U.S. patent number 3,786,899 [Application Number 05/174,441] was granted by the patent office on 1974-01-22 for ladder.
Invention is credited to Heinrich Zenhausern.
United States Patent |
3,786,899 |
Zenhausern |
January 22, 1974 |
LADDER
Abstract
A ladder comprises two stringers, a plurality of rungs and
fastening elements for fastening said ladder to structure, said
fastening elements and said rungs being provided, at their ends
with external toothing and the stringers carrying a plurality of
shiftable and clampable connecting elements some of which are
provided with a blind bores for receiving ends of said rungs and
others of which are provided with bores for receiving ends of said
fastening elements.
Inventors: |
Zenhausern; Heinrich (Urdorf,
CH) |
Family
ID: |
4388033 |
Appl.
No.: |
05/174,441 |
Filed: |
August 24, 1971 |
Foreign Application Priority Data
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|
|
|
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Aug 27, 1970 [CH] |
|
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12964/70 |
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Current U.S.
Class: |
182/93;
182/228.5 |
Current CPC
Class: |
E06C
7/182 (20130101); E06C 9/02 (20130101); E06C
9/08 (20130101) |
Current International
Class: |
E06C
9/08 (20060101); E06C 9/00 (20060101); E06C
9/02 (20060101); E06c 009/02 (); E06c 007/08 () |
Field of
Search: |
;182/46,93,229,52,194,228 ;52/704 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Machado; Reinaldo P.
Attorney, Agent or Firm: Stepno, Schwaab & Linn
Claims
I claim:
1. A ladder for attachment to a structure comprising
a pair of parallel, spaced continuous stringers, each formed of a
single, unbroken tubular element;
a plurality of generally tubular rungs;
first means connecting the ends of each of said rungs to said
stringers, each of said first connecting means secured in spaced
relation about one of said tubular stringers and defining a
frusto-conical bore having a plurality of independent circular
grooves each having a first flank perpendicular to the axis of said
groove and a second flank inclined thereto;
the ends of each of said rungs having a plurality of independent,
circular barb-like ribs formed thereon for establishing a permanent
interconnection between said rungs and said stringers upon direct
insertion of said rung ends into said first connecting means;
anchor means adapted to be permanently attached to the structure
and defining a frusto-conical bore having a plurality of
independent circular grooves each having a first flank
perpendicular to the axis of said groove and a second flank
inclined thereto;
a plurality of generally tubular fastening elements; and
second means connecting one end of each of said fastening elements
to one of said stringers, each of said connecting means secured in
spaced relation about one of said tubular stringers and defining a
frusto-conical bore having a plurality of independent circular
grooves each having a first flank perpendicular to the axis of said
groove and a second flank inclined thereto;
the ends of each of said fastening elements having a plurality of
independent, circular barb-like ribs formed thereon for
establishing a permanent interconnection between said stringers and
the structure upon direct insertion of said fastener element ends
into said second connecting means and said anchor means.
Description
FIELD OF THE INVENTION
This invention relates to ladders which can be attached to
structures to facilitate climbing thereon.
DISCUSSION OF PRIOR ART
In sewer shafts, water reservoirs or clarification plants, on house
walls, industrial chimneys or similar objects, an arrangement is
generally known which makes possible the negotiating of the same.
Thus in sewage plants there are climbing irons which are cemented
into the wall of the shaft and form a ladder or steps via which one
can easily climb down into the shaft.
Since the conventional mounting of these climbing irons by
cementing-in is not only complicated and time-consuming but also
expensive, it has already been proposed to mount such climbing
irons on brackets attached to plugs sunk in the shaft wall. By this
means the great danger of oxidation and rusting of the cemented-in
ends of the climbing irons can be reduced, particularly if the
brackets are produced from a material which has a great resistance
to moisture, corrosive gases and chemicals.
However, it is often more expedient, instead of mounting individual
climbing irons or elements on the wall, to mount a complete ladder.
A ladder possesses a great inherent stability and the number of
anchoring points is reduced quite substantially. However, a
disadvantage when using already formed ladders arises in that the
points of attachment of the ladder are fixed and so a highly
precise mounting of anchors on the shaft wall is necessary.
Moreover, for each shaft, a ladder adapted in its size to the shaft
must be used, which means that a large stock must be kept by a
supplier.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a ladder which
does not have the above disadvantages and can be used in all types
and sizes of shafts and on walls, chimneys and other
structures.
Accordingly the invention provides a ladder, for attachment to a
structure, comprising a plurality of rungs, two stringers and
fastening elements, said rungs and said fastening elements being
provided at their ends with external toothing and said stringers
carrying a number of shiftable and clampable connecting elements
some of which elements are provided with at least one blind bore
for receiving a free end of one of said rungs and others of which
are provided with bores for receiving respective one ends of said
fastening elements.
The ladder of the invention can be assembled in situ and be made up
to a desired size and configuration as desired. It is stable and
resistant to corrosion. The stability of the ladder of the
invention can be enhanced by the external toothing being formed by
a number of circular barb-like ribs, which ribs have an inclined
flank directed towards the end of the rungs or stringers and a
flank extending perpendicularly to the axis of the rungs or
stringers. Furthermore, it is advantageous if the rungs, stringers
and fastening elements are in the form of steel tubes provided with
a coating of polyethylene or aluminium. Alternatively the rungs,
fastening elements or stringers can be made from aluminium tube
provided for reinforcement, with internal radially directed webs or
cross pieces which extend over their entire length.
In a preferred embodiment of ladder conforming to the invention the
rungs and/or fastening elements can carry, on their ends, a
respective pressed-in plastic pins or tenons provided with the
external toothing. The external toothing can be formed in the
polyethylene coating or in an aluminium tube itself.
DESCRIPTION OF A PREFERRED EMBODIMENT
The invention will be described further, by way of example, with
reference to the accompanying drawings, wherein :
FIG. 1 is a perspective view of a preferred embodiment of ladder
conforming to the invention and mounted in a shaft;
FIG. 2 is a cross-section through a junction of a rung with a
stringer of the ladder of FIG. 1 showing a connecting element
thereof; and
FIG. 3 illustrates, partly in section, a fastening element of the
ladder of FIG. 1.
The ladder of FIG. 1 comprises a number of rungs 1, two stringers 2
and four fastening elements 3. Provided in the structure of shaft
4, for mounting the ladder are a number of sleeve-like anchoring
elements 5, each of which has a slightly frusto-conically tapered
bore which corresponds, in diameter to the fastening elements 3.
These elements 5 can be cast integral, for example during
construction of the shaft in accordance with a specific
arrangement, in which case not-needed sleeves are sealed with a
stopper 6 - or the sleeves can be subsequently inserted into holes
formed in the shaft. In this latter case the sleeves can be
provided with barb-like external ribs 7, as shown in FIG. 3.
Those ends of the elements 3 which are inserted into the bores of
the sleeves 5 are provided with barb-like ribs 8 which can be
formed directly in the polyethylene or aluminium coating
surrounding the fastening elements 3, as shown in FIG. 3, or a pin
or tenon 9 can be provided which is pressed into the end of each
fastening element 3, as is shown in FIG. 1.
The fastening elements 3 are fastened by means of connecting
elements 10 to the stringers 2. Similarly designed connecting
elements 11 connect the rungs 1 to the stringers 2, and one
embodiment of connecting element 11 is represented in section in
FIG. 2. It possesses a blind bore 12 which is slightly
frusto-conically tapered. The bore 12 serves for receiving the one
end of a rung 1. Each of the rungs 1 is provided, at its ends, with
barb-like toothing in the form of ribs 13 which ensure a secure fit
in the bore 12 of the connecting element 11. It is advantageous to
seal the hollow end of the rungs 1 in an air-tight and damp-proof
manner with a stopper 14. A corresponding sealing, which is not
represented in more detail in the drawing, is undertaken at the
ends of the fastening elements 3 and of the stringer 2. As is
further clearly evident from FIG. 2, the connecting elements 11
possess a continuous bore 15, which is likewise slightly
frusto-conically tapered and which has a somewhat greater diameter
than the stringer 2. They can thus be displaced, together with the
rungs 1, along the stringers 2 to any desired position and can be
fastened by means of frusto-conically shaped sleeves such as the
sleeve 16 which is pressed into the bore 15. If required, the outer
surface of the sleeve 16 and/or the inner surface of the conical
bore 15 can additionally be provided with barb-like toothing in the
form of ribs 17. If desired, connecting element 11 may have a
clamp-like connector structure, as shown with respect to element
10, for cooperation with stringers 2.
It has been proved to be very favourable to produce the connecting
elements 11, as well as the stoppers 16, from a resistant, but
nevertheless somewhat elastic, plastics material such as nylon.
If, moreover, steel tube provided with a polyethylene coating, is
used for the rungs 1, for the stringers 2 and for the fastening
elements 3, an excellent and permanent insulation of the entire
climbing arrangement in relation to the brickwork can be
achieved.
In FIG. 3, a second embodiment of a connecting element which may be
used in place of connector 10 or 11 is illustrated in which the
ends of rungs 1 and fastening elements 3 are provided with a
plurality of independent, circular barb-like flanges adapted to
directly cooperate with the grooved frusto-conical bore of the
connector.
With the ladder of the invention the possibility is provided of
guaranteeing the negotiability of structures provided with it for
years to come with great safety. There exists very little danger of
breakage as a result of corrosive attacks, and also tearing-out or
breaking-away of the fastening elements from the structure is
highly unlikely. However, the possibility exists of dismantling the
ladder undamaged, by means of suitable tools. Upon the erection of
the ladder arrangement, no working with hammer and chisel nor any
plaster work whatever is necessary, so that the erection can be
effected in the shortest time by unskilled labour.
The ladder can have an upper extension for resting on part of a
structure above it for extra support.
The invention is not limited to the precise details of the
foregoing embodiment and variations may be made thereto within the
scope of the following claims.
* * * * *