CA2119278A1 - Foldable shelf for stepladder - Google Patents

Abstract

The collapsible stepladder has a main ladder part, a front stay part, hinged to an upper portion of the ladder part, and a shelf mounted to an upper portion of the standards intermediate the top end of the standards and the hinge mount of the front stay part. The shelf includes first and second elongated, rigid bars, which are permanently mounted to the upper end portion of corresponding ladder part standards for relative motion of these bars between a first operative position, in which the bars are laterally spaced and extend generally transversely of the standards and overhang the front stay part, and a second inoperative position, in which the bars are drawn toward one another with the standards while being concurrently tilted to a position extending generally within the plane of the ladder part. A flexible fabric sheet, e.g., forms a template surface, extending between and joining the two elongated bars. The template surface defines a fully extended, generally flat, operative load-bearing condition, and a folded, collapsed inoperative condition. A cross bar, e.g., is further provided, for releasably locking the two bars and associated template in their operative position, against the downwardly-directed bias of a load supported by the template surface.

Description

FIELD OF THE INVENTION
This invention relates to stepladders of the collapsible type, i.e. where the standards of the ladder part can move toward one another in the storage condition of the stepladder, while the shelf proper can concurrently collapse.
BACKGROUND OF THE lNV~ ON
United States patent No 4,569,419 issued 11 February 1986 for a folda~le stepladder, and corresponding Canadian patent No 1,215,951 issued 30 December 1986 to Gerard and Denyse STOLTZ - and recently assigned to the present applicant - , each discloses a stepladder of the collapsible type. This patented stepladder includes a pair of main lateral uprights 1, 2, and a central upright 3 extending between the main uprights parallel thereto.
Successively spaced pairs of half-step 4, 5, are pivoted about pivot mounts 6,7 and 8, to uprights 1, 2, and 3 respectively. In the unfolded operative condition of the stepladder (figure 2), the main uprights 1, 2, are supported at their upper sections by a ground-engaging X-shape pair of legs, which consists of two auxiliary uprights 14, 15, pivoted to one another at their intermediate sections by a pivot means 18. The stay 14, 15, is maintained at a fixed angular relation from the steps 4, 5, by a transverse link arm 19, which is pivotally connected at end to the X-stay pivot 18 and at the other end to the intermediate upright 3.
In the folded stepladder condition, the standards 1, 2, move inwardly toward one another while the half-steps 4, 5, tilt upwardly; the link arm 19 is thus biased upwardly with the intermediate upright 3 (moving with the inner ends of the steps 4, 5), while the support legs 14, 15, both move toward the standards 1, 2 while pivoting about their axis 18 to close the X; wherein a compact storage assembly is attained (figure 1). No shelf is specifically envisioned for use with this collapsible stepladder.
Some basic collapsible shelves for use with collapsible stepladders have been developed in the past. In particular, United States patent No 3,084,760 issued on April 1963 to M. Battista LAMBERTI, discloses a collapsible top step comprising two pairs of standards 6-9 being pivotally interconnected at their top ends, see figure 2 of the drawings. All four standards 6 to 9 are further interconnected at upper sections thereof - short of their top pivotal interconnections - by a collapsible shelf member 24. This shelf member 24, illustrated in plan view in figure 5, consists of a pantograph like pivotal linkage assembly, where a number of link arms 24, 24, are pivotally interconnected in scissor-like fashion.
Accordingly, this shelf member 24 further constitutes the spacer member that controls the fixed angular value between the ladder part 6, 7, and the stay part 8, 9, of the operative (unfolded) stepladder.
Unfortunately, the LAMBERTI shelf does not fit onto the STOLTZ stepladder, since the top ends of the X-shape stay part of the STOLTZ stepladder move relative to one another during folding\unfolding of the stepladder. It is understood that the more recent STOLTZ stepladder architecture is preferred, for the reasons outlined in the corresponding granted patents, namely:

2I 192~8 enhanced stability, simpler folding\unfolding mechanisms, and easier handling.
OBJECTS OF THE l~.V~. ~ lON
The gist of the invention is therefore to provide a collapsible shelf which will fit a collapsible stepladder having X-disposed, scissor-type action, auxiliary support legs.
A more specific object of the invention is to address the need for a collapsible shelf specifically for use with a collapsible stepladder as generally disclosed in United States patent No 4,569,419 and corresponding Canadian patent No 1,215,951.
SUMMARY OF THE lNv~ ION
Accordingly with the objects of the invention, there is disclosed a collapsible shelf member for use with a collapsible stepladder, said stepladder of the type having a main ladder part, with laterally opposite standards joined by successive pairs of hinged half-steps, and a front stay part, hinged to the upper portion of the ladder part, said shelf member comprising: (a) first and second elongated, rigid frame members; (b) first and second means for mounting said first and second rigid frame members respectively to an upper end portion of corresponding said ladder part standards for relative motion of said first and second frame members between a first operative position, in which said first elongated frame members are laterally spaced and extend generally transversely of said standards and are destined to overhang said front stay part in a generally horizontal fashion, and a second inoperative position, in which said first and second frame members 211927~
-are drawn toward one another while being concurrently tilted upwardly and inwardly to a position extending generally within the plane of said ladder part; (c) a template member, extending between and joining said first and second frame members, said template member defining a fully extended, generally flat, operative load-bearing condition corresponding to said operative position of said frame members, and a folded, collapsed inoperative condition, corresponding to said inoperative condition of the frame members; and (d) means for releasably maintaining said frame members and associated template member in their said operative position, against the downwardly-directed bias of a load supported by said template member.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view of a stepladder according substantially to the STOLTZ architecture, supra, to which a shelf according to the invention is fitted;
figure 2 is an enlarged view of the area circumscribed by circle 2 in figure 1, suggesting how the fabric-template shelf member is pivoted at its inner end to the ladder part main standards, and showing the transverse abutment finger for supporting the shelf in its operative condition;
figure 3 is an isometric view of the upper portion of the stepladder, one of the ladder part standards thereof being shown in phantom lines, and being fitted with the fabric-template shelf member according to the invention, a pair of compasses transversely joining the standards beneath the inner portion of the shelf for 2119.~78 supporting the latter in its operative condition;
figure 4 is a view at an enlarged scale of the area circumscribed by circle 4 in figure 3, showing the pivotal mount of one lateral side elongated frame member of the shelf to the corresponding standard;
figures 5 and 6 are enlarged isometric views of the fabric-base template and of the multiple pair of compasses type shelf members, respectively, in their unfolded (operative) condition, with figure 6 further showing the adjacent portions of the stepladder standards and the additional pair of compasses beneath the inner portion of the shelf template for supporting same in its operative horizontal position;
figures 7 and 8 are views similar to figures 5 and 6, respectively, but showing these two different embodiments of shelf templates in their partially folded, partially upwardly tilted conditions; and figures 9, 10 and 11 are isometric views of a strap hinge like shelf template according to the invention, being shown sequentially in unfolded - operative - condition, partly folded condition, and completely folded condition, respectively, with figure 10 further illustrating the adjacent portions of the stepladder main uprights in phantom lines.
DETAILED DESCRIPTION OF THE DRAWING$
Figure 1 shows a stepladder 20 including a ladder part 22 and a stay part 24 for supporting the ladder 22 in its operative, upwardly forwardly inclined condition. Ladder part 22 itself includes a pair of parallel, cross-sectionally U-shape main standards 26, 28, movable relative to one another via a plurality of tiltable half-steps 30-31, 30'-31', 30''-31'', ... The half-steps are all hingedly carried at their inner ends to one another in pairs and by successively spaced sections of a single intermediate upright 32. Upright 32 extends parallel to main standards 26, 28, and the mouth of each standard 26, 28, opens toward intermediate upright 32. A pair of compasses 34 are pivoted at the bottom end of the intermediate upright 32, in hinged connection with the bottom ends 26a, 28, respectively of the main standards 26, 28 - as generally disclosed and for the purpose already stated in U.S. patent No 4,569,419.
The stay part 24 includes a pair of auxiliary upright legs 36, 38, being pivotally interconnected at an intermediate section thereof, 40, to form an X-shape in unfolded condition.
Pivot mount 40 is itself pivotally mounted to an upper section of the ladder intermediate upright 32, via a transverse link arm 42.
In the stepladder unfolded operative upright condition (figure 1), the ground-engaging bottom ends 36a, 38a, of the auxiliary uprights 36, 38, are spread apart by a distance much greater than that between the main uprights bottom ends 26a, 28a (which are of fixed relative distance all along their length). The top ends 36b, 38b, of the auxiliary uprights 36, 38, are pivotally mounted to an upper section of the main standards 26, 28, about pivot mounts (not illustrated, but already detailed in U.S. patent No 4569419), whereby an acute angle is formed between auxiliary uprights 36, 38, and main uprights 26, 28.

Preferably, an endless rigid (e.g. nylon) strip 48 is provided to interconnect a lower section of the intermediate upright 32 to a lower section of the auxiliary uprights 36, 38 (to prevent their accidental spreading apart under a high load).
Now, in accordance with the teachings of this invention, there is provided a shelf member, 50, being carried at the upper portion of the stepladder 20. More particularly, and as illustrated in figures 1, 2 and 4, shelf member 50 is pivotally mounted by pivot means 52, to each of the two main standards 26, 28, at a section thereof intermediate the auxiliary uprights pivoted top ends 36b, 38b, and the main standards top ends 26b, 28b. Moreover, an operative horizontal position of the shelf 50 is set by shelf stopper means 54 or 55, which are integral to the main standards 26, 28, whereby the shelf will hang freely over the extended X-disposed auxiliary support legs 36, 38, in generally horizontal fashion.
Three different embodiments of shelves 50 (50', 50'') are illustrated: a first one at figures 5 and 7, a second one at figures 6 and 8, and a third one at figures 9, 10 and 11.
The shelf member 50 illustrated in figures 5 and 7 includes a pair of elongated, rigid frame members or bars 56, 58, being interconnected by and maintained in parallel relation via a plurality of pair of compasses or linkage arms 60 and 62 (60' and 62', 60'' and 62'', ... - the number may vary). Each bar 56, 58, forms along most of its length an L-shape or U-shape in cross-sec-tion, defining orthogonal legs 56a, 56b, 58a, 58b, except that legs 56b, 58b extend short of legs 56a, 58a at one end thereof, to form extensions 56aa, 58aa. Each elongated link arms 60 and 62 is hinged at their inner ends by a first pivot mount 64, with link arm 60 being pivoted at its outer end 66 to horizontal leg 56b while coextensive link arm 62 is pivoted at its opposite outer end 68 to horizontal leg 58b of L-bar 58. Accordingly, and as suggested in figure 7, bars 56, 58, are movable relative to one another, but remain parallel to one another; i.e., the pair of compasses are hinged at their inner ends for pivotal motion within the plane of the shelf.
It is important that the distance between each two successive pairs of compass or link arms, e.g. 60, 62 and 60', 62', should be smaller than the diametrally smallest object to be supported by said shelf 50, so that said shelf 20 constitutes an appropriate template - albeit forming a discontinuous surface - for supporting and retaining thereover the various tools and the like to be used when a person stands on the stepladder and make use of the shelf 50.
Pivot means 52, illustrated in exploded view in fig 2, includes a sturdy block unit 70, being inserted into the channel of the upper portion of each U-shape standard 26 and 28 (through the interior mouth thereof), and locked in place by rivets 72. Block unit 70 includes a distal upper bore 74 (fig 4) and each bar extension 58aa, 56aa, includes a bore 73, whereby a rivet 75 is freely engageable through bores 73 and 75 for pivotally interconnecting the end 56aa or 58aa of the shelf bars 56 or 58 to the corresponding standards 26 and 28, respectively. A proximal lower flange 76 is further provided to block 70, projecting transversely inwardly therefrom to come in register with and being adapted for abutting engagement by the corresponding bar end 56aa or 58aa. By ''proximal'' and ''distal'', we mean close to and away from the side of the auxiliary uprights 36, 38, respectively.
Therefore, it is understood that, as shelf 50 pivots about transverse pivot mounts 73, 74 and 75, inturned flange 76 will constitute an abutment stop 76 against which the shelf lateral frame bars will be stably supported in a generally horizontal, forward limit position thereof, since this abutment flange 76 is located downwardly and forwardly (i.e. distally) from the pivot mount 74.
It is understood that the reason why bar leg end 56aa (58aa) extends beyond the corresponding bar leg end 56b (58b) is to clear the way for abutment tab 76 (which is engageable with bar extensions 56aa, 58aa). It is recognized that abutment tab 76 would remain operational even if the bars 56 and 58 were cross-sectionally L-shape all along their length (i.e., that there would be no extension 56aa, 58aa); however, because of the reduced thickness of bar end sections 56aa, 58aa, the shelf 50 will be able to desirably reach a more readily horizontal condition, in view of the already forwardly upwardly inclined condition of the standards 26 and 28 (when the stepladder is in its operative upright condition).
In this first embodiment of shelf 50, the plurality of pair of compasses may be made from any suitably rigid material, in particular steel, aluminium or a plastic material such as PVC.
In a second embodiment of shelf according to the invention (figs 6 and 8), the plurality of pair of compasses is reduced to a single pair of ''distal'' compasses or linkage arms, 77, 79, (i.e. distal relative to the main standards 26 and 28) with associated pivotal rivets 64, 66, 68, whereas a flexible sheet material 80 is extended between the bar legs 84, 86 of the shelf 50' and edgewisely riveted in position to the horizontal edge parts of the cross-sectionally L-shape bar legs 84, 86, by rivets 82.
Flexible sheet 80 may be fabric, or other suitable flexible sheet material. Moreover, the abutment tab 76 of the first embodiment is replaced by another pair of compasses, i.e. a pair of pivotally hinged linkage arms 90, 92, that pivotally interconnect - via pivots 94, 96, and 98 - the two standards 26 and 28, about a plane parallel to that defined by the two main standards 26, 28, i.e.
transverse to the plane of the shelf 50' in its operative (horizontal) condition.
It is noted that the single pair of compasses 90, 92, has an interlocking shoulder 100 at their inner ends. Shoulder 100 sets a limit colinear downward position for this pair of compasses 90, 92, as illustrated in figure 6, thus preventing link arms 90, 92, from caving in under a load supported by the shelf 50' - i.e.
the inner hinged ends of the link arms so, 92, cannot pivot downwardly beyond their horizontal colinear arrangement of figure 6 (but they may pivot upwardly during collapse for storage purpose, as suggested in figure 8). Such hinge shoulder was not essential for the shelf template link arms 77 and 79, or pair of compasses 60, 62; but could alternately be used, is desired.
It is further noted that figure 7 shows the link arms 9o, 92, and 96, being fitted to the multiple link shelf 50 of figure 5, instead of the tab 76 of figure 2; this is only to show the interchangeability of these shelf support members, being adaptable to either the fabric-based template shelf of figure 6 or the multiple pair of compasses-based template shelf of figure 5.
In a third embodiment of shelf 50'' - as illustrated in figures 9-11 -, the frame bars 56, 58 and the template linkage arms 60, 62, are all replaced by a strap hinge -like those used for securing a door to a door frame-, including a plurality of rectangular (or at least quadrangular) hinge plates 112a, 112b, 112c, 112d, 112e, 112f (the total number may vary with the dimensions of the stepladder) hinged in successive pairs about hinge means 113. Each successive pair of hinge plates 112a, 112b, ... of the strap hinge 50'' include edgewise shoulders 114 that lock the hinge plates in a coplanar, operative condition (figure 9), while not preventing upward pivotal motion of these hinge plates (figure 10) to bring the strap hinge-like shelf in its collapsed inoperative condition (figure 11) in which the laterally opposite hinge plates 112a and 112f are brought closest to one another and in generally parallel fashion. The inner ends of these lateral hinge plates 112a and 112f are pivotally hinged to the respective standards 26 and 28 by pivot means 116 which are similar to either the one disclosed in figure 2 or in figure 4.
It is understood that with such a strap hinge-like template assembly, there is no need for a separate abutment member such as element 76 in figure 2 or element 55 in figure 4, thanks to the shoulders 114. In the fully folded condition of this strap hinge 50'' (figure 11), a folded accordion-like structure is obtained. Such strap hinge member 50'' may be manufactured from extruded aluminum or from a steel matrix. Hence, as with the first, multiple pair of compasses sheIf 50 and second, fabric-based shelf 50', this strap hinge shelf 50'' has the advantageous feature of being foldable in a compact fashion when not in use (during storage thereof), without having to remove this shelf from the ladder part of the stepladder. That is to say, the structural integrity of the pivotal interconnection between the shelf and the ladder should never be compromised in normal operating conditions of the stepladder, even after repeated folding\unfolding thereof, since this pivotal interconnection is a permanent one.
Other alternate embodiments of such collapsible, permanently attached, stepladder shelves are not to be excluded from the scope of the invention, provided they ensure effective load-bearing capability in their horizontally extended operative condition, while maintaining a collapsible capability when storage of the stepladder is required. For example, in still another embodiment of the invention - not illustrated in the hereinenclosed drawings -, the block unit 70 of the embodiment of fig 2 would be replaced by a triangular casing defining a downwardly forwardly (i.e. outwardly) inclined top mouth. Moreover, each of the two opposite lateral frame bars of the shelf tapers at its inner end, so that the thinnest end section of a shelf side bar may engage through said triangular casing top mouth and into the hollow of this casing, to come to abut against this casing flooring (opposite its mouth) in the operative horizontal load-bearing condition of the shelf. Also, the pivotal mount of the shelf side bar would extend freely through bores made in both laterally spaced side walls of this hollow casing, so that, during upward pivotal motion of the shelf side bars, the casing side walls would constitute guide members for the shelf side bars.
It is understood that, although no pair of compasses or inturned support finger has been shown for use with the strap hinge tablet of figures 9-11, it is to be considered well within the scope of the present invention to install such a tablet support means, if necessary, when the load supported by the tablet exceeds a given threshold.

Claims (13)

The embodiments of the invention for which an exclusive property or privilege is claimed, are defined as follows:

1. A collapsible shelf member for use with a collapsible stepladder, with said stepladder being of the type having a main ladder part, with laterally opposite standards joined by successive pairs of hinged half-steps, and a front stay part, hinged to a first upper portion of the ladder part, said shelf member comprising:
(a) first and second elongated, rigid frame members;
(b) first and second means for mounting said first and second rigid frame members respectively to a second end portion of corresponding said ladder part standards for relative motion of said first and second frame members, said second end portion being located above said ladder first end portion, said frame members movable between a first operative position, in which said first elongated frame members are laterally spaced and extend generally transversely of said standards and are destined to overhang said front stay part in a generally horizontal fashion, and a second inoperative position, in which said first and second frame members can be drawn toward one another while being concurrently tilted upwardly and inwardly to a position extending generally within the plane of said ladder part;
(c) a template member, extending between and joining said first and second frame members, said template member defining a fully extended, generally flat, operative load-bearing surface corresponding to said operative position of said frame members, and having a folded, collapsed inoperative condition, corresponding to said inoperative condition of the frame members; and (d) means for releasably maintaining said frame members and associated template member in their said operative position, against the downwardly-directed bias of a load supported by said template member.

2. A collapsible shelf member as defined in claim 1, wherein said template member includes a flexible sheet, forming a continuous load-bearing surface, and anchor means for edgewisely anchoring said flexible sheet to said first and second frame members.

3. A collapsible shelf member as defined in claim 2, wherein said flexible sheet is made from fabric.

4. A collapsible shelf member as defined in claim 3, further including one pair of compasses, extending beneath said fabric sheet at the shelf member distal end relative to said ladder part, said one pair of compasses including one and another elongated linkage arms hinged at their inner ends by a first pivot means, second pivot means being provided for pivotally interconnecting each said one linkage arm to said first frame member, and third pivot means being provided for pivotallly interconnecting each said another linkage arm to said second frame member; wherein said first, second and third pivot means define pivotal axes which are transverse to the load-bearing surface defined by said template member in its operative position; whereby said pair of compasses enhance maximum load-bearing capability of said fabric sheet.

5. A collapsible shelf member as defined in claim 1, wherein said template member includes a plurality of pairs of compasses forming a discontinuous load-bearing surface, with each pair of compasses including one and another elongated linkage arms hinged at an inner end thereof by a first pivot means, second pivot means being provided for pivotally interconnecting an outer end of each said one linkage arm to said first frame member, and third pivot means being provided for pivotallly interconnecting an outer end of each said another linkage arm to said second frame member;
wherein said first, second and third pivot means define pivotal axes which extend transversely to the load-bearing surface defined by said template member in its operative position; and wherein the discontinuities of said discontinuous load-bearing surface are smaller than the smallest of the objects to the supported over said shelf member in its operative condition so that said template membere be able to retain all such objects.

6. A collapsible shelf member as defined in claim 1, wherein said template member consists of a rigid, strap hinge-like member forming a continuous flat load-bearing surface in its operative condition, said strap hinge like member defining a plurality of quadrangular hinge plates hinged in successive pairs by respective hinge joints, the laterally opposite said hinge plates being hinged by additional hinge joints to said first and second frame members, respectively.

7. A collapsible shelf member as defined in claim 6, wherein said releasable shelf maintaining means consists of shoulder means, cooperating with said hinge joints in locking said hinge plates in a flat planar condition, against downward caving in forces from load-borne bias, while not hampering upward pivotal motion of said hinge plates toward the collapsed inoperative shelf condition.

8. A collapsible shelf member as defined in claim 1, wherein said releasable shelf maintaining means consists of an elongated rigid bar, to extend beneath the shelf transversely of said first and second frame members and destined to be fixedly anchored to both said standards of the ladder part; whereby said first and second frame members come to abut against said rigid bar in said operative position of the template member.

9. A collapsible shelf member as defined in claim 1, wherein said releasable shelf maintaining means consists of a pair of compasses including one and another elongated linkage arms hinged at their inner ends by a first pivot means, second pivot means being provided for pivotally interconnecting an outer end of said one linkage arm to one of the two ladder standards, third pivot means being provided for pivotallly interconnecting an outer end of said another linkage arm to the other of the two ladder part standards; wherein said first, second and third pivot means define pivotal axes which extend generally parallel to the load-bearing surface defined by said template member in its operative position.

10. A collapsible shelf member as defined in claim 2, with each said elongated frame member being cross-sectionally L-shape so as to define - in the template member operative position -a generally vertical laterally outward leg and a generally horizontal laterally inward lower leg, whereby said anchor means fixedly anchor opposite edgewise portions of said flexible sheet to said laterally inward horizontal lower leg of said frame members.

11. A collapsible shelf member as defined in claim 1, with each said elongated frame member being cross-sectionally L-shape along most of its length so as to define - in the operative position of the template member - a generally vertical laterally outward leg and a generally horizontal laterally inward lower leg, said laterally outward leg further defining an inner extension extending beyond the inner end of the corresponding laterally inward horizontal lower leg; wherein said releasable locking means includes a rigid finger, to be anchored to each ladder part standard in transversely inwardly projecting fashion, said finger abuttingly receiving and supporting an edgewise section of said inner extension in the operative position of said template member.

12. A collapsible shelf member as defined in claim 1, wherein said means for relative movement of said first and second elongated frame members include a pivot member, extending through the inner end of each of said elongated frame members and destined to freely engage transversely through corresponding said ladder part standards, whereby said frame members are then pivotable at their inner ends along a substantially horizontal axis - in the operative condition of the template member.

13. In combination, a collapsible stepladder having a main ladder part with laterally opposite standards joined by successive pairs of hinged half-steps, a front stay part hinged at a hinge point to the ladder part at their upper portions, and a shelf member mounted to the upper portion of said standards intermediate said hinge point and the top end defined by said standards, said shelf member comprising:
(a) first and second elongated, rigid frame members;
(b) first and second means that permanently mount said first and second rigid frame members respectively to the upper end portion of corresponding said ladder part standards above said stay part hinge point, for relative motion of said first and second frame members between a first operative position, in which said first elongated frame members are laterally spaced and extend generally transversely of said standards and overhang said front stay part, and a second inoperative position, in which said first and second frame members can be drawn toward one another while being concurrently tilted upwardly and inwardly to a position extending generally within the plane of said ladder part;
(c) a template member, extending between and joining said first and second frame members, said template member defining a fully extended, generally flat, operative load-bearing surface corresponding to said operative position of said frame members, and a folded, collapsed inoperative condition, corresponding to said inoperative condition of the frame members; and (d) means for releasably maintaining said frame members and associated template member in their said operative position, against the downwardly-directed bias of a load supported by said template member.