Patent US3916939A successfully refreshed from Google Patents.
US3916939A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Locktop fire hydrant
Assignee: Individual
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Filing: 1974-11-25
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Granted: 1975-11-04
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Expires: 1994-11-25
Abstract
Abstract A fire hydrant which can only be activated by the use of an appropriate magnetic tool is disclosed, thus precluding improper use of the hydrant by unauthorized persons. The hydrant is provided with an inverted socket which protrudes through an opening in the top of the hydrant, and with an internal control rod to which a piston is slideably attached. The piston moves only in response to a magnetic force, and when such force is applied to the socket from an external tool, the piston slides into engagement with the socket, thereby connecting the socket to the control rod and permitting activation of the hydrant.
Inventors
- 👤 Clarence Gillard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:52
CPC Classifications
B; B25; B25B; B25B13/00; B25B13/48; B25B13/485; B25B23/00; B25B23/02; B25B23/08; B25B23/12; E; E03; E03B; E03B9/00; E03B9/02; E03B9/04; Y; Y10; Y10T; Y10T137/00; Y10T137/5327; Y10T137/5456; Y10T137/5468; Y10T137/6851; Y10T137/7043; Y10T137/7062
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
96 words
A locking mechanism for a fire hydrant comprising an upper hydrant wall having an aperture therein, a hydrant control shaft within said hydrant, means slidably mounted on said hydrant control shaft for selectively rotating said shaft, a socket mounting rotatably disposed within said aperture and supported by said upper hydrant wall, said mounting having an internal cavity for receiving and coupling said slidably mounted means for rotation, and electromagnetic means for selectively causing said slidably mounted means to move into said cavity to permit the transfer of rotational force from said mounting to said control shaft.
Claim 2
Dependent Claim
96 words
A locking mechanism for a fire hydrant comprising an upper hydrant wall having an aperture therein, a hydrant control shaft within said hydrant, means slidably mounted on said hydrant control shaft for selectively rotating said shaft, a socket mounting rotatably disposed within said aperture and supported by said upper hydrant wall, said mounting having an internal cavity for receiving and coupling said slidably mounted means for rotation, and electromagnetic means for selectively causing said slidably mounted means to move into said cavity to permit the transfer of rotational force from said mounting to said control shaft.
Claim 3
Dependent Claim
49 words
A locking mechanism as in claim 1 wherein said slidably mounted means includes a sleeve having an interior chamber for mating with said control shaft, and a cap mounted on said sleeve and adapted for mating with said internal cavity of said mounting in response to said electromagnetic means.
Claim 4
Dependent Claim
16 words
A locking mechanism as in claim 2 wherein said cap is fabricated of permanently magnetic material.
Claim 5
Dependent Claim
29 words
A locking mechanism as in claim 2 wherein said sleeve and said control shaft have corresponding hexagonal crosssections and said cap and said internal cavity have corresponding hexagonal cross-sections.
Claim 6
Dependent Claim
101 words
A locking mechanism as in claim 1 wherein said slidably mounted means includes at least a magnetically attracted element and wherein said electromagnetic means includes a wrench having a socket cavity adapted to mate with said socket mounting, an electromagnetic coil for selectively generating an electromagnetic field when said socket mounting is received within said socket cavity to draw said magnetically attracted element into said internal cavity and a handle for applying rotational force to said socket mounting to cause the rotation of said slidably mounted means and said control shaft when said magnetically attracted element is within said socket cavity.
Claim 7
Dependent Claim
20 words
A locking mechanism as in claim 5 wherein said socket cavity and said magnetically attracted element have corresponding hexaGonal cross-sections.
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) | 1978-11-03 | 1979-05-05 | 1979-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-03 | 1983-05-05 | 1983-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-03 | 1987-05-05 | 1987-11-04 | $7700.00 | Window Closed / Lapsed |