Patent US3974902A successfully refreshed from Google Patents.
US3974902A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic spring grip device
Assignee: REEL PRECISION Manufacturing CORP
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Filing: 1975-06-26
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Granted: 1976-08-17
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Expires: 1995-06-26
Abstract
Abstract An electromagnetically actuated clutch or the like having a helical spring disposed about the surface of a relatively rotatable drum, and an electromagnet with a fixed annular pole piece closely adjacent the free end coil of the spring. The spring is induced to grip the drum surface by the action of magnetic flux passing from the drum to the spring and thence directly to the polepiece.
Inventors
- 👤 Robert L. Wahlstedt
- 👤 Robert F. Rasmussen
- 👤 Lee W. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:35
CPC Classifications
F; F16; F16D; F16D27/00; F16D27/10; F16D27/105
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
91 words
A magnetic spring grip device comprising a drum or hub, a helical spring loosely engageably coiled about said drum and having a free end coil, said drum and spring being relatively rotatable, and an annular pole piece, fixed with respect to said drum and spring, closely adjacent said free end coil and defining, with said drum and coil, a magnetic path wherein magnetic lines of flux pass from said drum to said coil and directly to said pole piece; and a selectively actuable generating means for generating said lines of flux.
Claim 2
Dependent Claim
91 words
A magnetic spring grip device comprising a drum or hub, a helical spring loosely engageably coiled about said drum and having a free end coil, said drum and spring being relatively rotatable, and an annular pole piece, fixed with respect to said drum and spring, closely adjacent said free end coil and defining, with said drum and coil, a magnetic path wherein magnetic lines of flux pass from said drum to said coil and directly to said pole piece; and a selectively actuable generating means for generating said lines of flux.
Claim 3
Dependent Claim
22 words
Device of claim 1 wherein said spring is supported on a second drum closely coaxially disposed with respect to the first drum.
Claim 4
Dependent Claim
23 words
Device of claim 2 wherein said second drum is rotatably supported on a tubular shaft to which said first drum is fixedly attached.
Claim 5
Dependent Claim
25 words
Device of claim 3 wherein said flux generating means comprises a housing, including said pole piece, encircling said spring and rotatably supported about said drums.
Claim 6
Dependent Claim
19 words
Device of claim 4 wherein said pole piece includes an inner annular extension closely overlying said free end coil.
Claim 7
Dependent Claim
33 words
Device of claim 4 wherein said pole piece includes an inner annular extension closely adjacent the free end face of said spring and said first drum is of reduced diameter beneath said extension.
Claim 8
Dependent Claim
33 words
Device of claim 4 wherein said housing is supported on said first drum by an intervening polymeric anti-friction bushing and on said second drum by a ferromagnetic bearing and a polymeric anti-friction bushing.
Claim 9
Dependent Claim
26 words
Device of claim 7 wherein is included a ferromagnetic axle disposed within and keyed to said tubular shaft, and a sprocket keyed to said second drum.
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) | 1979-08-17 | 1980-02-16 | 1980-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-17 | 1984-02-16 | 1984-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-17 | 1988-02-16 | 1988-08-17 | $7700.00 | Window Closed / Lapsed |