Hydraulic circuit for agricultural machine and corresponding agricultural machine

Description

[0001] The present invention relates to the field of agricultural machinery and more particularly to an agricultural machine to which a hydraulic circuit is associated.

[0002] In the field of agricultural machinery, it is common for the position adjustment of a sub-assembly or machine element to be managed by one or more hydraulic cylinder(s).

[0003] For example, for a folding rotary harrow, the working depth adjustment of the tools is managed by hydraulic cylinders.

[0004] To maintain the harrow's road transport dimensions (as required by various French, European, etc. regulations), it may be necessary to fully retract the hydraulic adjustment cylinders to reduce overall size. This will result in the loss of any working depth setting made on the field before folding the machine.

[0005] The depth adjustment maneuver will need to be repeated on the next plot, or after the next unfolding of the machine in order to be able to find the previous setting.

[0006] Publication DE102004025522B4 already discloses a hydraulic circuit using a master-slave cylinder system, with a memory chamber integrated into the master cylinder, which thus has three chambers allowing a setting to be memorized. However, this configuration is problematic when it is necessary to retract the entire rod during folding or unfolding. In this case, the memory function is no longer operational.

[0007] Publication EP1648216A2 discloses a mower comprising, in particular, a maneuvering device. The maneuvering device allows switching from a working position to a maneuvering position and vice versa. This maneuvering device consists of a cylinder whose interior is divided into two chambers by a floating piston. One chamber of said chambers is connected to the hydraulic cylinder of the weight-relieving device by means of a second line, and the other chamber is connected to a hydraulic circuit of said power vehicle by means of a third line, so as to be able to inject from said first chamber an additional quantity of oil into the hydraulic cylinder of the weight-relieving device to move the cutting mechanism from the working position to the maneuvering position, and to be able to extract the same quantity of oil from said hydraulic cylinder to move said cutting mechanism from the maneuvering position to the working position.The main purpose of the solution presented in this document is to manage the ground pressure difference between two operating modes. The objective is to maintain and be able to return to a consistent ground pressure setting, while using a hydropneumatic accumulator to compensate for ground variations.

[0008] Publication US3415161A discloses a hydraulic circuit that limits the stroke of a cylinder via an intermediate component. However, this hydraulic circuit does not allow for the memorization of any cylinder position.

[0009] The present invention aims to overcome at least one of these drawbacks and more particularly to offer a solution allowing to easily, quickly and precisely memorize a position to be memorized of a hydraulic cylinder of a hydraulic circuit for agricultural machine in order to easily retrieve later this position to be memorized and thus minimize the time losses due to the repetition of adjustment maneuvers and this regardless of the modification of the position of the hydraulic cylinder to be carried out after memorization.

[0010] For this purpose, the invention relates to an agricultural machine according to claim 1.

[0011] The invention will be better understood from the following description, which relates to several preferred embodiments, given by way of non-limiting examples, and explained with reference to the accompanying schematic drawings, in which: [ Fig. 1 ] represents a hydraulic circuit, [ Fig. 2 ] represents a hydraulic circuit according to the invention in a first embodiment, [ Fig. 3 ] represents a hydraulic circuit according to the invention in a second embodiment, and [ Fig. 4 ] represents a hydraulic circuit according to the invention in a third embodiment.

[0012] With reference to figures 1 à 4 The hydraulic circuit of the agricultural machine, which includes at least one machine element (not shown) that is suitable and intended to be actuated by at least one main hydraulic cylinder 1, includes at least: a main hydraulic circuit comprising at least one main hydraulic cylinder 1 comprising at least one cylinder 2 comprising a first chamber 3 and a second chamber 4, which are separated from each other by a piston 5, and comprising an actuating member 6 which is mechanically connected to the piston 5 and is suitable and intended to be mechanically connected to said at least one machine element, said piston 5 being movable between successively an initial position P1 to be memorized for which the first chamber 3 or the second chamber 4 is suitable and intended to contain a volume of oil to be memorized V1,an intermediate position P2 for which the first chamber 3 is suitable and intended to contain any volume of oil V2 different from the volume of oil to be stored V1 and a final position P3 for which the first chamber 3 is suitable and intended to contain a volume of stored oil V3 equal or substantially equal to said volume of oil to be stored V1, a main pilot / distribution unit 7 hydraulically connected at least to one of the first and second chambers 3, 4 of said main hydraulic cylinder 1 by hydraulic conduction means and being arranged to actuate said main hydraulic cylinder 1 at least between the initial position P1 to be stored and the intermediate position P2, a hydraulic memory circuit hydraulically connected to said main hydraulic circuit comprising at least: a hydraulic storage cylinder 8 comprising at least a first storage chamber 9 and a second storage chamber 10,which are separated from each other by a movable piston 11, a pilot / distribution memory unit 12 hydraulically connected to the second storage chamber 10 of said storage cylinder 8 by hydraulic conduction means 13.

[0013] In said hydraulic circuit said hydraulic storage cylinder 8 is a separate entity from cylinder 2 of said main hydraulic cylinder 1, and the first storage chamber 9 of said hydraulic storage cylinder 8 is hydraulically connected to said first chamber 3 of said main hydraulic cylinder 1 at least by hydraulic conduction means 14, 14a, 14b, so that said volume of oil to be stored V1 contained in the first chamber 3 or the second chamber 4 corresponding to the initial position P1 of the piston 5 is transferred into the first storage chamber 9 of said hydraulic storage cylinder 8 to store the initial position P1 when said piston 5 moves from the initial position P1 to the intermediate position P2 of said piston 5.

[0014] This advantageous configuration allows for the easy and rapid retrieval of the position setting of at least one main hydraulic cylinder 1 should it need to be actuated, for whatever reason, to restore the position setting of a machine element, preferably a tool. Any individual position within the position adjustment range can therefore be stored via the initial position P1 and the stored oil volume V1, and subsequently retrieved via the final position P3 and the stored oil volume V3. The stored oil volume V1 can be a variable value. To achieve this, a hydraulic storage cylinder 8, located away from the main hydraulic cylinder 1, is configured to perform this storage function.The volume of oil to be stored, V1, contained in the first chamber 3 or the second chamber 4, corresponding to the setting, is transferred to the first storage chamber 9 of this storage cylinder 8 when the main hydraulic cylinder 1 is forced to move to another position, for example, due to the need to partially or fully retract / extend the main hydraulic cylinder 1. The storage cylinder 8 allows the oil volume corresponding to the cylinder setting to be received and then subsequently transferred each time it moves to another position. The principle of volume conservation is used in the present invention. The use of the main hydraulic cylinder 1 and the hydraulically operated storage cylinder is essential to implement the principle of oil volume conservation. The transfer is carried out at a constant volume.

[0015] The hydraulic conduction means 14, 14a, 14b are provided to hydraulically connect the first storage chamber 9 of said storage cylinder 8 to said first chamber 3 of said main hydraulic cylinder 1 in order to transfer the volume of oil to be stored V1 contained alternately in the first chamber 3 or in the first storage chamber 9.

[0016] The first storage chamber 9 of said storage cylinder 8 and said first chamber 3 of said main hydraulic cylinder 1 can be hydraulically connected directly or indirectly. According to the invention, the first storage chamber 9 of said storage cylinder 8 and said first chamber 3 of said main hydraulic cylinder 1 are hydraulically connected indirectly.

[0017] According to the figure 1 , the first storage chamber 9 of said storage cylinder 8 and said first chamber 3 of said main hydraulic cylinder 1 are hydraulically connected directly by hydraulic conduction means 14 comprising one or more hydraulic lines.

[0018] In accordance with the invention and according to the figures 2 , 3 And 4 which respectively illustrate a first variant, a second variant and a third variant of embodiment according to the invention, the first storage chamber 9 of said storage cylinder 8 and said first chamber 3 of said main hydraulic cylinder 1 are indirectly hydraulically connected by hydraulic conduction means 14a, 14b comprising one or more hydraulic lines 14a, 14b and by the memory pilot / distribution unit 12.

[0019] Hydraulic conduction means 14, 14a, 14b may include one or more hydraulic conduits and / or conduits dividing into two.

[0020] Preferably, said first storage chamber 9 of said storage cylinder 8 is indirectly hydraulically connected to said first chamber 3 of said main hydraulic cylinder 1 by said hydraulic conduction means 14, 14a, 14b comprising hydraulic lines 14a, 14b and by the memory pilot / distribution unit 12 so that said volume of oil to be stored V1 contained in the first storage chamber 9 of said storage cylinder 8 is transferred into the first chamber 3 or the second chamber 4 of said main hydraulic cylinder 1 to actuate the piston 5 of the main hydraulic cylinder 1 from the intermediate position P2 to the final position P3 of the piston 5 of said main hydraulic cylinder 1 corresponding to said initial position P1.

[0021] Advantageously, when the agricultural machine is again in a position where the previous setting needs to be restored, the volume contained in the first storage chamber 9 of the storage cylinder 8, corresponding to the previous setting, is transferred back to the main hydraulic cylinder 1. Thanks to the principle of volume conservation in a hydraulic circuit, the previous position of the main hydraulic cylinder 1 can be precisely recovered. The recovered setting is exactly the same as the previous one, thus guaranteeing the accuracy and consistency of the main hydraulic cylinder 1's positions over time. No "haphazard" manual adjustments that differ from one field to another are required.

[0022] Preferably, the main pilot unit 7 is arranged to actuate the piston 5 of the main hydraulic cylinder 1 from the initial position P1 to be memorized to the intermediate position P2 of said piston 5, so that said volume of oil to be memorized V1 contained in the first chamber 3 is transferred into the first storage chamber 9 of said storage cylinder 8 to memorize the initial position P1 when moving said piston 5 from the initial position P1 to the intermediate position P2 of said piston 5.

[0023] In this advantageous configuration, when a user operates the main pilot unit 7, the main hydraulic cylinder 1 moves from the initial position P1 to the intermediate position P2 and the volume of oil to be stored V1 contained in the first chamber 3 or the second chamber 4 is transferred into the first storage chamber 9 of said storage cylinder 8.

[0024] Preferably, the memory pilot / distribution unit 12 is arranged to actuate the piston 11 of the storage cylinder 8, so that said volume of oil to be stored V1 contained in the first storage chamber 9 of said storage cylinder 8 is transferred into the first chamber 3 or the second chamber 4 of said main hydraulic cylinder 1, to move the piston 5 of the main hydraulic cylinder 1 from the intermediate position P2 to the final position P3 of the piston 5 of said main hydraulic cylinder 1.

[0025] In this advantageous configuration, when a user operates the memory control / distribution unit 12, the main hydraulic cylinder 1 moves from the intermediate position P2 to the final position P3 and the volume of oil to be stored V1 contained in the first storage chamber 9 of the storage cylinder 8 is transferred into the first chamber 3 or the second chamber 4 of said main hydraulic cylinder 1. The final position P3 then advantageously corresponds to the initial position P1.

[0026] Preferably, and as illustrated by the figures 3 And 4 The main hydraulic circuit comprises a plurality of hydraulic cylinders.

[0027] In this case, a flow divider to supply the plurality of hydraulic cylinders can also be provided.

[0028] For example, and as illustrated by the figure 3 The hydraulic circuit may include a master main hydraulic cylinder and a slave secondary hydraulic cylinder.

[0029] In this case, the secondary hydraulic cylinder 1' slave may include at least one secondary cylinder 2' comprising a first secondary chamber 3' and a second secondary chamber 4', which are separated from each other by a secondary piston 5', and comprising a secondary actuating member 6' which is mechanically connected to the secondary piston 5' and is suitable and intended to be mechanically connected to at least one machine element.

[0030] According to a first possibility illustrated at the figure 3 , the first secondary chamber 3' of the secondary hydraulic cylinder 1' slave is hydraulically connected to the second hydraulic chamber 4 of the main hydraulic cylinder 1 by one or more hydraulic lines 16. The second secondary chamber 4' is hydraulically connected to the pilot / distribution memory unit 12 by one or more hydraulic lines 15 and to the main pilot unit 7 by one or more hydraulic lines 7a.

[0031] Consequently, when the main hydraulic cylinder 1 is moved into position, the secondary hydraulic cylinder 1' (slave) can also be moved to that same position. Thus, only one storage cylinder 8 is needed to store the initial position P1 of both the main hydraulic cylinder 1 (master) and the secondary hydraulic cylinder 1' (slave).

[0032] According to a second possibility illustrated in the figure 4 The first secondary chamber 3' of the secondary hydraulic cylinder 1' is hydraulically connected to the memory pilot / distribution unit 12 by one or more hydraulic lines 14b and to the main pilot unit 7 by one or more hydraulic lines 7a. The second secondary chamber 4' of the secondary hydraulic cylinder 1' is hydraulically connected to the memory pilot / distribution unit 12 by one or more hydraulic lines 15 and to the main pilot unit 7 by one or more hydraulic lines 7b.

[0033] Consequently, when the main hydraulic cylinder 1 is moved into position, the secondary hydraulic cylinder 1' can also be moved to that same position. Thus, only one storage cylinder 8 is needed to store the initial position P1 of both the main hydraulic cylinder 1 and the secondary hydraulic cylinder 1'.

[0034] There figure 1 This illustrates an example in which the hydraulic circuit comprises a single main hydraulic cylinder 1 and a single hydraulic storage cylinder 8. Furthermore, the main pilot unit 7 includes two pilot-operated check valves 71 and 72, which are hydraulically connected to the memory pilot / distribution unit 12 by parallel hydraulic lines 7a and 7b. The memory pilot / distribution unit 12 is also hydraulically connected to the second storage chamber 10 of said storage cylinder 8 and to the second chamber 4 of the main hydraulic cylinder, respectively, by hydraulic lines 13 and 15. The memory pilot / distribution unit 12 is hydraulically connected to the first storage chamber 9 of the storage cylinder 8 and to the first chamber 3 of the main hydraulic cylinder 1 by a hydraulic line 14, which splits into two.

[0035] There figure 2 This illustrates the first embodiment of the hydraulic circuit according to the invention, in which the hydraulic circuit comprises a main hydraulic cylinder 1 and a single hydraulic storage cylinder 8. Furthermore, the main pilot unit 7 includes two pilot-operated check valves 71 and 72, which are hydraulically connected to the memory pilot / distribution unit 12 by parallel hydraulic lines 7a and 7b. The memory pilot / distribution unit 12 is also hydraulically connected to the first storage chamber 9 and second storage chamber 10 of said storage cylinder 8, as well as to the first chamber 3 and second chamber 4 of the main hydraulic cylinder 1, respectively, by parallel hydraulic lines 14a, 13, 14b, and 15.

[0036] This first embodiment has the advantage of centralizing all fluid circulation from the storage cylinder 8 via the memory control / distribution unit 12. This is another possible embodiment of the solution shown in the figure 1 .

[0037] There figure 3 This illustrates the second embodiment of the hydraulic circuit according to the invention, in which the hydraulic circuit comprises a master main hydraulic cylinder 1, a slave secondary hydraulic cylinder 1' described previously, and a single storage cylinder 8. Furthermore, the main pilot unit 7 includes two pilot-operated check valves 71 and 72, which are hydraulically connected to the memory pilot / distribution unit 12 by parallel hydraulic lines 7a and 7b. The memory pilot / distribution unit 12 is also hydraulically connected to the first storage chamber 9 and second storage chamber 10 of said storage cylinder 8, as well as to the first chamber 3 of the master main hydraulic cylinder 1 and to the second secondary chamber 4' of the slave secondary hydraulic cylinder 1', respectively, by parallel hydraulic lines 14a, 13, 14b, and 15.

[0038] In this advantageous configuration, when a user actuates the main control unit 7, the main hydraulic cylinder 1 and the secondary hydraulic cylinder 1' (slave) move from the initial position P1 to the intermediate position P2, and the volume of oil to be stored V1 contained in the first chamber 3 is transferred to the first storage chamber 9 of said storage cylinder 8. In this advantageous configuration, when a user actuates the memory control / distribution unit 12, the main hydraulic cylinder 1 and the secondary hydraulic cylinder 1' (slave) move from the intermediate position P2 to the final position P3, and the volume of oil to be stored V1 contained in the first storage chamber 9 of the storage cylinder 8 is transferred to the first chamber 3 of said main hydraulic cylinder 1. The final position P3 then advantageously corresponds to the initial position P1.

[0039] This advantageous configuration allows for the simultaneous adjustment of settings on multiple machine components, such as tools, without the need for additional components like a flow divider. For example, in the case of a preferably folding agricultural machine with multiple sections, each containing a tool, it is possible to adjust the settings almost simultaneously on all of these tools.

[0040] There figure 4 illustrates the third embodiment of the hydraulic circuit according to the invention in which the hydraulic circuit comprises a main hydraulic cylinder 1, a secondary hydraulic cylinder 1' and a single storage cylinder 8. In addition, the main pilot unit 7 comprises two piloted check valves 71 and 72 which are hydraulically connected to the memory pilot / distribution unit 12 by parallel hydraulic lines 7a and 7b.The memory control / distribution unit 12 is also hydraulically connected to the first storage chamber 9 and second storage chamber 10 of said storage cylinder 8 by hydraulic lines 14a and 13, to the first chamber 3 of the main hydraulic cylinder 1 and to the first secondary chamber 3' of the secondary hydraulic cylinder 1' by a hydraulic line 14b dividing into two, and finally to the second chamber 4 of the main hydraulic cylinder 1 and to the second secondary chamber 4' of the secondary hydraulic cylinder 1' by a hydraulic line 15 dividing into two. The memory control / distribution unit 12 preferably includes a flow divider.

[0041] In this advantageous configuration, when a user operates the main pilot unit 7, the main hydraulic cylinder 1 and the secondary hydraulic cylinder 1' move from the initial position P1 to the intermediate position P2 and the volume of oil to be stored V1 contained in the first chamber 3 and the volume of oil to be stored V1' contained in the first secondary chamber 3' are transferred into the first storage chamber 9 of said storage cylinder 8.In this advantageous configuration, when a user actuates the memory control / distribution unit 12, the main hydraulic cylinder 1 and the secondary hydraulic cylinder 1' move from the intermediate position P2 to the final position P3, and the volume of oil to be stored V1+V1' contained in the first storage chamber 9 of the storage cylinder 8 is transferred half into the first chamber 3 of said main hydraulic cylinder 1 and half into the first secondary chamber 3' of the secondary hydraulic cylinder 1'. The final position P3 then advantageously corresponds to the initial position P1.

[0042] The advantage of the variant of the implementation illustrated in the figure 4 is that it allows for simultaneous resetting of multiple machine elements, such as tools. For example, in the case of a preferably folding agricultural machine with multiple sections, each containing a tool, it is possible to reset all tools simultaneously, quickly and without any time lag. All cylinders will be repositioned at the same time, guaranteeing a time saving compared to the variant of the figure 3 which imposes a slight time lag due to the master-slave system.

[0043] The memory 12 pilot / distribution unit can be selected from a hydraulic distributor, a solenoid valve, a double piloted check valve or a manually operated tap.

[0044] Optionally, the piston 11 of the storage cylinder 8 is connected to a measuring device for the position of the piston 11 within the storage cylinder 8 (not shown). This measuring device allows the position of the piston 11 within the storage cylinder 8 to be measured. This measuring device may be in the form of a sensor, for example, a position sensor, measuring the position of the piston 11 within the storage cylinder 8. The information measured by this device, such as a sensor, can be used in the control of the hydraulic system or for monitoring the proper functioning of the hydraulic circuit.

[0045] The actuation element of the hydraulic cylinders according to the invention can be a rod.

[0046] It should be noted that as the transfer is carried out at constant volume, it follows that a purge / reset of the storage cylinder 8 is not necessary because the management of the constant volume is done by means of a stop (not shown) of the storage cylinder 8.

[0047] According to a possible embodiment of the invention, which is not illustrated, it may be possible to store the volume of the second chamber 4 of the main hydraulic cylinder 1 instead of the volume of the third chamber 3. In this case, il It is simply a matter of reversing the hydraulic conduction means between the storage cylinder 8 and the main hydraulic cylinder 1.

[0048] The invention relates to an agricultural machine (not shown) comprising at least one machine element suitable and intended to be operated by at least one main hydraulic cylinder 1.

[0049] The agricultural machine includes the hydraulic circuit described previously.

[0050] This advantageous configuration allows for the retrieval of a position setting on at least one main hydraulic cylinder 1 of an agricultural machine. More specifically, it is possible to easily retrieve the setting of said at least one main hydraulic cylinder 1 after it has passed through another position. As a result, the present invention saves time since fewer adjustment maneuvers are required, and a precise setting is maintained each time.

[0051] Preferably, the agricultural machine is chosen from either a soil-working agricultural machine or a harvesting machine.

[0052] The agricultural machine may consist of a rotary harrow, preferably a folding rotary harrow.

[0053] The machine element can be a tool, for example, a tillage tool such as a roller, a leveling bar, or a toolbar including seeding elements. The machine element can also be a harvesting tool such as a cutter bar, a conditioner, a grouping unit, a rake rotor, or a pickup device.

[0054] Said at least one main hydraulic cylinder 1 may be a working depth adjustment cylinder of the machine element.

[0055] Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention as defined by the claims.

Claims

1. Agricultural machine comprising at least one machine element adapted and intended to be actuated by at least one main hydraulic cylinder (1) and a hydraulic circuit, said hydraulic circuit comprising at least: - a main hydraulic circuit comprising at least • said at least one main hydraulic cylinder (1) comprising at least one cylinder (2) comprising a first chamber (3) and a second chamber (4), which are separated from each other by a piston (5), and comprising an actuating member (6) which is mechanically connected to the piston (5) and is adapted and intended to be mechanically connected to said at least one machine element, said piston (5) being movable successively between an initial position (P1) to be memorised for which the first chamber (3) or the second chamber (4) is adapted and intended to contain a volume of oil to be memorised (V1), an intermediate position (P2) for which the first chamber (3) is adapted and intended to contain any volume of oil (V2) different from the volume of oil to be memorised (V1) and a final position (P3) for which the first chamber (3) is adapted and intended to contain a memorised volume of oil (V3) equal or substantially equal to said volume of oil to be memorised (V1), • a main control / distribution unit (7) hydraulically connected to at least one of the first and second chambers (3, 4) of said main hydraulic cylinder (1) by hydraulic conduction means and being arranged to actuate said main hydraulic cylinder (1) at least between the initial position (P1) to be memorised and the intermediate position (P2), - a memory hydraulic circuit hydraulically connected to said main hydraulic circuit comprising at least: • a hydraulic storage cylinder (8) comprising at least a first storage chamber (9) and a second storage chamber (10), which are separated from each other by a mobile piston (11), • a memory control / distribution unit (12) hydraulically connected to the second storage chamber (10) of said hydraulic storage cylinder (8) by hydraulic conduction means (13), said hydraulic storage cylinder (8) being a separate entity from the cylinder (2) of said main hydraulic cylinder (1), the agricultural machine is characterised in that: the first storage chamber (9) of said hydraulic storage cylinder (8) is hydraulically connected indirectly to said first chamber (3) of said main hydraulic cylinder (1) by hydraulic conduction means (14, 14a, 14b) comprising hydraulic pipes (14a, 14b) and by the memory control / distribution unit (12) so that said volume of oil to be memorised (V1) contained in the first chamber (3) or the second chamber (4) corresponding to the initial position (P1) of the piston (5) is transferred into the first storage chamber (9) of said hydraulic storage cylinder (8) in order to memorise the initial position (P1) during the displacement of said piston (5) from the initial position (P1) to the intermediate position (P2) of said piston (5).

2. Agricultural machine according to claim 1, characterized in that said first storage chamber (9) of said storage cylinder (8) is hydraulically connected indirectly to said first chamber (3) of said main hydraulic cylinder (1) at least by said hydraulic conduction means (14, 14a, 14b) comprising the hydraulic pipes (14a, 14b) and by the memory control / distribution unit (12), so that said volume of oil to be memorized (V1) contained in the first storage chamber (9) of said storage cylinder (8) is transferred into the first chamber (3) or the second chamber (4) of said main hydraulic cylinder (1) to actuate the piston (5) of the main hydraulic cylinder (1) from the intermediate position (P2) to the final position (P3) of the piston (5) of said main hydraulic cylinder (1) corresponding to said initial position (P1).

3. Agricultural machine according to any one of claims 1 to 2, characterized in that the main control unit (7) is arranged to actuate the piston (5) of the main hydraulic cylinder (1) from the initial position (P1) to be memorized to the intermediate position (P2) of said piston (5), so that said volume of oil to be memorized (V1) contained in the first chamber (3) or the second chamber (4) is transferred into the first storage chamber (9) of said storage cylinder (8) to memorize the initial position (P1) upon displacement of said piston (5) from the initial position (P1) to the intermediate position (P2) of said piston (5).

4. Agricultural machine according to any one of claims 2 to 3, characterized in that the memory control / distribution unit (12) is arranged to actuate the piston (11) of the storage cylinder (8), so that said volume of oil to be memorised (V1) contained in the first storage chamber (9) of said storage cylinder (8) is transferred to the first chamber (3) of said main hydraulic cylinder (1), to move the piston (5) of the main hydraulic cylinder (1) from the intermediate position (P2) to the final position (P3) of the piston (5) of said main hydraulic cylinder (1).

5. Agricultural machine according to any one of claims 1 to 4, characterized in that the main hydraulic circuit comprises a plurality of hydraulic cylinders and a flow divider for supplying the plurality of hydraulic cylinders.

6. Agricultural machine according to any one of claims 1 to 5, characterized in that said memory control / distribution unit (12) is selected from a hydraulic distributor, a solenoid valve, a double piloted non-return valve or a manually actuated valve.

7. Agricultural machine according to any one of claims 1 to 6, characterized in that the piston (11) of the storage cylinder (8) is connected to a device for measuring the position of the piston (11) within the storage cylinder (8).

8. Agricultural machine according to any one of claims 1 to 7, characterized in that the agricultural machine is selected from a soil working agricultural machine or a foldable machine.

9. Agricultural machine according to any one of claims 1 to 8, characterized in that the agricultural machine is a harrow, preferably a folding rotary harrow.