Soil-working machine

Abstract

The invention relates to a soil-working machine, comprising a frame (2), two rows (3) of soil-working tools (5) respectively coupled to the frame (2) by a connecting system (6) and each extending transversely to the longitudinal axis of the frame (2), the tools (5) of each row (3) of tools (5) being concave or frustoconical hollow discs. The connecting system (6) between one of the rows (3) of tools (5) and the frame (2) comprises an actuator (7) and a guide system (8), the row (3) of tools (5) is, in the actuated state of the actuator (7), movably mounted so as to travel in a guided manner along a travel stroke comprising at least one vertical component for a downward or upward travel of the tools (5) of the row (3), and a component in a direction transverse to the longitudinal axis of the frame (2), to enable, by means of the actuator (7), both a lowering, or a lifting, and a lateral shifting of the tools (5) of the row (3) of tools (5).

Description

Soil cultivation machine

[0001] The present invention relates to a soil cultivation machine.

[0002] It relates in particular to a soil-working machine comprising a chassis with a longitudinal axis taken along the front / rear direction of the chassis and at least two rows of soil-working tools, referred to respectively as front and rear, coupled respectively to the chassis by a linkage system and each extending transversely to the longitudinal axis of the chassis, said chassis being able to be maintained at a predetermined distance from the ground and at least part of the tools in each row of tools being concave or truncated conical hollow discs.

[0003] Such a tillage machine is known, as illustrated in particular by international application WO 2007 / 085713. These so-called disc harrows often have an unworked area between the discs. This unworked area is shown in Figure 1, which illustrates two partial views of a prior art tillage machine: one with new discs, the other with worn discs. As shown in the views in Figure 1, this unworked area tends to widen as the discs wear. When the discs are very worn, the rear row of discs works in the wake of the front row and no longer fulfills its function.

[0004] One aim of the invention is to provide a soil tillage machine whose design allows, in a simple way, for maintaining a substantially constant dimension of the unworked area regardless of the state of wear of the discs.

[0005] To this end, the invention relates to a soil-working machine, said machine comprising a chassis with a longitudinal axis taken along the front / rear direction of the chassis and at least two rows of soil-working tools, respectively referred to as front and rear, coupled respectively to the chassis by a linkage system and each extending transversely to the longitudinal axis of the chassis, said chassis being capable of being maintained at a predetermined distance from the ground and at least part of the tools of each row of tools being concave or frustoconical hollow discs, characterized in that for at least one of the rows of tools, the linkage system between said row of tools and the chassis comprises at least one actuator and a guidance system, said row of tools being, in the actuated state of the or at least one of the actuators, mounted in a guided movement manner along a travel stroke comprising at least two components,one of the components being a vertical component for downward or upward movement of the tools, said row, the other or another of the components being a component following a direction transverse to the longitudinal axis of the chassis, that is to say parallel to an axis corresponding to a longitudinal axis of the row of tools, to allow by means of said actuator both a lowering, or respectively a raising, and a lateral shift of the tools of said row of tools.

[0006] The ability to move at least one row of tools vertically and laterally using a single actuator makes it easy to maintain the same relative position of the tools from one row to another, even when the tools are worn, thus optimizing the soil areas worked. Having a single actuator that is active for both raising and lowering the tools and for lateral positioning—that is, positioning them transversely to the longitudinal axis of the frame—allows for a simplified design with maximum soil cultivation efficiency.

[0007] According to one embodiment of the invention, the actuator or one of the actuators of the linkage system between a row of tools and the chassis is a cylinder disposed between said row of tools and the chassis.

[0008] According to one embodiment of the invention, the at least two rows of tools, each coupled to the frame by a linkage system, comprise at least one beam extending transversely to the longitudinal axis of the frame and to which the tools are coupled by a linkage element. The positioning of the linkage system between the beam and the frame eliminates the need to modify the design of the tool connection to the beam. Thus, such linkage systems can be easily implemented, even on existing machines.

[0009] According to one embodiment of the invention, the guidance system comprises one or more guideways, each housing at least one guide element. Each guideway and its associated guide element are arranged, respectively, on the frame and on the row of tools to be driven. The fact that each guideway and its associated guide element can be arranged interchangeably on the frame and on the row of tools to be driven allows for relative movement of the guideway and its associated guide element depending on the actuator's actuated state.

[0010] According to one embodiment of the invention, the guide path and the at least one associated guide element are configured to allow at least partial retention of the at least one guide element within the guide path over at least a portion of the guide path's length in the actuator's actuated state. The arrangement allows for guidance during movement of said row of tools by simple contact.

[0011] According to one embodiment of the invention, the or at least one of the guide paths is inclined from a high point located from one of the ends, called the first end, of the row of tools by a first distance, towards a low point located from said first end of the row of tools by a second distance greater than the first distance.

[0012] According to one embodiment of the invention, the or at least one of the guide paths is a groove, and the at least one associated guide member is a protruding element, of the type stud or finger, housed at least partially inside said groove.

[0013] According to one embodiment of the invention, the travel stroke, which includes at least a vertical component and a lateral component along a direction transverse to the longitudinal axis of the frame, further includes an axial component parallel to the longitudinal axis of the frame. This arrangement increases the space between two rows of tools and thus facilitates machine maintenance, particularly during tool changes and adjustments.

[0014] According to one embodiment of the invention, the linkage system is configured to, in the actuation state of said actuator, generate an angular displacement of the row of tools around an axis forming a longitudinal axis of said row of tools.

[0015] According to one embodiment of the invention, the guide path(s) are arranged on the tool row, and the guide element(s) are housed within a ring coupled to the frame and surrounding at least a portion of the tool row. The ring cooperates with the actuator to allow angular displacement of the tool row around an axis forming a longitudinal axis of said tool row when the actuator is actuated, the portion of the tool row surrounded by the ring being formed by the beam of said tool row.

[0016] According to one embodiment of the invention, the actuator and the guideway(s) of the linkage system extend in parallel and the guideway(s) and at least one guide element associated with each guideway are mounted relative to each other in a sliding movable manner in the actuated state of said actuator.

[0017] According to one embodiment of the invention, at least one of the tools, formed by a hollow disc of at least one of the tool rows, is equipped with at least one indicator wear indicator. The presence of a wear indicator, for example in the form of multiple markings, helps to operate the actuator.

[0018] According to one embodiment of the invention, the chassis is, for maintaining it at a predetermined distance from the ground, equipped with at least one reference element.

[0019] According to one embodiment of the invention, the actuator or one of the actuators of the linkage system being a cylinder, said machine includes, for at least one actuator, a set of shims, each shim being positionable on the actuator to limit the stroke of said actuator, the number of shims being a function of the stroke of said actuator.

[0020] Brief description of the drawings

[0021] The invention will be better understood upon reading the following description of exemplary embodiments, with reference to the attached drawings in which:

[0022] Figure 1 represents, in the form of two partial views, a state-of-the-art machine with new and worn discs;

[0023] Figure 2 shows a side view of a soil-working machine according to the invention;

[0024] Figure 3 shows a perspective view of a soil-working machine according to the invention;

[0025] Figure 4 represents in the form of two partial views a soil-working machine according to the invention with new discs and worn discs;

[0026] Figure 5 represents a perspective view of a row of tools of a soil-working machine according to the invention associated with a detail view;

[0027] Figure 6 represents, in the form of two front views of a row of tools of a soil-working machine according to the invention, the passage of the actuator from a retracted position for new discs to an extended position for worn discs;

[0028] Figure 7 shows a side view of a row of discs to illustrate the positions a disc can take during wear while operating an actuator;

[0029] Figure 8 represents a perspective view of a row of tools of a soil-working machine according to the invention associated with a detail view;

[0030] Figure 9 shows, in the form of two front views of a row of tools of a soil-working machine according to the invention, the passage of the actuator of a retracted position for new discs to an extended position for worn discs.

[0031] As mentioned above, the invention relates to a soil-working machine of the type shown in Figure 2. This soil-working machine 1 comprises a frame 2 with a front and a rear portion, measured with respect to the direction of travel of the frame 2 and extending longitudinally from the front to the rear. The longitudinal axis of the frame 2 is represented as XX' in the figures and is more particularly visible in Figure 3.

[0032] This chassis 2 is essentially formed from a welded or bolted assembly of longitudinal and transverse members. This chassis 2 can be mounted or towed, for example, trailed or semi-trailed. In this case, the front part of the chassis is equipped with a hitch. This chassis 2 can also be a self-contained chassis. This chassis 2 is capable of being maintained at a predetermined distance from the ground to allow for operation at a predetermined depth or depth of the implements that will be described below.

[0033] For this purpose, the chassis 2 is equipped with at least one reference element 13 to maintain it at a predetermined distance from the ground. In the examples shown in Figures 2 and 3, there are two reference elements 13, one located at the front and the other at the rear of the chassis 2. In the case of a mounted chassis 2, no reference element is required.

[0034] Each reference element 13 is here formed by a non-motorized roller coupled to the chassis and extending transversely to the longitudinal axis XX' of the chassis 2. This reference element 13 could have, equivalently, been formed by wheels or pads without going out of the scope of the invention.

[0035] Ideally, the reference component 13 is coupled to the chassis 2 in an adjustable position. This adjustment allows the chassis to be maintained in a horizontal position at a predetermined elevation level relative to the ground.

[0036] The soil-working machine 1 comprises at least two rows 3 of soil-working tools 5. These rows 3 of tools 5 each extend transversely to the longitudinal axis XX' of the frame 2 and form, one, a front row 3 of tools 5, the other, a rear row 3 of tools 5, taken with respect to the direction of movement of the frame 2 in the front / rear direction.

[0037] Obviously, the number of rows 3 of 5 tillage tools can be greater than two without going out of the scope of the invention.

[0038] Each row 3 of tools 5 is coupled to the frame 2 by a linkage system 6. At least some of these tools 5 are non-powered concave or frustoconical hollow discs.

[0039] In the examples shown, the front and rear rows of discs extend along a working width, that is, along a line substantially perpendicular to the line of traction corresponding to the longitudinal axis XX' of the chassis 2. The rotational drive of each non-driven disc is caused by the friction force with the ground, a force generated by the movement of the towed chassis 2.

[0040] The discs of each row of discs work in the soil according to a depth or depth, set by means of the reference organ(s) 13.

[0041] In the examples shown, each row 3 of tools 5 coupled to the frame 2 by a linkage system 6 includes at least one beam 4 extending transversely to the longitudinal axis XX' of the frame 2 and to which the tools 5 are coupled by a linkage element 11.

[0042] This linking element 11 allows each disc or group of discs in a row of discs to be mounted independently and oscillating relative to the beam 4, so as to retract under a predetermined, generally adjustable pressure, thus obtaining constant depth soil work of the discs.

[0043] This connecting element 11 for a disc or group of discs can consist of an arm pivotally mounted on the beam around an axis substantially parallel to the axis of rotation of the disc. This arm then cooperates with a prestressing element, such as a spring, so as to allow the arm to pivot in the direction of disc retraction by lifting when the pressure exerted on the discs exceeds the set pressure of said prestressing element. The return to the working position occurs automatically under the combined force of the prestressing element and the weight of the disc.

[0044] An equivalent solution can be obtained by means of a spiral helical spring, as illustrated in Figures 1 and 2. One end of the spring is coupled to the beam 4, while the other end of the spring is coupled to the hub of a disk or to the hubs of several disks, the end of the spring being, for example, interposed between two disk hubs.

[0045] Each disc generally has a diameter of at least 450 mm and preferably greater than 550 mm.

[0046] It is understood that these discs wear down during their rotational drive, which leads to a reduction in their diameter.

[0047] Generally, disks exhibit a reversed concavity from one row to the next. Typically, the disks in a row have a non-zero opening angle and entry angle.

[0048] The opening angle is the angle formed by the plane of rotation of the disk without an entry angle with the vertical plane parallel to the longitudinal axis XX' of the chassis 2.

[0049] The entry angle corresponds to the angle formed by the axis of rotation of the disk with the horizontal plane formed by the ground.

[0050] The positioning of the disc hub relative to the beam connection element determines the orientation of the disc and consequently its opening angle and entry angle.

[0051] Such rows of discs will not be described in further detail as they are well known to those versed in this art.

[0052] The aim of the present invention is to propose a simple solution for maintaining an unworked area between the discs of a row of discs, as represented in 21 in figure 4, which does not increase in width, i.e. in a direction perpendicular to the longitudinal axis XX' of the chassis 2 during the wear of the discs which causes a modification of the contact area of ​​the discs with the ground.

[0053] The soil-working machine 1 includes, for this purpose, for each row 3 of tools 5, a linkage system 6 between the row 3 of tools 5 and the frame 2. This linkage system 6 extends in particular between the beam 4 of the row 3 of tools 5 and the frame 2. This linkage system 6 between the row 3 of tools 5 and the frame 2 includes at least one actuator 7 and a guidance system 8.

[0054] As illustrated in Figures 6 and 9, generally, a single actuator 7 is sufficient. However, several actuators 7 can be provided to work in parallel without departing from the scope of the invention.

[0055] The actuator or one of the actuators of the linkage system 6 between a row 3 of tools 5 and the chassis 2 is a cylinder disposed between said row 3 of tools 5 and the chassis 2.

[0056] In particular, this actuator 7 has a body and a rod coupled indifferently, one to the frame 2, the other to the beam 4 of the row 3 of tools 5, so that the retraction or extension of the cylinder rod generates a displacement of the row 3 of tools 5. Because of Due to the presence of a guidance system 8 and at least one actuator 7, the row 3 of tools 5, when actuated by said actuator 7 or series of actuators 7 operating in parallel, is mounted in a guided, movable manner along a travel stroke comprising at least two components. One of the components is a vertical component for moving the tools 5 of said row 3 downwards or upwards. The other component is a component along a direction transverse to the longitudinal axis XX' of the frame 2, that is, along a direction parallel to an axis corresponding to a longitudinal axis of the row of tools, to allow, by means of said actuator 7, both a lowering, or respectively a raising, and a lateral offset of the tools 5 of said row 3 of tools 5.

[0057] Figures 6 and 9 illustrate this movement of at least two components of the tools 5 in row 3 of discs, compensating for disc wear which is accompanied by a reduction in disc size. This movement of all the discs in the same row is achieved using a single actuator 7. This movement, along at least two components, maintains the position of the contact zone between the discs and the ground, so that the area not worked by the discs remains essentially unchanged regardless of disc wear, as illustrated in Figure 4 where the lower view shows worn discs, while the upper view shows new discs.

[0058] It should be noted that the displacement stroke, which includes at least a vertical component and a so-called lateral component following a direction transverse to the longitudinal axis of the chassis, may also include an axial component parallel to the longitudinal axis XX' of the chassis 2. It is the cooperation of the actuator 7 with the guidance system 8 which makes it possible to obtain such a displacement stroke of the row 3 of tools 5.

[0059] The guidance system 8 comprises one or more guide paths 9, each housing at least one guide element 10. Each guide path 9 and the at least one associated guide element 10 are arranged, one on the frame 2, the other on the row 3 of tools 5 to be driven in movement for a relative displacement of the guide path and the at least one associated guide element to the actuated state of the actuator 7.

[0060] In the examples shown, the guidance system 8 comprises at least two parallel guidance paths in each case. It should be noted that the guidance system could have been formed by an additional actuator acting in parallel with the actuator 7 described above.

[0061] The guide path 9 and the at least one associated guide element 10 can take a large number of forms. Examples are given in Figures 5 to 9.

[0062] In these two embodiment examples, the guide path 9 and the at least one associated guide element 10 are configured to allow at least partial retention of the at least one guide element 10 inside the guide path 9 over at least part of the length of the guide path 9 in the actuation state of the actuator 7 for the purpose of guiding the movement of said row of tools by simple contact.

[0063] Similarly, in each of these examples, the guidance path 9 is inclined from a high point PH, located from one of the ends, called the first end 31 of the row 3 of tools, by a first distance towards a low point PB, located from said first end 31 of the row 3 of tools by a second distance greater than the first distance.

[0064] The guide path(s) can be carried by the beam and the associated guide element(s) by the frame 2, or vice versa, without going out of the scope of the invention.

[0065] In the example shown in Figure 5, the actuator 7 is a cylinder whose body is coupled to the frame 2 and whose rod is coupled to a U-shaped piece fixed to the beam 4 of the tool row 3 5, with the web of the U extending parallel to the longitudinal axis of the beam. In this example, the linkage system 6 is configured so that, when the actuator 7 is actuated, it generates an angular displacement of the tool row 3 around an axis YY' forming a longitudinal axis of the tool row 3.

[0066] In particular, the extension or retraction of the cylinder rod causes at least one angular displacement of the beam 4 around its longitudinal axis YY'. The cylinder rod is, at its connection to the U-shaped piece, slidingly coupled to the web of the U to allow axial displacement of the beam when the actuator 7 is actuated. Similarly, the cylinder body is preferably coupled with clearance to the frame 2.

[0067] The guide system 8 comprises several parallel guide paths. Each guide path is a groove and the associated guide member 10 is a protruding element, such as a stud or finger, housed at least partially inside said groove.

[0068] The guide path 9 is provided on the beam 4 and is inclined from a high point close to the first end 31 of the row 3 of tools, in this case from the first end of the beam 4 towards a low point away from said first end.

[0069] The guide member 10 is housed inside a ring 15 coupled to the frame 2 and surrounding at least part of the tool row 3 5. Said ring 15 cooperates with the actuator 7 to allow angular displacement of the tool row around an axis forming a longitudinal axis of said tool row when the actuator is actuated. This ring surrounds the beam of the tool row.

[0070] The guide element is fixed and cooperates with the guide path which is mobile under the action of said actuator 7. It is understood, due to the inclination of the guide path, that the actuation of the actuator 7 in the direction here of an extension of the rod of the cylinder, as illustrated in figure 6, generates a displacement of the beam and consequently of the whole row of tools downwards and to the left in figure 6 of said row of tools and also forwards as illustrated in figure 7 due to the angular displacement of the beam.

[0071] To assist in the actuation of the actuator 7, and in particular in selecting the stroke of said actuator, at least one of the tools 5, formed by a hollow disc in at least one of the rows 3 of tools 5, is equipped with at least one wear indicator 12. This wear indicator 12 takes the form of a series of marks arranged along a radius of the disc, as illustrated in Figure 2.

[0072] Similarly, the tillage machine 1 may include, for the actuator 7, a set of shims 14. Each shim 14 can be positioned on the actuator 7 between the rod and the cylinder body to limit the actuator 7's travel, particularly the rod's travel. The number of shims 14 depends on the desired travel for the actuator 7.

[0073] Each mark constituting the wear indicator 12 can be defined in coincidence with a number of shims to be positioned on the actuator 7 to help the user define the stroke of said actuator 7.

[0074] In the example shown in Figures 5 to 7, when the rod of the actuator 7 is retracted, the discs are new. As the discs wear, the rod is extended, causing at least a lateral and vertical movement of the row of discs. This movement is guided by the interaction of each guide element with its corresponding guide track. The rod stroke is determined using the wear indicator and shims. It can also be determined visually and empirically by the operator, who, in this case, uses the position of the discs in the other rows of discs as a guide.

[0075] Figures 8 and 9 illustrate the case where the actuator 7 and the guide path 9 of the linkage system 6 extend in parallel and the path or each path 9 of guide and at least one guide element 10 associated with each guide path 9 are mounted relative to each other in a movable sliding manner in the actuated state of said actuator 7.

[0076] Again, several parallel inclined guide paths 9 are planned from a high point PH located by a first distance from one end 31 of the beam towards a low point PB located by a second distance greater than the first distance from the first end 31 of the beam.

[0077] Each guide path 9 is in the form of a sleeve mounted on the chassis 2 and each guide element by a rod carried by the beam and sliding inside the sleeve.

[0078] As illustrated in Figure 9, the extension of the rod of the actuator 7's cylinder causes the beam 4 to move away from the frame 2 in a downward direction and a lateral displacement, i.e., in a direction perpendicular to the longitudinal axis of the frame or parallel to the longitudinal axis of the beam. This allows the discs, whose size is reduced due to wear, to be positioned in an area where their contact area with the ground is substantially the same as when the discs are new, so that the unworked soil area remains substantially unchanged. Again, a wear indicator and shims can be provided to facilitate the selection of the actuator stroke.

[0079] The design of the linkage system 6, as described above, allows for simple adjustment, using a single actuator, of the optimal position of all the tools in a given row, according to their degree of wear. This results in optimized soil preparation throughout the entire service life of the tools in that row.

Claims

Demands

1. Soil-working machine (1), said machine (1) comprising a frame (2) with a longitudinal axis (XX') taken along the front / rear direction of the frame (2) and at least two rows (3) of soil-working tools (5), respectively referred to as front and rear, coupled respectively to the frame (2) by a linkage system (6) and each extending transversely to the longitudinal axis (XX') of the frame (2), said frame (2) being capable of being maintained at a predetermined distance from the ground and at least a portion of the tools (5) in each row (3) of tools (5) being concave or frustoconical hollow discs, characterized in that for at least one of the rows (3) of tools (5), the linkage system (6) between said row (3) of tools (5) and the frame (2) comprises at least one actuator (7) and a guidance system (8), said row (3) of tools (5) being, in the state actuated by one or more of the actuators (7),guided mobile mounting in a movement along a travel stroke comprising at least two components, one of the components being a vertical component for a downward or upward movement of the tools (5) of said row (3), the other or another of the components being a component along a direction transverse to the longitudinal axis (XX') of the frame (2), i.e. parallel to an axis corresponding to a longitudinal axis of the row of tools, to allow by means of said actuator (7) both a lowering, or respectively a raising, and a lateral offset of the tools (5) of said row (3) of tools (5).

2. Soil-working machine (1) according to claim 1, characterized in that the actuator (7) or one of the actuators (7) of the linkage system (6) between a row (3) of tools (5) and the chassis (2) is a cylinder disposed between said row (3) of tools (5) and the chassis (2).

3. Soil-working machine (1) according to any one of claims 1 or 2, characterized in that the at least two rows (3) of tools (5) coupled respectively to the frame (2) by a linkage system (6) each comprise at least one beam (4) extending transversely to the longitudinal axis (XX') of the frame (2) and to which the tools (5) are coupled by a linkage element (11).

4. Soil-working machine (1) according to any one of claims 1 to 3, characterized in that the guidance system (8) comprises one or more guide paths (9) each housing at least one guide element (10), each guide path (9) and the at least one associated guide element (10) being disposed, one on the chassis (2), the other on the row (3) of tools (5) to be driven in motion.

5. Soil-working machine (1) according to claim 4, characterized in that the guide path (9) and the at least one associated guide element (10) are configured to allow at least partial retention of the at least one guide element (10) inside the guide path (9) over at least a portion of the length of the guide path (9) in the actuated state of the actuator (7).

6. Soil-working machine (1) according to any one of claims 4 or 5, characterized in that the or at least one of the guidance paths (9) is inclined from a high point (PH) away from one of the ends, said first end (31), of the row (3) of tools (5) by a first distance, towards a low point (PB) away from said first end (31) of the row (3) of tools (5) by a second distance greater than the first distance.

7. Soil-working machine (1) according to any one of claims 4 to 6, characterized in that the or at least one of the guide paths (9) is a groove, and the at least one associated guide element (10) is a protruding element, of the type stud or finger, housed at least partially inside said groove.

8. Soil-working machine (1) according to any one of claims 1 to 7, characterized in that the travel stroke which includes at least a vertical component and a so-called lateral component along a direction transverse to the longitudinal axis (XX') of the chassis (2) further includes an axial component parallel to the longitudinal axis (XX') of the chassis (2).

9. Soil-working machine (1) according to any one of claims 1 to 8, characterized in that the linkage system (6) is configured to, in the actuated state of said actuator (7), generate an angular displacement of the row (3) of tools (5) around an axis (YY') forming a longitudinal axis of said row (3) of tools (5).

10. Soil-working machine (1) according to claim 9, characterized in that the guide path(s) (9) are arranged on the row (3) of tools (5) and in that the guide element(s) (10) or at least one of the guide elements (10) is housed inside a ring (15) coupled to the frame (2) and surrounding at least part of the row (3) of tools (5).

11. Soil-working machine (1) according to any one of claims 4 to 6, characterized in that the actuator (7) and the guide path(s) (9) of the linkage system (6) extend in parallel and in that the guide path(s) (9) and the at least one guide element (10) associated with each guide path (9) are mounted relative to each other in a sliding movable manner in the actuated state of said actuator (7).

12. A soil-working machine (1) according to any one of claims 1 to 11, characterized in that at least one of the tools (5), formed by a hollow disc, at least one of the rows (3) of tools (5), is equipped with at least one wear indicator (12).

13. Soil-working machine (1) according to any one of claims 1 to 12, characterized in that the chassis (2) is, for its maintenance at a predetermined distance from the ground, equipped with at least one reference element (13).

14. Soil-working machine (1) according to any one of claims 1 to 13, characterized in that the actuator (7) or one of the actuators (7) of the linkage system (6) being a cylinder, said machine comprises, for at least one actuator (7), a set of shims (14), each shim (14) being positionable on the actuator (7) to limit the travel of said actuator (7), the number of shims (14) being a function of the travel of said actuator (7).

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