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Патент USA US3085659

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April 16, 1963
Filed Aug. 21, 1962
F/c. /
FIG. a
United States Patent O
Patented Apr. 16, 1963
co-pending patent application, Serial No. 863,309, iiled
Deglember 31, 1959, in the names of Edward T. Gillman
Edward T. Gillman, Rutherford, N.J., assignor to Putnam
Rolling Ladder Co., Inc., New York, N.Y.
Filed Aug. 21, 1962, Ser. No. 218,261
3 Claims. (Cl. 182-46)
This invention has reference to ladders in general, and
more specifically to a rail used in such ladders.
The object of the present invention is the provision of
a rail of the type above referred to, which is of a great
strength relative to Weight. It is an improvement over
the rail disclosed in Patent 3,009,532, dated November
21, 1962, issued in the names of Charles D. Richard and
Edward T. Gìllman.
The rail disclosed in the patent above referred to makes
In the modification of the rail of this invention as
shown in FIG. 2, segment-shaped bars ST6 and ST7
are constructed of a low density material, such as balsa
wood, adhesively united to a plywood partition consist
ing, like the partition shown in FIG. 1, of a number of
layers ST3, ST4 and ST5, the assembly thus formed be
ing enclosed in a plastic impregnated fiberglass material
wrapped around the core by the winding machine form
ing the subject matter of the Edward T. Gillman et
al. co-pending application above mentioned.
The elliptical assemblies of the segment-shaped bars
15 and partitions in combination as shown in FIGS. 1 and
2 of the drawing, have been found to possess an amount
of rigidity not obtained by any rail construction hereto
use of a core of unit structure having an elliptical cross
fore known while descreasing its manufacturing cost and
section and constructed of a light density material, such
because of the rigidity of the partition obtained by dis
as balsa wood, with its peripheral surface wrapped there
over with a plurality of plastic impregnated fiberglass 20 posing the latter edgewise on the major axis of the semi
elliptically-shaped core, this partition has been found to
strips having different directions of orientation.
increase the strength to weight ratio of such rails to a
While ladders’ rails constructed according to the teach
degree not heretofore obtained.
ing of the above mentioned patent have been found to
What I claim is:
possess a satisfactory strength to weight ratio, it has been
1. A rail for use in a ladder, said rail consisting of
found desirable in such ladders to increase the resistance 25
an elliptically-shaped core formed of two parts of Foamed
of the rails as to avoid excessive flexing of the ladders
Polyurethane material and a flat partition of another ma
and therefore dangerous under unusually heavy loads to
terial disposed flatwise between said parts on the major
which such ladders are sometimes submitted.
axis of the elliptically-shaped core, and the whole en
The novel features of this invention will appear from
following description and by the claims appended there 30 closed in a wrapping of plastic impregnated iiberglass
material forming a homogeneous rail structure.
to, reference being had to the accompanying drawing in
FIG. 1 is a perspective view of a length portion of a
rail of the invention shown partly in transverse and lon
2. A rail for use in a ladder, the rail having a core
rail shown in FIG. 1, modified, also shown in partial
shaped core and adhesively united thereto, and the whole
of elliptical cross section formed of two segment-shaped
bars of Foamed Polyurethane material and a partition
35 of different material disposed between the ñat side of said
gitudinal sections; and
FIG. 2 is a perspective view of a length portion of the
segment-shaped bars on the major axis of the elliptically
transverse and longitudinal sections.
covered with a wrapping of plastic impregnated liber
As shown in FIG. 1 of the drawing, the -rail of the
glass material to form a homogeneous assembly.
present invention consists of two similar bars ST1 and 40
3. A rail for use in a ladder, the rail having a core
ST2 constructed of a material known in the trade as
of elliptical cross section formed of two bars having seg
Foamed Polyurethane, obtainable from the Foam Divis
ment-shaped cross section constructed of a molded foam
ion of Scott Paper Company, Chester, Pennsylvania, or
material and a reinforcing ilat partition constructed of
Acushnet Process Co., New Bedford, Mass., and of a
low density Silicone Rubber foam material generally 45 plywood adhesively united to the iiat sides of said foam
bars by a plastic material, said partition disposed on the
known in the trade as Ethafoam, produced and obtain
axis of the elliptically-shaped core and the whole
able from Dow Corning Corporation of Midland, Michi
assembly enclosed in a wrapping of plastic impregnated
gan. The bars ST1 and ST2 are of segment-shaped cross
fiberglass material to form a homogenous rail assembly.
section having the flat surface thereof adhesively united
by a plastic material to the opposite sides of a plywood 50
References Cited in the ñle of this patent
strip which may consist of any numbers of layers, as
ST3, ST4 and ST5, the assembly of the plywood strip
and the foam bars ST1 and ST2 being such as to form
a core having an elliptical cross section and the whole
Wrapped in an envelope F of plastic impregnated fiber
glass material in the form of strips to form a homogene
ous assembly, such Wrapping being effected by means of
a winding machine which forms the subject matter of a
Scott ________________ __ Dec. 2,
Bailey ______________ __ Jan. 27,
Campbell ____________ __ May 5,
Hopfeld ____________ __ Apr. 12,
|Richard ____________ __ Nov. 21,
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