c. means for furnishing electric current to said electromagnets, whereby the like polarity of said confronting poles generates a repulsion force tending to extend said related body sections telescopically, and d. a dashpot device interconnecting each successive pair of body sections, whereby to cushion and retard the extension and retraction movements of that pair of body sections.
Claim 2
Dependent Claim
144 words
A magnetic jack comprising: a. a body member consisting of a series of sections connected together for limited telescopic extension in a direction parallel to the lift axis of the jack, b. A pair of electromagnets carried between each successive pair of body sections, the magnets of said pair being affixed respectively to said related pair of body sections, being coaxial and having a magnetic axis parallel to the jack lift axis, and having confronting poles which are of like polarity when electric current is supplied thereto, c. means for furnishing electric current to said electromagnets, whereby the like polarity of said confronting poles generates a repulsion force tending to extend said related body sections telescopically, and d. a dashpot device interconnecting each successive pair of body sections, whereby to cushion and retard the extension and retraction movements of that pair of body sections.
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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) | 1987-03-06 | 1987-09-05 | 1988-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-06 | 1991-09-05 | 1992-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-06 | 1995-09-05 | 1996-03-06 | $7700.00 | Window Closed / Lapsed |