AGRICULTURAL IMPLEMENT WITH AN IMPROVED TYRE
The invention relates to the field of agricultural machines, in particular agricultural implements pro- vided with at least one tyre.
Among agricultural machines, there are seed drills comprising various implements working one after another: a head member, typically a plowshare, a disc or a tooth, is arranged so as to firstly open a furrow in the soil; then a deposition member is arranged so as to bring a seed or a grain to the bottom of the furrow; finally,
one or more tail wheels close the furrow and/or pack the soil.
Some seed drills further comprise an agricultural implement such as a press wheel for pressing and/or burying the grain at the bottom of the furrow.
This press wheel intervenes between the grain deposition mem- ber and the tail wheels closing the furrow.
Known press wheels generally have a high height-to-width ratio in order to be able to roll on the bottom of the furrow.
Such a press wheel is known from EP 2 145 775 Al.
Given their height-to-width ratio, the press wheels are particularly sensitive to the buckling phenomenon.
The tyre of the press wheel tends to bend laterally.
This leads, on the one hand, to the degradation of the furrows and, on the other hand, to the rapid wear of the tyre.
Furthermore, the compressive force applied at the bottom of the furrow makes the section of the tyre par- ticularly unstable.
Finally, in use, the press imple- ments are particularly sensitive to any unevenness or to the stones present in the furrows.
The Applicant has set the objective of improving the situation.
It proposes an agricultural implement according to claim 1.
Such an implement allows transmitting the force necessary to press the seeds in the soil while having a significant damping capable of absorbing any unevenness of the ground when rolling.
The risk of apparition of buckling is limited and the operating behaviour of the tyre is stabilised.
In use, the tyre preserves the shape of the furrows.
The furrows are barely degraded if not at all.
The dynamic behaviour of such tyres is better controlled, which allows slowing wear thereof and ex- tending their service life.
At high working speeds, for example at about 17 kilometres per hour, the transmis- sion of shocks from the tyre to the remainder of the seed drill is limited.
The vibrations and the fatigue of the machine are reduced.
Pressing the seeds in the soil here means either the burying them at a low depth or pushing them slightly, without covering them with soil, in order to fix them therein.
The compressive force and the burying depth are adapted according to the agronomic characteristics of the used crops.
The implement may have the following optional fea- tures, alone or in combination with one another:
- The footprint width of the casing of the tyre is less than 50 millimetres.
In this case, the tyre can press the seeds at the bottom of the finest furrows obtained with existing seed drill.
The footprint width could even be less than 35 or 30 millimetres.
- Fach of the two sidewalls comprises an inner part and an outer part.
The outer part partially delimits the casing.
The inner part belongs to the intermediate part and connects the casing to the tread plate by extending as an extension of the respective outer part.
The tread plate, the inner part of each of the two sidewalls and a part of the casing jointly define an annular space of the hollowed structure.
The profile of such a tyre is then substantially constant over the circumference.
Man- ufacture thereof is facilitated.
Furthermore, the ex- ternal surface of each sidewall can be made continuous.
The insertion of soil and debris in use is prevented.
Soiling of the tyre by soil is reduced. - The inner part of each of the two sidewalls has a configuration arranged so as to bend towards the an- nular space under the effect of a load during operation.
The deformation of the tyre at its circumference is substantially continuous when rolling.
The homogeneity of the pressure exerted by the implement on the seeds is improved.
- The intermediate part comprises spoke-like links each connecting the tread plate to the casing.
The de- formation of the intermediate part is then ensured by links rather than by walls.
The links have a better independence from one another.
Thus, if the tyre rolls on an obstacle such as a stone, the active link above the stone will absorb the shock almost alone.
The oper- ation of the adjacent portions of the tyre is barely impacted, if not at all.
- The links are distributed over the circumference of the tyre and spaced apart from each other.
Two adja- cent links, the tread plate and a portion of the casing
Jointly form an aperture of the hollowed structure.
The hollowed structures allow lightening the tyre and making it more controllable, in particular on rough terrains.
- Each of the links has a configuration arranged so as to bend towards an aperture of the tyre under the effect of a load during operation.
The initiation of the bending movement of the link is then better controlled, in particular when the tyre encounters a severe obstacle such as a stone or a clod.
According to another aspect of the invention, the Applicant proposes a seed drill equipped with an agri- cultural implement as described hereinbefore and wherein the tyre is mounted on a wheel body.
Other features, details and advantages of the in-
vention will appear upon reading the following detailed description, and the appended drawings, wherein:
- Figure 1 shows a perspective view of an implement according to a first embodiment of the invention,
- Figure 2 shows a side view of the implement of
Figure 1,
- Figure 3 shows a sectional view according to the double-segment III-III of Figure 1,
- Figure 4 shows a view similar to Figure 3 wherein only a portion of the tyre is illustrated,
- Figure 5 shows a section of the tyre of the implement of Figure 1,
- Figure 6 shows a perspective view of an implement according to a second embodiment of the invention, only the tyre being illustrated,
- Figure 7 shows a side view of the tyre of Figure 6,
- Figure 8 shows a perspective view of a section of the tyre of Figure €, - Figure 9 shows a sectional view according to the segment IX-IX of Figure 7, and 5 - Figure 10 shows an overview of a seed drill eguipped with an implement according to the invention.
The drawings and the description hereinafter es- sentially contain elements of a certain nature.
Hence, they could not only be used to better understand the present invention but also contribute to definition thereof, where appropriate.
It should be noted that el- ements like the geometry of tyres are difficult to de- fine completely, otherwise than through drawings.
Figures 1 to 5 show a first embodiment.
They show a field working implement 1 in the form of a wheel.
The wheel comprises a wheel body 3 around which a tyre 5 is mounted.
In the example described here, the wheel body 3 comprises two flanges 31, 32 assembled together.
The two flanges 31, 32 are substantially symmetrical to one an- other with respect to their junction plane.
When mounted on top of one another, the two flanges 31, 32 of the wheel body 3 accommodate a rolling block 33 known as such.
The assembly of the two flanges 31, 32 and of the rolling block 33 defines an axis of revolution XX of the wheel body 3. The axis XX corresponds substantially to the axis of rotation of the wheel in operation.
The rolling block 33 has a substantially cylindrical bore open at each of its ends for mounting the wheel body 3 around a wheel shaft.
As illustrated in Figure 3, in the mounted state, the wheel body 3 has a footprint width Lg, or maximum width.
In the example described here, the central por- tion of the wheel body 3 accommodating the rolling block 33 corresponds to the widest part of the wheel body 3. At the periphery of the wheel body 3, the two flanges 31, 32 define a groove 35 therebetween.
The groove 35 extends substantially over the circumference of the wheel body 3. It is shaped so as to receive the tyre 5. In the example described here, the shape of the groove 35 is adapted to fix a bead 61 of the tyre 5. The radial ends of the flanges 31, 32 fold towards one an- other so as to form hooks for retaining the bead 61. In this configuration, the removal of the tyre 5 is per- formed by separating the two flanges 31, 32 from one another.
In the mounted state, tyre dismounting, i.e. the accidental separation of the tyre 5 and of the wheel body 3 is prevented.
In some variants, other systems for attaching the tyre 5 around the wheel body 3 may be used.
For example, the wheel body 3 may have a substantially cylindrical peripheral surface and the tyre 5 is forcibly mounted.
Alternatively, the wheel body 3 may be made in one- piece or by assembly of more than two parts.
For example, the flanges 31, 32 are made based on metal or plastic materials, according to the intended use conditions.
The tyre 5 comprises a tread plate type part 51, a tread type part 53 and two sidewalls 55, 56.
The tyre 5 is mounted on the wheel body 3 via the tread plate 51. The tread plate 51 has a substantially annular shape extending over the circumference of the tyre 5. The tread plate 51 has a radial section, as illustrated in Figure 5, substantially constant over the circumference. In a radial direction, the tread plate 51 forms an inner part of the tyre 5. When mounted on the wheel body 3, the tread plate 51 forms the part of the tyre 5 the closest to the axis XX. In the example described here, the tread plate 51 comprises the bead 61 on the inner side. When accommo- dated in the groove 35 of the wheel body 3, the bead 61 is invisible from the outside. The tread plate 51 fur- ther comprises an outer part held around the wheel body 3 in the mounted state. The outer part and the bead 61 of the tread plate 51 are mutually delimited by two substantially annular slots in each lateral face. The two slots cooperate with the retention hooks of the flanges 31, 32 to attach the tyre 5 to the wheel body
3. In operation, the tread plate 51 is substantially fixed relative to the wheel body 3. In operation, the tread plate 51 is substantially non-deformable in com- parison with the other parts of the tyre 5 described hereinafter. The tread 53 has a substantially annular shape ex- tending according to the circumference of the tyre 5. In a rest state, the tread plate 51 and the tread 53 are substantially concentric and centred on the axis XX. The tread 53 substantially surrounds the tread plate 51. The tread 53 has a radial section, as illustrated in Figure 5, substantially constant over the circumference. In a radial direction, the tread 53 forms an outer part of the tyre 5. When viewed according to a radial section of the tyre 5 as illustrated in Figure 5, the tread 53 is substantially opposite the tread plate 51. When mounted on the wheel body 3, the tread 53 forms the part of the tyre 5 the furthest from the axis XX.
In the example described here, the tread 53 bears an outer peripheral surface.
The outer peripheral sur- face is intended to come into contact with the ground when rolling.
In the case of a use of the implement 1 as a press wheel for burying seeds, the outer peripheral surface of the tread 53 is intended to roll against the bottom of a furrow to press seeds therein.
In the example described here, the tread 53 has a substantially constant thickness.
The tread 53 has a radial profile that is substantially convex and rounded towards the outside.
In some variants, the shapes and dimensions of the tread 53 are adapted according to the type of seeds and to the properties of the worked soils.
The sidewalls 55 and 56 are substantially symmet- rical to one another according to a midplane of the tyre 5 perpendicular to the axis XX.
The tyre 5 comprises an intermediate part 54. The intermediate part 54 comprises an intermediate wall 63.
The intermediate wall 63 has a substantially annu- lar shape extending according to the circumference of the tyre 5. In a rest state, the intermediate wall 63 is substantially concentric with the tread plate 51, the tread 53 and centred on the axis XX.
The intermediate wall 63 extends substantially between the tread 53 and the tread plate 51. The intermediate wall 63 has a radial section, as illustrated in Figure 5, substantially con- stant over the circumference.
In the embodiment of Figures 1 to 5, each of the sidewalls 55 and 56 extends from the tread plate 51 to the tread 53. Each of the sidewalls 55 and 56 comprises an outer part 57, respectively 58, and an inner part 59, respectively 60. The outer part 57, 58 and the inner part 59, 60 extend respectively as an extension of one another.
The intermediate wall 63 connects the sidewalls 55, 56 to one another at the connection of the outer part 57, 58 with the corresponding inner part 59, 60 of each of the sidewalls 55, 56. Thus, the intermediate wall 63 forms an inner part of the tyre 5, invisible from the outside.
When viewed from the outside and in a rest state of the tyre 5, the external surfaces of the two sidewalls 55, 56 are substantially continuous be- tween the outer part 57, 58 and the respective inner part 59, 60. In the figures, a dotted line represents the boundary between the two parts of each sidewall 55, 56 and the position of the intermediate wall 63.
The outer parts 57 and 58 of the sidewalls 55 and 56, the tread 53 and the intermediate wall 63 jointly define a casing around a chamber 65. The chamber 65 forms a substantially annular hollow space inside the tyre 5 and located in the radially outer half of the section of the tyre 5.
In the example described here, the chamber 65 is not inflated.
The chamber 65 is in fluidic communication with the outside environment.
Thanks to this intentional absence of sealing, a moderate deformation of the casing facilitates the detachment of the soil that might adhere to the external surfaces.
The deformation may be gener- ated when rolling in operation or at a standstill during maintenance operations of the equipment.
In the example illustrated in Figure 5, the fluidic communication is enabled by an orifice 69. The orifice 69 passes through the intermediate wall 63 and opens,
on the one hand, into the chamber 65 and, on the other hand, into an annular space 67 described later on.
Hence, the orifice 69 used during vulcanisation could remain.
The orifice 69 forms an exception to the cir- cumferential homogeneity of the tyre 5.
Besides the intermediate wall 63, the intermediate part 54 comprises the internal parts 59 and 60 of the sidewalls 55 and 56. The internal parts 59 and 60 of the sidewalls 95 and 56 connect the intermediate wall 63 to the tread plate 51. The intermediate wall 63, the in- ternal parts 59 and 60 of the sidewalls 55 and 56 and the tread plate 51 jointly define an additional casing around the annular space 67. The annular space 67 forms a hollow space inside the tyre 5, located in the radially inner half of the section of the tyre 5. Hence, the intermediate part 54 has a hollowed structure.
In the example described here, the annular space 67 is not inflated.
The annular space 67 is in fluidic communication with the outside environment.
Thanks to this intentional absence of sealing, the deformation of the intermediate part 54 is facilitated.
In the example illustrated in Figure 5, the fluidic communication is enabled by an orifice 71. The orifice 71 passes through the tread plate 51 and opens, on the one hand, into the annular space 67 and, on the other hand, into an inter- mediate space between the two flanges 31, 32 of the wheel body 3. Hence, the orifice 71 used during vulcan- isation, like the orifice 69, could remain.
The orifice 71 also forms an exception to the circumferential homo-
geneity of the tyre 5. The chamber 65 is here in fluidic communication with the outside via the annular space 67.
In the example of the first embodiment illustrated in Figures 1 to 5, in the rest state, the tyre 5 has: - an internal diameter D comprised between 50 and 160 millimetres, for example about 132 millimetres, - an external diameter D' comprised between 250 and 350 millimetres, for example about 300 millimetres, - a footprint width Lp comprised between 25 and 40 millimetres, for example about 31 millimetres, - a tread 53 with a thickness es; comprised between 4 and 10 millimetres, for example about 8 millimetres, - a tread plate 51, with a thickness es; comprised between 10 and 14 millimetres, for example about 12 millimetres, without the bead 61, - an intermediate wall 63 with a thickness ess com- prised between 6 and 12 millimetres, for example about 8 millimetres, - sidewalls 55, 56 with a thickness ess, ess com- prised between 3 and 7 millimetres, for example about 5 millimetres, and - a section with a height H comprised between 70 and 100 millimetres, for example about 85 millimetres, with the bead 61. The footprint width Ly of the wheel body 3 is here comprised between 40 and 50 millimetres, for example about 44 millimetres.
The orifices 69 and 71 have a substantially cylindrical bore with a diameter comprised between 2 and 4 millimetres, for example about 3 milli- metres.
The thicknesses are shown in the figures.
Connec- tion areas between the different parts of the tyre 5 allow avoiding sudden variations in thickness and possible concentrations of stresses which might result therefrom.
The tyre 5 of the first embodiment is here made by assembling two separately extruded parts.
Afterwards, the two separately extruded parts are vulcanised to- gether.
In the sectional views, a dotted line represents the assembly surface of the two parts, substantially at the middle of the intermediate wall 63. Alternatively, the tyre 5 is obtained after a co-extrusion of the entire profile.
Furthermore, the two parts are here made of two different materials.
Making of a bi-material tyre could be implemented, for example, through two distinct ex- trusions followed by a common vulcanisation or through a bi-material co-extrusion.
In the finished state, the tyre 5 is made in one-piece.
In the example described here, the radially inner part, corresponding to the intermediate part 54 and to the tread plate 51, is made based on a rubber with a Shore A hardness comprised between 55 and 70, for exam- ple about 63 Shore.
The radially outer part, correspond- ing to the outer casing, is made based on a rubber with a Shore hardness comprised between 35 and 50, for exam- ple about 43 Shore.
Making the outer casing and the intermediate part 54 into two distinct materials allows further refining their respective dynamic behaviour.
Whether it is made with one or more extrusions, the tyre may alternatively be made of one single material.
The dimensional and Shore hardness values given hereinbefore are particularly suited to the dynamic be- haviour desired by the Applicant in the intended appli- cation.
These values could be adapted individually or jointly according to the intended applications.
The combination of the structures and the properties of the materials allow accurately selecting the desired defor- mations according to the applications.
For example, the hardness of the material of the intermediate part 54 may be lower than or substantially equal to the hardness of the radially outer part.
The hardness forms a parameter amongst others such as the shape, the structure and the dimensions, to confer the expected collapse behaviour on the tyre.
Furthermore, other elastomers may be used, for example polyurethanes.
Reference is now made to the second embodiment il- lustrated in Figures 6 to 9. The elements similar to those of the first embodiment bear identical reference numerals.
The second embodiment differs from the first one in particular in that the intermediate part 54 is devoid of internal parts 59 and 60 of the sidewalls 55 and 56. The intermediate part 54 is devoid of a sidewall.
Besides an intermediate wall 63, the intermediate part 54 comprises spoke-like links 81.
Each of the links 81 connects the tread plate 51 to the outer casing.
Each of the links 81 extends between a surface directed towards the axis XX of the interme- diate wall 63 and a surface facing the tread plate 51.
The links 81 form exceptions to the circumferential homogeneity of the tyre 5. In other words, the shape of the section of the tyre 5 depends on the considered angular position.
The links 81 are distributed over the circumference of the tyre 5. The links 81 are spaced apart from one another.
Two adjacent links 81 define an aperture 83 therebetween.
The aperture 83 is further delimited by an angular portion of the tread plate 51 and an angular portion of the intermediate wall 63.
Hence, like in the first embodiment, the intermediate part 54 has a hollowed structure.
In the second embod- iment, the hollowed structure takes on the shape of the apertures 83 opening onto both of the two main faces of the tyre 5. By "main faces”, it should be understood the two planes parallel to one another, perpendicular to the axis XX, spaced apart from one another by the footprint width Lp and which delimit the template of the tyre 5.
As visible in Figure 7, when the tyre 5 is at rest,
the links 81 extend substantially in a plane perpendic- ular to the axis XX, i.e. substantially between the two aforementioned main faces.
Unlike spokes in the conven- tional meaning, the orientation of each link 81 forms a non-zero angle with radial directions of the tyre 5.
In the example described here, the links 81 are fifteen in number.
The adjacent links 81 are equidistant from one another.
Thus, the homogeneity of the rolling behaviour is improved.
Geometrically, each link 81 is the result of a planar rotation of another link 81 about the axis XX.
Each link 81 has a slightly curved shape, directed according to the main plane of the tyre XX and curved in the same direction around the axis XX as the other links 81. Together, the links 81 have a spiral or partial helix general configuration.
In the example de-
scribed here, the tyre 5 is intended to roll in the clockwise direction according to the illustration of Figure 7. The tyre 5 then has a recommended mounting direction.
In any case and from a functional point of view,
the links 81 of the second embodiment are the analogues of the internal parts 59 and 60 of the sidewalls 55 and 56 of the first embodiment and the apertures 83 of the second embodiment are the analogues of the annular space 67 of the first embodiment.
In the example of the second embodiment illustrated in Figures 6 to 9, in the rest state, the tyre 5 has:
- an internal diameter D comprised between 50 and
160 millimetres, for example about 120 millimetres,
- an external diameter D' comprised between 250 and 350 millimetres, for example about 300 millimetres,
- a footprint width Lp comprised between 25 and 40 millimetres, for example about 30 millimetres,
- a tread 53 with a thickness es; comprised between 4 and 8 millimetres, for example about 6 millimetres, and of width Ls; comprised between 12 and 20 millimetres, for example about 17 millimetres,
- an outer casing with a height E comprised between 30 and 40 millimetres, for example about 35 millimetres,
- an intermediate wall 63 with a thickness ess sub- stantially equal to that of the tread 53, - sidewalls 55, 56 with thickness ess, ess comprised between 4 and 8 millimetres, for example about 5 milli- metres, and
- a section with a height H comprised between 80 and 100 millimetres, for example about 90 millimetres, without the bead 61.
The footprint width Ly of the non-illustrated wheel body 3 of the second embodiment is substantially eguiv- alent to that of the first embodiment.
The orifice 69, similar to that of the first embodiment but not visible in the figures, has a substantially cylindrical bore with a diameter comprised between 2 and 4 millimetres, for example about 3 millimetres.
The thicknesses are shown in the figures.
Connec- tion areas between the different parts of the tyre 5 allow avoiding sudden variations in thickness and pos- sible concentrations of stresses that might result therefrom.
The tyre 5 of the second embodiment is here made by moulding and vulcanisation in one-piece.
The tyre 5 is made based on one single material, for example a rubber with a Shore A hardness comprised between 35 and
50, for example about 43 Shore.
Alternatively, the tyre 5 is made based on several materials and/or by assem- bling several parts.
In the finished state, the tyre 5 is made in one-piece.
In the example described here, the links 81 have a solid section.
The dimensional and Shore hardness values given hereinbefore are particularly suited to the dynamic be- haviour desired by the Applicant in the intended appli- cation.
These values could be adapted individually or Jointly according to the intended applications.
The com-
bination of the structures and the properties of the materials allow accurately selecting the desired defor- mations according to the applications.
The dynamic behaviour, in operation, of the agri- cultural implements according to either of the previ-
ously-described two embodiments is now described.
In operation, during rolling of the tyre 5 on the ground, the dynamic behaviour of the outer casing around the chamber 65 and the dynamic behaviour of the intermediate part 54 differ from one another.
In the first embodi-
ment, the intermediate part 54 is formed by the internal parts 59 and 60 of the sidewalls 595 and 56 and the intermediate wall 63, whereas in the second embodiment,
the intermediate part 54 is formed by the links 81 and the intermediate wall 63.
The outer casing has a limited deformation during the contact of the tread 53 on the ground, for example at the bottom of the furrow.
Thus, the shape of the tread 53 is preserved in order to effectively press the seeds at the bottom of the furrow.
In comparison, the angular portion of the intermediate part 54 located be-
tween the axis XX of rotation and the ground has a significant collapse.
By “collapse”, it should be here understood the deformation according to a radial direc-
tion.
The intermediate part 54 then forms a deformation and damping area according to the radial direction of the tyre 5. When rolling, unevenness in the ground might cause sudden variations in stresses to which the tyre 5 is subjected in the substantially vertical direction.
The hollowed configuration of the intermediate part 54 allows absorbing the variations at least partially through a controlled deformation of the intermediate part 54. The outer casing and the tread 53 continue to ensure the seed burial function.
The Applicant has noticed that a footprint width of less than 50 millimetres would enable work at the bottom of most furrows formed by current machines.
A width smaller than 35 or 30 millimetres allows working in furrows that are more specific to some crops by work- ing on a restricted contact surface, which allows gen- erating a greater compressive force and/or a deeper pen- etration into the bottom of the furrow.
The collapse of the intermediate part 54 is greater than the collapse of the outer casing.
This is made possible thanks to the hollowed configuration of the tyre.
The tyre has a preferred collapse area.
When a compressive force is applied between the tread and the tread plate of the tyre, a portion of the material con- stituting the intermediate part 54 occupies the space left free of said intermediate part 54. In the first embodiment, the inner parts 59 and 60 of the sidewalls 55 and 56 partially occupy the annular space 67. In the second embodiment, the links 81 partially occupy the apertures 83.
The hollowed structure further allows guiding the deformation of the intermediate part 54. In particular, the deformed parts remain inscribed within a footprint with a limited width.
In particular, the intermediate wall 63 holds the two sidewalls 55, 56 proximate to each other.
It avoids their mutual separation.
Thus, a width- wise expansion is avoided.
Hence, when the collapse takes place in a furrow, the risk of scraping and deg- radation of the lateral walls of the furrow is reduced.
The footprint width of the intermediate part 54 remains smaller than the footprint of the outer casing of the tyre, including during the controlled collapse.
In other words, the hollowed structure allows fa- vouring the collapse of the intermediate part 54 rather than the collapse of the outer casing, and at the same time avoiding said collapse leading to widening of the tyre 5.
In the tyres used until now, it was freguent that an imbalance appears between one side and the other of the tyre.
The tyre then adopts a buckling behaviour.
In an imagined manner, the section of the tyres bends on one side while adopting the shape of a banana.
This leads to a degradation of the furrows in which the tyres evolve.
On the contrary, the hollowed structure of the tyre shown in the figures allows improving the symmetry of the dynamic behaviour.
By guiding the deformation of the sidewalls 55, 56 towards the midplane of the tyre 5 or by guiding the deformation of the links 81 in the main plane of the tyre 5, the risk of apparition of an imbalance between one side and the other of the tyre 5 is reduced.
The risk of buckling of the tyre 5 is also reduced.
In the second embodiment, the slightly curved shape of the links 81 imposes the direction of bending under the effect of a compression.
In particular, the links 81 bend in the main plane of the tyre 5, i.e. according to a direction perpendicular to the axis XX.
All of them bend in the same direction without interfering with one another.
The tread plate 51 and the tread 53 are barely deformable in comparison with the intermediate part 54. The localised collapse of the intermediate part 54 en-
ables a mutual approach of the tread plate 51 and of the tread 53. This collapse takes place in the angular por- tion of the tyre 5 the closest to the ground and sub- jected to the weight of the implement 1. Consequently, the generally annular shape of the tread plate 51 is off-centred with respect to the deformed annular shape of the tread 53 when rolling.
Under the effect of col- lapse, the axis of rotation XX descends towards the ground.
The collapse allows improving the mobility of the tread 53 relative to the axis XX while limiting its own deformation.
Figure 10 schematically shows a seed drill 100 and the organisation of the implements that equip it.
The arrow A represents the direction of advance of the seed drill 100 on the surface of the ground 201. The seed drill 100 is equipped with a head member 101, load- bearing wheels 103, a seed 205 deposition member 105 and an implement 1 according to the invention, here in the form of a press wheel. Here, the head member 101 comprises two discs 107. The two discs 107 are arranged in a "V”-like profile and are arranged so as to firstly open a furrow in the ground
201. The dashed line 202 represents the bottom of the furrow formed by the head member 101. The load-bearing wheels 103 support at least par- tially the weight of the seed drill 101 on either side of the furrow. The load-bearing wheels 103 further form gauge wheels for setting the depth of the furrow. The load-bearing wheels 103 are free to rotate but secured to the discs 107 according to a substantially vertical direction. Thus, even in the presence of unevenness in a field, the discs 107 work at a substantially constant depth with respect to the surface of the ground 201. The deposition member 105 is arranged so as to bring the seeds 205 to the bottom 202 of the furrow, behind the head member 101. The implement 1 in the form of a press wheel presses the seeds 205 into the bottom 202 of the furrow. In some variants, one or more tail wheels closes the furrow and/or packs the soil behind the implement 1 (on the left of Figure 10). The invention is not limited to the examples of agricultural implements described hereinabove, only as example, but it encompasses all variants that a person skilled in the art could consider within the scope of the claims hereinafter.