ARTICULATED STEP STOOL.

Abstract

L'invention concerne un escabeau articulé composé d'une échelle (1), d'une béquille (3) articulée à l'échelle et d'une plate-forme rabattable (10) reliée à l'échelle et à la béquille par des articulations (12, 41, 42). Toutes les articulations sont agencées de façon à permettre leur démontage et le remplacement de pièces usées. L'articulation de chaque montant (4) de la béquille sur le montant correspondant (2) de l'échelle comporte une pièce moulée ayant un tourillon qui pivote dans une douille amovible à profil extérieur non circulaire, engagé dans un trou du montant. La plate-forme (10) est reliée à une traverse (9) de la béquille au moyen d'une bielle (40) entourant un coussinet amovible (45) ajusté sur la traverse.

Description

ARTICULATED STEP STOOL The present invention relates to an articulated stepladder comprising a ladder and a support leg, each having two uprights formed by hollow profiles, each upright of the support leg having an upper end situated in the same substantially vertical plane as a corresponding upright of the ladder and connected to this ladder upright by a horizontal axis articulation, the upper end of each upright of the support leg being provided with an angled arm having a lateral trunnion, this arm extending from one side of the corresponding upright of the ladder, and the articulation of said uprights comprising said toggle, a synthetic material sleeve disposed through the ladder upright and provided with an axial bore in which the trunnion is pivotally housed, and retaining means arranged to hold the trunnion axially in both directions relative to the sleeve, according to claim 1 of the main patent. In such a stepladder, the parts most susceptible to wear are the joints, whether they are the joints between the uprights or those of a folding platform which, as is well known, forms the last step and also serves to hold the stepladder in the open position. In a high-quality stepladder, for example, one intended for professional use, it is desirable to arrange these components in such a way as to both reduce the risk of wear and allow for easy replacement if damaged, without having to disassemble the ladder or the support leg. The present invention aims to provide various improvements to the subject matter of the main patent in the direction indicated above. For this purpose, a stepladder according to the invention is characterized in that the socket of the articulation of the uprights has a cross-section whose perimeter is non-circular and cooperates with at least one hole of corresponding shape in the ladder upright. In one particular embodiment, the upper end of each upright of the crutch is provided with a connecting element made of a single piece molded from synthetic material and comprising a connecting end to the upright, the bent arm and the trunnion. A stepladder according to the invention may advantageously be of the type comprising a folding platform connected to the ladder by a first hinge and to a crossbar of the support leg by a connecting rod, which is connected to the platform by a second hinge and to the crossbar by a third hinge. An advantageous embodiment consists in the third hinge comprising a removable bearing mounted on the crossbar and having a cylindrical outer surface engaged in a corresponding transverse bore of the connecting rod. Preferably, the cross member has a non-circular cross profile and the bearing has a corresponding internal profile, preventing it from rotating on the cross member. The bearing may be provided with an internal lug that fits into a corresponding hole in the cross member, preventing it from sliding on it. In a preferred embodiment, the bearing is made from a single molded piece of synthetic material. Preferably, the bearing completely surrounds the cross member and comprises two shells connected by at least one thinned portion forming a flexible hinge between them. The second joint can be disassembled to allow the connecting rod to slide on the bearing of the third joint in order to release this bearing. Preferably, the first articulation of the platform includes, in each upright of the ladder, a removable socket engaged in a lateral opening of the upright and provided with a central bore forming a bearing for a horizontal rod removably fixed to the platform. The present invention and its advantages will become clearer from the following description of a preferred embodiment, with reference to the accompanying drawings, in which – Figure 1 shows in perspective an articulated stepladder according to the invention, - figure 2 is a partial horizontal cross-sectional view of a articulation of the stepladder, - figure 3 is a vertical cross-sectional view along line III-III of Figure 2, - Figure 4 is a schematic longitudinal cross-sectional view of a folding platform of the stepladder, equipped with a connecting rod, - figure 5 represents a bearing of a connecting rod joint, and - figure 6 is a cross-sectional view along line VI-VI of figure 4. Figure 1 shows an articulated stepladder (also called a "step stool") with a generally classic shape, consisting of a ladder 1 (also called the "climbing platform") with stiles 2 and a rear support 3 (also called the "support platform") with stiles 4, each of which is connected by a joint 5 to a corresponding stile 2 of the ladder. The stiles 2 and 4 are fitted with non-slip feet 6. The stiles 2 of the ladder 1 are rigidly connected to each other by rungs 7 and a top rail 8. The stiles 4 of the support leg 3 are rigidly connected by at least two rails 9, the uppermost of which, in the position shown, supports the rear edge of a folding platform 10. The front edge of this platform is connected to the stiles 2 of the ladder by hinges 12. When the stepladder is open, this platform maintains the opening angle between the ladder 1 and the support leg 3. Its rear edge is profiled to fit onto the top rail 9, thus ensuring good torsional rigidity of the stepladder about a vertical axis. The stiles 2 and 4 are formed by straight sections of lightweight metal profiles or profiles of another material, having a hollow rectangular cross-section as illustrated in Figure 2.The steps 7 and the crossbeams 9 can be made of metal or synthetic material and are rigidly fixed to these profiles in a known way, for example by means of rivets. On each side of the stepladder, the upright 2 of the ladder 1 and the upright 4 of the support 3 are substantially in the same plane. In order to avoid an external projection along the sides of the ladder, the upper end of each upright 4 is fitted with a connecting arm 13 linking the upright to the corresponding joint 5 and angled so as to extend along the inner side of the corresponding upright 2 of the ladder. This arm 13 is part of a one-piece connecting element 14 made from a single piece of light cast metal or synthetic material, comprising the connecting arm 13, a male end fitting for press fitting into the upper end of the upright 4, and a cylindrical trunnion 16 (figure 2) extending laterally from the end of the arm 13 in a direction orthogonal to that of the upright 4. The arm 13 has a skewed shape which is bent in several directions, in order to allow the uprights 2 and 4 to be folded down against each other. The structure of one of the joints 5 is shown more specifically in Figure 2. The upper end of the element 14 has, around the trunnion 16, a flat lateral surface 23 set slightly back from the arm 13. The trunnion 16 is traversed by an axial bore 24 which opens, on the side of the arm 13, into a hexagonal recess designed to receive a nut 25. The ladder upright 2 has two opposing, non-circular openings through which a synthetic sleeve 26 is inserted, forming a bearing for the trunnion 16, which is pivotally fitted in a cylindrical bore 27 of the sleeve 26. The sleeve has a peripheral rim 28 designed to bear against the outer face 29 of the upright 2, and a pair of opposing elastic tabs 30 which tend to spread apart like ratchets to lock the profile wall between themselves and the rim 28.On the other side of the upright 2, the socket 26 has a slightly protruding end 31 whose front surface slides against the surface 23 of the arm 13. A retaining screw 32, having a head 33 pressed against the head of the socket 26, is screwed into the nut 25 and thus holds the socket against the surface 23, eliminating any play between the arm and the socket. Furthermore, the joint can be easily disassembled by removing the screw 32, which allows the socket 26 to be pulled out by breaking the spring tabs 30. This allows the socket to be easily replaced if worn. If the trunnion 16 or another part of the element 14 is damaged, this element can be dislodged from the upright 4 of the support, thus freeing its trunnion from the ladder upright 2. The reverse order is used to put a new element 14 back in place. Figure 3 shows that the cross-section of the synthetic sleeve 26 has a non-circular external profile 34, specifically rectangular in the upper part of the sleeve. This profile matches an identical profile of the opening in the upright in which it is engaged, preventing the sleeve 26 from rotating and wearing within this opening. Furthermore, the upper part of the sleeve has a greater thickness E1 than the thickness E2 of its lower part, as it bears most of the load transmitted by the trunnion 16. Figure 4 shows how the folding platform 10, shown here in an intermediate position during the opening or closing of the stepladder, is connected to the upper crossbar 9 of the support leg 3 by a connecting rod 40 whose respective ends are connected to the platform 10 by a joint 41 and to the crossbar 9 by a joint 42. The joint 41 may include, for example, a stirrup 43 in the shape of U whose base is fixed under the platform 10 and whose wings carry a removable axis 44 on which the end of the connecting rod 40 pivots. In the joint 42, a bearing 45 is provided, mounted on the cross member 9 and having a cylindrical outer surface 46, this bearing sliding in a cylindrical bore of the connecting rod 40. In this example, the cross member 9 is a tubular profile with a square cross section, and the bearing 45 has a central orifice of corresponding cross section, preventing it from pivoting on the cross member. To allow for easy replacement, the bearing 45 is formed from a molded piece of synthetic material having, as it comes out of the mold, the shape shown in Figure 5. The bearing consists of two substantially symmetrical parts 47 and 48, connected by one or more tabs 49 forming a joint. Part 47 is provided with an internal lug 50 designed to fit into a corresponding hole in the cross member 9 and serving as a stop in the longitudinal direction of the cross member. The bearing 45 can be replaced easily and quickly if it is damaged. Simply disassemble the connecting rod joint 41 by removing the pin 44, then slide the connecting rod in the direction of the cross member 9 to disengage it from the bearing, allowing the bearing to be opened and replaced. Figure 6 shows an example of an embodiment of the joint 12 connecting the platform 10 to a stile 2 of the ladder 1. A sleeve 52 is engaged in an opening in the inner face 53 of the stile. Like the sleeve 26 described above, it preferably has a non-circular outer profile that prevents it from rotating. A screw 54 is pivotally housed in a central bore of the sleeve 52 and is engaged in a threaded bore in a thickened lateral portion 55 of the platform 10. The head 56 of the screw 54 is concealed inside the stile 2. For disassembly of the joint, it is accessible through an opening in the opposite wall of the stile, which is closed by a plug 57. The preceding description shows that any of the joint elements of a stepladder according to the invention can be easily replaced without dismantling or damaging the rigid structure of the ladder 1 or the support leg 3, in particular the rigid assembly between the steps of a crossbar and the uprights.

Claims

Demands I. An articulated stepladder comprising a ladder (1) and a support leg (3), each having two uprights formed by hollow profiles, each upright (4) of the support leg having an upper end situated in the same substantially vertical plane as a corresponding upright (2) of the ladder and connected to this ladder upright by a horizontally pivoted joint (5), the upper end of each upright (4) of the support leg being provided with an angled arm (13) fitted with a lateral trunnion (16), this arm extending on one side of the corresponding upright (2) of the ladder, the joint (5) of said uprights comprising said trunnion (16), a synthetic sleeve (26) disposed through the ladder upright (2) and provided with an axial bore (27) in which the trunnion is pivotally housed, and retaining means (23, 32) arranged to retain the trunnion (16) axially in both directions compared to the socket (26), according to claim 1 of the main patent,the stepladder being characterized in that the socket (26) of the articulation of the uprights (2,4) has a cross-section whose perimeter (34) is non-circular and cooperates with at least one hole of corresponding shape in the ladder upright (2).

2. Stepladder according to claim 1, characterized in that the upper end of each upright (4) of the support is provided with a connecting element (14) made of a single piece molded from synthetic material and comprising a connecting end to the upright (4), the bent arm (13) and the trunnion (16).

3. Stepladder according to claim 1, comprising a folding platform (10) connected to the ladder (1) by a first articulation (12) and to a cross member (9) of the support leg by a connecting rod (40), which is connected to the platform (10) by a second articulation (41) and to the cross member (9) by a third articulation (42), characterized in that the third articulation (42) comprises a removable bearing (45) mounted on the cross member (9) and provided with a cylindrical outer surface (46) engaged in a corresponding transverse bore of the connecting rod.

4. Stepladder according to claim 3, characterized in that the crossbar (9) has a non-circular transverse profile and the pad (45) has a corresponding internal profile, preventing it from rotating on the crossbar.

5. Stepladder according to claim 3, characterized in that the bearing (45) is provided with an internal lug (50) fitted into a corresponding hole in the crossbar (9) and preventing it from sliding on the latter.

6. Stepladder according to claim 3, characterized in that the bearing (45) is made of a single molded piece of synthetic material.

7. Stepladder according to claim 6, characterized in that the pad (45) completely surrounds the crossbar and comprises two shells (47,48) connected by at least one thinned portion (49) forming a flexible hinge between them.

8. Stepladder according to claim 5, characterized in that said second joint (41) is removable so as to allow the connecting rod (40) to slide on the bearing (45) of the third joint to release this bearing.

9. Stepladder according to claim 3, characterized in that said first articulation (12) of the platform comprises, in each upright (2) of the ladder, a removable socket (52) engaged in a lateral opening of the upright and provided with a central bore forming a bearing for a horizontal rod (54) removably fixed to the platform (10).