Note: Descriptions are shown in the official language in which they were submitted.
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~TEPI.ADDER
SPECIFICATION
The present invention pertains to a stepladder
as used, e.g., in swimming pool construction.
Such ladders extend from the edge of the pool
first vertically upward and are then bent over in
the direction of the pool, and then they pass over
into a vertical section which ends via another
angulated section in the zone of the water. The
1i5 ladders are usually anchored in the area of the pool
edge. In the zone of the water, they often only lie
against the pool wall.
Like other ladders, these ladders consist of
the two lateral guide rails and at least one step
connecting the guide rails. The guide rails of
prior-art stepladders are made in one piece and
consist of, e.g., steel, aluminum, or plastic. This
also applies to the ladder steps, which are usually
made in one piece with the corresponding sections of
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The state of the art and the present invention
will be explained below in greater detail on the
basis of an above-described stepladder for swimming
pools, without thereby limiting the field of
application of the stepladders according to the
present invention. Consequently, the term
"stepladder" also covers ladders which are used,
e.g., in the household, trade, or the like.
It is a disadvantage of the prior-art swimming
pool stepladders that, depending on the size of the
swimming pool, different formats must be provided.
However, not only do the ladders differ in terms of
their height/length, depending on, e.g., the depth
of the water, but the distances between the two
vertical legs of the stepladders also vary from one
case to the next, depending on where the stepladder
can be fastened, e.g., at the edge of the swimming
pool.
In addition, one customer wishes to have only
one or two steps, while another would like to have
three or four steps for a stepladder of otherwise
identical design.
This leads to increased costs for the
manufacturer of the stepladders, especially because
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of different tools for different shapes and types of
stepladders.
Finally, individually shaped stepladders, e.g.,
those with handgrips, can be manufactured only by
individual production.
Based on this state of the art, the basic task
of the present invention is to provide a stepladder,
especially for swimming pools, which permits
simplified production and is nevertheless
individually adaptable, depending on the customer's
wishes, in terms of size, shape, and design.
To accomplish the above-described task, the
present invention is based on the general
consideration that the stepladders or their guide
rails are assembled from discrete elements which can
be individually outfitted, ~epending on the desired
size, shape, and number of steps and are designed
such that they make it possible to design continuous
guide rails with steps located between them.
The present invention is based on the idea that
this can be realized in a particularly simple and
advantageous manner by designing the individual
segments in a tubular shape and with an axial
passage hole, wherein the segments arranged one
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behind the other are tensioned with one another via
a cable which connects the segments to one another,
extends through the axial passage holes of the
segments, and i5 anchored at the end.
In its most general embodiment, the present
invention suggests a stepladder of the type as
described above, which possesses the following
characteristics:
. - each guide rail consists of a plurality of
tubular segments arranged one behind the other,
each tubular segment being provided with an
axial passage hole,
- a cable is led along the passage holes of
the segments of each guide rail,
- each cable is fixed under tensile stress
at its free ends relative to the corresponding
segments,
- a step extends between at least two
segments of adjacent guide rails, which
segments are arranged next to one another at
spaced locations.
Any size and shape can be manufactured due to
the stepladder being assembled from individual,
discrete elements.
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In the simplest case, in which the stepladder
extends only linearly, its length can be varied very
simply by using more or fewer segments to form the
corresponding guide rails. In this case, additional
cross webs are preferably arranged between the guide
rails at the end in order to stiffen the ladder.
In the case of the stepladders of the above-
mentioned type, which are used, e.g., in swimming
pools, i.e., stepladders with bent guide rails, the
goal of the present invention can be accomplished
analogously; it is only necessary to design
individual segments in a bent shape, preferably in
the shape of circular segments.
Even though the stepladder is composed from a
plurality of individual segments according to the
present invention, it forms as a whole a more or
less rigid system. This is achieved by the cable
led through the segments, which is tensioned with
tensile stress at the ends of each guide rail. The
individual segments are thus lashed, so that they
will subsequently have a defined shape that is
extensively resistant to deformation.
An embodiment in which adjacent segments of one
guide rail are connected in a positive-locking
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manner, but detachably, is particularly preferxed.
The positive locking nature of the segments with one
another increases the stability of the ladder as a
whole.
In an advantageous embodiment, it is suggested
that each segment be provided, viewed in the
direction of the passage hole, with a recess
extending coaxially to the passage hole at one end
and -- at its opposite end -- with a projection that
extends coaxially to the passage hole and whose
cross section is equal to or slightly smaller than
that of the recess. It is thus possible to
introduce the projection of one segment into the
recess of the adjacent segment, as a result of which
the two are first connected. If the guide rail has
been thus designed, the cable, which has been pulled
through and tensioned at the ends, ensures that the
geometry thus established is preserved even under
mechanical stress on the ladder, e.g., by a person.
Contrary to the one-piece guide rails or one-
piece ladders, the ladder according to the present
invention offers the additional advantage that it
has a certain intrinsic elasticity and is able to
show a certain, reversible deformability in the case
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of, e.g., high loads caused by a large or heavy
person.
The projections and recesses of each segment
should advantageously have a circular cross section
and be part of a cylindrical segment. Cylindrical
segments which -- arranged one behind the other --
complement one another to form a cylindrical guide
rail have the advantage that they can easily be
grasped with the hand and rule out the risk of
injury due to edges.
From the viewpoint of high reliability of
operation, the present invention also suggests that
the proiections of the segments be designed --
viewed in the axial direction of the passage hole --
with a greater length than the corresponding
recesses. As a consequence of this, the tubular
segments inserted one into the other have a certain
distance from one another circumferentially, so that
there is no risk of pinching even if a person grasps
the guide rail precisely in the zone of adjacent
segments and the segments undergo a slight
deformation relative to one another, e.g., under a
high load.
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Experiments have shown that a distance of about
2 cm between adjacent segments is sufficient to
eliminate any risk of injury. For the same reason,
the largest diameter of the projection of each
segment should also be smaller by at least 4 cm than
the outside diameter of the segment, so that an
inwardly extending annular segment with a width of
ca. 2 cm will be obtained between adjacent segments.
While the recesses of each segment may also be
designed such that they slightly taper conically
toward the interior of the segment, the
corresponding projections should also be slightly
conical toward the free end in this case, so that
reliable positive connection of adjacent segments
will always be guaranteed.
The tensioning of the individual segments
relative to one another by means of the cable can
also be brought about in different ways. While it
is usually sufficient to mechanically anchor the
cable at one end of each guide rail, a tensioning
device for the cable should be provided at least at
the other end of each guide rail, with which
ttensioning device] the cable can be subjected to a
predeterminable tensile stress in order to securely
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fasten the individual segments relative to one
another. Such tensioning elements for cables have
been known from the construction industry, but they
are used for other purposes there. The tensioning
device may consist of, e.g., a receiving part with
internal threads fastened at the end of the cable,
which [receiving part] can be screwed onto a
threaded bolt fastened, for example, at the edge of
the pool, as a result of which the effective cable
length between the anchoring points in reduced.
To ensure high tensile forces and consequently
reliable positive-locking connection of the segments
to one another, the cable may be, e.g., a metal
cable, preferably a steel cable. However, plastic
cables, especially plastic cables twisted from a
plurality of fibers, which are characterized by
extremely high tensile strength and consequently can
be used within the framework of the present
invention, are also currently known.
The shape and the material for the segments can
, .
`~ be selected nearly completely freely. Cylindrical
segments are usually used for the vertical sections
of a ladder. However, to form handgrips, e.g.,
.
` above the surface of the water, it is also possible
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to arrange, along the ver~ical section, e.g.,
semicircular segments with bent end sections which
will then again extend coaxially to the adjacent
cylindrical segments and are connected to them in a
positive-loc~ing manner.
Designing the segments as plastic parts is
particularly advantageous. In this case, they can
be manufactured, e.g., by injection molding or
extrusion methods. The shaping and coloring that
can thus be achieved are practically unlimited.
For installation on a swimming pool, it is
usually sufficient to anchor the ladders in the area
of the pool edge. To do so, at least the last
segments at the corresponding end of the stepladder .
should be designed with a device for locking the
stepladder in the ground, deck, or wall. For this
purpose, any desired elements are available to the
person skilled in the art. For example, the last
segments may be designed with a circumferential
flange which is bolted against the pool edge.
The steps extending between the guide rails may
; be made in one piece with the corresponding
segments, or they may also be suspended from them,
` e.g., in a positive-locking manner~
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The design according to the present invention
makes it possible to arrange any desired number of
steps of any design between the guide rails,
depending on the customer's wishes. It is also
possible, for example, to manufacture a stepladder
that consists of three guide rails, as a result of
which basically two stepladders are provided, and,
for example, the distance between the steps of one
of the ladders is designed to be greater for adults
than the distance between the steps of the ladder
arranged next to it, which will thus preferably be
used, e.g., by children.
The description given above shows that the
design embodiments of the ladders are unlimited.
Nevertheless, only a small number of basic elements
are needed to manufacture any desired ladder.
The present invention will be described below
in greater detail on the basis of an embodiment.
The following views are represented in a
schematic representation:
Figure 1 shows a side view of a step fastened
to the edge of a swimming pool,
Figure 2 shows a top view of the step according
to Figure 1 as viewed from the water,
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Figure 3 shows a partially cutaway detail of
the last segment of a guide rail that rests against
the pool wall, and
Figure 4 shows a partially cutaway view of the
connection zone between adjacent segments.
Identical components and components with
equivalent functions are designated by identical
reference numerals in the figures.
In Figure 1, reference numeral 10 designates
the edge of a swimming pool and 12 designates its
wall. ;
Two guide rails 14 of the stepladder 16 are
firmly anchored at the pool edge 10.
Said guide rails 14 have a first section 14a
extending vertically in the upward direction from
the pool edge 10, an adjacent semicircular section
14b, another vertical section 14c adjoining the
latter in the downward direction, and, finally, at
the lower end, a section 14d extending in the inward
direction over a quarter circle, whose free end lies
loosely against said pool wall 12.
Each said guide rail 14 consists of a plurality
of segments 18. Said segments 18 of said sections
: 14a, 14c are cylindrical, while said segments 18 of
12
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said sections 14b and 14d are designed as curved
cylinders.
Each said segment 18 has a central passage hole
20. With the exception of the end segments 18,
which are connected to said pool edge 10 or lie
against said pool wall 12, each segment 18 is
provided with a recess 22 at one end and with a
projection 24 at the other end. Said recess 22 and
said projection 24 extend coaxially to the
respective passage hole 20, as is shown most clearly
in Figure 4.
Viewed in the direction of said passage hole
20, said projections 24 have a greater height than
do said recesses 22.
This causes said adjacent segments 18 to be
circumferentially spaced from one another by a
distance of d when a segment 18 with its projection
24 is introduced into the corresponding recess 22 o~
the adjacent segment 18 for positive-locking
connection (Figure 4).
Figure 4 also shows that --relative to said
:~ passage hole 20-- adjacent segments 18 are alsospaced apart in the radial direction, because said
projections 24 have a smaller diameter than do said
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segments 18 as a whole.
This leads to the formation of an annular
channel 26 of height "d" and width "B" between said
adjacent segments 18.
Comparison of Figures 1 and 4 shows that said
segments 18 are arranged one behind the other. To
fix them in this association, a steel cable 28,
which is locked in the last segment 18 at the end
that lies against said pool wall 12 and via a
tensioning device, under tensile stress, at the
opposite end (i.e., in the area of said segment 18),
which stands on said pool wall 10, is passed through
the continuous passage hole 20 of said segments 18.
The individual segments 18 are thus tensioned among
themselves and fixed relative to one another in a
positive-locking manner, so th~t said segments 18
that belong together always form a guide rail 14.
Adjacent to the pool wall 10, said segments 18
have, at their free ends, a circumferential flange
18a, which is used to fix the corresponding guide
rails 14 at said pool edge 10 by means of screws 30.
Figures 1 and 2 also show that two steps 32 are
arranged between the adjacent guide rails 14. Said
steps 32 always extend between two adjacent segments
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18 of each guide rail, and are made in one piece
with them.
Figure 3 shows an embodiment of a device for
tensioning said cable 28.
For tensioning, the end of said cable 28 is
provided with a section 28a, which has a
circumferential threading 28b. A nut 34 having
corresponding internal threads can be screwed onto
said threads 28b. A washer 36 is placed between
said nut 34 and said segment 18 in the area of an
expanded section 38 of said segment 18. Depending
on how far said nut 34 is screwed onto said threads
28b, said cable Z8, whose other end is anchored in
the same way within the corresponding segment 18,
can be tensioned.
It is obvious that the shape and design of the
stepladder according to the Figures 1 through 4 can
be varied within broad ranges by imparting a
different shape to the individual segments, by
making them shorter or longer, by arranging
additional steps between adjacent segments, or by
connecting, on the whole, a greater number of
seqments one behind the other, so that said guide
rails 14 on the whole will be longer.
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The stepladder would also be able, e.g., to
have the shape of an ord~nary ladder used in trade
or household, i.e., for example, to have a side view
having the shape of an inverted V, with a holding
member connecting the two legs of the ladder. Such ;~
a ladder can be erected by folding over at what will
subsequently be the apex and subsequently tensioning
the tensioning cable, but after releasing the
pulling cable, it can be folded up in nearly any
desired shape, so that is can easily be transported.
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