US3414081A - Contractible ladder - Google Patents

Description

Dec. 3, 1968 A. F. WEDVIK 3,414,081

CONTRACTIBLE LADDER Filed May 18, 1967 INVENTOR. 4155? F. W'DV/K I E. 5mm

United States Patent 3,414,081 CONTRACTIBLE LADDER Albert F. Wedvik, 1615 2nd Ave. W., Seattle, Wash. 98119 Filed May 18, 1967, Ser. No. 639,446 1 Claim. (Cl. 182-160) ABSTRACT OF THE DISCLOSURE A contractible ladder having spaced-apart legs joined by end-pivoted rungs provided with stops bearing on leg surfaces to maintain themselves horizontal and to limit downward movement of the outer leg even though otherwise unsupported.

BACKGROUND Collapsible ladders including a pair of oppositely disposed flanged leg members connected together by end-pivoted rungs are known from the Phifer Patent 248,607. However, in the prior art contractible ladders, where one leg member is attached to a support and the other or outboard leg member is shifted outward to dispose the rungs in the usual horizontal manner, either the outer leg has to be arranged to come to rest upon a base of support or it has to have some other suspension means provided to limit its downward movement. In the latter instance, a chain or other flexible linkage is required. Further, it has been foundthat with ladders constructed according to the prior art, there is a noticeable and very undesirable looseness and lack of rigidity when the ladder is under load.

It is the primary object of this invention to provide a laterally contractible ladder which when extended for use, becomes stiff and rigid despite there being no solid support for or suspension of the outboard leg member.

A still further object of this invention has been to provide a contractible ladder which is simple and easy to construct, may be installed with facility, and which when extended from its normal contracted condition, will move automatically, easily and rapidly under the forces of gravity into its useful configuration.

DESCRIPTION In the accompanying drawing is shown a preferred form of the invention. In the several views:

FIG. 1 is a perspective view of the ladder shown contracted and, in phantom, extended;

FIG. 2 is an enlarged detail of the upper end of the ladder in contracted condition, portions being broken away and omitted for the purposes of illustration;

3 shows the upper end of the ladder in extended position;

FIG. 4 is a cross section taken along line 44 of FIG. 2;

FIG. 5 is a cross section taken on line 55 of FIG. 3;

FIG. 6 is a perspective view of the upper end of the ladder in contracted condition illustrating latching means employed in holding the ladder legs in close juxtaposition; and

FIG. 7 is a perspective view of one end portion of a ladder rung.

The main structural elements of the ladder are the first flanged leg member 10 and the second flanged leg member 12. Both are L-shaped in cross section. When leg member 10 is mounted on a structure, as 14, which may be the side of a building or a house by means of support brackets 16, one flange 11 of member '10 will be normal to such structure. The second leg member 12 is disposed in relation to leg member 10 in opposition so that the opposite but like flange 13 is parallel to flange 11 of leg 10 but lies in a plane substantially offset therefrom. This can best be seen in FIG. 4.

Patented Dec. 3, 1968 A plurality of spaced-apart flat rung members are pivotally connected at their ends by pins 20 to the flanges 11 and 13. In order to accommodate the offset disposition of the flanges 11 and 13, there are bends 22 which bring the rung ends 24 into substantial face-to-face juxtaposition with the inner faces of the leg flanges 11 and 13.

As shown in FIG. 7, each rung end 24 is provided with a curved portion 26, substantially concentric with hole 28 through which passes pivot pin 20. Rung end 24 also has a squared corner 30 which comprises a stop when it is swung to abutting relationship with the flange inner surface, e.g., that flange of leg 10 which is disposed parallel to structure 14. Similarly, the other end of rung 18 is provided with an oppositely arranged curved surface 26 and stop or abutment 30', as may be seen in FIG. 3. When the leg members 10 and 12 are contracted together, as shown in FIG. 1, they are held by means of a latch pin 32 engaged by the knots of a latch arm 34 pivoted at 36 and provided with a lever 38 from which they depend a cord or chain 40.

It should be apparent that a ladder as described would be very useful as an escape or emergency ladder from an upper story to a point nearer the ground and that during 1 periods of nonuse, it is out of the way, unobtrusive, and yet immediately ready for use as the need may arise. All that -a user need do is to trip the draw string 40 or move the lever 38, disengaging the latch arm 34 from the pin 32. By so locating the pivots 20 on the inboard end of the rungs 18 closer to the structure 14 than are the pivots 20 on the leg 12, the weight of the outboard leg 12 and of the rungs will be outside of a vertical plane including the inboard pivots. Gravity will immediately cause the outer leg to swing outward and downward. This is facilitated by insuring that the pivotal connections 20 are loose or free and preferably not tight enough so that they will freeze. This looseness, however, would normally be expected to produce a ladder which is shaky and one that would give the user a feeling of instability. However, as the other leg 12 swings out and the rungs moving with it reach the horizontal position, the stops 30 come into abutting relation with the inner surfaces of legs 10 and 12 which are parallel to the supporting structure 14. In part, the weight of the outer unsupported portion of the ladder and, particularly, the weight applied by a person using the ladder causes the rung ends to jam and to bear rigidly against the leg members. This produces a stiffening and rigidifying of the over-all assembly despite the fact that the leg 12 neither bears on a base support or in some other manner is suspended.

It will, of course, be apparent to those skilled in the art that the preferred embodiment shown and described herein may be subject to numerous variations in proportion, or substitution of materials, or other modifications. All such as falls within the spirit of the doctrine of equivalents, liberally applied in accordance with the law as may be justified in this case, are intended to be covered by this patent.

For example, it is pointed out that in FIGS. 4 and 6 the flanges 11 and 13 are shown to lie in parallel offset relationship to each other, spaced apart a substantial distance. Each rung 18, by reason of its bends at 22, is disposed in an angular relationship between the parallel flanges 11 and 13. This arrangement accommodates the spaced-apart relationship of the two flanges 11, 13 to which each of the rungs is pivoted at its ends. It has been shown in the drawings that the rungs, in the collapsed or contracted position of the ladder, are end-to-end and do not overlap each other. However, it should be readily apparent that this offset relationship permits an overlapping of adjacent rungs 18. If it be assumed that the side members 10 and 12 in the extended position are, say, twelve 3 inches apart, the lengths of the rungs 18 would be approximately that same dimension in the end-toend arrangement shown. Because of the described potential overlapping relationship permitted by the angular relation produced by the bent shape of the rung, the spacing between the rungs may be only eight or nine inches even though the side rails 10 and 12 are to be spaced apart ten, twelve, fourteen or more inches. Thus, one can accommodate specific circumstances encountered, as where a ladder may be used in connection with a primary school or a home with many small children, or the like, and it is desired to have the rungs closer together than are the side rails.

I claim:

1. A contractible ladder, comprising:

a first flanged leg member, L-shaped in cross section, adapted to be supported upright by independent structure with one flange normal to such structure;

a second flanged leg member, L-shaped in cross section, and disposed in opposed relation to said first leg member in such manner that a like flange is normal to said structure and resides in a plane offset from the plane of said one flange of the first leg memher;

a plurality of spaced-apart, flat bar rung members extending between said leg members disposed substantially normal to said structure;

each of said bar rung members being disposed on edge and pivotally connected with flat faced juxtaposition at one end to said one flange of said first leg member and at the other end to the like but opposed flange of said second leg member, said rung members being shaped between the ends to accommodate Cir the offset planar relation of said opposed flange members; and

each of the rung members at their pivotally connected ends being shaped to permit pivoting and movement of the second flanged leg member into close parallel relationship with said first flange leg member with the pivots of said rung members connecting the same to said first leg member being located closer to said structure than the pivots connecting said rung members to said second leg member, when said leg members are in said close parallel relationship, and each said rung member end including stop means to abut the inner faces of the other flanges of each of said flanged leg members when said rung members are disposed substantially horizontal and the second flanged leg member is positioned in outward spaced relation to said structure; and

releasable means is included for securing said first and second leg members in said close parallel relationship.

References Cited UNITED STATES PATENTS 248,607 10/1881 Phifer 182-460 278,301 5/1883 Welsh 182-160 704,126 7/1902 Seessle 182160 719,990 2/1903 Bracklo 182-460 FOREIGN PATENTS 23,853 11/1929 Australia.

I REINALDO P. MACHADO, Primary Examiner.

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