GB2322898A

GB2322898A - An adjustable platform assembly

Info

Publication number: GB2322898A
Application number: GB9803962A
Authority: GB
Inventors: Mark Redsell
Original assignee: ABRU Ltd
Current assignee: ABRU Ltd
Priority date: 1997-02-28
Filing date: 1998-02-26
Publication date: 1998-09-09
Anticipated expiration: 2018-02-26
Also published as: GB9803962D0; GB2322898B

Abstract

An adjustable platform assembly (11) comprises a platform (12) adapted to be carried at each of two ends by respective upright supports (13,14). One end of the platform (12) is connected to the support by a carrier member (20). The carrier member (20) has means for adjusting the height of the platform (12) with respect to the upright (14) on which it is carried. This adjustment may be effected at the interconnection between the platform (12) and the carrier member (20), and may be incrementally adjustable. The upright supports (13,14) may take the form of ladders or ladder sections having rungs (17,18), in which case the adjustment means will be over a maximum range of half the pitch of the rungs. The height adjusting means may include clamp means and elongate guides (21,22).

Description

AN ADJUSTABLE PLATFORM ASSEMBLY The present invention relates generally to an adjustable platform assembly, and particularly (but not exclusively) to a platform assembly suitable for use by homeowners undertaking decorating tasks.

In many situations a home owner requires to gain access to parts of a building which are higher than can be reached conveniently when standing on the ground. Ladders and stepladders which are used for this purpose, although satisfactory from many points of view, do not provide a wide enough range of movement, and this can sometimes lead to accidents. When working on a ladder or stepladder the user has only the rung or tread on which to stand, and this limits the available range of movement of the feet to a few centimetres on either side of an otherwise fixed position. The user's reach is thereby limited to those regions which can be reached from a virtually stationary standing position, namely in the region of a metre or less to either side of the central point. Many tasks, particularly decorating tasks, require access to a very much wider range of positions than this, which results in the necessity continually to reposition the ladder or stepladder. This is particularly onerous when working on walls or ceilings.

Prior art attempts to provide a more extensive platform have involved the use of wooden boards or planks spanning two low supports such as trestles, and although this allows access to be gained the inherent lack of stability in such an arrangement is unacceptable in the modern safety-conscious world. Moreover, such a configuration cannot conveniently be used in a stairwell where asymmetric supports are needed to maintain a platform in a secure horizontal position. Likewise, when used outside, if the ground is inclined or rough, prior art platforms cannot easily be set horizontal, and the potential lack of stability is dangerous.

The present invention seeks to provide a platform assembly which solves these problems by having means for adjustment of the height of at least one end of the platform so that it can be positioned horizontally regardless of the inclination of, or the presence of steps in, the underlying surface. Such a platform should be light so that it is easy to move from place to place, and preferably should be stowable so that, in domestic environments where space is at a premium, it does not occupy valuable space.

The present invention also seeks to provide a platform assembly which is rigid and secure in use. Embodiments of the present invention can be made which employ the separable sections of a stepladder (formed so as to be separable at least in part for this purpose) and which therefore allows the stepladder sections to be used separately from the platform thereby saving the space which would be occupied by a separate ladder.

According to one aspect of the present invention, therefore, there is provided an adjustable platform assembly adapted to be carried at one end by an upright support, the platform assembly comprising a platform, a platform carrier member for connecting one end of the platform to the said platform support, the platform carrier member having means for adjusting the height of the platform with respect to the upright support on which it is carried.

In one embodiment the platform carrier member includes support means for connecting one end of the platform to the said upright support, in a position determined by the form of the upright support, and means for adjustably interconnecting the platform and the said platform carrier member whereby to adjust the height of the said one end of the platform with respect to the upright support on which it is carried.

The said upright support may be a ladder or ladder section and the platform suspension member may then be adapted to engage on a rung or rungs of the ladder or ladder section.

In one embodiment of the invention the said means for interconnecting the platform and the platform suspension member are incrementally adjustable. Other embodiments may provide for infinite adjustment however.

There may be provided a platform carrier member at each end of the said platform, for supporting the platform on respective upright supports at each end thereof.

The said two upright supports may be the two, separable, sections of an appropriately formed ladder or stepladder.

In such an embodiment the means for interconnecting the platform and the platform carrier member may be adjustable over a maximum range of half the pitch of the rungs of the ladder or ladder section. This allows an efficient use of space and resources since, by appropriate adjustment of the suspension arrangement at each end of the platform differences of up to one rung pitch in the vertical height of the ground on which the two supports are rested can be accommodated; differences greater than this can be accommodated by changing the rung on which the platform is carried.

The or each platform carrier member may be connectable to at least one rung (but preferably two rungs) of the or the adjacent ladder section. For this purpose the or each platform carrier member preferably has at least two hook members for engagement with two vertically separated rungs of a respective ladder or ladder section, and one of the said hook members engages the associated rung over more than 900.

At least one of the said hook members may have associated clamp means by which the hook member can be clamped in a selected position with respect to the interconnection means whereby to determine the said adjustment. The clamp means may be any suitable form including toggle clamps or screw clamps.

The same clamp member may engage the said platform carrier member, for example by a threaded connection, with the arrangement being such that the interconnection means pass between the carrier suspension member and the hook member so as to be clamped between them upon tightening of the clamp member.

The interconnection means preferably has a member with an elongate slot having a plurality of notches in at least one side wall thereof engageable by at least one cooperating tooth on the said one hook member. These notches provide the incremental adjustment and, at the same time, offer secure rigidity of connection even if the screw clamp member is not tightened to its maximum extent.

The or each interconnection means may comprise two elongate members each pivotally connected to the platform at a respective end thereof and braced by a strut releasably connectable to the platform. Such pivotal connection allows the interconnection means to be turned between a use position, in which it extends transverse the platform, and a stowed position in which it lies generally parallel to the platform thereby minimising the space occupied for storage.

In an alternative embodiment the said means for adjusting the height of the platform with respect to the upright support on which it is carried includes releasable clamp means. The said means for adjusting the height of the platform with respect to the upright support on which it is carried may include elongate guides on the upright support for guiding adjustment movement of the carrier means.

Two embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a simplified perspective view of a platform assembly formed as an embodiment of the present invention shown in position on two upright ladder sections; Figure 2 is a partial side view of a platform assembly formed as an embodiment of the present invention; Figure 3 is a plan view from above of the part of the platform assembly shown in Figure 2; Figure 4 is an end view of the part of the platform assembly illustrated in Figure 2; Figure 5 is a side view of the platform assembly shown in use on a stepped surface; Figure 6 is a side view of part of the interconnection means of the platform suspension assembly; Figure 7 is a face view of part of a suspension member suitable for use in the platform assembly of the present invention; Figure 8 is a perspective view similar to Figure 1, of a second embodiment of the invention; Figure 9 is a detail view of part of the embodiment of Figure 8; and Figure 10 is a section taken on the line X-X of Figure 8.

Referring first to Figures 1 to 7 of the drawings, a platform assembly generally indicated 11 comprises an elongate platform 12 shown supported on two upright supports 13, 14 which, as illustrated in Figure 1, comprise two ladder sections of a separable stepladder each comprising parallel stiles 15, 16 joined by regularly spaced rungs 17, 18 respectively.

At each end of the platform 12 is a respective platform suspension assembly generally indicated 19 and 20 which are identical to one another and the individual components of which will thus be identified with the same reference numerals. Each platform suspension assembly comprises two parallel elongate suspension guides 21, 22 the cross-sectional shape of which is seen in Figure 3.

The two guides 21, 22 are "handed" so that they can engage corresponding opposite stiles 15, 16. The crosssectional shape of, for example, the guide 22, as shown in Figure 3, can be considered as two L-shape sections joined at the ends of adjacent limbs. In more detail, the first L-section comprises a limb 23 and a limb 24 at right angles to it whilst the second L-section comprises a limb 25 and a limb 26 at right angles to one another.

The two limbs 23, 24 join at an elbow 27 which is directed oppositely from the respective elbows 28, 29 at the junctions of the limbs 23, 24 and the limbs 25, 26 respectively. The "inverse" elbow 27 thus defines an internal channel which receives and is guided by a corner of the stile 15.

The two guides 21, 22 are joined at their lower ends by a transverse strut 30 defining, with the two guides 21, 22, an interconnection frame as will be described in more detail below. Referring now to Figure 4, it will be seen that the limb 23 of the guide 22 has two longitudinally extending aligned slots, an upper slot 30 and a lower slot 31. The upper slot 30 has a series of notches 32, 33 in opposite longitudinal edges defining a series of aligned teeth 34, 35 the purpose of which will be described in more detail below.

The platform assembly is suspended from rungs 17, 18 of the upright supports 13, 14 by a suspension assembly which can be seen in Figure 2. The suspension assembly comprises an elongate strip 36 carrying, at each of its opposite ends respective hook assemblies 37, 38. The lower hook assembly 38 comprises an arcuately curved hook member 39 the internal curved hook surface 40 of which spans an arc of 90 , which is secured to the strip 36 by a threaded bolt 41 passing through an opening in the strip 36 and secured into a threaded nut 42 secured, such as by riveting or welding, to the far side of the strip 36. A spacer 43 holds the hook member 39 separated from the strip 36 by a distance D which corresponds to the thickness of the limb 23 of the guide 22 for purposes which will be described in more detail below.

The upper hook assembly 37 comprises a hook member 44 having an internally curved arcuate surface 45 which extends over more than 90 from a base part 46 to a nose 47. The base part 46 has a projecting rib 48 the depth of which is slightly less than the distance D determined by the thickness of the spacer 43 of the lower hook assembly 38. The hook 44 is secured to the strip 36 by a threaded shaft 49 engaged in a threaded nut 50 like the nut 42 riveted or welded to one end of the strip 36, and the threaded shaft 49 has a manually-operable knob or handle 51 by which the shaft 49 can be turned.

The suspension assembly is mounted to the limb 23 of the guide 22 in such a way that the bolt 41 passes through the lower slot 31 and the threaded shaft 49 passes through the upper slot 30. It will be appreciated that the dimensions of the rib 48 are such that it can enter two aligned notches 32, 33 between adjacent teeth 34, 35 of the slot 30 so that the hook 44 can be located in one of the five positions defined by these notches. Upon tightening the knob 51, however, the hook 44 is pressed against the limb 23 with this limb being clamped between the face 52 of the body portion 46 and the strip 36 due to the fact that the depth of the rib 48 is slightly less than the thickness of the limb 23.

In use of the platform assembly the interconnection frames defined by the guides 21, 22 and the spanning strut 30 are held in a perpendicular orientation with respect to the platform 12 by two diagonal struts 55, 56 each having an end 57 which is pivotally connected to the lower end of a guide 21, 22 respectively and an upper end which is secured by a threaded bolt 58 to the platform 12. The threaded bolt 58 may be released by unscrewing, and repositioned in a further threaded hole 60 in the guide 22 thereby allowing the guide 22 to be turned around its pivotal connection 61 to the platform 12 for stowage purposes.

In the erected position illustrated in Figure 2, however, the guide 22 carries the two hooks 39, 44 in an appropriate orientation to be engaged over respective rungs 17, 18 with the guides 21, 22 engaged over the corners of the stiles 15, 16 of the upright ladder sections 13, 14. In the normal adjustment the hook assembly is positioned at the upper ends of the respective slots 30, 31 and the platform 12 lies substantially horizontally when the upright ladder sections 13, 14 are standing on horizontal ground. Should the ground be inclined or stepped, for example as illustrated in Figure 5, this can be accommodated by repositioning the hooks 44, 39 on different pairs of rungs on one of the ladder sections. If the vertical distance between the surfaces on which the lower ends of the ladder sections 13, 14 rest (identified H in Figure 5) is not an integral number of rung pitch units then fine adjustment can be made by slackening the hand wheel 51 to release the rib 48 from the notches 32, 33 allowing the guides 21, 22 to be displaced with respect to the hook assembly until an appropriate adjustment is reached, whereupon the hand wheel 51 is tightened to engage the rib 48 in a fresh pair of aligned notches 32, 33. As illustrated in the drawings there are five notches providing five incremental adjustment positions at each end of the platform, each increment being one tenth of the rung pitch.

The hook 44, when clamped on to a rung, provides a very secure connection since, as mentioned, the internal curved surface 45 extends over more than 90a so that, when a rung is clamped against the face of the guide 22 it is held against displacement both up and down. The platform assembly is thereby held very securely and rigidly making a safe platform for the user.

The second embodiment of Figures 8 to 10 differs from that of Figures 1 to 7 in that it has means for effecting infinite adjustment, within a certain range, of the height of one end of the platform. The basic components of the platform assembly, namely the platform 12 and the two uprights 13, 14 formed as sections of a separable stepladder, are substantially the same as in the embodiment of Figures 1 to 7, with the exception that the ladder section 14 has a wide foot 60 spanning the stiles 15, 16 at their lower ends to provide added stability.

At a first end 12' the platform 12 is provided with means for fixing it in a selected discrete position on the ladder section 16 determined by the position of the rungs 18. The attachment means at the first end 12' of the platform 12 includes two cranked pivoted bracing struts 61, 62 extending from the sides of the platform 12. As can be seen in Figure 9 the cranked bracing struts are pivoted at 63, 64 to the sides of the platform 12 and have free end portions 65, 66 which have respective lateral notches 67, 68 for hooking onto the rungs 18 of the ladder section 14. The free end portions 65, 66 of the bracing struts 61, 62 are each cranked inwardly with respect to the sides of the platform 12 so that the end of the platform 12 can abut against the stiles 15, 16 and the free end portions 65, 66 of the bracing struts fit between the stiles.

Projecting from the end 12' of the platform 12 are two hook arms 69, 70 which, like the bracing struts 61, 62 are cranked so that their free end portions 96, 97 are spaced inwardly from the sides of the platform 12 and in alignment with the free end portions 65, 66 of the bracing struts 61, 62.

Like the free end portions 65, 66 of the bracing struts 61, 62 the cranked arms 69, 70 have lateral notches 71, 72 shaped to hook over the rungs 18 of the ladder section 14. All of the notches 67, 68 and 71, 72 have respective locking slides 73, 74 and 75, 76 respectively. These comprise rectangular plates having two aligned slots retained on the free end portions of the bracing struts or the crank arms respectively at an inclined position with respect to the associated lateral notch. Two clamping nuts on threaded pins projecting from the respective free ends of the arms or struts clamp the locking plates in one of two end positions, either the retracted position illustrated in Figure 9 allowing the arms and struts to be positioned over the rungs 18, or an extended position where they extend partly under the associated rung to prevent lifting of the arm or strut away from the rung.

In this way the said first end 12' of the platform 12 can be securely fitted at the required height with the height increments of adjustment at this end being determined by the separation between the rungs 18 of the ladder section 14.

At the other or second end 12" of the platform 12 there is provided an infinitely adjustable attachment to the ladder section 13. This allows the platform 12 to be set at a horizontal position regardless of any slope in the ground, or any steps which may be present. The infinitely adjustable attachment comprises two slides 80, 81 which engage the stiles 15, 16 of the ladder section 13. Each slide is identical and only the slide 80, therefore, will be described in detail with particular reference to Figure 10. It comprises a section of extruded aluminium having a generally flattened C-shape with a main body 82 and two lateral flanges 83, 84 which engage over respective sides of the ladder stile 15. The ladder stile 15 is itself one having a generally C-shape cross section, with two inwardly facing aligned flanges 85, 86. Within the interior cavity defined by the body 82 of the slide 80 fitted over the flanges 85, 86 of the stile 15 are located three clamp plates, only one of which, indicated 85, is shown in Figure 10. The clamp plate 85 has a captive nut 86 engaged by a threaded shaft 87 the other end of which carries a butterfly lever 88.

This is located centrally of the slide body 80. At each end secondary clamp plates (not visible) are engaged by hand wheels 89, 90. They are substantially the same in configuration as the clamp plate 85 but whereas this is a metal plate, the secondary clamp plates are made of plastics. The secondary clamps which are operated by the hand wheels 88, 89 engage respective bracing struts 91, 9L connected to the side wall of the platform 12.

It has been found that, by making the main or central clamp 88 with a metal clamp plate 85 the frictional restraint which can be exerted between the slide 80 and the stile 15 is sufficiently great to resist even the maximum loading required by the statutory regulations. By slackening the main clamp lever 88 it is possible to move the slide 80 (and the corresponding slide 81 on the stile 16) along the respective stile until the required position has been reached. Tightening the main clamp lever 88 then secures the second end 12" of the platform 12 at the desired adjustment.

The bracing struts, 61, 62 and 91, 92 ensure that the platform 12 is connected rigidly to the uprights comprising the ladder section 13, 14 to provide a secure platform which can then be used for decorating or other home maintenance purposes.

When not in use the platform 12 can easily be removed from the ladder sections, collapsed with the bracing struts lying alongside the sides of the platform 12, and stored in a garage or a loft. The ladder sections 13, 14 can be interconnected as described in relation to the embodiment of Figures 1 to 7 for use as a stepladder or extension ladder.

Claims

1. An adjustable platform assembly comprising a platform adapted to be carried at each of two ends by respective upright supports, in which one end of the platform is provided with a platform carrier member for connecting the said one end of the platform to a respective platform support, the platform carrier member having means for adjusting the height of the platform with respect to the upright support on which it is carried.

2. An adjustable platform assembly as claimed in Claim 1, in which the platform carrier member includes support means for connecting one end of the platform to the said upright support in a position determined by the form of the upright support, and means for adjustably interconnecting the platform and the said platform carrier member whereby to adjust the height of the said one end of the platform with respect to the upright support on which it is carried.

3. An adjustable platform assembly as claimed in Claim 2, in which said means for interconnecting the platform and the platform carrier member is incrementally adjustable.

4. An adjustable platform assembly as claimed in Claim 3, in which there is provided a platform carrier member at each end of the said platform, for supporting the platform on respective upright supports at each end thereof.

5. An adjustable platform assembly as claimed in any of Claims 1 to 4, in which the upright support or supports are ladders or ladder sections and the said means for interconnecting the platform and the platform carrier member are adjustable over a maximum range of half of the pitch of the rungs of the ladder or ladder section.

6. An adjustable platform assembly as claimed in Claim 5, in which the or each platform carrier member is engaged to at least one rung of the or the adjacent ladder section.

7. An adjustable platform assembly as claimed in Claim 5 or Claim 6, in which the or each platform carrier member has at least two hook members for engagement with two vertically separated rungs of a respective ladder or ladder section, and one of the said hook members engages the rung over more than 90 .

8. An adjustable platform assembly as claimed in Claim 7, in which at least one of the said hook members has associated screw clamp means by which the hook member can be clamped in a selected position with respect to the interconnection means whereby to determine the said adjustment.

9. An adjustable platform assembly as claimed in Claim 8, in which the said screw clamp member threadedly engages in a threaded hole in the said platform carrier member.

10. An adjustable platform assembly as claimed in any of Claims 7 to 9, in which the interconnection means has a member with an elongate slot having a plurality of notches in at least one side wall thereof engageable by at least one co-operating tooth on the said one hook member.

11. An adjustable platform assembly as claimed in any of Claims 2 to 10, in which the or each adjustable interconnection means comprises two elongate members each pivotally connected to the platform at a respective end thereof and braced by a strut releasably connectable to the platform.

12. An adjustable platform assembly as claimed in Claim 1, in which the said means for adjusting the height of the platform with respect to the upright support on which it is carried includes releasable clamp means.

13. An adjustable platform assembly as claimed in Claim 1 or Claim 12, in which the said means for adjusting the height of the platform with respect to the upright support on which it is carried include elongate guides on the upright support for guiding adjustment of the carrier means.

14. A adjustable platform assembly as claimed in Claim 12 or Claim 13 when dependant thereon, in which the platform carrier member is provided with screw clamp means operable to clamp the platform carrier in a selected position on the upright support.

15. An adjustable platform assembly as claimed in any of Claims 12, 13 or 14 in which the platform carrier member is an elongate slide engaged to guide means of the upright support and having clamping means at each end thereof for engagement of the platform and a bracing strut therefor.

16. An adjustable platform assembly as claimed in any of Claims 12 to 15, in which the clamp means have a manually operable lever for manipulation by a user in clamping and releasing the carrier member with respect to the upright support.

17. An adjustable platform assembly as claimed in any of Claims 12 to 16, in which the upright support is a ladder or ladder section the stiles of which have oppositely directed facing flanges defining the said guides for the platform carrier slide member.

18. An adjustable platform assembly as claimed in Claim 17, in which the platform carrier member has lateral flanges engageable when the said flanges of the ladder stile and is provided with a clamp member with a screw threaded stem, the clamp member having opposite edges engageable under the said facing flanges of a ladder stile to clamp them, upon tightening of the said operating lever, between the platform carrier slide and the said clamp member.

19. An adjustable platform substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

Amendments to the claims have been fled as follows 1. An adjustable platform assembly comprising a platform adapted to be carried at each of two ends by respective upright supports, in which one end of the platform is adjustable incrementally with respect to a respective support whereby to vary the height of the platform and the other end of the platform is provided with a platform carrier member for connecting the said one end of the platform to a respective platform support, the platform carrier member having means for adjusting the height of the platform incrementally or infinitely with respect to the upright support on which it is carried, in such a way that adjustments can be made which are smaller than those of the said one end whereby to compensate for inclination of the ground on which the platform stands.

2. An adjustable platform assembly as claimed in Claim 1, in which the platform carrier member includes support means for connecting the said other end of the platform to the said upright support in a position determined by the form of the upright support, and means for adjusting the platform with respect to the said platform carrier member whereby to adjust the height of the said one end of the platform with respect to the upright support on which it is carried.

5. An adjustable platform assembly as claimed in any of Claims 1 to 4, in which the upright support or supports are ladders or ladder sections and the said means for adjusting the platform with respect to the platform carrier member are adjustable over a maximum range of half of the pitch of the rungs of the ladder or ladder section.

11. An adjustable platform assembly as claimed in any of Claims 2 to 10, in which the said platform carrier member comprises two elongate members each pivotally connected to the platform at a respective end thereof and braced by a strut releasably connectable to the platform.

13. An adjustable platform assembly as claimed in Claim 1 or Claim 12, in which the said means for adjusting the height of the platform with respect to the upright support on which it is carried include elongate guides on the upright support for guiding adjustment of the daid platform carrier.

15. An adjustable platform assembly as claimed in any of Claims 12, 13 or 14 in which the platform carrier member is an elongate slide engaged to guide means of the upright support and having clamping means at each end thereof, for engagement of the platform, and a bracing strut therefor.