Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Hinge – Including means to hold or retard hinged members against...
Reexamination Certificate
2002-07-18
2004-03-30
Mah, Chuck Y. (Department: 3676)
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Hinge
Including means to hold or retard hinged members against...
C016S328000, C016S334000
Reexamination Certificate
active
06711780
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hinge for collapsible ladders, and more particularly, to a hinge for collapsible ladders having an improved structure in which a hinge spring for the collapsible ladders is not exposed externally.
Korean Utility Model Registration No. 1991-303 discloses a common hinge for collapsible ladders. As shown in
FIGS. 1A and 1B
, this conventional invention discloses the hinge having an auxiliary round plate
3
″ disposed between a pair of round plates
3
and
3
′. A rotary plate
11
contacts one side of the auxiliary round plate
3
″ by a flange
11
′ formed around the auxiliary round plate
3
″ and can be rotated. Center apertures,
4
,
4
′ and
4
″ which mate with a center aperture
4
″′ of the rotary plate
11
are locked with a bushing
5
, and a gap formed between portions A and B positioned in one direction of the flange
11
′ is used with an operating part
13
of the rotary plate
11
. One end of a tension spring
14
is mounted in an aperture
13
′ of the operating part
13
. Locking rods
8
and
8
′ of a locking handle
7
extend into apertures
15
and
16
and locking apertures
9
and
9
′ by pressure from a press part
18
having a press axle
6
with a spring
17
surrounding press axle
6
. At the same time, the operating part
13
which is rotatably biased in the direction of portion A, provides that the locking rods
8
and
8
′ smoothly enter along inclined planes
16
′ of the apertures
16
.
Since an operation of the hinge for the collapsible ladders disclosed in the above Korean Utility Model Registration has been already known, and also its structure does not include a characterized portion of the present invention, a detailed description thereof shall be omitted.
The hinge for the collapsible ladders described above has problems that may cause damage or breakdown of the spring due to its external exposure, and further, hands or gloves of an operator may be jammed in the spring when the press part is pressed.
SUMMARY OF THE INVENTION
In order to solve the above problems, it is an object of the present invention to provide a hinge for collapsible ladders having a safety structure which can inwardly house a hinge spring for the collapsible ladders, prevent any damage or breakdown of the spring, and keep an operator safe during use of the ladder.
To accomplish the above object of the present invention, a hinge for collapsible ladders, includes an external frame including a center aperture and a pair of locking apertures; an inner frame including a center aperture and a plurality of pairs of locking apertures, the inner frame being rotatably movable relative to the external frame around the center apertures; a rotary plate rotatably disposed between the inner frame and the external frame and having locking apertures therein; a substantially flat rotary spring having one end mounted to the inner frame and an opposite end mounted to the rotary plate to impart a turning force to the rotary plate; a hub member rotatably connecting the inner frame and the external frame about the center apertures, and supporting the frames, the hub member including a locking end at one side thereof; a locking part having a locking end for extension into the locking apertures of the external and inner frames to fix an angle of the inner frame and the external frame relative to each other; a press axle connected with the locking part and passing through the hub member, the press axle including a spring bearing end; and a spring positioned between the locking end of the hub member and the bearing end of the press axle.
REFERENCES:
patent: 1696357 (1928-12-01), Johnson
patent: 3811151 (1974-05-01), Kuemmerlin
patent: 4085899 (1978-04-01), Boothe
patent: 4210224 (1980-07-01), Kümmerlin et al.
patent: 4216844 (1980-08-01), Klafs
patent: 4403373 (1983-09-01), Kummerlin
patent: 4407045 (1983-10-01), Boothe
patent: 4566150 (1986-01-01), Boothe
patent: 4577986 (1986-03-01), Wang
patent: 4666327 (1987-05-01), Su
patent: 4666328 (1987-05-01), Ryu
patent: 4697305 (1987-10-01), Boothe
patent: 4770559 (1988-09-01), Yoo
patent: 4890950 (1990-01-01), Yoo
patent: D309502 (1990-07-01), Wing et al.
patent: 6343406 (2002-02-01), Yeh
patent: 2321346 (1974-10-01), None
patent: 3005692 (1981-08-01), None
patent: 3900176 (1990-07-01), None
patent: 0000499 (1978-07-01), None
patent: 2392268 (1978-12-01), None
patent: WO 01/83929 (2001-11-01), None
Goldberg Richard M.
Mah Chuck Y.
Sinclair Worldwide, Inc.
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