US2178856A - Ladder construction - Google Patents

Description

Nov. 7, 1939. i H. J. HElDER 2,178,856

LADDER CONSTRUCTION Filed Jan. 24, 1938 Patented Nov. 7, 1939 unrrs srs 1 Claim.

The object of my invention is to provide an improved ladder construction wherein the strength of the ladder may be greatly increased Without materially increasing the weight of the ladder.

More particularly, it is the object of my invention to increase the strength of the side rails of a ladder against strains being imparted to them in one direction, by providing a suitable truss rod construction, and in connection therewith, improved means for anchoring the ends of the rods to support them against longitudinal movement relative to the side rail.

A further. object of my invention is to provide a ladder of simple, durable and inexpensive construction having improved means for strengthening the side rails, and also improved means for tying the side rails and cross rungs together.

My invention consists in the construction, arrangement and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claim, and illustrated in the accompanying drawing, in which:

Figure 1 is a plan view of a ladder including my improved construction.

Figure 2 is a segmental side elevation of the same, one of the sections of one of the side rails being in longitudinal section.

Figure 3 is an inverted plan view of Figure 2.

Figure 4 is an enlarged segmental top view of the ladder showing the manner in which one of the rungs is tied into the side rails, a portion of the junction of one end of the rung and the side rail being shown in section.

Figure 5 is a diagrammatic longitudinal sectional view of one of the rails as bent, showing the manner in which the top edge or cord of the rail is compressed when the rail is so bent.

Figure 6 is an enlarged detail sectional View taken on the line 5-5 of Figure 3.

Figure 7 is an enlarged detail sectional View taken on the line 'l! of Figure 4.

In the drawing 1' have used the reference numeral it to indicate the side rails of a ladder and H the rungs, each of the rungs I! having a pin i2 turned on each of its ends, of a length substantially equal to one-half the thickness of the rails iii, said members l2 being designed to fit into openings l3 formed in the inner faces of the side rails. The lower side of each of the rungs i !-is provided with a longitudinal groove M for receiving a rod l5 having each of its ends screw-threaded and projecting through openings I6 adjacent to the bottom side of the openings 58, each end of the rod 15 being provided with a. washer l1 and a nut l8, thus providing means whereby the rails Hi may be rigidly tied to the rungs H. The said rod l5 rests in a groove I4 so that the said rod I5, will be within the outer contour of the rung and thus support the said rod l5 in such a manner as not to be engaged by ladder hooks or like devices such as are commonly used on extensionladders, when the said ladder section is used in connection with an extension ladder. The rod l5 also serves as a truss to strengthen the middle of the rung against bending downwardly when a heavy weight is carried thereby. The lower edge of each of the rails Ill is provided with a longitudinal groove Hi. The upper corner of each end of each side rail is provided with a beveled portion 25. Each end of each of the side rails is also provided with a diagonal hole 2|, said hole being bored from the beveled faces 20 inwardly and downwardly and intersecting the grooves lit at the points 22, the said hole 2| beingsubstantially at right angles to the faces 20. In each of the grooves 59 I haveprovided a truss rod 23 having each of its ends screw-threaded and extended through the openings 2i, as clearly illustrated in Figure 2. Each end of the rod 23 is provided with a washer 2t and a nut 25.

Adjacent to the inner face of the rod 23 and adjacent to each of the intersecting points 22 I have provided a transversely arranged bolt 26 to serve as a pressure saddle for the truss rod 23,- the said bolt 26 extending through the side rail in the manner clearly illustrated in Figure 6, and serves to strengthen the side rail against splitting due to the excessive strain being applied to the rod in order to give the desired strength.

The bolts 26 also serve to prevent crushing and cutting of the material from which the siderail is constructed, atthe points 22. In the actual manufacture of the ladder I preferably construct the side rails of a light and somewhat porous material, such as spruce, and, of course, the

rods i5 and 23 are constructed of wrought iron or steel.

The bending of the ends of the rods 23 upwardly and outwardly to the upper corners of the rails provides suitable arrangement of the rod to give the maximum strength to the rail against downward movement when a load is applied to the upper surface of the center of the rails and with each end supported against downward movement.

By providing the inclined faces 20 at substantially right angles to the bent ends of the rods 23, and providing suitable washers and nuts, I have provided means whereby great strains may be applied to the rods 23 without compressing or otherwise distorting the material from which the rails are made, so that the truss rods will not become loose after the rails have been bent a few times, as would be the case if the abutments or ends of the rails were not properly constructed. The rods 23 are of such diameter and of such tensile strength that the rods will not materially stretch when the rails are bent downwardly in the manner illustrated in Figure 5, and or such strength that the material in the upper edges of the rails will be compressed without stretching the said truss rods when excessive loads are applied to the rails. By this arrangement I have provided means whereby the ladder will always return to its original position as soon as the weight has been removed, and whereby the truss rods are always maintained in a tight and eificient condition.

If, for any reason, the abutments or faces 20 should give, due to softening of the wood or other material from which the ladder rail may be constructed, by atmospheric or weather conditions, the tension of the rod may be again established by simply tightening one or more of the nuts 24.

I am Well aware that the broad idea of applying longitudinal truss rods to the rail of a ladder v is not new, but heretofore difficulty has been experienced in keeping the truss rods provided with proper tension to assist in strengthening the rail. This I have accomplished by providing suitable abutments for the rods and suitable saddles at the points where excessive strains are applied, said saddles preferably being arranged to prevent splitting of the rail and also prevent compression of that portion of the rail adjacent to the junction of the hole 2| and the groove I9.

Thus, it will be seen I have provided means whereby the rails may be greatly strengthened against bending and also means whereby the ladder is rigidly tied together and the rungs of the ladder are also reinforced against downward bending.

I claim as my invention:

A ladder, comprising side rails and. cross rungs, the lower edge of each rail being provided with a longitudinal groove, the upper corner of each being provided with a beveled face, each face having an opening inclined downwardly and inwardly and intersecting said groove, a truss rod supported in said groove having its ends threaded through said openings, a nut and washer on each end of said rod, a bolt supported transversely through said rail against the inner face of said rod and adjacent to the intersection of said groove and each of said openings,-the rails being formed of compressible material and the truss rods of such size and tensile strength so that if a load be placed on the center of said rails of sufiicient weight to bend the same with the ends supported against downward movement, the upper edges of the rails will be compressed without appreciably stretching said truss rods.

HENRY J. HEIDER.

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