US2885132A - Ladder - Google Patents

Description

May 5, 1959 T. c. CAMPBELL LADDER 2 Sheets-Sheet 1 Filed May 26, 1954 R 0 m w W May 5, 1959 T. c. CAMPBELL LADDER 2 Sheets-Sheet 2 Filed May 26, 1954 FIG. 5

INVENTOR United States Patent C LADDER Thaddeus C. Campbell, Rutherford, NJ., assignor to Putnam Rolling Ladder Company, Incorporated, New York, N .Y., a corporation of New York Application May 26, 1954, Serial No. 432,421

3 Claims. (Cl. 228-58) This invention relates to extension type ladders and more particularly has reference to a light weight ladder of relatively great strength and long life in actual use.

It is a well-recognized fact that in wood and metal ladders as heretofore constructed so far as applicant is aware, the point at which the rung is mounted in the siderail constitutes a point of major weakness, both initially as a result of the reduction in cross section of the siderail and subsequently by offering a critical area for rotting or corrosion.

One object of this invention is to provide a ladder having a high degree of resistance to deterioration combining light weight and strength and having high dielectric characteristics.

In one embodiment of the ladder of this invention the side rails of a ladder section are composed of a plurality of woven fiber glass strips laid over a core formed of two longitudinal sections of a light weight cellular material such as cellular cellulose acetate or balsa wood, while fluted tubular rungs constructed of a light density material, for example aluminum or metallic magnesium, are supported at their opposite ends within fiber glass strips disposed between and longitudinally of the balsa wood core sections with the strips encircling the fluted tubular rungs in the manner of two part bearings, the tubular rungs being closed at both ends by plugs inserted therein prior to the placing of the fiber glass strips over the core.

A novel feature of the invention resides in a ladder which is impervious to weathering, non-corrosive and which possesses a high dielectric characteristic thereby enhancing the safety factor of the ladder when the ladder is used for example in proximity to electrically charged high tension wires.

Another novel feature resides in embedding by means of a plastic compound the rung ends into the cores to form an integral part thereof and thereby reenforcing the rails of the ladder at these points in contradistinction to ladders as heretofore constructed.

These and other novel features of the present invention will be apparent from the following description and by the claims appended thereto, reference being had to the accompanying drawing in which:

Fig. l is a perspective view of an extension ladder section constructed according to the present invention;

Fig. 2 is a perspective view of a section of the two part core;

Fig. 3 shows the same core material with a strip of glass support material laid on the core section;

Fig. 4 depicts by a series of cutaway sections a builtup portion of side rail constructed in accordance with this invention;

Fig. 5 is a sectional view of a side rail taken at the section 55; and

Fig. 6 is a further sectional view taken through the side rail both laterally and longitudinally to show the manner in which the rung is supported.

Turning first to Fig. 5, the manner in which the side rail is built may be readily seen. Two core sections'22 and 23 of cellular material for example, cellular cellulose acetate, or wood as above mentioned, form the central longitudinal members.

Referring to Fig. 2 there is shown one of the core sections 12 having channels 13 for the setting therein of the rung ends. Laid between the core sections in Fig. 5 are two layers 24 and 25 of glass-reinforced plastic.

As shown in Fig. 4 these two layers 24 and 25 extend for the entire length of the side rail and encircle each rung end. As indicated in Fig. 6, the rung is hollow permitting the insertion of a glass-reinforced plastic plug member 19. The rung is thus supported in the side rail by an encircling band of glass-reinforced plastic formed by layers 24 and 25 and having the internal support resulting from the molded-in plug 19. 1

Continuing outwardly in Fig. 4 and Fig. 5 from th core material there is applied next a wrap-around sheet 16 of glass fiber extending lengthwise of the side rail, thus serving to enclose the core sections. A further layer 17 of continuous glass fibers running around the side rail next covers the inner layer 16. Finally, an outer sheet 18 also of continuous glass fibers extending longitudinally is applied to provide the outer covering.

The entire structure is then subjected to heat and pressure in accordance with methods well-known in the art to produce a molded, integral structure of unusual strength. It will be seen that the final side rail section comprises a series of plastic laminations in which the fibrosity alternates in direction with each layer. Additionally, the fluted rungs are molded and sealed in the side rail through the unique combination of the glass reinforced plastic plug member and the encircling glassreinforced plastic layers.

Further, it is evident that the materials thus employed are relatively impervious to deterioration under even extreme atmospheric conditions.

While a particular embodiment of the invention has been disclosed, it will be obvious to one skilled in the art that various modifications may be made without departing from the scope and spirit of the invention as defined by the claims.

While a particular embodiment of the invention has been disclosed, it will be obvious to one skilled in the art that various modifications may be made without departing from the scope and spirit of the invention as defined by the claims.

What is claimed is:

1. A ladder including in combination a pair of side rail members and a plurality of tubular rung members having plugs inserted at both ends therein, each said side rail member comprising a pair of core members each having a. plurality of semicircular recesses in one surface thereof for receiving said rung members, a pair of fiber glass strips separating said core membrs longitudinally and surrounding the ends of said rung members, a plurality of fiber glass strips surrounding said core members and having different orientations of fibrosity and a plastic material filling the interstices between said core members, the ends of each of said rung members at their periphery, the flat outer disposed surface of said plugs and said outer disposed strips for securing and forming a coating over the rail assembly.

2. A ladder having side rails and a plurality of cylindrical tubular rung members for connecting said side rails, a plug fitted at each end of each of said rung members, each of said side rails comprising a core formed of two similarly shaped sections, each having a series of plain semicircular recesses equally spaced along one of their surfaces for receiving the ends of said rung members when said core sections are positioned to place said fitted in said semicircular recesses for completely encirdill: the, g of said rung members, a plurality of fiber My! lengthwise of said cores cooperating with mentioned strips to form an envelope each or said core sections longitudinally thereof, lmlhsrfibfirl w Strip disposed over the outer disposed sides ofbotlt of said longitudinally formed envelopes and a plastic material filling the interstices between said core members the ends of each of said rung members and laid harming, a bonding coating thereover.

3. A comprising side rails, cylindrical rung connecting said side rails, each of said side a core formed of two similar longitudi- Ill mm having a plurality of registering semicircular and IIIIIII to one side thereof, a pair of woven fiber glass strip herposed between said core sections coopersting for completely encircling the ends of said rung members when said longitudinal core sections are placed to position said means in registering relation, a plurality of fiber glass strips disposed over the three outer disposed sides of each of said core sections in said relation extending longitudinally thereof, another woven fiber glass strip disposed over said longitudinally extending fiber glass strips, and a plastic material securely bonding each of said fiber glass strips to said core sections and the cylindrical end portions of said rung members to form a unitary structure.

References Cited in the tile of this patent UNITED STATES PATENTS 285,605 Flora Sept. 25, 1883 1,575,208 Jacobs Mar. 2, 1926 1,887,546 Cowell Nov. 15, 1932 2,171,863 Pirsch Sept. 5, 1939 2,414,125 Rheinfrank Jan. 14, 1947 2,484,608 Cheyney et al. Oct. 11, 1949 2,594,561 Huck Apr. 29, 1952 2,727,672 De Luca Dec. 20, 1955

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