US3085649A - Ladders - Google Patents

Description

April 16, 1963 E. T. GILLMAN LADDERS Filed Aug. 21, 1962 FIG. a

vl/EA/TOA EDWARD 7S G/LLMAN 5V ATTORNE Y United States Patent O 3,085,649 LADDERS 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. Gllman.

The rail disclosed in the patent above referred to makes use of a core of unit structure having an elliptical cross section and constructed of a light density material, such as balsa wood, with its peripheral surface wrapped thereover with a plurality of plastic impregnated fiberglass strips having different directions of orientation.

While ladders rails constructed according to the teaching of the above mentioned patent have been found to possess a satisfactory strength to weight ratio, it has been found desirable in such ladders to increase the resistance of the rails as to avoid excessive flexing of the ladders and therefore dangerous under unusually heavy loads to which such ladders are sometimes submitted.

The novel features of this invention will appear from following description and by the claims appended thereto, reference being had to the accompanying drawing in which:

FIG. 1 is a perspective view of a length portion of a rail of the invention shown partly in transverse and longitudinal sections; and

FIG. 2 is a perspective view of a length portion of the rail shown in FIG. 1, modified, also shown in partial transverse and longitudinal sections.

As shown in FIG. 1 of the drawing, the -rail of the present invention consists of two similar bars ST1 and ST2 constructed of a material known in the trade as Foamed Polyurethane, obtainable from the Foam Division of Scott Paper Company, Chester, Pennsylvania, or Acushnet Process Co., New Bedford, Mass., and of a low density Silicone Rubber foam material generally known in the trade as Ethafoam, produced and obtainable from Dow Corning Corporation of Midland, Michigan. The bars ST1 and ST2 are of segment-shaped cross section having the flat surface thereof adhesively united by a plastic material to the opposite sides of a plywood 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 fiberglass material in the form of strips to form a homogeneous assembly, such Wrapping being effected by means of a winding machine which forms the subject matter of a co-pending patent application, Serial No. 863,309, iiled Deglember 31, 1959, in the names of Edward T. Gillman et ,f

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 consisting, like the partition shown in FIG. 1, of a number of layers ST3, ST4 and ST5, the assembly thus formed being enclosed in a plastic impregnated fiberglass material wrapped around the core by the winding machine forming the subject matter of the Edward T. Gillman et al. co-pending application above mentioned.

The elliptical assemblies of the segment-shaped bars 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 heretofore known while descreasing its manufacturing cost and because of the rigidity of the partition obtained by disposing the latter edgewise on the major axis of the semielliptically-shaped core, this partition has been found to increase the strength to weight ratio of such rails to a degree not heretofore obtained.

What I claim is:

1. A rail for use in a ladder, said rail consisting of an elliptically-shaped core formed of two parts of Foamed Polyurethane material and a flat partition of another material disposed flatwise between said parts on the major axis of the elliptically-shaped core, and the whole enclosed in a wrapping of plastic impregnated iiberglass material forming a homogeneous rail structure.

2. A rail for use in a ladder, the rail having a core of elliptical cross section formed of two segment-shaped bars of Foamed Polyurethane material and a partition of different material disposed between the at side of said segment-shaped bars on the major axis of the ellipticallyshaped core and adhesively united thereto, and the whole covered with a wrapping of plastic impregnated liberglass material to form a homogeneous assembly.

3. A rail for use in a ladder, the rail having a core of elliptical cross section formed of two bars having segment-shaped cross section constructed of a molded foam material and a reinforcing ilat partition constructed of plywood adhesively united to the iiat sides of said foam bars by a plastic material, said partition disposed on the major axis of the elliptically-shaped core and the whole assembly enclosed in a wrapping of plastic impregnated fiberglass material to form a homogenous rail assembly.

References Cited in the le of this patent UNITED STATES PATENTS 2,862,650 Scott Dec. 2, 1958 2,870,793 Bailey Jan. 27, 1959 2,885,132 Campbell May 5, 1959 2,932,358 Hopfeld Apr. 12, 1960 3,009,532 |Richard Nov. 21, 1961

Claims (1)

1. A RAIL FOR USE IN A LADDER, SAID RAIL CONSISTING OF AN ELLIPTICALLY-SHAPED CORE FORMED OF TWO PARTS OF FOAMED POLYURETHANE MATERIAL AND A FLAT PARTITION OF ANOTHER MATERIAL DISPOSED FLATWISE BETWEEN SAID PARTS ON THE MAJOR AXIS OF THE ELLIPTICALLY-SHAPED CORE, AND THE WHOLE ENCLOSED IN A WRAPPING OF PLASTIC IMPREGNATED FIBERGLASS MATERIAL FORMING A HOMOGENEOUS RAIL STRUCTURE.

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