EP1989374A2

EP1989374A2 - A plastic platform for a foldable ladder, a ladder with telescopical sections and a ladder with a stabilizer beam

Info

Publication number: EP1989374A2
Application number: EP07715831A
Authority: EP
Inventors: Caspar Bernard Lampe
Original assignee: LAMPE HOLDING BV
Current assignee: LAMPE HOLDING BV
Priority date: 2006-02-03
Filing date: 2007-02-05
Publication date: 2008-11-12
Anticipated expiration: 2027-02-05
Also published as: ATE515607T1; EP1989374B1; WO2007089137A2; WO2007089137A3; NL1031512C1

Abstract

A platform for installation on a folding ladder in scaffolding position, which folding ladder is of the type comprising multiple folding ladder sections, which are connected to one another by hinges, in which, in the scaffolding position, outer folding ladder sections form a ground support and central folding ladder sections form a bridge. The platform is composed of one or more plastic panels. These one or more panels are preferably made using a plastic blow-moulding technique . Particularly preferably, the platform is composed of two panels and the panels are of different length, which is preferably chosen such that the connection of the two panels is situated above a rung of a folding ladder section, preferably the rung closest to a central hinge of the folding ladder.

Description

PLASTIC PLATFORM FOR A FOLDING LADDER.

A first aspect of the application relates to a platform which can be used in combination with a folding ladder.

Folding ladders are generally known from the prior art. In a common embodiment, the ladder has four sections which are connected to one another by means of hinges. The hinges are provided with an (automatic) locking mechanism which ensures the position of the folding ladder sections with respect to one another in (preferably predetermined) positions.

As is generally known, such a folding ladder can be placed in a "scaffolding position", in which the central two folding ladder sections form an essentially horizontal bridge and the outer folding ladder sections form the "legs" of the bridge.

The known folding ladders have folding ladder sections comprising "uprights" with rungs between them, so that the "bridge", in the scaffolding position is made up of rungs. It will be clear that walking over the bridge and standing on the bridge is dangerous, as one can miss the rungs. Furthermore, it is not comfortable to sit on or easy to place equipment thereon.

For the above reason, it is known to combine the folding ladder with a platform which lies on the rungs of the "bridge section" when the folding ladder is being used in the scaffolding position.

Known platforms for this application are made from wood, steel and aluminum. These known platforms are not satisfactory in practice.

It is an object of the first aspect of the invention to provide an improved platform for use with a folding ladder.

According to the first aspect thereof the invention provides a platform according to claim 1.

By using plastic as the material for the platform, considerable advantages can be achieved, as will be clear from the embodiments according to the subclaims and the following description.

The first aspect of the invention also relates to the combination of a folding ladder and a platform.

A second aspect of the invention is related to a ladder having one or more telescopic sections. Form the prior art ladders are known with a telescopic section having a first and second part which can be telescoped with respect to one another. In a known embodiment the first part is essentially composed of outer upright members interconnected by rungs, the second part being essentially composed of inner upright members interconnected by rungs . The outer upright members each form a elongated slot at the inner side thereof (facing the opposed outer upright member) and the inner upright members of the second part are slidable received in said elongated slot. For instance the outer upright members have a U-shaped cross-section, the inner upright members sliding in the slots provided by said U- shape. It is quite common and advantageous to produce said outer and inner upright members, and the rungs, from aluminum, in particular from aluminum extrusions.

A problem associated with these known ladders is that extending and shortening the telescopic section takes too much effort.

The second aspect of the present invention aims to overcome, or at least reduce, said problem.

The second aspect of the present inventions provides a ladder according to the preamble of claim 17, which is characterized in that a steel guide member is fitted on each of the ends of the outer upright members of the first part of the telescopic section, said steel guide member at least extending between said outer and inner upright members .

The steel guide members act to reduce the friction between the outer and inner upright members, and thus facilitate extension and shortening of the telescopic section. They also allow for local (at the respective end of the outer upright), reduction of the play- between the outer and inner upright members, thus contributing to the stability of the ladder.

It is envisaged that in a folding ladder having four sections - two outer sections and two central sections - the sections being interconnected by three hinges as described with respect to the first aspect of the invention (but then possibly without the provision of a platform or with a different platform) , the outer sections are both embodied as telescopic section. This can be according to the preamble of claim 17, preferably according to the claim 17 with the provision of steel guide members.

In the latter embodiment it can be envisaged that the locking mechanisms of the hinges are provided with operating levers (as is known in the art) , the steel guide members effectively preventing that such a lever becomes stuck in the gap between the outer and inner upright members of the telescopic section.

In a preferred embodiment the steel guide member extends both on the inner face and the outer face of the respective end of the outer upright and also over the stirn face of said outer upright, thereby taking away any sharp edges of the outer upright. This enhances safety and lowers costs to produce the ladder.

Preferably the steel guide member is press-fitted on the outer upright member, most preferably by applying local indentations in the steel guide member and the upright, preferably on an inner face thereof.

Preferably the steel guide member is made of stainless steel.

Preferably the uprights are made of aluminum.

A third aspect of the present invention relates to a ladder having one or more section, including a section with uprights and interconnecting rungs, as well as a stabilizer beam extending essentially transvexse with respect to the uprights and fastened to an ends of the uprights of said section.

It is known to form the end of each of the uprights as a forked end with a central cut-out between the fork members, the stabilizer beam being received into said cut-outs and fastened in said position with e.g. a bolt extending through said fork members and the stabilizer •beam.

It is well known to produce the uprights and the stabilizer beam out of aluminum.

A problem associated with said known connection between the stabilizer beam and the forked ends of the uprights relates to the manufacturing of the forked ends. The stability of the connection basically requires little or no play between the parts. Yet sharp edges, e.g. of the forked ends, can easily lead to scratches on the stabilizer beam during assembly which is not acceptable for commercial reasons .

The third aspect of the present invention aims to overcome, or at least reduce, one or more of the above mentioned problems.

The third aspect of the present invention achieves this goal by providing a ladder according to the preamble of claim 20, which is characterized in that a plastic insert member is fitted in the forked end of each of the uprights, said insert member having a cavity in which said stabilizer beam is received essentially without play, said forked ends being spaced from the stabilizer beam by said plastic insert member.

In a preferred embodiment the insert member covers the end faces of the forked ends of the upright as well as the faces of the upright along the cutout between the forked ends. As explained this avoids scratches upon assembly of the stabilizer beam and also allows more efficient production as any sharp edges of the upright are now covered by the insert obviating the need to treat these edges.

Preferably the insert comprises a passage for a fastening bolt extending through both forked ends and the stabilizer beam, the insert preferably also being provided with a metallic nut into which said bolt can be screwed.

Preferably the bolt is an Allen bolt, both ends of the bolt being flush with an associated outer face of the upright so as not to extend outwardly from the upright. This avoids making scratching surfaces by said bolt as happens with prior art designs of this connection. It will be appreciated that this third aspect of the invention can advantageously be integrated in the ladder according to the first aspect of the invention and/or the second aspect of the invention.

In the drawings :

Fig. 1 shows a folding ladder in scaffolding position provided with an exemplary embodiment of a platform according to the invention,

Fig. 2 shows the folding ladder from Fig. 1 in the folded-away position,

Figs. 3a, b, c show a top view, side view and perspective view, respectively, of a panel of the platform from Fig. 1,

Figs. 4a, b, c show a top view, side view and perspective view, respectively, of another panel of the platform from Fig. 1, Figs. 5a, b show a top view and side view of a variant embodiment of a panel of the platform from Fig. 1,

Figs. 6a, b show a top view and side view of the complementary panel of the platform from Fig. 5,

Fig. 7a shows a part of an exemplary ladder according to the second aspect of the invention with a telescopic outer section, Fig. 7b shows a detail thereof with the telescopic section being extended,

Fig. 7c shows the first part of said telescopic section with the steel guide member in more detail,

Fig. 7d the steel guiding member removed from the end of the outer upright member,

Fig. 8a an example of the connection between an ladder upright and stabilizer beam according to the third aspect of the present invention,

Fig. 8b the end of the upright of figure 8a with the insert mounted therein and also an insert shown when not mounted.

The first aspect of the present invention will now be explained referring to figures 1-6.

Fig. 1 shows a folding ladder in scaffolding position with an accompanying exemplary embodiment of a platform according to the invention .

The folding ladder 1 is composed of four sections 2, 3, 4, 5 in the usual way, which are connected to one another by hinges 6, 7, 8. The outer folding ladder sections 2, 5 are provided at their free ends with a ground support, in this case a transverse beam 2a, 5a, having supporting feet.

Each of the hinges 6, 7, 8 is provided with an automatic locking mechanism (known per se) which ensures the position of the ^• folding ladder sections with respect to one another in predefined positions.

In the illustrated "scaffolding position", the central two folding ladder sections 3, 4 form an essentially horizontal bridge and the outer folding ladder sections 2, 5 form the "legs" of the bridge. As can be seen, the folding ladder sections comprise two "uprights" with rungs between them, so that, in the scaffolding position, the "bridge" consists of rungs.

The platform 10 is situated on the rungs of the "bridge section" when the folding ladder is being used in the scaffolding position.

Here, the platform 10 is composed of two panels 11, 12, which are of different lengths in this preferred embodiment. These different lengths have been chosen such that the adjoining position of the two panels 11, 12 is situated above a rung of a folding ladder section, preferably the rung closest to the central hinge of the folding ladder (in this case rung 13, but it _i could thus also be rung 14 if the panels 11, 12 were positioned differently) .

Preferably, the panels 11, 12 (as is the case here) are of a width which is adapted to the distance between the uprights of the central folding ladder sections, so that lateral displacement and undesirable openings are prevented.

On their underside, the panels 11, 12 have formations, preferably (as is the case here) formations which have been formed integrally from plastic as a single part during the production of the panels, which engage with the rungs underneath.

In the embodiment shown in Figs. 3 and 4, the panels 11, 12 are provided on the underside with projecting ribs 15, in each case one rung fitting between a pair of adjacent, parallel ribs 15.

At one end of a panel 11, 12, there is a pair of ribs, while at the other end only a single rib is present. This arrangement is provided because this side is supposed to abut the other panel. Then, the "single ribs" together form a pair of ribs with a slot between them into which the aforementioned rung 13 (or 14) fits. Figs. 5, 6 show alternative panels 11', 12'. On their underside, these panels 11', 12' have slots 20 running transversely for accommodating the rungs of the folding ladder which are obtained by designing these slots 20 to be "recessed" relative to the bottom surface of the panels 11' , 12' . In particular, this is achieved by designing the panels 11', 12' to be thicker than the panels 11, 12.

Preferably, the formations (in Figs. 3, 4 the ribs; in Figs. 5, 6 the recessed slots) are of such a design that the panels clamp onto the rungs without any further action by the user. This may be effected, for example, by designing the ribs 15 or slots 20 to be tapering or otherwise clamping in combination with the design of the rungs. Due to the fact that clamping of the platform (or panels thereof) on the rungs is effected without additional action, there is no risk of the user forgetting anything, making the platform very safe. The panels 11, 12 and 11', 12' are in this case provided with (small) through-holes in the panel surface, for example to improve the drainage of water.

In this case, the panels are each provided with a grip opening 16, 17 in order to be able to lift the panels easily. The grip opening is preferably located in the area between two rungs.

Preferably, a grip opening is disposed along a longitudinal side of the panel .

It will be clear that one or more of the panels 11, 12; 11', 12' can also be used in other positions of the folding ladder. The panels 11, 12 and 11' , 12' can suitably be made from plastic as a single part and particularly preferably using a plastic blow-moulding technique. As a result, it is possible to keep the weight low while providing sufficient mechanical strength.

When using the blow-moulding technique, it is advantageous to provide a pattern of holes 18 in the panels, as the peripheral wall surrounding each hole (see partial sections in Figs. 3b, 4b, 5b, 6b of a hole 18) then forms a supporting column, as it were, between the wall which forms the top surface and the wall which forms the bottom surface of a panel. It will be clear that a single-part design of the platform or, on the contrary, a design comprising more than two panels is also conceivable. However, the design comprising two panels is clearly preferred, partly due to the strength, ease of handling and transportation.

Fig. 2 shows that the panels 11, 12; 11', 12', in the folded- away position of the folding ladder, fit between the folded together central folding ladder sections 3, 4. This saves space and facilitates transportation of the folding ladder.

Now referring to figures 7a-d the second aspect of the present invention will be illustrated. It is noted that the figure 7a already discloses to the skilled person that the second aspect of the invention can be combined with ladder according to the preamble of claim 1 with or possibly without a platform. The second aspect can basically be integrated in any ladder having a telescopic section.

Figure 7a shows a part of a ladder similar to the ladder 1 in figure 1, the main difference being that the outer section 30 now is a telescopic section (just as the other outer section of this ladder) .

The telescopic section 30 has a first part 30a and a second part 30b which can be telescoped with respect to one another. As shown in the figures the first part 30a is composed outer upright members 31 interconnected by rungs 32, the second part 30b being composed of inner upright members 33 interconnected by rungs 34. The inner upright members 33 are here each connected to a hinge 6 having an integral locking mechanism with associated operating lever 6a as is known in the art.

To allow for locking the telescopic section in predetermined extended or non-extended positions a further locking mechanism is shown, here a mechanism which is known in the art and is generally indicated with reference numeral 40. This mechanism has hand- operable locking brackets 41 on each side of the ladder with a locking leg of each bracket that can fit through holes in the uprights of both the first and second part of the telescopic section, said holes being arranged corresponding to predetermined lengths of the telescopic section. Here the other leg of each bracket is connected to a spring accommodated in a rung 32 to urge said locking leg in its locking position extending through aligned holes. The skilled person will appreciate that another locking mechanism can be provided for this purpose.

The outer upright members 31 each form an elongated slot at the inner side thereof (facing the opposed outer upright member) and the inner upright members 33 are slidable received in said elongated slot. The outer upright members 31 each have a U-shaped cross- section, the inner upright members 33 being slideable in the slots provided by said U-shape. Both the outer and inner upright members 31, 33 are made of aluminum.

A steel guide member 35 is fitted on each of the ends of the outer upright members 31, said steel guide member 35 at least extending between said outer and inner upright members 31, 33.

The steel guide members 35 act to reduce the friction between the aluminum outer and inner upright members 31, 33, and thus facilitate extension and shortening of the telescopic section. They also allow for local (at the respective end of the outer upright) reduction of the play between the outer and inner upright members, thus contributing to the stability of the ladder.

Figure 7a shows that the steel guiding members 35 here also act to prevent that a lever 6a becomes stuck in the gap between the outer and inner upright members 31, 33. Here the steel member 35 is a folded sheet metal part having flaps 35a, b, c covering the inside of both legs of the U-shaped cross-section upright 33 and of the main body between the legs of said upright 33. As is preferred the steel member 35 also covers the stirn face of the upright and extends over an adjacent area of the outside of the upright. This takes away any sharp edges of the aluminum outer upright 33.

In the embodiment shown here the steel guide member 35 is press-fitted on the outer upright member 33, here by applying local indentations in the steel member on one or more inner flaps 35b thereof.

Preferably the steel member 35 is made of stainless steel.

Referring to figures 8a, b now the third aspect of the invention will be illustrated. The skilled person will readily understand that the third aspect of the invention can be integrated in the figure 1 ladder, with or without platform being provided, but also in other ladders including telescopic ladders, other types of foldable ladders, etc.

Figure 8a shows an aluminum upright 40 of a ladder as well as a an aluminum stabilizer beam 45 which extends essentially transverse with respect to the upright 40 and fastened to the end of the upright 40. Obviously the beam 45 is connected to the other upright of this ladder (section) in similar manner.

The upright 40 here is of rectangular cross-section. The end of the upright 40 has a forked end with a central, here rectangular cut-out between the fork members 40a, b.

A plastic insert member 50 is fitted in the forked end of the upright 40, said insert member 50 having a cavity in which said stabilizer beam 45 is received essentially without play. So it is the insert that defines the cavity for the stabilizer beam 45 not the cut-out in the aluminum upright. This has the advantages explained in the introduction. The insert member 50 is shown in figure 8b, both in pre-mounted condition and when mounted with a bolt arranged there through for illustrative purposes.

The member 50 here covers the end faces of the forked ends of the upright 40 as well as the faces of the upright 40 along the cut- out between the forked ends 40a, b. As explained this avoids scratches upon assembly of the stabilizer beam 45 and also allows more efficient production as any sharp edges of the upright 40 are now covered by the insert member 50 obviating the need to treat these edges. As depicted in figures 8a,b the insert member 50 has a passage for a fastening bolt, here an Allen bolt 60, extending through both forked ends 40a, b, the insert, and the stabilizer beam 45.

The insert member 50 here carries a metallic nut 61 into which said bolt 60 can be screwed. As is preferred both ends of the bolt 60 are flush with an associated outer face of the upright 40 so as not to extend outwardly from the upright 40. This avoids making scratching surfaces by said bolt 60 as happens with prior art designs of this connection.

Claims

C L A I M S

1. Platform for installation on a folding ladder in scaffolding position, which folding ladder is of the type comprising multiple folding ladder sections, which are connected to one another by hinges, in which, in the scaffolding position, outer folding ladder sections form a ground support and central folding ladder sections form a bridge, characterized in that the platform is composed of one or more plastic panels.

2. Platform according to claim 1, in which the one or more panels are made using a plastic blow-moulding technique.

3. Platform according to claim 1 or 2, in which the platform is composed of two panels.

4. Platform according to claim 3, in which the platform is composed of two panels and the panels are of different lengths, which has preferably been chosen such that the adjoining position of the two panels is situated above a rung of a folding ladder section, preferably the rung closest to a central hinge of the folding ladder.

5. Platform according to one or more of the preceding claims, in which the panels are of a width which is adapted to the distance between the uprights of the central folding ladder sections.

6. Platform according to one or more of the preceding claims, in which the one or more panels have formations on their underside, preferably formations which have been formed integrally from plastic as a single part during the production of the panels, which engage with the rungs underneath.

7. Platform according to claim 6, in which the one or more panels are provided with slots on their underside in order to accommodate the rungs underneath.

8. Platform according to claim 6 or 7, in which the one or more panels are provided with projecting ribs on the underside, in each case one rung fitting between a pair of adjacent, parallel ribs.

9. Platform according to claim 7, in which several, preferably two, panels are provided and in which, at one end of a panel, there is a pair of ribs, while at the other end only a single rib is present, which other side is supposed to abut the other panel, so that the single ribs together form a pair of ribs with a slot between them into which a rung then fits .

10. Platform according to claim 6, in which the formations are of such a design that the panels clamp onto the rungs without any further action by the user, for example by designing the ribs to be tapering or otherwise clamping in combination with the design of the rungs.

11. Platform according to one or more of the preceding claims, in which the one or more panels are each made from plastic as a single part and particularly preferably using a plastic blow-moulding technique.

12. Platform according to claim 11, in which the one or more panels are each made from plastic as a single part using a plastic blow- moulding technique, and in which a pattern of holes is provided in each of the panels, in which the peripheral wall surrounding each hole forms a supporting column between the wall which forms the top surface and the wall which forms the bottom surface of a panel.

13. A combination of a folding ladder and a platform according to one or more of the preceding claims.

14. The combination of claim 13, in which, in the folded-away position of the folding ladder, a platform consisting of several, preferably two, panels fits between the central folding ladder sections.

15. The combination of claim 13 or 14, wherein the ladder has two outer sections and two central sections, said sections being interconnected by hinges, and wherein the outer sections are telescopic, preferably as disclosed in claim 17.

16. The combination of any of claims 13-15, wherein the ladder comprises a stabilizer beam connected to the ends of the uprights of a ladder section, said connection being embodied as disclosed in claim 20.

17. A ladder having one or more telescopic sections, each telescopic section having a first and second part which can be telescoped with respect to one another, the first part essentially being composed of outer upright members interconnected by rungs, the second part essentially being composed of inner upright members interconnected by rungs, the outer upright members each forming an elongated slot at the inner side thereof and the inner upright members of the second part being slidable received in said elongated slot, characterized in that a steel guide member, preferably of stainless steel, is fitted on each of the ends of the outer upright members of the first part of the telescopic section, said steel guide member at least extending between said outer and inner upright members.

18. A ladder according to claim 17, wherein the steel guide member extends both on the inner face and the outer face of the respective end of the outer upright and also over the stirn face of said outer upright, thereby taking away any sharp edges of the outer upright.

19. A ladder according to claim 17 or 18, wherein the steel guide member is press-fitted on the outer upright member, preferably by applying local indentations in the steel guide member and the upright, preferably on an inner face thereof.

20. A ladder having a section with uprights and interconnecting ^• rungs, as well as a stabilizer beam extending essentially transverse with respect to the uprights and fastened to ends of the uprights, said ends being forked with fork members on opposed sided of a cutout there between, characterized in that a plastic insert member is fitted in the forked end of each of the uprights, said insert member having a cavity in which said stabilizer beam is received essentially without play, said forked ends being spaced from the stabilizer beam by said plastic insert member.

21. A ladder according to claim 20, wherein the insert member covers the end faces of the forked ends of the upright as well as the faces of the upright along the cut-out between the forked ends .

22. A ladder according to claim 20 or 21, wherein the insert member comprises a passage for a fastening bolt extending through both forked ends and the stabilizer beam, the insert preferably also being provided with a metallic nut into which said bolt can be screwed.

23. A ladder according to claim 22, wherein the bolt is an Allen bolt, both ends of the bolt being flush with an associated outer face of the upright so as not to extend outwardly from the upright.