CA1225975A - Fold-up ladder - Google Patents

Abstract

ABSTRACT
A fold-up portable ladder has U-shaped sections that are connected by hinges. The lower arm of each U-shaped section defines the ladder rungs. Latches adapt-ed to fit into and mate with an aperture located in the vertical portions of the U-shaped section are position-ed at the lower ends of each U-shaped section. These sections become progressively narrower as they approach the top section of the ladder.

Description

NEW FOLD-UP LADDER
BACKGROUND OF T~E INVENTION
It is known to use various forms of collapsible and fold up ladders for both domestic and commercial use.
A number of these prior art embodiments are very bulky when folded and are extremely difficult to carry. In addition several of these ladders require time-consuming and difficult processes for disengaging the ladder after use. Correspondingly, most of these known ladders are troublesome to set up for use after storage.
Typical fold up ladders are disclosed in U. S.
patents 3~216,526; 3,554,318; 3,655,012; 3,730~295 and 3,811,151, At present~ the fold up ladders known on the market consist of sections of several treads which are almost o the same length as that o the main strut of the portable ladder itsel~, to which i-t backs. These additional sections are linked by clamps to the couple o maln struts between which the treads are placed.
These clamps secure the struts of the main and ~~~

secondary sections allowing the longitudinal extension o~ this secondary section along the main one in the length it allows and its securing required by means of anchorage o~ one section in relation to the other.
Another design consists in linking both sections, main and secondary on their ends by a hinged joint.

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Nevertheless, this other solution is less reliable for the use of the ladder, as the securing lug-ged nut has to exert a great pressure in the aligned position in order to avoid the collapsing of the end of the ladder once it has been subject to the load of the person stepping on the additional top section, the effect of which load is still aggravated by the increase originated by the lever arm of the lengthen-ing section itself. Therefore/ this model is still less safer than the first. Nevertheless, both show the drawbac~ of the difficulty of handling of collaps-ible ladders~ as well as that of their weightiness and of that of requiring too much space when not in use, specially if they have to be carried from one working site to another, as they usually do not fit into small cars.
As noted above, the presently availahle ladders have serious drawbacks when assembling for use, or dis-engaging for storage. In addition they are relatively ~ expensive to manufacture and not always structurally reliable when in use.
SUMMARY OF THE INVENTION
It is therefore an object of an aspect of this invention to provide a fold-up portable ladder devoid of the above noted disadvantages.
An object of an aspect of this invention is to provide a fold-up and portable ladder that is compara-tively easy and relatively inexpensive to manufacture.

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An object of an aspect of this lnvention is to provide a ladder that is structurally sound, and reliable for both domestic and commercial use.
An object of an aspect of this invention is to provide a fold-up ladder that is relatively compact when folded, is easily stored or carried, and simple to fold down when not in use.
An object of an aspect of this invention is to provide a lightweight ladder that can be easily converted into stepladders of various lengths and designs, even stepladders where the A-frames are of different lengths.
Various aspects of the invention are as follows:
A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising means adapted to movably fit into and mate with a means located in the upper sections of said vertical portions of said modules, and guide portions immediately adjacent said apertures to facilitate easy entrance of said latch into said aperture.
A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said 3a locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising latches adapted to movably fit into and mate with an aperture located in the upper sections of said vertical portions of said modulesl and tapered grooved guide portions immediately adjacent sald apertures to facilitate easy entrance of said latch into said aperture.
By way of added explanation, in accordance with an aspect of this invention there is provided a novel fold-up portable ladder which comprises a plurality of U-shaped sections, that form both the rungs and side rails of a ladder when assembled, each section attached and hinged at lts lower portion to :~0 ~5 ~`

the next adjacent section, positioned below each of said hinges are latches adapted to fit into and mate with an aperture loca~ed in the vertical wall of the said next adjacent section~ the lowest of said U-shaped sections being the widest and the top uppermost of said U-shaped sections being the narrowest and each of said sections in between being progressively narrower as they approach the top section. The latches are spring loaded so that when aligned with and mated into said aperture they will remain in place and securely hold each rung in position. To disengage each latch~ there is positioned in each horizontal rung portion a spring and an external latch or spring release. When the pair of latch or spring releases are pinched together~ the latch is forced away from said apertures and releases each U-shaped section from the next adjacent section. The vertical arms of each U~shaped section thus are connected to and aligned with the next section by the use of latches located in the horizontal base of each U-shaped section. The latches in the horizontal base fit into the orifice or aperture in each vertical section adjacent to it.
Each aperture has tapered grooves or slide portions that allow the latches to slip into the aperture easily when setting the ladder up for use. Also, the tips of each latch portion is tapered to conform to the configuration of each orifice or aperture slide portion that facilitates the movement of the latch into the aperture. The spring releases need not be manipulated when setting up the ladder, only when the ladder is to be folded up after use.
Any suitable material may be used in the con-struction of the ladder, typical materials are steel7 aluminum, other metals, plastics such as polycarbonates, polyurethanes, polyesters, polyvinyl materials, or - other polymers. ~lso wood fiberglass7 or other synthe-tic materials may be used. To avoid this drawback, the subject of the present model of utility has been design-ed, thanks to which the ladder consists of as many different sections as treads compose it, being hinged one to that immediately following it, upwards in dimension, all of them being inscribed in the lowermost tread or section of dimensions greater than all ~he remaining components of the ladder. In this manner, when the ladder has been folded down, the same consists of a multiplicity of tread-sections inscribed ones inside the others, the whole constituting an assembly easy to taking with shouldered and passing

2~ the arm through the central orifice in the same manner as a roll or rope is borne.
On the other hand, this design also allows it to place the folded-down ladder inside the luggage compart-ment of passenger cars.
To its correct understanding, a case of practical realization is described beneath, as an example only~ with no limitative character, of the new fold-up ladder, enclosing one sheet of drawings on which:

37~i BRIEF DESCRIPTION OF DRAWINGS AND
DESCRIPTION OF THE PREFERRED EMBODIMEN~S
The preferred embodiment of this invention is illustrated in the accompanying drawings and descrip-tion.
Figure 1 shows diagramatically a ladder built in accordance with the in~ention, unfolded so that every section is aligned with respect to the foregoing one, being fixed through the corresponding rectract-able securing fasteners;
Figure 2 shows the same ladder~ after having capsized its sections and folded them down completely being carried by the user on his shoulder;
Figure 3 is a partial side view of the lock-ing mechanism of this invention, illustrating the latch and aperture mating section; and Figure 4 is a partial top view of this same locking mechanism.

The invention consists in the ladder being.
made up of a multiplicity of U-shaped modules or sections, showing the shape of a rectangular frame lacking of one of the smaller laterals (2), each of which frames has its two arms hinged (3) to the two arms of the following smaller module, for which reason, in the folded position, every module (1) of the ladder is inscribed inside the frame of the foregoing one, except the larges~(lA) corresponding to one end of the ladder and by swinging them, the modules (1) become alternatively placed in such a position ones to the others~ that the ends of the arms of one group ~5~

of modules faces the ends of the arms o the other group of modules, all them becoming placed in the same plane, out of which they are taken at the user's will by pulling the last smallest module llB) upwards, so that the assembly of modules (l) advances up to a certain limit, after which every module ~l) is swung around itself for 180 with reference to the formers, so that all the modules (l) become aligned to each other, by keying elements ~4) arranged on each module so that in the aligned position of the greater lateral struts, the keying elements of one of the individual frames introduce in the orifices arranged in the lateral struts of the aligned opposite module, the treads of the ladder therefore forming the own bases l5) of every U-shaped module. While in Figs. l and 2 keying elements (4) extend beyond the plane of arms ~l), in Figs. 3 and 4 they do not. Latch (11) in Figs. 3 and 4 are locked internally.
DESCRIPTION OF DRAWINGS AND PREFERRED EMBODIMENTS
The invention consists as earlier noted in that the foldable portable ladders of the type made up by a multiplicity of U-shaped sections (1) duly linked one to the other by hinged means l3)~ inscribed in the external one, which is the largest of said sections and the following of smaller size in what concerns the foregoing section and with retractable means of fastening the frames in their extended position, characterized by the fact that the latch (ll) securing one section (12) with reference to its immediately ~.~2~7~

following section ~13) is arranged in the tread-base (5) of the U-shape of e~ery section, the head of rung (5) which is shaped ogivally with its peak blunted or shaped in any other form that eases the sliding of the latch (11) that emerges out of every arm or rung (5) of the "U" in its linking point to the base and nearer to the end of the mentioned tubular arm of rectangular section, a chamber (15) being shaped in every one of the vertical edges of the inside face of every arm (15) and at the same height to each other.
At the centre of said internal face and between two chambers, the opening or orifice (6) of the location for the head of the latch lll) has been envisaged, which chambers (15) on being one section swung with reference to the immediate other section~ the head of the latch (11) emerging from the base (5) of the "U"
of a section (12) encounters the corresponding chamber ~15) of the adjacent section (13)~ which, in view of the inexistence of the chamber, this acts as a ramp on which the head of the latch (11) is forced back, and which on becoming one section (12) aligned with another (13) penetrates into the central location orifice ~6). Latch (11) in Figs. 3 and 4 only extend into orifice (6) and does not protrude through arm section 13 or section 1 of Figs. 1 and 2. In Fig. 4 the solid line drawing show rung (5) in released position and dotted line in locked position. Fig. 4 shows by dotted line adjacent release (16) the direction release (16) will go when pinched together for release. Spring 117) facilitates both holding and releasing latch (11) from orifice 16). Dotted line adjacent ~5) show~ 15) in locked position.
Latch release 116) when pinched together will release latch ~11) and withdraw it from orifice 16~
permitting the ladder to be folded as hinges (3) hold the sections together for folding.
At present in prior art ladders there exists the drawback that if one section swings around its pivot to fold and becomes applied to the following section, in the moment in which the section of longitudinal beam that constitutes the folding or unfolding section comes to a position in which it grates the longitudinal beam of the immediate following section, the latch that always aims to emerge totally has to be pulled back by hand, as it is expelled by virtue of the antagonist action of the incorporated elastic means, and which, in the aligned position of the sections arranged perpend~cularly or juxtaposed will make up every strut ~ o~ the unfolded ladder or the inscription of one section inside the other when the ladder has been fold-ed down.
To avoid the drawback of having to actuate by hand every one of the latches of every section of the ~5 right strut as well as that o~ the left one of he ladder~ the present model of utility has been applied forr as it allows ! hat this retention and re-emergency of the latch be carried out automatically without the intervention of the hands of the user of the ladder, 5~

merely by the friction of the matching surfaces of the latch and of the strut's edges.
Figures 1 and 2 illustrate an embodiment of this invention where latch or Xeying element ~4) extends through the vertical arms 1, lA or lB and can be seen external of the ladder. A second embodiment is shown in Figs. 3 and 4 where latch lll) does not extend through the arm ~13) but merely penetrates into orifice (6) in section (15) of arm ~13)~ and cannot be seen beyond the outer edge of arm ~13)~ or vertical arms 1, lA or lB of Figures 1 and 2. Figure 2 clearly shows the tapered grooves or chambers (15) that facil-itate the entrance of latch lll) into orifice (6) of Figs, 3 and 4.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising means adapted to movably fit into and mate with a means located in the upper sections of said vertical portions of said modules, and guide portions immediately adjacent said apertures to facilitate easy entrance of said latch into said aperture.

2. A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising latches adapted to movably fit into and mate with an aperture located in the upper sections of said vertical portions of said modules, and tapered grooved guide portions immediately adjacent said apertures to facilitate easy entrance of said latch into said aperture.

3. The ladder of claim 2 wherein said hinges are positioned in the lower portion of said U-shaped section.

4. The ladder of claim 2 wherein said hinges are positioned above said latches in each U-shaped section.

5. The ladder of claim 2 wherein said hinges connect the lower portion of a U-shaped section to the upper vertical portion of the U-shaped section immediately below it.

6. The ladder of claim 2 wherein said latches are spring loaded permitting them to be locked in position when located in said aperture.

7. The ladder of claim 2 wherein said latches are connected to latch releases, said latch releases located externally of the rungs of said ladder.

8. The ladder of claim 2 wherein said aperture has immediately adjacent it on both sides a tapered groove portion that permits easy entrance of said latch into said aperture.

9. The ladder of claim 2 wherein said latch and aperture are square.

10. The ladder of claim 2 wherein said latch and aperture have the same configuration to permit easy mating of the two.