Stick to help individuals with reduced mobility to move around

Abstract

Stick (1) comprising a handgrip (10) and a supporting structure (3) comprising a support tube (4) and four curved branches (5, 6, 7 and 8) which are connected to the support tube (4), each one having a vertical lower end and a caster (9) and extending downward away from the support tube, a first and a second curved branch (5, 6) having their vertical lower ends extending in a first vertical plane, a third and a fourth curved branch (7, 8) having their vertical ends extending in a second vertical plane, parallel to the first, the distance between the vertical ends of the first and of the second curved branches being greater than the distance between the vertical ends of the third and of the fourth curved branches, the first vertical plane being situated at a distance from the support tube that is shorter than the distance between the second vertical plane and this support tube.

Description

[0001] The present invention relates to a cane for moving people with reduced mobility.

[0002] The present invention also relates to a method of assembling this cane.

[0003] The walking aid systems known from the state of the art are mainly canes and walkers.

[0004] Walking sticks and variants such as crutches generally consist of a simple rod, adjustable in height to suit the user's height, and also include a support handle. In operation, the user with walking difficulties performs a 3-step walk which consists of lifting the stick, positioning it correctly to avoid the risk of slipping, and moving one foot forward then the other while leaning on the stick. The user then repeats the process until the destination point. Depending on the degree of disability and / or the user's degree of independence, the walking stick is not necessarily suitable.

[0005] For a larger walking aid system, there are two types of walkers, intended more specifically for the elderly. Walking frames, which require the user to lift the walking frame with both hands, place the walking frame on the ground and move both feet forward, and so on, and wheeled walkers, which rest on the ground on 3 or 4 casters and are equipped with a braking system. Unfortunately, these two types of walkers are not suitable for certain uses given their bulkiness, and the user will therefore have to adapt and use the walking stick when necessary. Another disadvantage of these walkers is that they are not usable for a person with hemiplegia.

[0006] Document CN110772004 discloses a fall-prevention walking aid crutch for the elderly. The crutch comprises a height-adjustable main rod and at least 6 side rods. Each side rod is connected to the main rod by two springs, which on the one hand secure the side rods to the main rod and on the other hand allow the crutch to be tilted according to the user's support area. In operation, when the elderly person uses the crutch in a situation where their center of gravity is unstable and they tilt to one side (usually forward or to the left and right sides), the side rod on the side of the imbalance will open to the maximum to support the main rod, thus supporting the user and preventing a fall.

[0007] Document US9016297 discloses a cane comprising at least one vertical height-adjustable shaft, a handle, a base, 4 wheels and 4 rigid supports. The 4 rigid supports are safety brakes extending distally beyond the wheels and the 4 wheels are retractable wheels in the base. In operation, when the cane is tilted away from the substantially vertical position in any direction, one or more rigid supports come into contact with the ground. The cane therefore has two positions: a stop position where the rigid support is in contact with the ground and a movement position where the 4 wheels are in contact with the ground.

[0008] Unfortunately, using such devices is not easy and does not meet users' expectations.

[0009] Depending on the degree of disability, the person with reduced mobility has a cane and / or a walker. The user must choose between a cane and a walker; both cannot be used simultaneously. If the user chooses to use a cane, the cane must be constantly repositioned with each step to move forward, which creates a risk of falling by unbalancing the user each time they have to lift the cane. If the user chooses to use a walker, they must adapt to the weight and bulk of the walker; moreover, the walker is not easily maneuverable.

[0010] Also known are utility model CN208228504 and patent application CN101332146, both of which propose a cane composed of a stem ending in a small crosspiece whose branches are identical and end in a wheel. These canes lack stability and are not very ergonomic. Patent application US6158453 describes a cane whose stem ends in a plate equipped with 4 unidirectional wheels.

[0011] CN208228504U discloses a device according to the preamble of claim 1.

[0012] The object of the invention is to provide an ergonomic cane whose structure, and therefore assembly, are simple and whose use and handling are easy, allowing the user to move easily, without stopping to reposition the cane and therefore without having to go through a 3-step walk. It is desirable that this cane provides stability to the user without being too bulky.

[0013] To solve this problem, the invention provides a walking stick for people with reduced mobility, comprising: a handle, for gripping the cane, and a support structure comprising o a support tube on which the handle is fixed, o four curved branches connected to the support tube, each having a vertical lower end, and o a wheel, fixedly connected to the vertical lower end of each of said branches, being capable of pivoting freely about a vertical axis, a first curved branch and a second curved branch having their vertical lower ends extending at a distance from each other in a first vertical plane, a third curved branch and a fourth curved branch having their vertical ends extending at a distance from each other in a second vertical plane, parallel to the first vertical plane, these two planes being located on either side of the aforementioned support tube.In this cane according to the invention said four curved branches connected to the support tube (4) extend downwards away from the latter and the distance between the vertical ends of the first and second branches in said first vertical plane is greater than the distance between the vertical ends of the third and fourth branches in said second vertical plane, the first vertical plane being located at a distance from the support tube less than the distance presented between the second vertical plane and this support tube.

[0014] The four curved arms are connected to the support tube and extend downwards, forming a curve. The curvature of the arms helps strengthen the support structure, increasing the stability of the cane and the strength of the structure. This is because when the user leans on the cane, the weight is borne by the support structure, which must be strong enough to support the user without collapsing / crushing the casters.

[0015] Each vertical lower end of the curved branches is fixedly connected to a caster in a way that prevents the branches from touching the ground, even when the user presses harder in one direction or another. In addition, the castors can rotate 360° freely around a vertical axis, thus allowing the user to move in all directions of space, whether laterally, transversely, forwards or backwards.

[0016] The advantage of these wheels is that they maintain constant contact between the user and the ground, without having to lift the cane with each step. The user can therefore walk smoothly by alternating between the right and left feet without stopping to move the cane, lift it, and move it forward, and without ceasing to be able to lean on the cane. The user can therefore be helped throughout their walk. The wheels must roll and pivot freely, without noise or discomfort. The curved branches never touch the ground; it is the wheels that remain in permanent contact with the ground.

[0017] The casters are functional, and for this reason they must be positioned in such a way that they are not too close together, which would cause a stability problem, or too far apart, which would increase the bulk and reduce maneuverability.

[0018] The four curved branches can advantageously be identical two by two, which facilitates manufacturing and assembly. For example, the two branches furthest from the user (the third and fourth branches) are identical and the two branches closest to the user (the first curved branch and the second curved branch) are identical.

[0019] The vertical lower ends of the two branches closest to the user extend in a first vertical plane parallel to a second vertical plane defined by the vertical lower ends of the two furthest branches, each plane being arranged on either side of the axis of the support tube. In addition, the vertical lower ends of the branches closest to the user are spaced apart by a distance greater than the distance between the two vertical lower ends of the branches furthest from the user. This configuration has the advantage of creating a sufficient support surface to ensure the balance and stabilization of the user when moving forward and / or backward.

[0020] By the term "supporting surface" according to the present invention is meant the surface on which the orthogonal projection of the center of gravity of a solid on the ground, or on a support, must be located to ensure equilibrium. In the case where a person adopts a posture which causes the center of mass of the object to be above the supporting surface of the object, the reaction of the ground will automatically adjust to prevent the object from falling to the ground by placing the center of pressure below the center of mass.

[0021] In application, the smaller the support surface, the greater the instability. The configuration of the curved branches of the cane according to the present invention has the advantage of having a sufficient support surface to provide stability to the user without being too bulky thanks to the spacing of the first branch and the second curved branch.

[0022] In addition, the configuration of the cane does not require a braking system, the arrangement of the curved branches and the wheels allow the speed of the cane to be managed and the trajectories to be adapted. The balance provided by this configuration allows the cane to be kept stationary when no force is applied to the cane. In operation, the support on the cane depends on the user, the pathology, the degree of disability. The configuration of the curved branches therefore makes it possible to adapt to all types of user by stabilizing the cane regardless of the source of the force applied to the cane.

[0023] Particularly advantageously, an upper part of the first curved branch and an upper part of the second curved branch form between them an angle of between 105 and 120°, preferably between 110 and 115°, preferably between 112 and 113°.

[0024] Advantageously, an upper part of the third curved branch and an upper part of the fourth curved branch form between them an angle of between 72 and 88°, preferably between 77 and 83°, preferably between 80 and 81°.

[0025] Preferably, the upper part of the second curved branch and the upper part of the third curved branch form between them an angle of between 75 and 91°, preferably between 80 and 86°, preferably between 83 and 84°.

[0026] Preferably, the upper part of the first curved branch and the upper part of the fourth curved branch form between them an angle of between 75 and 91°, preferably between 80 and 86°, preferably between 83 and 84°.

[0027] The total of the angles formed between the 4 curved branches is equal to 360°. The angle formed between the first and second curved branches (closest to the user) is greater than the angle formed between the third and fourth curved branches (furthest from the user). This allows the user to walk smoothly without being hindered by the curved branches. To stabilize the cane, the first and second curved branches will be further apart than the branches on the outside. In operation, the user is at a distance of a forearm (approximately 20-30cm) and must therefore position the cane on their right or left side for support. This arrangement of the curved branches allows for easier maneuverability of the cane.

[0028] The angles are calculated in a bottom plan view as shown in the figure 4 .

[0029] Advantageously, the vertical lower ends of the curved branches form a quadrilateral having a surface area of between 550 cm 2< and 570 cm 2< , preferably between 555 cm 2< and 565 cm 2< , preferably 561 cm 2< .

[0030] The term "quadrilateral" according to the present invention means a four-sided polygon. The surface area covered by the quadrilateral is sufficient to keep the cane stable on the one hand and on the other hand allows the user to balance without the need for a heavy, bulky and difficult to handle walking aid.

[0031] Preferably, each vertical lower end of the curved branches has a height of between 40 and 60 mm, preferably between 45 and 55 mm.

[0032] Preferably, the handle is an ambidextrous handle. It can therefore be used by all types of users, right-handed or left-handed, and regardless of the pathology and / or degree of disability. The advantage is that it can be used with one hand, particularly when the user has hemiplegia.

[0033] Preferably, the support structure is at least partially made of steel. This helps stabilize the cane. Indeed, the heavier the cane, the greater the stability.

[0034] Preferably, however, one of the two support tubes may be at least partially made of anodized aluminum. Anodized aluminum has the advantage of obtaining a corrosion-resistant, durable tube and a shiny appearance.

[0035] Other embodiments of the cane according to the invention are indicated in the appended claims.

[0036] The invention also relates to a method of assembling a cane according to the present invention comprising the steps of: fitting an upper vertical tube into a handle, fixing the handle to the upper vertical tube by fixing means, fitting a finishing ring onto an upper part of a lower vertical tube, fitting a finishing ring onto a lower part of the lower vertical tube, welding a first curved branch and a second curved branch at a first level of the lower vertical tube, an upper part of said first curved branch and an upper part of said second curved branch forming between them an angle of between 105 and 120°, preferably between 110 and 115°, preferably between 112 and 113°, welding a third curved branch and a fourth curved branch at a second level of the lower vertical tube, different from the first level,an upper part of said third curved branch and an upper part of said fourth curved branch forming between them an angle of between 72 and 88°, preferably between 77 and 83°, preferably between 80 and 81°, sliding of the upper vertical tube in the lower vertical tube so as to be adjustable in height, with fixing of one to the other at the adjusted height, and fixing of a caster to the lower vertical end of each of said curved branches, so as to allow it to pivot around a vertical axis.

[0037] The upper vertical tube is fitted into the handle, preferably the fitting is done in such a way that the two holes in the upper vertical tube correspond to the two holes in the handle. The handle is fixed to the upper vertical tube by means of fasteners, preferably by two rivets fixed through the handle.

[0038] The handle is the contact element between the user and the cane, it is essential that the handle is securely attached to the upper vertical tube to avoid movement / play between the handle and the tube.

[0039] Welding the first and second curved branches at a different first level than welding the third and fourth branches at a second level allows for sufficient space to make strong and durable welds.

[0040] Preferably, the finishing rings are fixed by snap-fitting to the lower vertical tube. Preferably, the finishing rings are snap-fitted after applying a dot of glue.

[0041] Sliding the upper vertical tube into the lower vertical tube allows the height of the cane to be adjusted, and more particularly the height of the handle connected to the upper vertical tube. Preferably, the upper vertical tube includes openings on only one side of the upper vertical tube and an indexing finger is intended to lock the position of the upper vertical tube at the chosen height.

[0042] The term "indexing finger" is understood to mean, within the meaning of the present invention, an element making it possible to block and lock the sliding movement of the two vertical tubes. The indexing finger makes it possible to adjust and fix the height of the handle according to the size of the user.

[0043] The indexing finger is screwed in. During use, the indexing finger cannot be unscrewed manually. However, the indexing finger returns to its position after each pull.

[0044] The casters are attached to the vertical lower ends of the curved branches, preferably the casters are screwed to the ends. When in use, the 4 casters touch the ground, rotate easily in all directions but cannot be unscrewed manually.

[0045] Assembly is quick and does not require modification of the cane depending on the degree of disability and / or autonomy of the user. The rolling cane must be supplied without knock, with functional bearings (without noise and without discomfort), without traces of glue and with vertical tubes sliding correctly between them.

[0046] For transport purposes, the upper vertical tube can be slid into the support structure so that the handle is at the same level as the casters. It is necessary to have no play between the two vertical tubes.

[0047] Other embodiments of the method of assembling a cane according to the invention are indicated in the appended claims.

[0048] Other characteristics, details and advantages of the invention will emerge from the description given below, without limitation and with reference to the drawings. There figure 1 is an exploded schematic view of the cane. The figure 2 is a schematic side view of the cane. The figure 3 is a schematic view of the front of the cane. The figure 4 is a schematic view from above of the cane.

[0049] In the figures, identical or similar elements bear the same references.

[0050] The list of references used is described below: 1- cane 2- upper vertical tube 3- support structure 4- lower vertical tube 5- first curved branch 6- second curved branch 7- third curved branch 8- fourth curved branch 9- wheel 10- handle 11- upper finishing ring 12- lower finishing ring 13- indexing finger X - first vertical plane Y- second vertical plane Z- axis of the support tube

[0051] Other features and advantages of the present invention will be drawn from the following non-limiting description, and with reference to the drawings.

[0052] There figure 1 illustrates an exploded view of an example of a walking aid cane 1 for people with reduced mobility, which is in accordance with the invention. This cane is provided with a handle 10. The support structure 3 of the handle, as illustrated in the figure 1 , comprises a support tube, formed of an upper vertical tube 2 and a lower vertical tube 4, four curved branches 5, 6, 7 and 8 and casters 9. A finishing ring 11 is fitted onto the upper part of the lower vertical tube 4 and a finishing ring 12 is fitted onto the lower part of the lower vertical tube 4.

[0053] The handle 10 is connected to the support structure, more particularly to the upper vertical tube 2. The handle 10 serves as a contact element between the user and the cane 1. The fixing of the upper vertical tube 2 in the handle is made in such a way that the two holes of the upper vertical tube 2 correspond to the two holes of the handle 10. These two elements are connected by two rivets fixed through the handle and pass through the two corresponding holes. The handle 10 can be pebble-shaped, round, or any other shape allowing it to be gripped. The handle is preferably ambidextrous.

[0054] In the example shown, the upper vertical tube 2 can be slid through the lower vertical tube 4 so as to allow height adjustment of the cane. As can be seen in the figure 1 , the upper vertical tube 2 has openings aligned along a vertical axis. The lower vertical tube 4 comprises an indexing finger 13 intended to lock the position of the upper vertical tube 2 at the chosen height.

[0055] In another embodiment, adjustment of the cane to the user's height may be achieved by a clamp.

[0056] Particularly advantageously, the cane comprises a support structure according to the present invention, arranged to be crossed by sliding by the upper vertical tube. This makes it possible to adjust the height of the cane according to the size of the user. In the case of pathology such as for example hemiplegia, during rehabilitation, the height of the cane will be adjusted in such a way that the handle surmounting the upper vertical tube replaces the hand of the helping / accompanying person. This possibility of mutual sliding between the vertical tubes has the advantage of facilitating and simplifying the assembly and disassembly of the cane according to the present invention.

[0057] The four curved branches 5, 6, 7 and 8 are connected to the lower vertical tube 4. They extend downwards away from the lower vertical tube 4 and form a bend. The bend is preferably in the shape of an arc of a circle. Each curved branch ends in a vertical lower end where rollers are attached. Each vertical lower end preferably has a height of 50 mm.

[0058] The support structure 3 is made of steel, preferably epoxy-coated steel. The support tube 4 may be flat or round. The support tube 4 is preferably hollow and allows the upper vertical tube 2 to pass through it. The upper vertical tube 2 is preferably made of anodized aluminum. The rollers 9 are fixedly connected to each lower vertical end of the curved branches, so as to be able to pivot about the vertical axis of the lower ends. Each roller 9 is fixed to each lower vertical end of the curved branches by screwing and possibly gluing. Preferably, the glue is a threadlocker applied to the end of the screw thread of the roller.

[0059] There figure 2 illustrates the cane seen in profile, from the user's position. The configuration of the four curved branches 5, 6, 7 and 8 are connected to the lower vertical tube 4. The first curved branch 5 and the second curved branch 6 are connected to the lower vertical tube 4 at a first level and the third curved branch 7 and the fourth curved branch 8 are connected to the lower vertical tube 4 at a second level, different from the first level. The first level is in this case higher than the second level.

[0060] The indexing finger 13 is positioned in the lower third of the lower vertical tube 4, below the two levels where the curved branches are welded. In operation, the indexing finger 13 is an element for blocking and locking the sliding movement of the two vertical tubes. The indexing finger 13 makes it possible to adjust and fix the height of the handle 10 according to the user's height. In the case where the user needs to change the height of the cane 1, he must pull on the indexing finger 13, adjust the desired height and release the indexing finger 13 to lock the height. The indexing finger 13 returns to position after each pull. The indexing finger 13 is fixed to the lower vertical tube 4 by screwing and possibly gluing. Preferably, the glue is a thread locking glue applied to the end of the screw thread of the indexing finger 13.When the upper vertical tube 2 slides into the lower vertical tube 4, the indexing finger 13 is housed in one of the holes in the upper vertical tube 2.

[0061] There figure 3 is a view of the cane of figures 1 And 2, from the front, the user must be on the right of the cane in the drawing. The first curved branch 5 and the second curved branch (retracted by the first branch) extend in a first vertical plane X passing through their vertical lower ends. The third curved branch (retracted by the fourth branch) and the fourth curved branch 8 extend in a second vertical plane Y passing through their vertical lower ends. The first vertical plane X and the second vertical plane Y are parallel and are located on either side of the lower vertical tube 4 through which the Z axis of the support tube passes. The first vertical plane X is located at a distance from the Z axis of the support tube less than the distance shown between the second vertical plane Y and this Z axis.

[0062] There figure 4illustrates the configuration of the curved branches in top view, with the user on the right side of the drawing. In the illustrated example, the upper part of the first curved branch 5 and the upper part of the second curved branch 6 form an angle of 112.5° with each other. The upper part of the third curved branch 7 and the upper part of the fourth curved branch 8 form an angle of 80.5° with each other. The upper part of the second curved branch 6 and the upper part of the third curved branch 7 form an angle of 83.5° with each other. The upper part of the first curved branch 5 and the upper part of the fourth curved branch 8 form an angle of 83.5° with each other. The vertical planes X, Y and the Z axis are parallel. The angles are calculated in an orthogonal projection on the drawing plane.

[0063] The distance between the vertical ends of the first 5 and second 6 curved branches in the first vertical plane is greater than the distance between the vertical ends of the third 7 and fourth 8 curved branches in the second vertical plane.

[0064] In the illustrated example, the lower end of the first curved branch 5 and the lower end of the second curved branch 6 are spaced apart by a distance of 270 mm. The lower end of the third curved branch 7 and the lower end of the fourth curved branch 8 are spaced apart by a distance of 220 mm. The lower end of the second curved branch 6 and the lower end of the third curved branch 7 are spaced apart by a distance of 220 mm. The lower end of the first curved branch 5 and the lower end of the fourth curved branch 8 are spaced apart by a distance of 220 mm.

[0065] The lower end of the first curved branch 5 is spaced from the central vertical plane passing the vertical tubes parallel to the X and Y planes by a distance of 90 mm. The lower end of the second curved branch 6 is spaced from the central vertical plane passing the vertical tubes parallel to the X and Y planes by a distance of 90 mm. The lower end of the third curved branch 7 is spaced from the central vertical plane passing the vertical tubes parallel to the X and Y planes by a distance of 130 mm. The lower end of the fourth curved branch 8 is spaced from the central vertical plane passing the vertical tubes parallel to the X and Y planes by a distance of 130 mm.

[0066] The lower end of the first curved branch 5 is spaced from the central vertical plane passing the vertical tubes perpendicular to the X and Y planes by a distance of 135 mm. The lower end of the second curved branch 6 is spaced from the central vertical plane passing the vertical tubes perpendicular to the X and Y planes by a distance of 135 mm. The lower end of the third curved branch 7 is spaced from the central vertical plane passing the vertical tubes perpendicular to the X and Y planes by a distance of 110 mm. The lower end of the fourth curved branch 8 is spaced from the central vertical plane passing the vertical tubes perpendicular to the X and Y planes by a distance of 110 mm.

[0067] The vertical lower ends of the curved branches 5, 6, 7 and 8 form a quadrilateral with a surface area of 561 cm 2< . In this example the quadrilateral is a regular trapezoid.

[0068] In another embodiment, it is possible to manufacture the rod by reducing the distances by 30 mm.

[0069] It is understood that the present invention is in no way limited to the embodiments described above and that many modifications may be made thereto without departing from the scope of the appended claims.

Claims

1. Walking stick (1) for the movement of persons with reduced mobility, comprising: - a handle (10) to hold the walking stick, and - a support structure (3) comprising o a support tube (4) on which the handle is fixed, o four curved branches (5, 6, 7 and 8) connected to the support tube (4), by each having a vertical lower end, and o a wheel (9), fixedly connected to the vertical lower end of each of said branches, by being capable of pivoting freely about a vertical axis, a first curved branch (5) and a second curved branch (6) being presented with their vertical lower ends extending at a distance from one another in a first vertical plane, a third curved branch (7) and a fourth curved branch (8) being presented with their vertical lower ends extending at a distance from one another in a second vertical plane, parallel to the first vertical plane, these two planes being located on either side of the abovesaid support tube, characterised in that said four curved branches (5, 6, 7, 8) connected to the support tube (4) extending downwards away from it, and in that the distance between the vertical ends of the first and of the second curved branches in said first vertical plane is greater than the distance between the vertical ends of the third and of the fourth curved branches in said second vertical plane, the first vertical plane being located at a distance from the support tube less than the distance presented between the second vertical plane and this support tube.

2. Walking stick according to claim 1, wherein an upper part of the first curved branch (5) and an upper part of the second curved branch (6) together form an angle of between 105 and 120°, preferably between 110 and 115°, preferably between 112 and 113°.

3. Walking stick according to claim 2, wherein an upper part of the third curved branch (7) and an upper part of the fourth curved branch (8) together form an angle of between 72 and 88°, preferably between 77 and 83°, preferably between 80 and 81°.

4. Walking stick according to claim 3, wherein the upper part of the second curved branch (6) and the upper part of the third curved branch (7) together form an angle of between 75 and 91°, preferably between 80 and 86°, preferably between 83 and 84°.

5. Walking stick according to any one of claims 3 and 4, wherein the upper part of the first curved branch (5) and the upper part of the fourth curved branch (8) together form an angle of between 75 and 91°, preferably between 80 and 86°, preferably between 83 and 84°.

6. Walking stick according to any one of the preceding claims, wherein said vertical lower ends of said curved branches (5, 6, 7 and 8) form a quadrilateral having a surface area of between 550cm2 and 570cm2, preferably between 555cm2 and 565cm2, preferably of 561cm2.

7. Walking stick according to any one of the preceding claims, wherein each vertical lower end of the curved branches (5, 6, 7 and 8) has a height of between 40 and 60mm, preferably between 45 and 55mm.

8. Walking stick according to any one of the preceding claims, wherein the handle (10) is an ambidextrous handle.

9. Walking stick according to any one of the preceding claims, wherein the support tube (4) is formed of two tubes which are height-adjustable in one another.

10. Walking stick according to claim 9, wherein one of the two support tubes (4) is at least partially made of anodised aluminium.

11. Walking stick according to any one of the preceding claims, wherein the support structure (3) is at least partially made of steel.

12. Method for assembling a walking stick according to any one of claims 1 to 11, comprising the steps of: - interlocking an upper vertical tube (2) in a handle (10), - fixing the handle (10) to the upper vertical tube (2) by fixing means, - interlocking a finishing ring (11) on an upper part of a lower vertical tube (4), - interlocking a finishing ring (12) on a lower part of the lower vertical tube (4), - welding a first curved branch (5) and a second curved branch (6) to a first level of the lower vertical tube (4), an upper part of said first curved branch (5) and an upper part of said second curved branch (6) together forming an angle of between 105 and 120°, preferably between 110 and 115°, preferably between 112 and 113°, - welding a third curved branch (7) and a fourth curved branch (8) to a second level of the lower vertical tube (4), different from the first level, an upper part of said third curved branch (7) and an upper part of said fourth curved branch (8) together forming an angle of between 72 and 88°, preferably between 77 and 83°, preferably between 80 and 81°, - sliding the upper vertical tube (2) into the lower vertical tube (4) so as to be height-adjustable, with fixing of one to the other at the adjusted height, and - fixing a wheel (9) to the vertical lower end of each of said curved branches, so as to enable it to pivot about a vertical axis.

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