Note: Descriptions are shown in the official language in which they were submitted.
63S
This invention relates to a ladder and in particular
to a collapsible ladder.
In general, emergency ladders of the types used as
fire escapes in multi-level dwellings are rather bulky, often
heavy devices which are difficult to store. Moreover, such
ladders are not always readily transformed from the storage or
folded condition to the e~tended or use condition.
The object of the present invention is to offer a
solution to the above-identified problems by providing a
relatively simple collapsible ladder, which is lightweight,
capable of being folded to a compact storage condition, and
easily unfolded to an extended or use condition.
Accordingly, the present invention relates to a
collapsible ladder comprising a plurality of panel means
pivotally interconnected in end-to-end relationship to form a
compact body when folded into overlapping relationship with
each other and to define an elongated body when unolded so
that the panel means are end-to-end in a plane, each said
panel means including substantially rigid, central,
transversely extending rung means and at least one side bar
means on each end of said rung means pivotally connected to
said rung means and to any subjacent or superjacent side bar
means for rotation between a storage position in the same
plane as said rung means and a use position perpendicular to
said rung means; and spring means for biasing at least one and
consequently all other said side bar means to the use
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position, whereby, when the said panel means are unfolded, the
side bar means automatically rotate to the use position.
The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, perspective view from above
and one side of a collapsible ladder in accordance with the
present invention;
Figure 2 is a schematic, perspective view of the
ladder of Figure 1 in the partly extended condition;
Figure 3 is a schematic, perspective view of the
ladder of Figs. 1 and 2 in the fully extended, use position;
Figure 4 is a bottom, elevational view of a panel
used in the ladder of Figs. 1 to 3;
Figure 5 is an end view of the panel of Fig. 4;
Figure 6 is a side view of the panel of Fig. 4;
Figure 7 is a plan view of a second panel used in
the ladder of Figs. 1 to 3;
Figure 8 is a side view of the panel of Fig. 7;
Figure 9 is an end view of the panel of Fig. 7;
Figure 10 is a schematic plan view of the panels of
Figs. 4 to 6 and 7 to 9 interconnected to form a ladder
section; and
Figure 11, which appears on the third sheet of
drawings with Fig. 5, is a perspective view of a torsion
spring used in the ladder of Figs. 1 to 3.
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With reference to Figs. 1 to 3, the ladder of the
present invention includes a plurality of generally H-shaped
sections generally indicated at 1, which can be folded
accordion style into a stacked, storage condition (Fig. 1) or
unfolded (Fig. 2) to a flat condition (not shown). In the
flat condition, the sides of the sections 1 fold automatically
upwardly and inwardly to define ladder side bars 2 of
generally U-shaped cross section. Such side bars impart
relative high strength to the ladder, even though thin
aluminum is used in the construction of the sections 1.
Referring to Figs. 4 to 6, each section 1 of the
ladder is defined by a wide H-shaped panel 4, the crossbar of
which defines a rung 5 of the ladder. Longitudinally
extending, rectangular projections 6 alternating with grooves
8 on the rear surface of the rung 5 strengthen the structure.
The sides 9 of the panel 4 define portions of the ladder side
bars 2. For such purpose, generally circular lugs 10, 12 and
13 are provided on the top, bottom and outer side edges,
respectively o~ each side 9 of the panel 4.
The lugs 10 and 12 define loops with holes 14
therethrough for receiving hinge pins tnot shown) for
pivotally interconnecting panels 4 in end-to-end relationship.
The lugs 10 are staggered with respect to the lugs 12, so that
panels 4 can be connected end-to-end with the lugs 10 and 12
of adjacent panels overlapping. As shown in Fig. 6, the lugs
10 and 12 on one panel are reversed with respect to the lugs
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10' and 12' on the next super~acent or subjacent panel 4, so
that the panels can be folded accordion-style into full
contact, overlapping relationship [Fig. 1). By "reversed" in
this case is meant that one set of lugs 10 or 12 extends
outwardly and towards the front or rear of the panel 4 (in the
erect position of the ladder), and the other set of lugs 10"
or 12" extends in the opposite direction ont he superjacent or
subjacent panel 4.
The lugs 13 are generally C-shaped and alternate,
i.e. alternately open towards the front or rear of the panel 4
(in the erect position of the ladder) for receiving hinge pins
(not shown) for pivotally connecting the sides 9 of the panel
4 to rectangular panels 15. The lugs 13 overlap with similar
lugs 17 on the panels 15. In cooperation with the sides 9 of
the panels 4, the panels 15 define the ladder side bars 2.
The panel 15 is defined by a planar, rectangular body 18, with
the lugs 17 on each side thereof, and lugs 19 and 20 on the
ends thereof. The lugs 17 are similar to the lugs 13, i.e.
generally C-shaped, and the lugs 19 and 20 are similar in
terms of shape and si~e to the lugs 10 or 12. Moreaver, the
lugs 19 are reversed with respect to the lugs 20 in the same
manner as the lugs 10 and 12. The lugs 19 alternate with the
lugs 20 for connecting the panels 15 together in end-to--end
relationship. The lugs 17 are opposite to each other. When
forming the side bars 2 of the ladder, the panels 25 of the
second or outer row of panels 15 are reversed with respect to
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the panels 15 of the first or inner row, so that the lugs 17
of one panel overlap the lugs 17 of the other panel 15.
A torsion spring 22 (Figs. lO and 11~ is defined by
a rod 23 with hook ends 24. The spring 22 replaces the hinge
pin between adjacent panels 4 and 15 or between two panels 15.
A spring 22 can be provided at each joint between a panel 6
and a panel lS or ~etween each adjacent pair of panels 15.
However, a spring at alternate connections along the length of
the ladder will perform the required task of causing the
panels to snap into the ladder or use position as soon as the
sections have been completely unfolded to the flat condition.
In use, the ladder is stored in the completely
folded condition (Fig. 1), forming a tidy, compact bundle.
When aluminum is used to form the panels 4 and 15, the ladder
lS is relatively lightweight and easy to carry. In order to use
the ladder, sections 1 thereof are unfolded (Fig. 2) until the
entire assembly is flat on the floor or other surface. As
soon as the last section 1 has been unfolded, the torsion
springs 22 cause the panels 15 to rotate around the sides 9 of
the panel 4 to define the ladder side bars 2 (Fig. 3). It is
easy to force the sections 1 to the flat condition manually
for refolding of the ladder to the storage condition.
It is readily apparent that the simplest form of
the ladder includes fixed rung sections or panels 4 with lugs
~n the outer side, top and bottom edges thereof for pivotally
interconnecting the rung panels to each other and to at least
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one set of side bar panels at each end of the rung panels.
In the use position, the resulting ladder would have L-shaped
sides, and would still function as a ladder. Admittedly,
greater strength is achieved by having side bars of U-shaped
S cross section. In fact, ladders formed in the manner
described hereinbefore, i.e including sections 1 defined by a
panel 4 and a pair of panels 15 on each side thereof are
surprisingly strong in the use condition and can take a heavy
load when laid horizontally between two end supports. Typical
overall dimensions for the panels 4 are a length or height of
24 cm and a width of 47.6 cm. Lightweight material such as
aluminum can be used to fabricate each of the elements of the
invention, except for the torsion spring 22.
Thus, there has been described a relatively simple,
lightweight collapsible ladder, which can readily be unfolded
to a flat condition. Once collapsed to a flat condition, the
sides of the ladder automatically pivot to form U-shaped side
bars. A nylon belt or rope can be provided between such side
bars for ensuring that the side bars remain in the folded, use
position. In order to collapse the ladder, the side bars are
folded outwardly to the flat condition against the bias of the
torsion springs and the sections are refolded to the collapsed
condition.
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