GB2358215A

GB2358215A - Extension ladder guide fitting

Info

Publication number: GB2358215A
Application number: GB0000760A
Authority: GB
Inventors: James Dimitrios Williamson; Adrian Butter; David Simon Draddy James
Original assignee: SGB Services PLC
Current assignee: SGB Services PLC
Priority date: 2000-01-13
Filing date: 2000-01-13
Publication date: 2001-07-18
Also published as: GB0000760D0

Abstract

An extension ladder comprises a first ladder section (1) and a second ladder section which is moveable relative to the first ladder section. The first ladder section has a guide for guiding movement of the stile of the second ladder section. The guide comprises a hung (31) secured to the stile (2) of the first ladder section at a predetermined location and a separate guide element (43) positioned relative to the bung (31) so that the guide element and hung form a guide that will accommodate the stile of the second ladder section. The guide element (43) is selectively positioned relative to the hung to accommodate the stile, and thus using a minimum number of components a relatively large number of different stile sizes can be accommodated.

Description

2358215 PATENT ACT 1977 P13974QB-NWisd DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO A LADDEW THE PRESENT INVENTION relates to a ladder and a method of making a ladder. The invention relates particularly to extension ladders.

In an extension ladder it is necessary to provide the first, or groundengaging, section of the ladder with a guide at the upper end thereof that will slidably guide the next or upper section of the ladder. If the extending ladder is a multi-section extending ladder each section of the ladder must have a guide to slidably guide the next ladder section.

In manufacturing extension ladders is usual for the ground engaging section of the ladder to have the large stiles, and for the next sections of the ladder to have stiles of reducing dimensions. Thus guides to receive stiles of different sizes have to be provided.

In many previous ladders each guide is an appropriately dimensioned 1 extrusion. Thus, if a range of ladders is manufactured, there may be a need for a large number of different extrusions for use as guides. This is expensive in terms of dies, and also expensive in terms of stock control.

2 The present invention seeks to provide an improved ladder, designIld. so that a range of ladders using different sizes of stile may be manufactured 4sing a minimum number of components to make the guides.

According to one aspect of this invention there is provided an extension la, er incorporating a first ladder section and a second ladder section which:' IS movable relative to the first ladder section, the first ladder section ha a guide for guiding movement of a stile of the second ladder section, the de comprising a bung secured to the stile of the first ladder section 4t a predetermined location and separate guide element positioned relative tq the bung so that the guide element and bung form a guide that will accommOdAte the stile of the second ladder section.

Preferably the bung is mounted on the stile of the first ladder sectio i'by i fastening means that pass through at least one aperture pre-formed in the sti-116.

Conveniently the stile of each ladder section is a hollow stile ano [he bung is mounted, with a snap action, on the end of a mounting pin that p4sses through co-aligned apertures in opposed side-walls of the hollow stile.

Preferably the guide element forms part of a top clip, the top,' 'lip incorporating a plate, with the guide element extending perpendicularly t fhe plate, the plate abutting the bung and being positioned with the guide elem;m't located a selected distance from the bung.

Conveniently the bung has two orthogonal faces, one aid face e,ng directed towards the guide element, the other face abutting the plate, the Olate being secured to the stile with self piercing screws.

3 According to another aspect of this invention there is provided a method of making a section of an extending ladder, the method comprising the steps of securing a first element to a stile of the ladder, selectively positioning a top clip which carries a guide element with part of the clip engaging the stile and abutting the first element and with the guide element being a selected distance from the first element and securing the top clip to the stile in that position, Preferably the top clip incorporates a plate that is the part of the top clip which engages the stile, the plate being provided with a plurality of preformed apertures, the plate being secured to the stile with self piercmg screws that are passed through said apertures.

Conveniently the first element is a bung, and the bung is mounted on the stile by inserting a mounting pin through the stile and snap fitting the bung on the protruding end of the mounting pin.

Preferably the mounting pin additionally secures an end cap to the stile.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is an exploded perspective view of an end pail of one stile of a ladder showing various components, including a top cap and a top clip, that are mounted on the end of the stile of the ladder, 4 FIGURE 2 is a part sectional View illustrating the top cap of FigOre 1 inserted in the stile of the ladder, the top cap being shown in section, FIGURE 3 is a view showing an intermediate stage in the assemb ly of the ladder, FIGURE 4 is a view corresponding to Figure 3 showing a flirther stage in the assembly of the ladder, FIGURE 5 is a sectional view of the ladder taken on line V-V: of Figure 4, FIGURE 6 is a view corresponding to Figure 4 showing yet a fu 1 tther stage in the assembly of the ladder, FIGURE 7 is a view corresponding to Figure 6 showing a subse uent further stage in the assembly of the ladder, FIGURE 8 is a perspective view of part of an extension ladder shov two stiles provided with fittings of the type illustrated in Figures 1 to 7.

Referring initially to Figure 1 of the accompanying drawings, a sec6P 1 of an extending ladder is of conventional form, being provided withAwo parallel stiles, only one of which, 2, is illustrated. The ladder incorporafie5 a plurality of rungs only one of which, 3, is illustrated.

One end of 4 of the stile, as shown in Figure 1, is intended to be he upper end of the stile. The stile is either formed as a hollow extrusio'. iof aluminium or an aluminium alloy, or formed as a sewn welded rffi ed aluminium or aluminium alloy hollow section. The stile has two relatively large opposed parallel side walls 5, 6, inter-connected by two relatively narrow side walls 7, 8.

A pair of aligned apertures 9, 10 are provided in the relatively large walls 5 and 6.

A moulded plastics material top cap 12 is provided which is adapted to be mounted on the open end 4 of the stile. The end cap 12 presents an end face 13 of generally rectangular form adapted to be substantially normal to the axis of the stile of the ladder. The end face 13 is provided, at each end of the rectangular end face, with a partial skirt 14, 15. The partial skirt 14, 15 is adapted to embrace the end part of the stile 2. The junction between the exterior of the partial skirt 14, 15 at each end of the end cap, and the rectangular end face 13 defines an inclined ribbed wall 16, 17. The ribbed wall is so located that the plane of the wall makes an angle of approximately 20' with the axis of the stile. The reason for this is that a ladder, when correctly positioned against a wall, makes an angle of 700 to the ground and 20' to the wall, and thus an end face, such as the end face 16, 17, will firmly abut the wall when the ladder is in the correct position.

On the rear part of the end face 13 is a projection 18 which is generally of rectangular section and which is dimensioned to be received within the open end of the stile 2. The nature of the projection can be seen more clearly in Figure 2. The projection 18 has two opposed chamfered faces 19, 20, on the relatively narrow side faces thereof remote from the end face 13 to facilitate insertion of the projection 18 into the hollow end of the stile.

6 The projection 18 is provided with a transverse bore 21. In the cen el, of the bore, as can be seen in Figure 2, four evenly spaced diametrically inw#d-ly extending tabs 22 are provided. The four tabs thus extend radially into the osre at a substantially central position. The tabs are resilient to provide a s ap function, as will become clear fi-om the following description.

The end cap is symmetric and can be used either way round. Two b1p (es 23, 24 are provided in the end cap 12, opening on the end face 13, to mmulpise the quantity of material used in fabricating the end cap.

A fixing pin 25, for example of steel, is provided having a head 26 a shank 27. The shank 27 is provided with a circumferential groove 28 ad+td to receive the tabs 22, with a snap function.. The fixing pin is also provic ed with a further portion 29 which is tapered and which abuts against the er diameter end of a tenninal conical head 30, defining an abutment which;!a1so provides a further snap function.

The pin 25 is of such a length that it will pass through the co-alio'ed i apertures 9 and 10 of the stile 2, whilst simultaneously passing throughl -he bore 21 of the top cap when the projection 18 is received within the oped c nd of the stile 2, with part of the pin 25 projecting on the far side of the stile. That part of the pin includes the tapered portion 29 and the conical head 30. is part of the pin is adapted to engage a bung 31 which is of generally squp're cross-section with rounded comers, and which has an axially exterifflng bore 32. The bore 32, as can be seen most clearly in Figure 5, is provided Jth diametrically opposed inwardly directed lugs 33 adapted to form a snap-fit:ith the rear face of the conical head 30 of the fixing pin. As can be seen, there-Fore, that initially the top cap 12 will have the projection 18 thereof inserted into (he open end 4 of the stile 2, and subsequently the pin 25 will be passed throtgh' 7 the apertures 9 and 10 co-aligned with the bore 21 until the tabs 22 engage the peripheral groove 28 formed in the pin 25. Subsequently the bung 31 will be urged onto the then exposed end part of the pin 25 until the lugs 33 within the bore 32 engage, with a snap action, the abutment between the conical head 30 and the tapering portion 29 of the pin 25.

A top clip 41 is provided. The top clip 41 is part of a generally "Usectioned extrusion formed of aluminium or the like. The top clip 41 presents a relatively large rectangular plate 42, formed on one arm of the 'L' and a guide portion 43, formed by the other ann of the U, extending perpendicularly from one end of the rectangular plate 42. The top clip 4 1, together with the bung 3 1, define a guide assembly.

The rectangular plate 42 is provided with two apertures 43, 44 adapted to receive self-tapping screws 45, 46 that may be used to secure the top clip 41 to the stile 2. It is intended that the top clip 41 will be located with the plate 42 in contact with the stile, with one edge of the plate in abutment with one face of the bung 3 1. The top clip will be positioned so that there is an appropriate distance between the under- surface of the guide element 43 and the face of the bung 31 which is closest to the guide element 43. The face of the bung that is closest to the guide element 43 is ortliogonal to the face that abuts the bung. The self-piercing screws will then be used to secure the top clip in position on the ladder. The top clip is thus selectively positioned ( see Figure 6) so that the spacing between the guide element 43 and the bung 31 is just sufficient to receive the stile of the next adjacent ladder section of an extending ladder. The self piercing screws 45, 46 are then used to secure the top clip in place ( see Figure 7).

8 A single size top clip may be positioned, relative to the bung, to reocive one of a plurality of different sizes of stile of an adjacent ladder. Thus. iii't-ad of having to provide a different top clip extrusion for each size of stile, a, few different extrusions may be able to accommodate a complete range of istile sizes. This may reduce the costs of manufacturing a range of ladders.

The position of the top clip is selected to control the "overlap" of the adjacent ladder sections, and also serves to restrict the maximum "opelil' 1 1J tg angle between the two ladder sections to 100.

At this stage it is to be mentioned that in a conventional extending 1a4Jer the size of the stile of each ladder section is slightly less than the size of the stile of the adjacent ladder section. Thus, when manufacturing a rang e of ladders, it is desirable to be able to provide various top guide assemblies wich can accommodate any one of a number of different stile sizes. Previously i has been proposed to provide a separate extruded clip for each size of stile. This:;; is, of course, a relatively expensive expedient. However, it is to be apprec a: ted : t that in using an arrangement as described, the top clip can be positioned appropriately, relative to the top bung 3 1, to constitute a guide to receive a is ffle of any selected size within a predetermined range of sizes, the range of sizb,') is dependent upon the size of the plate 42 of the top clip 4 1, and alsol (he dimension of the side walls 6 of the stile 2. Nevertheless, by utilisin,161' ,an arrangement as disclosed in the present invention, it is envisaged that it wil:: be 1 possible to manufacture a conunercially sensible range of ladders W list utilising a minimum number of different components.

Figure 8 illustrates part of an extension ladder utilising a la er section 1 as described with reference to Figures 1 to 7. It can be seen tha[ the (M,; ladder section 1 is operating in conjunction with a second ladder secti 50 9 which has two stiles 51, 52, and a plurality of rungs 53, 54. It can be seen that the stiles 51, 52 are snugly received between the bungs 31 and the top clips 41 so that the ladder section 50 may slide relatively freely relative to the ladder section 1, but movement in a plane transverse to the plane of the ladder section 1 is prevented.

In the present specification "comprise" means "includes or consists of' and "comprising" means "including or consisting of'.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. An extension ladder incorporating a first ladder section and a sec: pd ladder section which is movable relative to the first ladder section, the 1 st ladder section having a guide for guiding movement of a stile of the se c; nd ladder section, the guide comprising a bung secured to the stile of the Ifirst ladder section at a predetermined location and separate guide elelfient positioned relative to the bung so that the guide element and bung form a gWide that will accommodate the stile of the second ladder section.

2. A ladder according to claim 1 wherein the bung is mounted on the plile of the first ladder section by fastening means that pass through at least c ne aperture pre-formed in the stile.

3. A ladder according to claim 2 wherein the stile of each ladder secti h is a hollow stile and the bung is mounted, with a snap action, on the end a mounting pin that passes through co-aligned apertures in opposed side-wa s of the hollow stile.

4. A ladder according to any one of the preceding claims wherein the gid, e element forms part of a top clip, the top clip incorporating a plate, withl. the guide element extending perpendicularly to the plate, the plate abutting! the bung and being positioned with the guide element located a selected distnpe from the bung.

11 5. A ladder according to claim 4 wherein the bung has two orthogonal faces, one aid face being directed towards the guide element, the other face abutting the plate, the plate being secured to the stile with self piercing screws.

6. A method of making a section of an extending ladder, the method comprising the steps of securing a first element to a stile of the ladder, selectively positioning a top clip which carries a guide element with part of the clip engaging the stile and abutting the first element and with the guide element being a selected distance from the first element and securing the top clip to the stile in that position.

7. A method according to claim 6 wherein the top clip incorporates a plate that is the part of the top clip which engages the stile, the plate being provided with a plurality of preformed apertures, the plate being secured to the stile with self piercing screws that are passed through said apertures.

8. A method according to claim 5 or claim 6 wherein the first element is a bung, and the bung is mounted on the stile by inserting a mounting pin through the stile and snap fitting the bung on the protruding end of the mounting pin.

9. A method according to claim 8 wherein the mounting pin additionally secures an end cap to the stile.

10. A ladder substantially as herein described with reference to and as shown in the accompanying drawings.

11. A method of making a ladder substantially as herein described with reference to the accompanying drawings.

12 12. Any novel feature or combination of features disclosed herein.

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