Road structure – process – or apparatus – Pavement – Vault cover-closure
Reexamination Certificate
1999-07-01
2001-05-15
Saether, Flemming (Department: 3627)
Road structure, process, or apparatus
Pavement
Vault cover-closure
C411S171000, C294S001200, C294S089000
Reexamination Certificate
active
06231267
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fastening devices and, more particularly, to threaded plugs for attachment to trench plates for accommodating swivel hoist rings therein.
2. Description of Related Art
Steel trench plates are used to cover trenches in streets and roadways in order to facilitate traffic flow during construction or repair. In order to lift a steel trench plate, one or more fastening devices, such as hoist rings, are typically secured to the steel trench plate. Prior art fastening devices have included threaded rods formed into a loop and permanently affixed to the steel trench plate. Swivel hoist rings have also been used as fastening devices for steel trench plates. A typical swivel hoist ring, such as disclosed in U.S. Pat. No. 3,297,293 to Andrews et al., may comprise an eye member which is pivotally and rotationally mounted onto a base.
SUMMARY OF THE INVENTION
In accordance with the present invention, threaded plugs are secured into a steel trench plate for removably accommodating fastening devices thereto. Even though the steel trench plate may be formed of common, commercial grade steel, each threaded plug is formed of high-quality, 4140 chrome molly aircraft steel, which is heat treated to Rockwell standard hardness. Moreover, the tolerance of each threaded plug is precisely controlled, and each threaded plug is preferably formed to have a round head, which is then beveled, before the threaded plug is permanently secured to the steel trench plate.
The present invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.
REFERENCES:
patent: 1792711 (1931-02-01), Rockstad
patent: 2250580 (1941-07-01), Gregory
patent: 2674485 (1954-04-01), Jamison
patent: 3219790 (1965-11-01), Johnson
patent: 3297293 (1967-01-01), Andrews
patent: 3710468 (1973-01-01), Calvert
patent: 3920347 (1975-11-01), Sauriol
patent: 4170918 (1979-10-01), Burge
patent: 4600332 (1986-07-01), Sharp
patent: 4770584 (1988-09-01), Vinciguerra
patent: 4973191 (1990-11-01), Dannhauser
patent: 5713695 (1998-02-01), Rogers
Actek Enterprises, Inc.
Saether Flemming
Stout, Uxa Buyan & Mullins, LLP
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