CA1206454A - Ladder - Google Patents
LadderInfo
- Publication number
- CA1206454A CA1206454A CA000421992A CA421992A CA1206454A CA 1206454 A CA1206454 A CA 1206454A CA 000421992 A CA000421992 A CA 000421992A CA 421992 A CA421992 A CA 421992A CA 1206454 A CA1206454 A CA 1206454A
- Authority
- CA
- Canada
- Prior art keywords
- ladder
- rungs
- side pieces
- shank
- rung
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C7/00—Component parts, supporting parts, or accessories
- E06C7/08—Special construction of longitudinal members, or rungs or other treads
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C7/00—Component parts, supporting parts, or accessories
- E06C7/08—Special construction of longitudinal members, or rungs or other treads
- E06C7/082—Connections between rungs or treads and longitudinal members
- E06C7/086—Connections between rungs or treads and longitudinal members with a connecting piece inserted in a hollow rung
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C1/00—Ladders in general
- E06C1/02—Ladders in general with rigid longitudinal member or members
- E06C1/04—Ladders for resting against objects, e.g. walls poles, trees
- E06C1/08—Ladders for resting against objects, e.g. walls poles, trees multi-part
- E06C1/12—Ladders for resting against objects, e.g. walls poles, trees multi-part extensible, e.g. telescopic
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C7/00—Component parts, supporting parts, or accessories
- E06C7/10—Reinforcements for ladders
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Ladders (AREA)
Abstract
A B S T R A C T
The disclosure relates to a ladder set with mutually interconnectable sections which are disposed for varying the effective length of the ladder and which comprise two side pieces (1) and a number of rungs (2) fixedly disposable therein, in which both the side pieces and the rungs are manufactured of a profiled material. The side pieces have longitudinal, substantially enclosed pockets (4) for accommodating longitudinal projection members (3) on an adjacent section.
The ladder is designed so as to be manufactured as an easily assembled kit and so as to possess extremely good resistance forces to the composite and extreme loadings which prevail when the ladder is in use.
The ladder is characterized in that the rungs (2) are of closed cross-section with non-rotational symmetrical cross-sectional configuration, and that each end of the rungs has at least one projection (15). The projections consist of protruding portions of the wall material (14) of the rungs and are torsionally rigidly disposable in corresponding recesses in the side pieces. The rungs are urged against the side pieces by anchorage means (16) discrete from the projections.
The disclosure relates to a ladder set with mutually interconnectable sections which are disposed for varying the effective length of the ladder and which comprise two side pieces (1) and a number of rungs (2) fixedly disposable therein, in which both the side pieces and the rungs are manufactured of a profiled material. The side pieces have longitudinal, substantially enclosed pockets (4) for accommodating longitudinal projection members (3) on an adjacent section.
The ladder is designed so as to be manufactured as an easily assembled kit and so as to possess extremely good resistance forces to the composite and extreme loadings which prevail when the ladder is in use.
The ladder is characterized in that the rungs (2) are of closed cross-section with non-rotational symmetrical cross-sectional configuration, and that each end of the rungs has at least one projection (15). The projections consist of protruding portions of the wall material (14) of the rungs and are torsionally rigidly disposable in corresponding recesses in the side pieces. The rungs are urged against the side pieces by anchorage means (16) discrete from the projections.
Description
Applicants: Lennart Holgersson and Berne Mahl Title of the invention: Ladder The present invention relates to a ladder which is designed as a so-called ladder set with several different sections which may be interconnected to one another such -that the effective length of the ladder may be varied. The ladder according to the invention is, furthermore, manufactured of profiled material and is designed in such a manner that, in the unassembled state, it may be distributed and sold for assembly at the site of use.
The art abounds in different types of ladder sets manufactured of aluminium profiles. These prior art ladders are, however, manufactured and assembled at one and the same place, rivet connections being often used to connect the different co~ponents which make up the ladder. This entails that the ladder must be transported in the fully assembled state which, because of the bulky nature of the ladder, is an expensive matter in itself and which, moreover, entails that a purchaser of the ladder must pay for the assembly work even though he himself would perhaps have preferred to carry out this work. In the handling and use of a ladder in such a manner that the ladder is subjected to oblique loading, extremely high demands are placed on the points of connection oF the ladder. This applies not only to connections between the different sections of the ladder but also between the different fittings which form part of a ladder section. Thus, for example, older ladders in which the different ladder sections are interconnected to one another by means of catches may be experienced as highly unstable in many situations. Furthermore, it is not entirely possible that such a ladder may inadvertently come apart even under loading.
One form of loading which is particularly difficult to deal with in a satisfactory manner is rotation of the ladder about its longitudinal axis.
Such loading occurrences may arise if, for example, the ladder is placed on uneven ground, if the one upright of the ladder sinks into the ground or if the ladder is placed with its uppermost rung resting against a corner, a narrow tree or the like so that the support area will be asymmetrically located. In such oblique loading, the joint between the different ladder sections will, naturally, be subjected to extreme loading, but an even more - ~V~
L5~
serious problem is the twisting load or torsion which occurs in the rungs themselves and in their anchorage in the uprights. Since deformation of the ladder rungs and their anchorages is slight but the forces that much greater, this will entail, in particular if the material of which -the ladder is manufactured consists of an easily-deformable aluminium material, that extremely great care must be devoted to these details. If, for example, the ladder is joined together by rivet connec-tions, the ex-treme loadings which occur more or less as point loading in these rivet connections will rapidly deform the rivet connections so that play occurs whereby the ladder will feel completely unstable. As a rule, it is not possible to subsequently adjust or reset the rivet connections.
The object of the present invention is to realize a so-called ladder set which may be manufactured as an easily-assemblable kit and which, in the assembled state, possesses very good resis-tant forces to the extreme loadings to which the ladder is often subjected when in use.
This object is achieved according to the invention by means of a ladder of the type intimated by way of introduction which, in each section, comprises two uprights and a number of rungs fixedly mountable therein, both the up-rights and the rungs being designed of profiled material and the uprights having a longitudinal, substantially enclosed, channel portion, and a longitudinal projection member so tha-t the projection members on one ladder section are torsionally rigidly disposable as longitudinally shiftable in the channels of another ladder section, if the ladder according to the present invention is characterized in that the cross-section of the rungs has an enclosed profile, that each end of the rungs has at least one projection which, on assembly of the ladder, is torsionally rigidly fixable in a recess in the upright, and that the rung is urgable against the upright by means of anchorage members discrete from the projections.
In one practical embodiment, the ladder according to the present invention is suitably characterized in that the rungs possess non-rotational symmetric cross-sectional profile and that the projection and anchorage members are disposed on opposing sides thereof.
A particularly simple and advantageous embodiment of the present invention will be attained if the ladder is characterized in that the projection consists of a portion of the wall material of the rung projecting beyond the end surface of the rung.
In order to eliminate play between di-fferent ladder sections, and in order to improve the slide running therebe-tween, the ladder is also suitably charac-teri~ed in that interconnec-ted ladder sections are in guiding engagement with one another by the intermediary of a number of longitudinal guiding ribs, preferably disposecl interiorly in -the channels.
The nature of the present invention ancl its apsects will be more readily understood from the following brief description of the accompanying drawings, and discussion relating thereto.
In the accompanying drawings:
Fig. 1 shows, from beneath, a portion of two mutually interconnected ladder sections; and Fig. 2 illustrates an end por-tion of a rung.
It will be apparent to the skilled reader of Fig. 1 that -two of the side pieces, or uprights, in two mutually interconnected ladder sections are designated 1 on the drawings, whereas the rungs fixed -to the side pieces are designated 2. Thus, the drawing figure shows adetailed view of two ladders seen from beneath.
It is further apparent from Fig. 1 that the side pieces are manufactured of profiled material, preferably aluminium profiles which have U-shaped cross-section and which, on the one free shank, have two projections 3 and, on the other free shank, a bent-over portion 4 which forms an as good as enclosed channel. It will moreover be apparent from the figure tha-t the projections 3 on the one side piece may be accommodated in the channel 4 of the other side piece, the one shank of the profiled material of the side piece ex-tending in through the opening 5 in the channel on the adjacen-t side piece. When the side pieces are interconnected with one another in this manner, they are freely shiftable in the longitudinal direction, at the same time as the webs 6 in the profiled ,naterial of the side pieces lie in a plane with one another.
This entails that the ladder sections may be identically designed and inter-;
~' q ~ s~
connectable with one another, for which reason a ladder design~d accordingto the present invention may be built up from a number of identical sections without it being necessary to distinguish between a top section, central section or foot section or the like.
The interior dimensions of the channels 4 are adapted in such a manner that the projections 3 and the adjacent portion of the one shank 7 may, along their major extent~ be accommodated in the channel 4 with relatively large play, in other words in such a manner that, for example, sand, gravel or other foreign matter will not cause seizure or in any other way prevent the relative shifting between mutually cooperatiny aluminium parts on two interconnected ladder sections.- In order that the ladder not feel unstable while in use, it is, however, important that cooperation between the side pieces be such that no play can occur in practice and, moreover, such that torsion about the longitudinal axis of the ladder efficiently be trans-mitted from the one ladder section to the other. For this reason, the .side pieces are provided with a number of guide ribs, also referred to as "protrusions" of which two guide ribs 8 are placed on the outer side of the second shank 9 of the side piece. Hence, the guide ribs 8 are placed so as to face towards the interior of the profied channel 4. Furthermore, the profiled channel is interiorly provided with two opposingly directed guide ribs 10 and 17 which are intended to laterally guide the ladder sections in relation to one another.
Naturally, it would also be possible to place all of the guide ribs on the first shank 7 of the profiled material of the side pieces and instead render the second shank 9 and the channel 4 interiorly smooth. The essential factor is merely that the side pieces possess fully acceptable guiding in relation to one another, at the same time as there must be space to allow for the departure of foreign matter without causing damage or without possibly causing the side pieces to jam in their relative movements.
As has been intimated above, a ladder of this current type is exposed to great, and many times composite loads while in use. The single loadings which affect the ladder symmetrically may be exemplified by a bending of the ladder as a whole, the bending plane lying parallel to the webs 6 of the side pieces. Loadings of this single type need not be dealt with further~
since they hardly cause problems of any magnitude. If, on the other hand, the ladder is obliquely loaded, for example in that one side piece sinks down into the ground on which it is resting or if the ladder i5 placed with ,0 5 ~2~S'~
its upper end against a building corner or a narrow tree, loading phenomena which are much more difficult to appreciate will occur. Particularly difficult loadings occur in such situations int al in that the ladder is exposed to rotation about its longitudinal axis. This twisting or rotation is transmitted to the rungs by the intermediary of the joints between the rungs and the side pieces, acting then in the form of a torsion loading.
For this reason, it is vital, on the one hand, that the proFile of the rung be of such design that it is torsionally rigid and, on the o-ther hand, that the joint between the rung and the side pieces be capable of transmitting the torsional forces which occur. The situation will be particularly troublesome if one takes into account the fact that the subject matter of the present invention is designed so as to be assembled at the site of use, in other words to be manufactured and sold in the form of a kit which cannot be joined together by, for example, welding. Furthermore9 such material properties as the softness of the aluminium material entail serious problems, since, on oblique loading of the ladder, extremely great local loadings easily occur which readily deform the material permanently, giving rise to play and a consequential instability of the ladder.
According -to the present invention, the rungs 2 are manufactured in the form of profiled rods which preferably may be extruded. The cross-section of these profiled rods is designed so as -to impar-t to the rung great load-absorption capacity in the vertical direction, at the same time as the rung must be able to withstand great torsional loadings.
The cross-sectional configuration of the rung illustrated in Fig 2 has been conceived taking into account the above-mentioned factors. Thus, the rung according to this drawing figure has two vertical and opposing side walls 11 which permit the accommodation and absorption of large vertical loadings. In order to reduce the risk of slip, but also in order to render the rung safer and easier to stand on, the upper face 12 of the rung is substantially planar - and fluted in its surface structure. In the corner regions between the side-walls 11 and the upper face 12, screw pockets 13 are provided for accommodating screws which are intended for joining together the rungs and the side pieces. Furthermore, the rung 2 has a subs-tantially planar underface 14 whereby the cross-section of the rung will be fully enclosed.The presence of the planar underface 14 entails that it is easy, by simple machining, to realize a projecting tongue 15 which extends throughout the entire width of the underface of the rung.
I ;
6 ~L~ 5 ~
On mounting of the rungs 2 in the side pieces, openings made pairwise in the side pieces corresponding to the screw pockets 13 are used so that screws 15'may be passed there-through. However, a screw connection is not sufficient to impart to the ladder its requisite stability, in particular not as regards the torsional loadings which rest upon the rungs. For this reason, the tongue 15 in the underface 14 of the rung is also employed for assembly purposes. Consequently, openings are also provided in the web 6 of the side pieces 1, apart from the openings for the screws 16, for the tongues 15, these openings being designed for tight fit with the tongues.
As was mentioned above, the rung 2 is of completely enclosed cross-sectional configura-tion, which greatly increases its capacity to withstand torsional loadings. Furthermore, the anchorage points between the rungs 2 and the side pieces are placed in such great spaced apart relationship to one another as is possible, so as thereby to reduce the effect of those loadings which occur in the joint regions. Cooperation between the tongue 15 and the corresponding opening in the web 6 of the side piece is also of particular importance in this context, whereby the torsion-transmitting capacity of the joint will be increased and the cross-sectional configuration of the rung will be locked in such a manner that it is highly unlikely that any alteration of the cross-sectional configuration can occur under extreme loading conditions.
The described method of joining the rung and side pieces involves greatadvantages partly because assembly may simply and readily be effected without access to particular tools directly at the site of use of the ladder. Furthermore, the described joint makes for a high degree of strength in particular under severe loading situations. Finally, it is also possible to reset and realign the joints if the ladder were to be damaged as the result of some form of overloading. Such resetting and realignment of the anchorage points of the ladder rungs can hardly be carried out to a ladder having permanent fixation, in particular not if it is manufactured by folding or riveting.
The invention may be modified without departing from the spirit and scope of the appended claims. Hence, it is possible to use rungs of a slightly different cross-sectional configuration than that shown in Fig 2. For example, such a cross-sectional configuration of the rung could have 7 ~2~ i4 substantially straight lower portions of the side-walls 11, these lower portions being provided with tongues corresponding to the tongue 15.
Naturally, it is also possible to place projecting tongues at the end of the rungs at other and, possibly, more places than has been suggested above; but the considerable weakening which would occur in the web 16 of the side pieces must, however, be taken into account if far too many and far too large projections are employed.
The art abounds in different types of ladder sets manufactured of aluminium profiles. These prior art ladders are, however, manufactured and assembled at one and the same place, rivet connections being often used to connect the different co~ponents which make up the ladder. This entails that the ladder must be transported in the fully assembled state which, because of the bulky nature of the ladder, is an expensive matter in itself and which, moreover, entails that a purchaser of the ladder must pay for the assembly work even though he himself would perhaps have preferred to carry out this work. In the handling and use of a ladder in such a manner that the ladder is subjected to oblique loading, extremely high demands are placed on the points of connection oF the ladder. This applies not only to connections between the different sections of the ladder but also between the different fittings which form part of a ladder section. Thus, for example, older ladders in which the different ladder sections are interconnected to one another by means of catches may be experienced as highly unstable in many situations. Furthermore, it is not entirely possible that such a ladder may inadvertently come apart even under loading.
One form of loading which is particularly difficult to deal with in a satisfactory manner is rotation of the ladder about its longitudinal axis.
Such loading occurrences may arise if, for example, the ladder is placed on uneven ground, if the one upright of the ladder sinks into the ground or if the ladder is placed with its uppermost rung resting against a corner, a narrow tree or the like so that the support area will be asymmetrically located. In such oblique loading, the joint between the different ladder sections will, naturally, be subjected to extreme loading, but an even more - ~V~
L5~
serious problem is the twisting load or torsion which occurs in the rungs themselves and in their anchorage in the uprights. Since deformation of the ladder rungs and their anchorages is slight but the forces that much greater, this will entail, in particular if the material of which -the ladder is manufactured consists of an easily-deformable aluminium material, that extremely great care must be devoted to these details. If, for example, the ladder is joined together by rivet connec-tions, the ex-treme loadings which occur more or less as point loading in these rivet connections will rapidly deform the rivet connections so that play occurs whereby the ladder will feel completely unstable. As a rule, it is not possible to subsequently adjust or reset the rivet connections.
The object of the present invention is to realize a so-called ladder set which may be manufactured as an easily-assemblable kit and which, in the assembled state, possesses very good resis-tant forces to the extreme loadings to which the ladder is often subjected when in use.
This object is achieved according to the invention by means of a ladder of the type intimated by way of introduction which, in each section, comprises two uprights and a number of rungs fixedly mountable therein, both the up-rights and the rungs being designed of profiled material and the uprights having a longitudinal, substantially enclosed, channel portion, and a longitudinal projection member so tha-t the projection members on one ladder section are torsionally rigidly disposable as longitudinally shiftable in the channels of another ladder section, if the ladder according to the present invention is characterized in that the cross-section of the rungs has an enclosed profile, that each end of the rungs has at least one projection which, on assembly of the ladder, is torsionally rigidly fixable in a recess in the upright, and that the rung is urgable against the upright by means of anchorage members discrete from the projections.
In one practical embodiment, the ladder according to the present invention is suitably characterized in that the rungs possess non-rotational symmetric cross-sectional profile and that the projection and anchorage members are disposed on opposing sides thereof.
A particularly simple and advantageous embodiment of the present invention will be attained if the ladder is characterized in that the projection consists of a portion of the wall material of the rung projecting beyond the end surface of the rung.
In order to eliminate play between di-fferent ladder sections, and in order to improve the slide running therebe-tween, the ladder is also suitably charac-teri~ed in that interconnec-ted ladder sections are in guiding engagement with one another by the intermediary of a number of longitudinal guiding ribs, preferably disposecl interiorly in -the channels.
The nature of the present invention ancl its apsects will be more readily understood from the following brief description of the accompanying drawings, and discussion relating thereto.
In the accompanying drawings:
Fig. 1 shows, from beneath, a portion of two mutually interconnected ladder sections; and Fig. 2 illustrates an end por-tion of a rung.
It will be apparent to the skilled reader of Fig. 1 that -two of the side pieces, or uprights, in two mutually interconnected ladder sections are designated 1 on the drawings, whereas the rungs fixed -to the side pieces are designated 2. Thus, the drawing figure shows adetailed view of two ladders seen from beneath.
It is further apparent from Fig. 1 that the side pieces are manufactured of profiled material, preferably aluminium profiles which have U-shaped cross-section and which, on the one free shank, have two projections 3 and, on the other free shank, a bent-over portion 4 which forms an as good as enclosed channel. It will moreover be apparent from the figure tha-t the projections 3 on the one side piece may be accommodated in the channel 4 of the other side piece, the one shank of the profiled material of the side piece ex-tending in through the opening 5 in the channel on the adjacen-t side piece. When the side pieces are interconnected with one another in this manner, they are freely shiftable in the longitudinal direction, at the same time as the webs 6 in the profiled ,naterial of the side pieces lie in a plane with one another.
This entails that the ladder sections may be identically designed and inter-;
~' q ~ s~
connectable with one another, for which reason a ladder design~d accordingto the present invention may be built up from a number of identical sections without it being necessary to distinguish between a top section, central section or foot section or the like.
The interior dimensions of the channels 4 are adapted in such a manner that the projections 3 and the adjacent portion of the one shank 7 may, along their major extent~ be accommodated in the channel 4 with relatively large play, in other words in such a manner that, for example, sand, gravel or other foreign matter will not cause seizure or in any other way prevent the relative shifting between mutually cooperatiny aluminium parts on two interconnected ladder sections.- In order that the ladder not feel unstable while in use, it is, however, important that cooperation between the side pieces be such that no play can occur in practice and, moreover, such that torsion about the longitudinal axis of the ladder efficiently be trans-mitted from the one ladder section to the other. For this reason, the .side pieces are provided with a number of guide ribs, also referred to as "protrusions" of which two guide ribs 8 are placed on the outer side of the second shank 9 of the side piece. Hence, the guide ribs 8 are placed so as to face towards the interior of the profied channel 4. Furthermore, the profiled channel is interiorly provided with two opposingly directed guide ribs 10 and 17 which are intended to laterally guide the ladder sections in relation to one another.
Naturally, it would also be possible to place all of the guide ribs on the first shank 7 of the profiled material of the side pieces and instead render the second shank 9 and the channel 4 interiorly smooth. The essential factor is merely that the side pieces possess fully acceptable guiding in relation to one another, at the same time as there must be space to allow for the departure of foreign matter without causing damage or without possibly causing the side pieces to jam in their relative movements.
As has been intimated above, a ladder of this current type is exposed to great, and many times composite loads while in use. The single loadings which affect the ladder symmetrically may be exemplified by a bending of the ladder as a whole, the bending plane lying parallel to the webs 6 of the side pieces. Loadings of this single type need not be dealt with further~
since they hardly cause problems of any magnitude. If, on the other hand, the ladder is obliquely loaded, for example in that one side piece sinks down into the ground on which it is resting or if the ladder i5 placed with ,0 5 ~2~S'~
its upper end against a building corner or a narrow tree, loading phenomena which are much more difficult to appreciate will occur. Particularly difficult loadings occur in such situations int al in that the ladder is exposed to rotation about its longitudinal axis. This twisting or rotation is transmitted to the rungs by the intermediary of the joints between the rungs and the side pieces, acting then in the form of a torsion loading.
For this reason, it is vital, on the one hand, that the proFile of the rung be of such design that it is torsionally rigid and, on the o-ther hand, that the joint between the rung and the side pieces be capable of transmitting the torsional forces which occur. The situation will be particularly troublesome if one takes into account the fact that the subject matter of the present invention is designed so as to be assembled at the site of use, in other words to be manufactured and sold in the form of a kit which cannot be joined together by, for example, welding. Furthermore9 such material properties as the softness of the aluminium material entail serious problems, since, on oblique loading of the ladder, extremely great local loadings easily occur which readily deform the material permanently, giving rise to play and a consequential instability of the ladder.
According -to the present invention, the rungs 2 are manufactured in the form of profiled rods which preferably may be extruded. The cross-section of these profiled rods is designed so as -to impar-t to the rung great load-absorption capacity in the vertical direction, at the same time as the rung must be able to withstand great torsional loadings.
The cross-sectional configuration of the rung illustrated in Fig 2 has been conceived taking into account the above-mentioned factors. Thus, the rung according to this drawing figure has two vertical and opposing side walls 11 which permit the accommodation and absorption of large vertical loadings. In order to reduce the risk of slip, but also in order to render the rung safer and easier to stand on, the upper face 12 of the rung is substantially planar - and fluted in its surface structure. In the corner regions between the side-walls 11 and the upper face 12, screw pockets 13 are provided for accommodating screws which are intended for joining together the rungs and the side pieces. Furthermore, the rung 2 has a subs-tantially planar underface 14 whereby the cross-section of the rung will be fully enclosed.The presence of the planar underface 14 entails that it is easy, by simple machining, to realize a projecting tongue 15 which extends throughout the entire width of the underface of the rung.
I ;
6 ~L~ 5 ~
On mounting of the rungs 2 in the side pieces, openings made pairwise in the side pieces corresponding to the screw pockets 13 are used so that screws 15'may be passed there-through. However, a screw connection is not sufficient to impart to the ladder its requisite stability, in particular not as regards the torsional loadings which rest upon the rungs. For this reason, the tongue 15 in the underface 14 of the rung is also employed for assembly purposes. Consequently, openings are also provided in the web 6 of the side pieces 1, apart from the openings for the screws 16, for the tongues 15, these openings being designed for tight fit with the tongues.
As was mentioned above, the rung 2 is of completely enclosed cross-sectional configura-tion, which greatly increases its capacity to withstand torsional loadings. Furthermore, the anchorage points between the rungs 2 and the side pieces are placed in such great spaced apart relationship to one another as is possible, so as thereby to reduce the effect of those loadings which occur in the joint regions. Cooperation between the tongue 15 and the corresponding opening in the web 6 of the side piece is also of particular importance in this context, whereby the torsion-transmitting capacity of the joint will be increased and the cross-sectional configuration of the rung will be locked in such a manner that it is highly unlikely that any alteration of the cross-sectional configuration can occur under extreme loading conditions.
The described method of joining the rung and side pieces involves greatadvantages partly because assembly may simply and readily be effected without access to particular tools directly at the site of use of the ladder. Furthermore, the described joint makes for a high degree of strength in particular under severe loading situations. Finally, it is also possible to reset and realign the joints if the ladder were to be damaged as the result of some form of overloading. Such resetting and realignment of the anchorage points of the ladder rungs can hardly be carried out to a ladder having permanent fixation, in particular not if it is manufactured by folding or riveting.
The invention may be modified without departing from the spirit and scope of the appended claims. Hence, it is possible to use rungs of a slightly different cross-sectional configuration than that shown in Fig 2. For example, such a cross-sectional configuration of the rung could have 7 ~2~ i4 substantially straight lower portions of the side-walls 11, these lower portions being provided with tongues corresponding to the tongue 15.
Naturally, it is also possible to place projecting tongues at the end of the rungs at other and, possibly, more places than has been suggested above; but the considerable weakening which would occur in the web 16 of the side pieces must, however, be taken into account if far too many and far too large projections are employed.
Claims (4)
1. A ladder of the type including at least two ladder sections connected with each other for a sliding movement relative to each other, each ladder section comprising a number of rungs and a pair of uprights, both the rungs and the uprights being made of profiled material, each upright including a longitudinal channel portion and a longitudinal projection member, the channel portion of one ladder section being adapted to slidably received the longitudinal projection of an adjacent ladder section, there being a plurality of longitudinally arranged protrusions for guiding a respective projection member along the associated channel portion and for maintaining mutually facing major surface portions thereof at a spacing from each other.
2. A ladder as claimed in claim 1 wherein the protrusions protrude from a second shank of the respective upright, said second shank supporting the respective channel portion.
3. A ladder as claimed in claim 2, comprising two protrusions transversely spaced from each other and protruding from said second shank, for abutting against an outer surface of a first shank of the upright on an adjacent ladder section, said first shank being that which is integral with the respective projection member, and two protrusions provided for abutting one against each of two opposed surfaces of the respective projection member.
4. A ladder as claimed in one of claims 1, 2, or 3, wherein said rungs have each an enclosed cross-sectional profile, the rungs being each secured to the respective uprights by means of projecting tongues and anchoring means, the tongues extending along substantially the entire width of the respective rung, said anchoring means being provided at each end of the respective rung.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8202358A SE455430B (en) | 1982-04-15 | 1982-04-15 | KIT STEPS WITH IN CONNECTABLE SECTIONS SUBJECT TO VARIABLE EFFECTIVE LENGTH OF THE STEP |
| SE8202358-1 | 1982-04-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1206454A true CA1206454A (en) | 1986-06-24 |
Family
ID=20346533
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000421992A Expired CA1206454A (en) | 1982-04-15 | 1983-02-21 | Ladder |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS58185892A (en) |
| KR (1) | KR840004473A (en) |
| CA (1) | CA1206454A (en) |
| DE (1) | DE3313169A1 (en) |
| DK (1) | DK158105C (en) |
| FI (1) | FI74326C (en) |
| FR (1) | FR2525273B1 (en) |
| GB (1) | GB2118237B (en) |
| IS (1) | IS1259B6 (en) |
| NO (1) | NO161278C (en) |
| SE (1) | SE455430B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0462797U (en) * | 1990-10-01 | 1992-05-28 | ||
| AU643324B2 (en) * | 1990-10-09 | 1993-11-11 | Bp Chemicals Limited | Phenolic resin alkoxylates |
| GB2261248B (en) * | 1991-10-29 | 1996-05-15 | Abru Aluminium Ltd | A ladder structure |
| US5580014A (en) * | 1993-12-22 | 1996-12-03 | B-Line Systems, Inc. | Ladder-type cable tray |
| CA2137879C (en) * | 1993-12-22 | 1999-03-23 | Eric R. Rinderer | Ladder-type cable tray |
| EP0746663B1 (en) * | 1994-03-01 | 1998-05-20 | Foxdale Developments Ltd. | Extensible ladder |
| GB9403863D0 (en) * | 1994-03-01 | 1994-04-20 | Foxdale Dev Ltd | Extensible ladder |
| DE19501689C2 (en) * | 1995-01-20 | 1999-02-25 | Johann Brenner | Pull-out ladder |
| US9887523B2 (en) | 2014-03-26 | 2018-02-06 | Cooper Technologies Company | Ladder-type cable tray |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB842963A (en) * | 1957-10-15 | 1960-08-04 | A V R Achat Ventes Representat | Ladders |
| GB921383A (en) * | 1959-08-11 | 1963-03-20 | Frank Boram | Improvements in or relating to ladders, steps, trestles and the like |
| US3232378A (en) * | 1963-12-19 | 1966-02-01 | White Metal Rolling & Stamping | Ladder rungs |
| GB1243771A (en) * | 1967-07-21 | 1971-08-25 | Derek Harcourt Matthews | Improvements relating to metal extension ladders |
| DE1919643B2 (en) * | 1969-04-18 | 1977-03-31 | Hymer Leichtmetallbau Ing. Erwin Hymer, 7988 Wangen | Light metal ladder with rungs secured by screws - has hollow stringers with channel for screws concealed by capping strip |
| US3559763A (en) * | 1969-10-27 | 1971-02-02 | Lawnlite Co | Ladder structure |
-
1982
- 1982-04-15 SE SE8202358A patent/SE455430B/en not_active IP Right Cessation
-
1983
- 1983-02-21 CA CA000421992A patent/CA1206454A/en not_active Expired
- 1983-04-05 FI FI831137A patent/FI74326C/en not_active IP Right Cessation
- 1983-04-05 NO NO831195A patent/NO161278C/en unknown
- 1983-04-06 IS IS2801A patent/IS1259B6/en unknown
- 1983-04-06 KR KR1019830001422A patent/KR840004473A/en not_active Application Discontinuation
- 1983-04-08 GB GB08309590A patent/GB2118237B/en not_active Expired
- 1983-04-12 DE DE3313169A patent/DE3313169A1/en not_active Withdrawn
- 1983-04-13 DK DK162683A patent/DK158105C/en not_active IP Right Cessation
- 1983-04-13 FR FR8306031A patent/FR2525273B1/en not_active Expired
- 1983-04-14 JP JP58064637A patent/JPS58185892A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2118237B (en) | 1985-12-04 |
| FI831137L (en) | 1983-10-16 |
| NO161278B (en) | 1989-04-17 |
| DK162683D0 (en) | 1983-04-13 |
| GB2118237A (en) | 1983-10-26 |
| GB8309590D0 (en) | 1983-05-11 |
| DE3313169A1 (en) | 1983-10-20 |
| FI74326B (en) | 1987-09-30 |
| FR2525273A1 (en) | 1983-10-21 |
| FI831137A0 (en) | 1983-04-05 |
| IS2801A7 (en) | 1983-10-16 |
| FI74326C (en) | 1988-01-11 |
| DK162683A (en) | 1983-10-16 |
| KR840004473A (en) | 1984-10-15 |
| SE455430B (en) | 1988-07-11 |
| SE8202358L (en) | 1983-10-16 |
| NO831195L (en) | 1983-10-17 |
| FR2525273B1 (en) | 1986-11-14 |
| JPS58185892A (en) | 1983-10-29 |
| DK158105B (en) | 1990-03-26 |
| NO161278C (en) | 1989-07-26 |
| DK158105C (en) | 1990-08-20 |
| IS1259B6 (en) | 1986-11-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |