TRACTOR CAB SUSPENSION SYSTEM

Abstract

SUSPENSION SYSTEM FOR A TRACTOR CAB The invention relates to a system for suspending a cab of an agricultural tractor on a chassis of the tractor, connecting said cab and said chassis, said suspension system having vertical mechanical connections comprising at least one unsuspended articulated mechanical connection at the front of the cab; two suspended mechanical connections, each comprising a hydraulic cylinder, arranged at the rear of the cab; said system further comprising a hydraulic circuit comprising, for each cylinder, at least one pressure accumulator, and two pipes fluidically and respectively connecting the piston side of the cylinder of each suspended connection to the rod side of the cylinder of the other suspended connection so as to form a hydraulic intersecting of the cylinders. Figure for the abstract: figure 3

Description

Title of the invention: SUSPENSION SYSTEM FOR A TRACTOR CAB Technical field of the invention

[0001] The invention relates to a suspension system for a tractor cabin. More particularly, the invention relates to a suspension system for an agricultural tractor cabin comprising a non-suspended articulated mechanical connection, two suspended mechanical connections and a device for hydraulically managing the suspended connections. Technological background

[0002] The suspension of a tractor cab is a crucial device in the driver's feeling of comfort. In work machines and particularly in agricultural tractors, the attachment and fixing points of the cab in relation to the chassis as well as the elements allowing the suspension and damping are essential to offer the driver the best possible comfort.

[0003] In a more concrete kinematic approach at the user level, it is then appropriate to control the movements induced by the suspension system such as pitching, rolling and yaw movements. Each of these movements corresponds respectively to a rotation around a transverse, longitudinal and vertical axis.

[0004] Known cab suspension systems generally use springs, dampers and other motion control devices to absorb road shocks and vibrations and thus improve driver comfort. Most of these systems can in practice reduce the negative effects of driving and can contribute to a better quality of work for the user.

[0005] Existing cab suspension solutions are diverse. From a structural or mechanical connection point of view of the cab with the chassis, there are generally between three and four attachment points with suspended or unsuspended connections. Suspended and unsuspended connections are connections mechanically connecting the cab and the chassis and arranged between said cab and said chassis. As such, a suspended connection is defined as a connection intended to suspend the cab relative to the chassis; this connection may include springs, shock absorbers and other movement control devices to absorb shocks and vibrations. An unsuspended connection can be defined as a connection connecting the cab and the chassis not including such means.

[0006] In this regard, tractor cabins with four attachment points are known from the prior art, two of which include mechanically suspended connections, tire matically or oleopneumatically at the rear of the cabin. The unsprung connection points at the front include flexible connection elements such as anti-vibration mounts known under the English name "silent-bloc" or conical studs. In this configuration, the power take-off at the front of the vehicle is not permitted, there is no rolling movement but only a pitching movement.

[0007] Four-point suspension systems are also known, the four points of which are suspended mechanically, pneumatically or oleopneumatically. In this configuration, anti-roll management is made possible with anti-roll bars, which complicates the integration between the cabin and the chassis and can constitute a higher cost during design.

[0008] Some four-point configurations also offer oleopneumatic suspended links at the rear, the combination of which with an anti-roll bar or with mechanical means aimed at increasing the stiffness of each suspension element makes it possible to limit the production of rolling movement; however, these configurations do not include integrated anti-roll management.

[0009] In addition, there is also a pneumatically suspended three-point cabin suspension system. Anti-roll management is then carried out by adding stiffness at the suspension points, which has the effect of limiting the rolling movement to the detriment of the pitching movement of the cabin. As a result, user comfort during pitching is not optimized.

[0010] There is therefore a need to provide a suspension system for a cabin of an agricultural tractor which makes it possible to overcome the drawbacks of the prior art. Objectives of the invention

[0011] The invention aims to provide a suspension system for a cabin of an agricultural tractor making it possible to improve user comfort.

[0012] The invention also aims to provide, in at least one embodiment, a suspension system allowing controlled management of the rolling and pitching movement while preventing the yaw movement.

[0013] The invention also aims to provide, in at least one embodiment, a suspension system making it possible to facilitate the integration of an anti-roll system.

[0014] The invention also aims to provide, in at least one embodiment, a suspension system comprising hydraulic anti-roll management.

[0015] The invention also aims to provide, in at least one embodiment, a suspension system having a moderate cost. Statement of the invention

[0016] An aim of the present invention is to overcome the drawbacks of the prior art, to do this, the invention relates to a system for suspending a cabin of an agricultural tractor on a chassis of the tractor, said chassis extending in a longitudinal direction corresponding to the direction of movement of the tractor, said cabin extending above the chassis, said system comprising vertical mechanical connections connecting said cabin and said chassis, said suspension system according to which said vertical mechanical connections comprise at least:

[0017] - an unsuspended articulated mechanical connection whose articulation is a connection ball joint, said connection being arranged longitudinally at the front of the cabin;

[0018] - two suspended mechanical connections each comprising a hydraulic cylinder with double-acting, said cylinder having a piston side and a rod side, said suspended connections being arranged longitudinally at the rear of the cabin and spaced transversely opposite each other;

[0019] and in that it comprises a hydraulic circuit comprising, for each cylinder, at least one pressure accumulator fluidly connected to said cylinder, and two pipes fluidly connecting respectively the piston side of the cylinder of each suspended connection to the rod side of the cylinder of the other suspended connection so as to form a hydraulic intersection of the cylinders.

[0020] Throughout the following description the terms "longitudinal", "transverse" or "vertical" are understood with reference to a cab suspension system as arranged in a tractor. Furthermore, the X axis corresponds to the longitudinal axis of the vehicle, the Y axis corresponds to a transverse axis perpendicular to the X axis and lying in the horizontal plane. The Z axis is a vertical axis perpendicular to the plane formed by the X and Y axes, it being understood that each previously defined axis can be assimilated to an equivalent respective direction.

[0021] Furthermore, the terms "front" and "rear" refer to the longitudinal direction of the tractor chassis.

[0022] For the purposes of the invention, the term "suspended connections" refers to suspended mechanical connections comprising an oleo-pneumatic damping means, and located at the rear of the cabin, and the terms "unsuspended connection" or "articulated connection" refer to the unsuspended articulated mechanical connection. The suspension system according to the invention therefore does not include a spring damping means.

[0023] The optimal suspension of a cabin must allow rolling and pitching movements to be suspended in a measured and controlled manner.

[0024] Thus and according to the invention, the inventors have developed a system for suspending a cabin relative to a chassis in which the suspension of the cabin during the pitching movement is ensured by the rotation of said cabin around the unsprung articulated connection along the transverse axis Y and by the compression of the cylinders of the suspended links located respectively at the left rear and right rear of the tractor cab.

[0025] Furthermore, the suspension of the cabin during the rolling movement is ensured by a movement take-off around the unsprung articulated connection along the longitudinal axis X as well as by the compression of the cylinder of the right rear suspended connection and the relaxation of the cylinder of the left rear suspended connection, or vice versa.

[0026] It is understood within the meaning of the invention that the movement of the cabin is only possible from the unsprung connection located at the front of the cabin.

[0027] According to the invention, the compression of the hydraulic cylinders is made possible by means of pressure accumulators fluidically connected to each of the cylinders of the suspended connections. The pressure accumulators are oleo-pneumatic membrane pressure accumulators which ensure a seal between the gas and the oil. Preferably, the accumulators of the invention benefit from a lower installed gas pressure than the installed oil pressure of the hydraulic circuit in order to be able to return the oil pressure resulting from the compression of a cylinder when the cabin is moving, for example.

[0028] Furthermore, the suspension system according to the invention comprises two pipes fluidly connecting respectively the piston side of the cylinder of each suspended connection to the rod side of the cylinder of the other suspended connection so as to form a hydraulic intersecting of the cylinders.

[0029] In this way, roll control is provided by a hydraulic circuit returning the oil compression pressure of one cylinder to the expansion pressure of the other cylinder in order to limit the expansion movement of the cylinder and therefore the rolling movement of the cabin.

[0030] Thus, advantageously and according to the invention, the intersecting of the pipes and the pressure accumulators of the suspension system according to the invention makes it possible to generate anti-roll without influencing the pitching movement. According to another advantage of the invention, the hydraulic circuit allows the genesis of the anti-roll by returning pressure directly into the cylinders via hydraulic pipes, which makes it possible to avoid the installation of a mechanical anti-roll device arranged between the cabin and the chassis. In other words, the invention allows easy integration of a hydraulic anti-roll device. The term "anti-roll" device means a device intended to limit the rolling movement.

[0031] By crossing the pipes, we mean a schematic of installation of the pipes in the form of a cross, thus, the hydraulic cylinders of the suspended connections of the suspension system according to the invention are connected to each other by the crossing of said pipes. Advantageously, the cross arrangement of the pipes connecting the cylinders developed by the inventors also makes it possible to prevent potential leakage flows. at the cylinders by acting as an inter-cylinder compensation system. This hydraulic interweaving also helps to maintain the fluid balance in the closed circuit which ensures that the initial position of the cabin is maintained without the addition of a control module, in other words the circuit of this embodiment is self-compensated.

[0032] Advantageously and according to the invention, the non-suspended articulated mechanical connection comprises an articulation, said articulation being a ball joint.

[0033] Thus, the unsprung link located at the front of the vehicle allows the movement of the cabin suspension system. For this purpose, the ball joint allows three degrees of freedom for the rotation of the cabin around the X, Y and Z axes.

[0034] Advantageously and according to the invention, the pressure accumulator is fluidically connected to the piston side of said cylinder.

[0035] Thus and according to this advantageous variant, the system evolves under the action of a constant pressure, which allows the suspension system according to the invention to work in balance.

[0036] Advantageously and according to the invention, each cylinder further comprises a second pressure accumulator fluidly connected to the rod side of said cylinder.

[0037] Advantageously and according to the invention, the suspension system further comprises a stabilizer bar arranged in the transverse direction between the two suspended connections, said stabilizer bar mechanically connecting the cabin and the chassis. Preferably, the stabilizer bar is a Panhard bar. The stabilizer bar transversely connects the chassis to the cabin and is placed longitudinally at the rear of the cabin, thus making it possible to guide the rear of said cabin transversely. The connection between the stabilizer bar and the cabin is of the pivot type, possibly of the elastic type. The connection between the stabilizer bar and the chassis is of the ball joint type, possibly elastic.

[0038] Thus and according to this advantageous variant, the suspension system prevents the yaw movement corresponding to the rotation of the cabin along the vertical axis Z during the pitching or rolling phases.

[0039] Advantageously and according to the invention, the suspension system further comprises at least one position sensor configured to detect the vertical position of the cabin relative to the chassis. In one embodiment, said sensor is electrically connected to said suspension system.

[0040] When mounting the cabin on the chassis, the cabin is suspended by the suspension system according to the invention. Thus, the cabin is in a predetermined vertical suspension state. This suspension state corresponds to a position called the nominal position of the cabin. The latter is caused to change when a user takes a seat in the cabin or more generally when the cabin is subjected to stress.

[0041] Generally speaking, and within the meaning of the invention, a change in the nominal position of the cabin can be interpreted as a change occurring during the vertical movement of the piston of a cylinder, beyond a position corresponding to the nominal position of the cabin, during compression or expansion along the vertical axis Z. The nominal position of the cabin corresponds to the average of the position of said cabin over a given period of time. The position sensor can be located on the suspended or unsuspended links or on the stabilizer bar of the suspension system according to the invention.

[0042] The position sensor may be a sensor known to those skilled in the art such as a wired or cabled sensor. The latter may be configured to send a signal upon detection of a change in position of the cabin. The signal from the sensor may be an electrical signal continuously or periodically returning the vertical position along the Z axis of the cabin relative to the chassis.

[0043] Thus and according to this advantageous variant, the position sensor makes it possible to detect a change in the nominal position of the cabin relative to the vertical axis Z and to send a signal associated with this change in position.

[0044] Advantageously and according to the invention, the suspension system further comprises a hydraulic circuit control module, said module being electrically connected to said position sensor and comprising at least one solenoid valve fluidically connected to the pressure accumulators connected to the piston side of each cylinder, said control module being configured to adjust the position of the cabin as a function of the data received by said position sensor.

[0045] Preferably, the control module may comprise two solenoid valves arranged in series.

[0046] According to one embodiment of the invention, the control module can be arranged on the cab or on the chassis of the tractor and is electrically connected to the position sensor.

[0047] The control module is configured to acquire angular position data from the position sensor. Furthermore, it is an electronic control module configured to process the received data and convert it into vertical position data of the cabin. The vertical position data can then be compared with the nominal position of the cabin so that the control module can decide whether position regulation is necessary.

[0048] This decision can be made by setting a threshold value associated with the value of the nominal position of the cabin. When this threshold value is crossed, then the module controls the regulation of the position of the cabin by adding or removing oil in the system via the control of one or more solenoid valves.

[0049] The solenoid valve of the control module according to the invention is fluidically connected to the pressure accumulators via a hydraulic line and thus allows oil to be added or removed from the hydraulic circuit.

[0050] Thus and according to this advantageous variant, the control module makes it possible to rectify the oil pressure of the cylinders as a function of the stroke of the cylinders along the Z axis.

[0051] Advantageously and according to the invention, the hydraulic circuit comprises a pipe fluidly connecting the pressure accumulators connected to the piston side of each cylinder.

[0052] Advantageously and according to the invention, the hydraulic circuit comprises at least one flow regulator mounted on the pipe fluidly connecting the pressure accumulators connected to the piston side of each cylinder.

[0053] Thus and according to this advantageous variant, the suspension system makes it possible to prevent sudden movements of the cylinders when adjusting the pressure, thus improving user comfort.

[0054] The invention also relates to an agricultural tractor comprising a cabin mounted on a chassis, said tractor comprising a suspension system characterized in combination by all or part of the features mentioned above or below. List of figures

[0055] Other aims, characteristics and advantages of the invention will appear on reading the following description given solely for non-limiting purposes and which refers to the appended figures in which: • [Fig.l] is a schematic isometric perspective view of the suspension system of a tractor cabin according to a first embodiment of the invention. • [Fig.2] is a schematic view showing the arrangement of the system of suspension at the rear of the vehicle according to the embodiment shown [Fig.l]. • [Fig.3] is a schematic view showing the hy circuit in more detail hydraulics of the suspension system according to another embodiment of the invention.

[0056] Detailed description of an embodiment of the invention

[0057] In the figures, the scales and proportions are not strictly respected, for the purposes of illustration and clarity.

[0058] Identical, similar or analogous elements are designated by the same references in all the figures.

[0059] Throughout the detailed description which follows with reference to the figures, unless otherwise indicated, each element of the suspension system is described as it is arranged within a tractor.

[0060] Figures 1 and 2 illustrate a first embodiment of the invention, and the [Fig.3] another embodiment of the invention.

[0061] The suspension system 1 of a tractor cabin 2 mounted on a chassis 3 is arranged between the cabin 2 and the chassis 3. More particularly, the suspension system 1 mechanically connects the cabin 2 and the chassis 3 of the tractor in a vertical direction comparable to the vertical axis Z. The chassis 3 extends in a longitudinal direction comparable to the longitudinal axis X corresponding to the direction of movement of the tractor. The cabin 2 extends above the chassis in the same direction.

[0062] The system 1 for suspending the cabin 2 relative to the chassis 3, comprises vertical links mechanically connecting the lower part 2a of the cabin 2 with the upper part 3a of the chassis 3.

[0063] More particularly, the suspension system 1 comprises an unsprung articulated connection 10 arranged at the front of the cabin 2 as well as two suspended connections 20 arranged at the rear of the cabin, said connections 10 and 20 being longitudinally opposite along the axis X of the chassis 3. The two suspended connections 20 are arranged opposite each other and spaced apart along the transverse axis Y. The suspension system 1 of the embodiment described thus has three points for attaching the cabin to the chassis, two of which are suspended.

[0064] The unsuspended articulated connection 10 comprises a joint 11 allowing the cabin 2 to rotate along the X and / or Y axes. As such, the connection 10 comprises a ball-and-socket type joint 11.

[0065] The suspended connections 20 are double-ball jointed connections each comprising a double-acting hydraulic cylinder 21. The hydraulic cylinder 21 comprises a rod 22 connected to a piston 23 and is further fluidically connected to at least one pressure accumulator 40. Each hydraulic cylinder 21 of the suspended connections 20 has a rod side 21a and a piston side 21b.

[0066] The suspension system 1 according to one embodiment thus comprises a hydraulic circuit 60 in which two pipes 21c fluidly connect the rod side 21a of a first cylinder 21 to the piston side 21b of a second cylinder 21, respectively. A part of the hydraulic circuit 60 thus forms an inter-cylinder connection between the cylinders 21 of the two suspended links 20. The hydraulic intersection 24 is thus formed by the two pipes 21c and makes it possible to form a suspension system incorporating integrated hydraulic management of the anti-roll via the hydraulics of the circuit 60.

[0067] The cabin suspension system 1 further comprises a control module 50 for the hydraulic circuit 60. In the embodiment described, the control module 50 comprises two solenoid valves 51, 52 mounted in series and fluidically connected to a pipe 4L. When a stress is exerted on the cabin 2, the suspension system 1 will adjust the position of the cabin so that it returns to its initial position. For this, the control module 50 will control the fluid exchanges, and in particular the oil exchanges of the hydraulic circuit 60.

[0068] Advantageously, when a movement is taken at the level of the articulation 11 of the non-suspended connection 10 causes a rotation of the cabin 2 along the longitudinal axis X for example, a cylinder 21 of a first suspended connection 20 will enter into compression while the cylinder 21 of a second suspended connection 20 will reciprocally enter into relaxation. As a result, the hydraulic pressure accumulator 40 being an oleopneumatic device fluidly connected to the cylinder in the compressed state will receive an oil pressure greater than the installed pressure of the gas which it comprises. Said gas being a compressible gas, such as nitrogen, it will thus make it possible to absorb the pressure increases of the fluidic system and to expel the excess oil towards the pipes 21c, in order to compensate for the relaxation of the other cylinder and reestablish a hydraulic balance between each of the cylinders 21 of each of the suspended connections 20.This balance also results in the return to a comfortable position of cabin 2 for the user.

[0069] The suspension of the movement is made possible via the pressure accumulator 40. During an increase in pressure associated with a bump for example, the gas will compress until the pressures in the accumulator 40 between the gas and the oil are balanced. The compression of the gas will cause the accumulator to fill with oil, and therefore generate a movement of the cylinder.

[0070] The reduction in roll results in an exchange of oil between the cylinders 21 by means of the hydraulic interlock 24. Under the effect of the compression, there will be an absorption of flow by an accumulator on the one hand and a depression on the opposite cylinder on the other hand, the balance of the oil pressures will reduce the gas pressure which will allow the cylinder to relax and the release of oil towards the opposite cylinder.

[0071] In one embodiment, the suspension system 1 further comprises a stabilizer bar 30 arranged obliquely in the transverse direction between the two unsprung links 20. The stabilizer bar 30 is connected both to the chassis 3 and to the cabin 2 and makes it possible to suppress the yaw movement corresponding to a rotation of the cabin along the vertical axis Z. The suspension system 1 may comprise a means for detecting the angular position of the cabin 2 relative to the chassis 3 and determining the position, called the nominal position of the cabin 2, which corresponds to the average of the angular position of the cabin 2 in a given time without taking into account shocks. The control module 50 makes it possible to process and convert the angular position data from the sensor into data indicating the vertical position of the cabin 2 relative to the chassis 3. This acquired position data corresponds to the stroke of the cylinders.The control module 50 is also configured to average the acquired position data over . a period of time and thus be able to determine a nominal position of the cabin. The module makes it possible to compare the value of the position data with the value of a determined nominal position. A threshold value can be previously recorded so that the control module can compare this average position value of the cabin 2 with the value of the nominal position of the cabin 2 previously recorded or determined. According to the invention, the control module 50 can be configured to be able to readjust the position of the cabin relative to the stroke of the cylinders 21 via the solenoid valves 51, 52 depending on a threshold value higher or lower than the value of the nominal position of the cabin 2.By way of illustration, when a stress exerted on the cabin causes a compression greater than half the stroke of a jack 21, the adjustment and return to equilibrium or to the nominal position of the cabin 2 can be carried out by controlling the solenoid valves 51, 52.

[0072] The oil level of the hydraulic circuit 60 can thus be readjusted by a set of two solenoid valves in series, the first of which allows oil to be added to the system and a second of which allows excess oil to be removed.

[0073] The solenoid valves can be fluidly connected to a pipe 4L. The pipe 41 is fluidly connected to an accumulator 40 and said accumulator 40 is fluidly connected to a jack 21 of each of the suspended connections 20.

[0074] In addition, the system 1 may also include flow regulators 53 mounted on the pipe 41 to prevent excessively rapid vertical movement of the cylinders during the circulation of oil in the circuit 60.

[0075] According to the embodiment described, the suspension system 1 not only makes it possible to overcome the theoretical leakage flows likely to occur in the circuit 60 at the level of the cylinders 21 but also to generate anti-roll in an integrated manner and without influencing the pitching phase, which makes it possible to obtain optimal cabin suspension.

[0076] [Fig.l] illustrates in isometric perspective the arrangement of a suspension system 1 according to an embodiment of the invention where said system 1 comprises a stabilizer bar 30 arranged between the two suspended links 20.

[0077] In this embodiment, the articulated unsprung connection 10 comprises a joint 11 which is a ball joint. This ball joint allows movement to be taken by rotation of the cabin 2 around the ball joint along the X and Y axes. In this configuration, the stabilizer bar 30 prevents the yaw movement corresponding to the rotation of the cabin along the Z axis.

[0078] [Fig.2] schematically illustrates a view of the rear of the cabin 2 explaining in more detail the configuration of the suspension system 1 at the rear of the cabin according to the embodiment of [Fig.l].

[0079] In the embodiment shown in Figures 1 and 2, the suspended links 20 and the stabilizer bar 30 form vertical links mechanically connecting a lower part 2a of the cabin 2 with an upper part 3a of the chassis 3 of the tractor. In addition, the suspended links 20 and the stabilizer bar 30 comprise ball joints on either side.

[0080] [Fig. 3] schematically illustrates another embodiment of the invention. This figure illustrates more particularly the hydraulic management of the cylinders 21 of the suspension system 1, according to which the control of the circuit 60 is done via the control module 50 comprising the two solenoid valves 51 and 52. The role of the solenoid valve 51 is to remove oil from the circuit 60 when it is in the actuated state. In the closed state, the solenoid valve 51 comprises a non-return valve allowing the passage of oil from the solenoid valve 52 only in a unidirectional manner towards the hydraulic circuit 60. The solenoid valve 52 is fluidically connected to the solenoid valve 51 and has the role of distributing oil to the circuit 60 when it is in the actuated state. In the closed state, solenoid valve 52 returns the oil to an oil reservoir.

Claims

Claims

1. System (1) for suspending a cabin (2) of an agricultural tractor on a chassis (3) of the tractor, said chassis (3) extending in a longitudinal direction corresponding to the direction of movement of the tractor, said cabin (2) extending above the chassis (3), said system (1) comprising vertical mechanical connections connecting said cabin (2) and said chassis (3), said suspension system (1) being characterized in that said vertical mechanical connections comprise at least: • an unsuspended articulated mechanical connection (10), the articulation (11) of which is a ball joint, said connection (10) being arranged longitudinally at the front of the cabin (2);• two suspended mechanical connections (20) each comprising a double-acting hydraulic cylinder (21), said cylinder (21) having a piston side (21b) and a rod side (21a), said suspended connections (20) being arranged longitudinally at the rear of the cabin (2) and spaced transversely opposite one another; and in that it comprises a hydraulic circuit (60) comprising, for each cylinder (21), at least one pressure accumulator (40) fluidly connected to said cylinder (21), and two pipes (21c) fluidly connecting and respectively the piston side (21b) of the cylinder (21) of each suspended connection (20) to the rod side (21a) of the cylinder (21) of the other suspended connection (20) so as to form a hydraulic intersection (24) of the cylinders.;

2. System according to claim 1, characterized in that the pressure accumulator (40) is fluidically connected to the piston side (21b) of said cylinder (21).

3. System according to claim 2, characterized in that each cylinder (21) further comprises a second pressure accumulator fluidly connected to the rod side (21a) of said cylinder (21).

4. System according to one of claims 1 to 3, characterized in that it further comprises a stabilizer bar (30) arranged in the transverse direction between the two suspended links (20), said stabilizer bar (30) mechanically connecting the cabin (2) and the chassis (3).

5. System according to claim 4, characterized in that it further comprises a position sensor configured to detect the vertical position of the cabin (2) relative to the chassis (3).

6. System according to one of the preceding claims, characterized in that it further comprises a control module (50) of the hydraulic circuit (60), said module (50) being electrically connected to said position sensor and comprising at least one solenoid valve fluidly connected to the pressure accumulators connected to the piston side of each cylinder, said control module being further configured to adjust the position of the cabin according to the data received by said position sensor.

7. System according to one of claims 2 to 6, characterized in that the hydraulic circuit (60) comprises a pipe (41), said pipe (41) fluidly connecting the pressure accumulators (40) connected to the piston side (21b) of each cylinder (21).

8. System according to claim 7, characterized in that the hydraulic circuit (60) comprises at least one flow regulator (53) mounted on the pipe (41).

9. Agricultural tractor comprising a cabin (2) mounted on a chassis (3) characterized in that it comprises a suspension system (1) according to one of claims 1 to 8 arranged between said cabin (2) and said chassis (3).

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