a set of tillage implements that can be moved along a row of crops and a tillage device incorporating at least one such set

Abstract

A tillage assembly comprising a tool-bearing support (2), a non-powered rotary tool (3), and a system (4) for connecting the tool (3) to the support (2). The connection system (4) comprises a first arm (5) coupled to the support (2) pivoting about a first pivot axis, a second tool-bearing arm (6) coupled to the first arm (5) pivoting about a second pivot axis (YY') parallel to the first pivot axis for moving the second arm (6) between a position close to the first arm (5) and a position away from the first arm (5), the rotary tool (3) having an axis of rotation extending substantially parallel to the second pivot axis (YY'), said assembly comprising a device (7) for locking the first arm (5) in an adjustable angular position about the first pivot axis, and said assembly comprising at least one element (9) for returning the second arm (6) to a position away from the first arm (5). Figure for the abbreviation: Fig. 4

Description

Title of the invention: a soil tillage assembly movable along a row of crops and a soil tillage device incorporating at least one such assembly

[0001] The present invention relates to a soil-working assembly that can be moved along a row of crops, as well as a soil-working device incorporating at least one such assembly.

[0002] It relates in particular to a soil-working assembly movable along a row of crops comprising at least a tool carrier support that can be coupled to a chassis of a soil-working machine or a tractor vehicle and having a direction of movement, a non-powered rotary tool, such as a disc, and a system for linking the tool to the support.

[0003] Row crops, such as fruit trees, vines, shrubs, or others, require hoeing at the base of the plants. The difficulty lies in the fact that the width between two rows of crops can vary. Similarly, the distance between two crops within the same row can vary. Current solutions use sensors to work as close as possible to the plants, which leads to complex solutions that do not allow for the simultaneous treatment of two rows of crops within a wide range of widths.

[0004] One object of the invention is to offer a soil preparation unit whose design allows work to be carried out as close as possible to plants arranged in rows, and work that is easily adaptable to different inter-row widths when several units are mounted on the same frame.

[0005] To this end, the invention relates to a soil cultivation assembly comprising at least one tool carrier support that can be coupled to the chassis of a soil cultivation machine or a tractor vehicle, a non-powered rotary tool, such as a disc, and a system for linking the tool to the support, characterized in that the linking system comprises a first arm coupled to the support pivoting about an axis called the first pivot axis, a second tool carrier arm coupled to the first arm pivoting about an axis called the second pivot axis parallel to the first pivot axis for a displacement of the second arm between a position close to the first arm and a position away from the first arm, in that the rotary tool has an axis of rotation extending substantially parallel, that is to say parallel to within ±15 degrees, to the second pivot axis,in that said assembly comprises a device for immobilizing the first arm in an adjustable angular position around the first pivot axis, and in that said assembly comprises at least one element for returning the second arm to position, Positioned away from the first arm, this return element is configured so that, when the second arm is driven from its extended position to its closer position to the first arm, it exerts a return force on the second arm to its extended position. The presence of two arms allows the first arm to preposition the second arm / tool ​​assembly more or less close to the crop being worked. The presence of a second arm equipped with a return mechanism allows for continuous working as close as possible to the crop without the need for a feeler. Such a tillage system is easy to use, suitable for all soil types, and does not require high power from the tractor or tillage machine to which it is coupled. Its design allows it to be mounted at the front or rear of the tractor or tillage machine.

[0006] According to one embodiment of the invention, the restoring force of the restoring element is an adjustable force. This results in the possibility of adapting it to each type of crop.

[0007] According to one embodiment of the invention, the return element is an energy accumulator configured to store energy during the movement of the second arm from the extended position to the close position of the first arm, and to release said energy during the movement of the second arm from the close position of the first arm to the extended position of the first arm. This energy accumulator is selected from the group of energy accumulators consisting of springs and hydraulic or hydropneumatic accumulators. The design of such a tillage system is simple.

[0008] According to one embodiment of the invention, the return element is a spring disposed between the support and the second arm.

[0009] According to one embodiment of the invention, the spring is associated with a spring preloading element capable of preloading the spring in an adjustable manner to vary the restoring force of the restoring element formed by said spring.

[0010] According to one embodiment of the invention, said assembly comprises a pivoting actuator for controlling the movement of the second arm, disposed between the support and the second arm. This actuator is configured to control at least the movement of the second arm from a position away from the first arm to a position closer to the first arm. It is thus possible, at the end of a row, to bring the tillage unit into a more compact position. This design also facilitates the road transport of such a tillage unit.

[0011] According to one embodiment of the invention, the pivoting control actuator of the second arm is a hydraulic or pneumatic cylinder connectable to a pressurized fluid source, this cylinder comprising a first chamber, configured to, when supplied with pressurized fluid, control a movement of the second arm in the direction of bringing the first arm closer together, and a second chamber.

[0012] According to one embodiment of the invention, the return element is a hydraulic or hydropneumatic accumulator in fluidic communication with the second chamber of the cylinder constituting the control actuator in pivoting movement of the second arm.

[0013] According to one embodiment of the invention, the accumulator, which is a hydropneumatic accumulator, is composed of two parts separated from each other, one of the parts being filled with a gas under pressure, the other part in fluidic communication with the second chamber of the cylinder, which is a hydraulic cylinder being able to be filled with a hydraulic fluid.

[0014] According to one embodiment of the invention, the soil preparation unit includes a device, such as a pressure gauge, for measuring the pressure in the second chamber. The presence of this pressure gauge makes it possible to control the restoring force exerted.

[0015] According to one embodiment of the invention, the immobilizing device of the first arm in an adjustable angular position around the first pivot axis is a cylinder.

[0016] According to one embodiment of the invention, the immobilizing device of the first arm in an adjustable angular position around the first pivot axis being a hydraulic cylinder referred to as the first cylinder and the actuator controlling the pivoting movement of the second arm being a hydraulic cylinder referred to as the second cylinder, the assembly includes, for connecting the first and second cylinders to at least one source of pressurized fluid, at least one distributor and fluid circulation lines disposed at least between the distributor and the first and second cylinders, and said assembly includes a distributor control unit equipped with at least three control elements, one of the control elements being configured to control the fluid supply to the first cylinder,One of the control units is configured to control the fluid supply to the second chamber of the second cylinder, and one of the control units is configured to control the fluid supply to the first chamber of the second cylinder.

[0017] The invention also relates to a soil cultivation device comprising at least one chassis of a tractor vehicle or soil cultivation machine and at least one soil cultivation unit coupling to said chassis, characterized in that the or at least one of the soil cultivation units is of the aforementioned type.

[0018] According to one embodiment of the invention, the number of tillage units being at least 2, the locking device for the first arm in an adjustable angular position around the first pivot axis of each unit being a hydraulic cylinder referred to as the first cylinder, each tillage unit comprising a pivoting actuator for the second arm of each assembly, in the form of a hydraulic cylinder called the second cylinder, and each assembly comprising, for connecting the first and second cylinders of each assembly to at least one pressurized fluid source, at least one distributor and fluid circulation lines arranged at least between the distributor and the first and second cylinders, the distributor is common to said assemblies and the distributor is associated with a distributor control unit equipped with at least four control elements, one of the control elements is configured to control the fluid supply to the first cylinder of one of the assemblies, one of the control elements is configured to control the fluid supply to the first cylinder of the other of the assemblies,One of the control units is configured to control the fluid supply to the second chamber of the second cylinder in each assembly, and one of the control units is configured to control the fluid supply to the first chamber of the second cylinder in each assembly. Brief description of the drawings

[0019] The invention will be better understood upon reading the following description of exemplary embodiments, with reference to the accompanying drawings in which:

[0020] [Fig. 1] represents a partial perspective view of a soil working device equipped with two soil working assemblies according to the invention, in a position close to the second arm of the first arm;

[0021] [Fig.2] represents a partial elevational view of a soil-working device equipped with a soil working assembly according to the invention, in a position close to the second arm of the first arm;

[0022] [Fig.3] represents a partial top view of a soil-working device equipped of two soil working assemblies according to the invention, in a position close to the second arm of the first arm;

[0023] [Fig.4] shows a top view of a soil-working device equipped with two soil working assemblies according to the invention, in a position close to the second arm of the first arm, the hydraulic circuits having been shown;

[0024] [Fig. 5] shows a partial top view of a soil-working device equipped of two soil-working assemblies according to the invention when moving the soil-working device between two rows of crops;

[0025] [Fig. 6] represents a partial top view of a soil-working device equipped of two sets of soil cultivation equipment conforming to the invention;

[0026] [Fig.7] represents a schematic view of an accumulator;

[0027] [Fig.8] represents a partially cross-sectional view of the control actuator moving the second arm.

[0028] As mentioned above, the invention relates to a tillage unit 1 and a tillage device that can incorporate one or more tillage units 1, as illustrated in Figures 1 and 2. The tillage unit or units 1 are thus coupled to a chassis 21 of a tractor vehicle of a tillage machine to form a tillage device. The tillage unit or units 1 are more particularly intended to move along a row 20 of crops, as illustrated in [Fig. 5]. When the tillage device comprises two tillage units 1, as illustrated in [Fig. 5], it is possible to work two parallel rows of crops in parallel, the tillage device being arranged between said rows of crops. Obviously, when the tillage device comprises only one tillage unit 1, only one row of crops is worked.This row of crops could be a row of fruit trees, vines, nursery plantings, or something else.

[0029] When the soil-working device comprises several soil-working assemblies 1, these soil-working assemblies 1 are generally identical, so only one soil-working assembly 1 will be described below. This soil-working assembly 1 has a direction of travel represented by an arrow in [Fig. 5]. Generally, the frame 21 to which the soil-working assembly 1 is coupled comprises at least one beam extending transversely to the direction of travel of said soil-working assembly 1.

[0030] This soil-working assembly 1 comprises at least: - a tool-holder support 2 attached to the frame 21, - a non-powered rotary tool 3, here in the form of a disc, and - a system 4 for connecting the tool 3 to the tool-holder support 2. In the example shown, the tool-holder support 2 is a plate fixed to a leading or driven side of the beam forming part of the frame 21.

[0031] The linkage system 4 comprises a first arm 5 coupled to the support 2, pivoting about an axis of the first pivot axis XX'. This first pivot axis XX' extends vertically in the operating configuration of said tillage assembly 1. This linkage system 4 comprises a second tool-carrying arm 6 coupled to the first arm 5, pivoting about an axis called the second pivot axis YY', parallel to the first pivot axis XX', for movement of the second arm 6 between a position close to the first arm 5 and a position away from the first arm 5. The second arm 6 carries the tool 3, in this case the disc, which is mounted for rotation about an axis of rotation ZZ' extending substantially parallel, that is to say, parallel to within ±15° to the second pivot axis YY'. This tool 3 therefore extends partially under the second arm 6 to position itself as close as possible to the base of the crop, as illustrated in [Fig.5].

[0032] This soil-working assembly 1 includes a locking device 7 for the first arm 5 in an adjustable angular position around the first pivot axis XX'. It is thus possible to adapt the position of the first arm 5 according to the width between two rows, in particular when the soil-working device comprises two assemblies 1 as illustrated in Figures 3 and 5 for example.

[0033] In the example of Figures 1 and 2, the device 7 for immobilizing the first arm 5 in an adjustable angular position around the first pivot axis XX' is a cylinder 71 disposed between the first arm 5 and the tool holder support 2. Alternatively, and as illustrated in [Fig. 6], this device 7 for immobilizing the first arm 5 in an adjustable angular position can be formed by a connecting rod disposed between the first arm 5 and the tool holder support 2, this connecting rod being of adjustable length. It is also possible to imagine, at the connection of the first arm 5 to the tool holder support 2, a plurality of bores in the first arm 5 and the tool holder support 2 that can be positioned in pairs in coincidence and immobilized in the selected position by, for example, a pin. The advantage of making the immobilizing element 7 for the first arm 5 in the form of a cylinder 71 is that the position of the first arm 5 can be adjusted remotely by simply actuating the cylinder.

[0034] In the example shown, the cylinder 71 is a hydraulic cylinder connectable to a pressurized fluid source 22, and the soil cultivation assembly 1 comprises, for connecting the cylinder 71 to said pressurized fluid source 22, a distributor 11 and fluid circulation lines 121, 122 represented by a line and a dot in [Fig. 4] for one of the assemblies and by a dashed line for supplying the cylinder 71 from the other assembly 1. These lines 121 and 122 supply each chamber of the cylinder 71. Thus, supplying pressurized fluid to one of the chambers of the cylinder 71 generates a pivoting movement of the first arm 5 outwards from the soil cultivation assembly 1, while supplying pressurized fluid to the other chamber of the cylinder 71 generates a pivoting movement of the first arm 5 arm 5 following an opposite direction.The greater the width between crop rows, the more the tendency is to position the first arm 5 at an angle towards the outside of the tillage unit 1. It is understood that, thanks to this arrangement of the first arm 5, a wide range of widths between two crop rows can be covered.

[0035] The soil-working assembly 1 includes a return element 9 for the second arm 6 in the position away from the first arm 5. This return element 9 is configured so that, when the second arm 6 is driven from the position away from the first arm 5 to the position closer to the first arm 5, it exerts a return force on the second arm 6 towards the position away from the first arm 5. of the first arm 5. Ideally, the restoring force of the restoring element 9 is an adjustable force. This restoring element 9 is an energy accumulator configured to store energy in the form of pressure in the driven state during the movement of the second arm 6 from the extended position to the close position of the first arm 5 and to release said energy for a driving movement of the second arm 6 from the close position of the first arm 5 to the extended position of the first arm. 5. This energy accumulator is selected from the group of energy accumulators formed by the springs 91 and the hydraulic or hydropneumatic accumulators 92.

[0036] In a simplified version of the invention, as illustrated in [Fig. 6], the restoring element 9 is a spring 91 disposed between the support 2 and the second arm 6.This spring 91 is associated with a spring preload element 911 capable of preloading the spring 91 in an adjustable manner to vary the restoring force of the restoring element 9 formed by said spring 91.

[0037] Thus, this spring 91 is equipped at one end with a nut cooperating with a threaded rod to variably pre-compress the spring 91 according to the resistance to the approach of the second arm towards the desired first arm.

[0038] In the example of Figures 1 and 4, the tillage assembly 1 includes a pivoting actuator 8 for controlling the movement of the second arm 6, located between the tool holder support 2 and the second arm 6. This actuator 8 is configured to control at least the movement of the second arm 6 from a position away from the first arm 5 to a position closer to the first arm 5. The pivoting actuator 8 for controlling the movement of the second arm 6 is a cylinder 81, preferably hydraulic, connectable to a pressurized fluid source 22. This cylinder 81 includes a first chamber 811 configured, when supplied with pressurized fluid, to control a movement of the second arm 6 in the direction of a movement towards the first arm 5, and a second chamber 812. Details of this cylinder 81 are provided in [Fig. 8].In this embodiment, the return element 9 is a hydraulic or hydropneumatic accumulator 92 in fluidic communication with the second chamber 812 of the cylinder 81 constituting the actuator 8 for controlling the pivoting movement of the second arm 6. A detailed view of a hydraulic or hydropneumatic accumulator 92 is provided in [Fig. 7]. This accumulator is composed of two separate parts 921, 922. One part is filled with a pressurized gas, while the other part, in fluidic communication with the second chamber of the cylinder 81, is suitable for being filled with a hydraulic fluid. Generally, the pressurized gas is nitrogen. This is why such an accumulator can be called a nitrogen sphere. The element separating the two parts of the accumulator, shown as 923 in [Fig. 7], can take different forms depending on the type of accumulator. Thus, this separating element can be a membrane, a... piston, a bladder or other. Again, for the operation of the actuator 8 for the pivoting movement control of the second arm 6, when the latter is a hydraulic cylinder 81, the soil working assembly 1 includes a distributor 11, which may be common with the distributor of the actuator for the pivoting movement control of the first arm when the latter is a cylinder 71, and fluid circulation lines arranged between the distributor 11 and the pivoting movement control cylinder 81 of the second arm.

[0039] In the example of [Fig. 4], the conduit 123, shown with crosses, supplies the first chamber 811 of the cylinder 81, while the conduit 124, shown with a solid line, supplies the second chamber 812 of the cylinder 81, which is in fluidic communication with one of the parts of the hydropneumatic or hydraulic accumulator 92 and, consequently, with said part of the hydropneumatic or hydraulic accumulator. The second chamber 812 of the cylinder 81 is in fluidic communication with one of the parts of the hydropneumatic or hydraulic accumulator 92 via a connection that may be closable.

[0040] To control this pre-filling of this second chamber 812 in relation to the accumulator and the resulting restoring force, the soil working assembly 1 includes a device such as a pressure gauge 10, for measuring the pressure in the second chamber 812.

[0041] The advantage of this solution lies in its simplicity of implementation. The chosen pressure is defined empirically by the user. This user can adjust the pressure according to the desired soil treatment result.

[0042] Finally, to complete the soil preparation assembly 1, this soil preparation assembly 1 includes a control unit 13 for the distributor 11, equipped with at least three control elements, such as switches, capable of controlling the opening / closing of each pipe. The distributor 11 is a spool valve, and the opening / closing of each pipe depends on the position of the spool.

[0043] In the example of [Fig. 4], four control elements are provided, represented as 141, 142, 143, and 144, with each control element associated with the line(s) it operates. Thus, control element 141 controls the opening / closing of line 121, i.e., the operation of the control cylinder 71 by pivoting the first arm 5 of one of the soil-working units 1. Control element 142 controls the opening / closing of line 122, i.e., the operation of the control cylinder 71 by pivoting the first arm 5 of the other soil-working unit 1 when the soil-working device comprises two soil-working units 1.

[0044] The control member 143 controls the opening / closing of the pressurized fluid supply line 123 to the first chamber 811 of the actuator 8 The control element 144 controls the pivoting movement of the second arm 6 of one or both of the tillage units when the tillage device comprises two tillage units, and the control element 124 controls the opening / closing of the pressurized fluid supply line 124 to the second chamber 812 of the pivoting movement control actuator 8 of the second arm, which is in fluidic communication with the hydraulic or hydropneumatic accumulator of one or both of the tillage units when the tillage device comprises two tillage units 1.

[0045] Obviously, one of the control elements can be omitted when the tillage device comprises only one tillage unit 1. In practice, the operation of the tillage device is as follows.It is assumed that the tillage device is positioned along a row of crops or between two parallel rows of crops, as illustrated in [Fig. 5]. Initially, the user determines the angular position of the first arm 5 using the first arm 5 locking device 7. This position is determined based on the distance between rows, i.e., the width between crop rows. The return force of the return element 9 is then adjusted. In the case of an accumulator, for example, in the offset position of the second arm 6 from the first arm 5, fluid is supplied to the second chamber 812 of the actuator 8 controlling the movement of the second arm 6, and consequently to the fluidic communication portion of the accumulator until a desired pressure value is reached. When the tillage device moves along the row following the arrow shown in [Fig. 5], the user determines the angular position of the first arm 5.5], the non-driven disc of each tillage unit 1, or of the tillage unit 1 when the tillage device comprises only one tillage unit 1, encounters, as it advances, a crop in the row which tends, by the pressure of the disc on the crop, to bring the second arm 6 closer to the first arm 5 against the restoring force exerted by the restoring element 9. At the end of the row, the second arm 6 can be brought closer to the first arm 5 by actuating the pivoting control actuator 8 of the second arm 6 when this actuator 8 is present to facilitate maneuvering at the end of the row before traveling, if necessary, through another alley between two rows.

[0046] Such a soil-working device can work at a high travel speed and can be placed at the front or rear of the chassis of the tractor vehicle to which it is coupled.

Claims

Demands

1. A tillage assembly (1) comprising at least one tool-carrying support (2) that can be coupled to a frame (21) of a tillage machine or tractor, a non-powered rotary tool (3), such as a disc, and a system (4) for connecting the tool (3) to the support (2), characterized in that the connecting system (4) comprises a first arm (5) coupled to the support (2) pivoting about an axis called the first pivot axis (XX'), a second tool-carrying arm (6) coupled to the first arm (5) pivoting about an axis called the second pivot axis (YY') parallel to the first pivot axis (XX') for moving the second arm (6) between a position close to the first arm (5) and a position away from the first arm (5), in that the rotary tool (3) has an axis of rotation (ZZ') extending substantially parallel, that is to say, parallel to more or less To within 15 degrees, at the second pivot axis (YY'),in that said assembly (1) comprises a device (7) for immobilizing the first arm (5) in an adjustable angular position about the first pivot axis (XX'), and in that said assembly (1) comprises at least one element (9) for returning the second arm (6) to a position away from the first arm (5), this return element (9) being configured so that, in the driven state of the second arm (6) from the position away to the position closer to the first arm (5), it exerts a restoring force on the second arm (6) towards the position away from the first arm (5).

2. Soil working assembly (1) according to claim 1, characterized in that the return force of the return element (9) is an adjustable force.

3. Soil working assembly (1) according to any one of claims 1 or 2, characterized in that the return element (9) is an energy accumulator configured to store energy in the driven state by moving the second arm (6) from the extended position to the close position of the first arm (5) and to release said energy for driving the second arm (6) from the close position of the first arm to the extended position of the first arm (5), this energy accumulator being selected from the group of energy accumulators formed by springs (91) and hydraulic or hydropneumatic accumulators (92).

4. Soil working assembly (1) according to any one of claims 1 to 3, characterized in that the return element (9) is a spring (91) disposed between the support (2) and the second arm (6).

5. Soil working assembly (1) according to claim 4, characterized in that the spring (91) is associated with a spring preloading element (911) capable of preloading the spring (91) in an adjustable manner to vary the restoring force of the restoring element (9) formed by said spring (91).

6. Soil working assembly (1) according to any one of claims 1 to 5, characterized in that said assembly (1) comprises a pivoting displacement control actuator (8) of the second arm (6) disposed between the support (2) and the second arm (6), this actuator (8) being configured to control at least the passage of the second arm (6) from a position away from the first arm (5) to a position close to the first arm (5).

7. Soil working assembly (1) according to claim 6, characterized in that the actuator (8) for controlling the pivoting movement of the second arm (6) is a hydraulic or pneumatic cylinder (81) connectable to a source (22) of pressurized fluid, this cylinder (81) comprising a first chamber (811) configured to, when supplied with pressurized fluid, control a movement of the second arm (6) in the direction of bringing the first arm (5) closer together and a second chamber (812).

8. Soil working assembly (1) according to claim 7, characterized in that the return element (9) is a hydraulic or hydropneumatic accumulator (92) in fluidic communication with the second chamber (812) of the cylinder (81) constituting the actuator (8) for controlling the pivoting movement of the second arm (6).

9. Soil working assembly (1) according to claim 8, characterized in that the accumulator, which is a hydropneumatic accumulator (92), is composed of two parts (921, 922) separated from each other, one of the parts being filled with a gas under pressure, the other part in fluidic communication with the second chamber of the cylinder (81), which is a hydraulic cylinder, being able to be filled with a hydraulic fluid.

10. A tillage assembly (1) according to any one of claims 8 or 9, characterized in that the tillage assembly (1) comprises a device, such as a pressure gauge (10), for measuring the pressure in the second chamber (812).

11. Soil working assembly (1) according to any one of claims 1 to 10, characterized in that the immobilizing device (7) of the first arm (5) in an adjustable angular position around the first pivot axis (XX') is a cylinder (71).

12. A tillage assembly (1) according to any one of claims 7 to 10, characterized in that the locking device (7) of the first arm (5) in an adjustable angular position about the first pivot axis (XX') is a hydraulic cylinder (71), referred to as the first cylinder (71), and the actuator (8) for controlling the pivoting movement of the second arm (6) is a hydraulic cylinder (81), referred to as the second cylinder (81). The assembly (1) comprises, for connecting the first and second cylinders (71, 81) to at least one source (22) of pressurized fluid, at least one distributor (11) and fluid circulation lines (121, 122, 123, 124) disposed at least between the distributor (11) and the first and second cylinders (71, 81), and in that said assembly (1) comprises a distributor control unit (13). (11) equipped with at least three control devices (141, 142, 143, 144),in that one of the control elements is configured to control the fluid supply to the first cylinder (71), in that one of the control elements is configured to control the fluid supply to the second chamber (812) of the second cylinder (81), and in that one of the control elements is configured to control the fluid supply to the first chamber (811) of the second cylinder (81).

13. Soil cultivation device comprising at least one chassis (21) of a tractor vehicle or soil cultivation machine and at least one soil cultivation assembly (1) couplingable to said chassis (21), characterized in that the or at least one of the soil cultivation assemblies (1) conforms to one of claims 1 to 12.

14. A soil cultivation device according to claim 13, characterized in that the number of soil cultivation assemblies (1) is at least 2, in that the immobilizing element (7) of the first arm (5) in an adjustable angular position about the first pivot axis (XX') of each assembly (1) is a hydraulic cylinder referred to as the first cylinder (71), in that each soil cultivation assembly (1) comprises a control actuator (18) for movement at pivoting of the second arm (6) of each assembly (1) in the form of a hydraulic cylinder called the second cylinder (81) and each assembly (1) comprising, for the connection of the first and second cylinders (71, 81) of each assembly (1) to at least one source (22) of pressurized fluid, at least one distributor (11) and fluid circulation lines (121, 122, 123, 124) disposed at least between the distributor (11) and the first and second cylinders (71, 81), in that the distributor (11) is common to said assemblies (1) and in that the distributor (11) is associated with a control unit (13) for the distributor (11) equipped with at least four control elements (141, 142, 143, 144), in that one of the control elements is configured to control the fluid supply to the first cylinder (71) of one of the assemblies (1), in that one of the control elements is configured to control the fluid supply to the first cylinder (71) of the other of the assemblies (1),in that one of the control elements is configured to control the fluid supply to the second chamber (812) of the second cylinder (81) of each assembly (1) and in that one of the control elements is configured to control the fluid supply to the first chamber (811) of the second cylinder (81) of each assembly (1).

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