TRANSVERSE STABILIZATION UNIT OF A RAILWAY TRACK

Abstract

A transverse stabilization unit for a railway track (10) comprises a chassis (12) resting on at least two pairs of rollers (14, 16) defining a rolling plane (PR) and a median longitudinal plane (PL) of the chassis (12) perpendicular to the rolling plane (PR), each pair of rollers (14, 16) comprising a right roller (142, 162) and a left roller (141, 161) located respectively on a right side and a left side of the median longitudinal plane (PL) and intended to roll respectively on a right rail (22) and a left rail (21) of the railway track, the chassis (12) carrying a vibration exciter (18) with four unbalanced masses (1, 2, 3, 4), each of the four unbalanced masses being rotatable about an axis of rotation (A1, A2, A3, A4), the axes of rotation (A1, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) being parallel to the same reference direction (A) of the chassis (12),the stabilization unit (10) being characterized in that the reference direction (A) is perpendicular to the rolling plane (PR) (Abstract figure: Figure 2),

Description

Title of the invention: TRANSVERSE STABILIZATION UNIT FOR A RAILWAY TRACK TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a unit for transverse stabilization of unbalanced railway tracks, the unit being intended to be integrated into a railway stabilization machine or, more generally, into a railway works machine. STATE OF THE PRIOR ART

[0002] Railway track stabilizing machines are used after tamping of railway tracks to increase the lateral strength of the tracks and allow rapid use of the tracks without excessive speed limitations.

[0003] In document US2021071369, a railway track stabilization machine is presented, comprising a track stabilization unit. The track stabilization unit comprises a chassis resting on pairs of wheel rollers which form a running plane and a median longitudinal plane perpendicular to the running plane. The stabilization unit is vertically adjustable and comprises a vibration exciter comprising at least one pair of unbalanced masses, each unbalanced mass rotating about an axis of rotation parallel to the running plane and extending in a longitudinal direction of the tracks. The stabilization unit is associated with a drive device for controlling the rotational speed of the unbalanced masses and their relative phase. The unbalanced masses of a pair rotate in opposite directions, which creates a resultant vibration force whose direction is parallel to the running plane.In practice, the machine is equipped with at least two pairs of unbalanced masses, a first pair being at a first distance from the running surface, and a second pair at a second distance from the running surface greater than the first. However, due to the positioning of the two pairs of unbalanced masses, the resulting force of the vibrations is centered between the two pairs, that is to say at a certain distance above the running surface, which is not favorable for the perfect control of the forces transmitted to the track and requires special provisions to ensure the stability of the stabilization unit. Furthermore, in the event of desynchronization of the unbalanced masses, for example during an emergency stop, it is possible that a vertical component of force appears and damages the tracks or the stabilization unit. Statement of the invention

[0004] The invention aims to propose a railway track stabilization unit which at least partially overcomes the drawbacks of the state of the art.

[0005] To this end, according to a first aspect of the invention, a transverse stabilization unit for a railway track is proposed, comprising a chassis resting on at least two pairs of rollers defining a rolling plane and a median longitudinal plane of the chassis perpendicular to the rolling plane, each pair of rollers comprising a right roller and a left roller located respectively on a right side and a left side of the median longitudinal plane and intended to roll respectively on a right rail and a left rail of the railway track, the chassis carrying a vibration exciter with four unbalanced masses, each of the four unbalanced masses being rotatable about an axis of rotation, the axes of rotation of the four unbalanced masses being parallel to the same reference direction of the chassis. The reference direction of the stabilization unit is perpendicular to the rolling plane.

[0006] In rotation, the unbalanced masses generate a resultant force parallel to the rolling plane. In the event of an emergency stop, the vertical rotation axes have the advantage of keeping the resultant force horizontal and allow the stabilization of the tracks to be preserved.

[0007] The stabilizing unit is preferably vertically adjustable by adjustment tools, for example by a left support cylinder and a right support cylinder located respectively on the left and right side of the median longitudinal plane. Two unbalanced masses are on the left side of the median longitudinal plane and two unbalanced masses on the right side of the median longitudinal plane.

[0008] In practice, several stabilization units can be integrated longitudinally into a track stabilization machine which moves continuously on the track rails.

[0009] According to one embodiment, each of the four unbalanced masses has a center of gravity, the centers of gravity of the four unbalanced masses being located at an equal distance from the rolling plane. The centers of gravity of the unbalanced masses being aligned, the force vectors of the four unbalanced masses are collinear and add up to obtain a resultant force whose direction is parallel to the rolling plane. The alignment of the unbalanced masses also makes it possible to avoid the appearance of a torque which could cause uneven stabilization of the tracks.

[0010] The closer the resultant of the forces is to the running surface, the more accelerated and precise the stabilization of the tracks is. Consequently, the centers of gravity of the four unbalanced masses are located at a distance from the running surface of less than 30 cm.

[0011] In practice, the four unbalanced masses have the same mass and the centers of gravity of the four unbalanced masses are located at equal distance from their axis of rotation.

[0012] Remarkably, the four unbalanced masses are located at a constant distance from their axis of rotation. In other words, the stabilization unit is not equipped with means for varying this distance. The unbalanced masses can, for example, form each a non-deformable part or structure having a reference axis coincident with the corresponding axis of rotation.

[0013] According to one embodiment, each of the two pairs of rollers is associated with a transverse plane perpendicular to the rolling plane, the transverse plane containing an axis of rotation of the right roller and an axis of rotation of the left roller of the associated pair of rollers, the transverse plane being perpendicular to the median longitudinal plane of the chassis of the stabilization unit. For a compact stabilization unit, the axes of rotation of the four unbalanced masses are located between the transverse planes associated with the two pairs of rollers. Preferably, the axes of rotation of the four unbalanced masses include two first axes of rotation located at an equal distance from the transverse plane associated with a first of the two pairs of rollers and two second axes of rotation located at an equal distance from the transverse plane associated with a second of the two pairs of rollers.This arrangement also makes it possible, in the event of desynchronization of the unbalances and generation of an unwanted torque around a median vertical axis of the stabilization unit, to limit the amplitude of this torque.

[0014] According to various embodiments: • the axes of rotation of the four unbalances include two right axes of rotation located on the right side of the median longitudinal plane, equidistant from the median longitudinal plane, and two left axes of rotation located on the left side of the median longitudinal plane, equidistant from the median longitudinal plane; or • the axes of rotation of the four unbalanced masses are located in the same transverse vertical plane perpendicular to the median longitudinal plane; or • the axes of rotation of the four unbalanced masses are located in the same longitudinal vertical plane parallel to the median longitudinal plane; • the axes of rotation of the four unbalances are located in the median longitudinal plane.

[0015] To obtain identical stabilization of the two rails of the railway track over their entire length, the distance between the two right axes of rotation and the median longitudinal plane is equal to the distance between the two left axes of rotation and the median longitudinal plane. According to another embodiment, the distance between the two axes of rotation and the median longitudinal plane is variable on command to allow the stabilization unit to adapt to the gauge of the rails of the railway track.

[0016] According to a preferred embodiment, the axes of rotation of the four unbalanced masses are closer to the median longitudinal plane than the four rollers. In this configuration, the resulting force acts mainly on the inside of the rails of the railway tracks, and the stabilization unit thus obtained is compact.

[0017] According to one embodiment, the stabilization unit comprises four bearings, each associated with one of the four rollers for guiding the associated roller in rotation, each of the four rollers being located between the associated bearing and the median longitudinal plane. Alternatively, the stabilization unit comprises four bearings, each associated with one of the four rollers for guiding the associated roller in rotation, each of the four bearings is located between the associated roller and the median longitudinal plane.

[0018] According to one embodiment, the stabilization unit comprises a device for driving the four unbalanced masses to drive the four unbalanced masses in a synchronized manner at the same rotation frequency, two of the four unbalanced masses in one direction of rotation and two others of the four unbalanced masses in an opposite direction of rotation, so as to generate a resultant force directed perpendicular to the median longitudinal plane. The drive device drives the four unbalanced masses directly, and the eccentricities of the four unbalanced masses are fixed. The drive device is preferably carried by the chassis, and may comprise, according to various alternative embodiments: - four independent motors, each to drive one of the four unbalanced masses; or - two motors to guide the rotation of the four unbalanced masses, each motor to drive two unbalanced masses in opposite directions. This configuration increases the compactness of the track stabilization unit; or - a single motor to drive the four unbalanced weights.

[0019] The connections between the motor(s) and the four unbalanced masses may implement fixed ratio gear trains, for example a combination of epicyclic type gears, or any means of mechanically varying the relative phase of the unbalanced masses.

[0020] According to another embodiment, the drive device preferably comprises angular sensors of the incremental encoder type, preferably absolute, making it possible to measure the relative position of the unbalanced masses; and an electronic control implementing a phase-locked loop type servocontrol to ensure the synchronization of the unbalanced masses.

[0021] According to one embodiment, the drive device is capable of varying the relative rotation phase of the four unbalanced masses, in a coordinated manner and in such a way as to vary the amplitude of the resulting force between 0 and a maximum value. Controlling the relative phase of the unbalanced masses makes it possible to vary the amplitude of the vibrations between a zero value and a maximum value.

[0022] According to one embodiment, the rotation frequency is between 35 Hz and 45 Hz. This frequency range is particularly suitable for exciting the ballast with a view to stabilizing it. Preferably, the rotation frequency is adjustable in a frequency range including the interval between 35 Hz and 45 Hz. Ballast excitation is allowed within a frequency range. BRIEF DESCRIPTION OF THE FIGURES

[0023] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures among which: • [Fig.l] [Fig.l] schematically illustrates a front view of a four-unbalance track stabilization unit according to one embodiment of the invention; • [Fig.2] [Fig.2] schematically illustrates a top view of the unit stabilization of the tracks of [Fig.l]; • [Fig.3] [Fig.3] illustrates an overview of the stabilization unit of the ways of [Fig.l]; • [Fig.4a] [Fig.4a] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a first instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.4b] [Fig.4b] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a second instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.4c] [Fig.4c] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a third instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.4d] [Fig.4d] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a fourth instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.5a] [Fig.5a] schematically illustrates in top view another mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a first instant of a rotation of the four unbalanced masses, resulting in a transverse force of maximum amplitude; • [Fig.5b] [Fig.5b] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a second instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.5c] [Fig.5c] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a third instant of a rotation of the four unbalanced masses, resulting in a transverse force of maximum amplitude; • [Fig.5d] [Fig.5d] schematically illustrates in top view a mode of synchronization of the four unbalanced masses of the stabilization unit of [Fig.l], at a fourth instant of a rotation of the four unbalanced masses, resulting in a transverse force of zero amplitude; • [Fig.6] [Fig.6] illustrates the variation of the resultant force over time according to a second embodiment.

[0024] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of embodiments

[0025] In Figures 1 to 3 is shown a track stabilization unit 10 mounted on a chassis 12, the stabilization unit 10 being inserted into a track stabilization machine.

[0026] The chassis 12 of the stabilization unit 10 moves on a right rail 22 and on a left rail 21 of a railway track using at least a first pair of rollers 14 rotating about a first axis of rotation 140 and a second pair of rollers 16 rotating about a second axis of rotation 160. The axes of rotation 140, 160 are located in a rolling plane PR parallel to the track. Each pair of rollers (14, 16) contains a left roller (141, 161) and a right roller (142, 162) located respectively to the left and to the right of a median longitudinal plane PL perpendicular to the rolling plane PR.A first transverse plane PT1, perpendicular to the rolling plane PR and comprising the axis of rotation 140 of the first pair of rollers 14 is associated with the first pair of rollers 14; a second transverse plane PT2, perpendicular to the rolling plane PR and comprising the axis of rotation 160 of the second pair of rollers 16, is associated with the second pair of rollers 16.

[0027] Between each roller of the chassis 12 and the median longitudinal plane PL there are bearings 11 for guiding the rollers in rotation on the tracks. According to another embodiment not shown, the guide bearings are located laterally outside the rails, so that each roller (141,142,161162) is located between the median longitudinal plane PL and the bearing 11.

[0028] A spacing cylinder 30 connects the left (141, 161) and right (161, 162) rollers of the pairs of rollers (14, 16), and makes it possible to adjust the distance between the rollers (141, 142, 161, 162) to the spacing of the rails of the track which are being treated. A left support cylinder 32 and a right support cylinder 34, mounted respectively to the left and right of the median longitudinal plane PL, make it possible to vertically adjust the stabilization unit 10 to secure / bring it closer to or separate / move it away from the railway track. According to another embodiment, the stabilization unit 10 comprises a single support jack placed in its center.

[0029] On the chassis 12 is also mounted, on each side of the median longitudinal plane PL, an external roller 36. When the stabilization unit 10 is in operation, a control member clamps the external rollers 36 against the rails (21, 22), from outside the railway track, so as to transmit to the rails (21, 22) the vibrations generated by the stabilization unit 10. According to one embodiment, the control member is a lever 38.

[0030] The stabilization unit 10 comprises an unbalanced vibration exciter 18 of identical mass, composed of a first unbalanced mass 1 rotating about a first axis of rotation A1, a second unbalanced mass 2 rotating about a second axis of rotation A2, a third unbalanced mass 3 rotating about a third axis of rotation A3 and a fourth unbalanced mass 4 rotating about a fourth axis of rotation A4, the four axes of rotation (A1, A2, A3, A4) being parallel to a vertical reference direction A. The centers of gravity of the four unbalanced masses (1, 2, 3, 4) are preferably located at an equal distance from the rolling plane PR, the distance being less than 30 cm, and at an equal distance from their respective axis of rotation (A1, A2, A3, A4). It should be noted that the centers of gravity of the four unbalances (1, 2, 3, 4) are here at a constant distance from their respective axis of rotation (A1, A2, A3, A4).

[0031] The four axes of rotation (A1, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) are preferably located at an equal distance from the median longitudinal plane PL, the first axis A1 and the third axis A3 being located on a left side and the second axis A2 and the fourth axis A4 being located on a right side of the median longitudinal plane PL. In addition, the axes of rotation (A1, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) are closer to the median longitudinal plane PL than the four rollers (141,142,161,162) of the stabilization unit 10, which makes it possible to obtain a compact stabilization unit 10 and to simultaneously carry out stabilization operations on adjacent tracks. Finally, the axes of rotation (A1, A2, A3, A4) of the unbalanced masses (1, 2, 3, 4) are located between the first transverse plane PT1 and the second transverse plane PT2 associated with the two pairs of rollers (14, 16).

[0032] The four unbalanced masses (1, 2, 3, 4) of the stabilization unit 10 are driven in rotation by a drive device 20 formed of four motors, one motor per unbalanced mass. An electronic control integrated in the drive device ensures the synchronization of the motors. This electronic control implements a phase-locked loop type servocontrol to ensure the synchronization of the unbalanced masses. If necessary, the drive can be direct, that is to say without a reduction gear between the output shaft of the motor and the shaft of the driven unbalanced mass.

[0033] According to another embodiment not shown, the drive device 20 is formed of two motors, the first motor driving two unbalanced masses (1, 3) in opposite directions to each other and the second motor driving two other unbalanced masses (2, 4) in opposite directions to each other. In this configuration, the synchronization of the unbalanced masses (1, 3) and the unbalanced masses (2, 4) is obtained by a gear connection of the two axes (A1, A3) and the two axes (A2, A4).

[0034] When the stabilization unit 10 is in operation, the unbalanced masses 1 and 3 and the unbalanced masses 2 and 4 rotate in opposite directions, so that at any time, a resultant force Fres parallel to the rolling plane PR and in a transverse direction of the tracks is obtained. The resultant force Fres exerts vibrations which are transmitted to the rails (21, 22) and to the sleepers of the tracks through the rollers (141, 142, 161, 162) of the chassis 12 and the external rollers 36, which vibrate the track ballast and thus allow it to be compacted and consolidated.

[0035] Thus, the unbalanced masses 1, 2, 3 and 4 generate, at each instant, respective forces Fl, F2, F3 and F4, defined by: [Math 1] F1 (t) = mrœ2ei(.wt+(p) [Math 2] [Math.l] F2(t)= [Math 3] [Math.2] F3 ( t ) = mrcû2^^) [Math 4] [Math.3] F4 ( t ) = with [Math.4] 9 , the phase shift angle of the unbalanced masses (1, 2, 3, 4) relative to an initial position and imposed by the drive device 20, and [Math.4] w the pulsation of the unbalanced masses (1, 2, 3, 4).

[0036] The resulting force Fres, is such that:

[0037] [Math 5] Fres (t) = F1 (t) + F2(t) + F3(t) + F4(t) = 4mrœ2cos(œt)cos( <p)-

[0038] The amplitude of the force Fres depends on the phase shift angle q>, and its direction is only transverse to the tracks, the longitudinal component of the force Fres being zero.

[0039] Figures 4 show the positions of the four unbalanced masses (1, 2, 3, 4) at different times, the unbalanced masses being out of phase by an angle q>i equal to 90°.

[0040] In [Fig.4a], the forces produced by the unbalanced masses of a pair cancel each other out: the first unbalanced mass 1 and the second unbalanced mass 2 respectively produce the forces F1 and F2, which are in the same direction, of the same intensity and in opposite directions; the third unbalanced mass 3 and the fourth unbalanced mass 4 respectively produce the forces F3 and F4, which are in the same direction, of the same intensity and in opposite directions. The resulting force Fres is therefore zero.

[0041] Similarly, the unbalances (1, 2, 3, 4) shown in Figures 4b, 4c and 4d cancel each other out two by two. The resulting force Fres is therefore zero. In all intermediate positions between the positions illustrated in Figure 4, the resulting force Fres remains zero.

[0042] Figures 5 show the positions of the unbalanced masses (1, 2, 3, 4) at different times and for a zero phase shift q>2.

[0043] In [Fig.5a], the first unbalanced mass 1 and the second unbalanced mass 2 respectively produce the forces F1 and F2 which are in the same direction, in the same sense and of the same intensity, and the third unbalanced mass 3 and the fourth unbalanced mass 4 respectively produce the forces F3 and F4 which are in the same direction, in the same sense and of the same intensity. The resulting force Fres obtained is therefore a force parallel to the rolling plane PR and equal to the sum of the forces F1, F2, F3 and F4.

[0044] In [Fig.5b], the forces produced by the unbalanced masses cancel each other out two by two: the first unbalanced mass 1 and the third unbalanced mass 3 respectively produce the forces F1 and F3, which are in the same direction, of the same intensity and in opposite directions; the second unbalanced mass 2 and the fourth unbalanced mass 4 respectively produce the forces F2 and F4, which are in the same direction, of the same intensity and in opposite directions. The resulting force Fres is therefore zero.

[0045] In a similar manner to [Fig.5a], the forces produced by the unbalanced masses (1, 2, 3, 4) shown in [Fig.5c] add up to generate a resultant force Fres parallel to the rolling plane PR and equal to the sum of the forces Fl, F2, F3 and F4.

[0046] Similarly, by analogy with [Fig.5b], the forces produced by the unbalanced masses (1, 2, 3, 4) shown in [Fig.5d] cancel each other out two by two. The resulting force Fres is zero.

[0047] It is thus understood that over one revolution, the amplitude of the transverse resultant force Fres varies sinusoidally with an amplitude equal to 4mrœ2. [Fig.6] represents the variation of the force Fres over time for the phase shift angle q>2.

[0048] Between the angles q>i and q>2, it is possible to impose other phase shift angles q> on the unbalances ( 1, 2, 3, 4 ). The resulting force Fres then remains transverse, i.e. perpendicular to the median longitudinal plane PL, and its variation over time is sinusoidal, of frequency 5^ and amplitude 4mrœ2cos((p), which varies with q> between 0 and 4mrœ2. It is thus possible, by keeping the frequency constant and varying the phase shift q>, to vary the intensity of the vibration transmitted to the track. This modulation capacity is used to adapt to the type of track treated, for example concrete or wooden tracks, and / or to the forward speed of the stabilizing machine.

[0049] Thus, a means of varying the amplitude of the transverse stabilizing force is obtained which does not require varying the distance between the centers of gravity of the unbalanced masses and their axis of rotation, which simplifies the structure of the stabilizing unit.

[0050] Naturally, the examples shown in the figures and discussed above are given for illustrative purposes only and are not limiting. It is explicitly provided that the different embodiments illustrated can be combined with each other to propose others.

Claims

Claims

1. Transverse stabilization unit for a railway track (10), comprising a chassis (12) resting on at least two pairs of rollers (14, 16) defining a rolling plane (PR) and a median longitudinal plane (PL) of the chassis (12) perpendicular to the rolling plane (PR), each pair of rollers (14, 16) comprising a right roller (142, 162) and a left roller (141, 161) located respectively on a right side and a left side of the median longitudinal plane (PL) and intended to roll respectively on a right rail (22) and a left rail (21) of the railway track, the chassis (12) carrying a vibration exciter (18) with four unbalanced masses (1, 2, 3, 4), each of the four unbalanced masses being rotatable about an axis of rotation (A1, A2, A3, A4), the axes of rotation (A1, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) being parallel to the same reference direction (A) of the chassis (12),the stabilization unit (10) being characterized in that the reference direction (A) is perpendicular to the rolling plane (PR).,

2. Transverse stabilization unit (10) according to claim 1, characterized in that each of the four unbalanced masses (1, 2, 3, 4) has a center of gravity, the centers of gravity of the four unbalanced masses (1, 2, 3, 4) being located at an equal distance from the rolling plane (PR).

3. Transverse stabilization unit (10) according to claim 2, characterized in that the centers of gravity of the four unbalances (1, 2, 3, 4) are located at a distance from the rolling plane (PR) of less than 30 cm.

4. Transverse stabilization unit (10) according to any one of claims 2 or 3, characterized in that the four unbalanced masses (1, 2, 3, 4) have the same mass and the centers of gravity of the four unbalanced masses (1, 2, 3, 4) are located at equal distance from their axis of rotation (A1, A2, A3, A4).

5. Transverse stabilization unit (10) according to any one of claims 2 to 4, characterized in that the four unbalances (1, 2, 3, 4) are located at a constant distance from their axis of rotation (A1, A2, A3, A4).

6. Transverse stabilization unit according to any one of the preceding claims, characterized in that each of the two pairs of rollers (14, 16) is associated with a transverse plane (PT1, PT2) perpendicular to the rolling plane (PR), the transverse plane (PT1, PT2) containing an axis of rotation (140) of the right roller (142, 162) and an axis of rotation of the left roller (141, 161) of the associated pair of rollers (14, 16), the transverse plane being perpendicular to the median longitudinal plane (PL) of the chassis (12) of the stabilization unit (10).

7. Transverse stabilization unit (10) according to claim 6, characterized in that: - the axes of rotation (A1, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) are located between the transverse planes (PT1, PT2) associated with the two pairs of rollers (14, 16); and / or - the axes of rotation of the four unbalanced masses (1, 2, 3, 4) include two first axes of rotation (A3, A4) located at equal distance from the transverse plane (PT1) associated with a first of the two pairs of rollers (14) and two second axes of rotation (A1, A2) located at equal distance from the transverse plane (PT2) associated with a second of the two pairs of rollers (16).

8. Transverse stabilization unit (10) according to one of the preceding claims, characterized in that one of the following alternative arrangements is adopted: - the axes of rotation (A1, A2, A3, A4) of the four unbalances (1, 2, 3, 4) include two right axes of rotation (A2, A4) located on the right side of the median longitudinal plane (PL), at an equal distance from the median longitudinal plane (PL), and two left axes of rotation (A1, A3) located on the left side of the median longitudinal plane (PL), at an equal distance from the median longitudinal plane (PL); or - the axes of rotation (A1, A2, A3, A4) of the four unbalances (1, 2, 3, 4) are located in the same transverse vertical plane perpendicular to the median longitudinal plane; or - the axes of rotation (Al, A2, A3, A4) of the four unbalanced masses (1, 2, 3, 4) are located in the same longitudinal vertical plane parallel to the median longitudinal plane;- the axes of rotation (Al, A2, A3, A4) of the four unbalances (1, 2, 3, 4) are located in the median longitudinal plane.;

9. Transverse stabilization unit (10) according to one of the preceding claims, characterized in that the axes of rotation of the four unbalances (1, 2, 3, 4) are closer to the median longitudinal plane (PL) than the four rollers (14, 16).

10. Transverse stabilization unit (10) according to one of claims 1 to 9, characterized in that the stabilization unit (10) comprises four bearings (11), each associated with one of the four rollers (14, 16) for guiding the associated roller in rotation, each of the four rollers (1, 2, 3, 4) being located between the associated bearing and the median longitudinal plane (PL).

11. Transverse stabilization unit (10) according to one of claims 1 to 9, characterized in that the stabilization unit (10) comprises four bearings (11), each associated with one of the four rollers (14, 16) for guiding the associated roller in rotation, each of the four bearings is located between the associated roller and the median longitudinal plane (PL).

12. Transverse stabilization unit (10) according to one of the preceding claims, characterized in that the stabilization unit (10) comprises a drive device (20) for the four unbalanced masses (1, 2, 3, 4) to drive the four unbalanced masses synchronously at the same rotation frequency, two of the four unbalanced masses in one direction of rotation and two others of the four unbalanced masses in an opposite direction of rotation, so as to generate a resultant force directed perpendicular to the median longitudinal plane.

13. Transverse stabilization unit (10) according to claim 12, characterized in that the drive device (20) is capable of varying the relative rotation phase of the four unbalances (1, 2, 3, 4), in a coordinated manner and in such a way as to vary the amplitude of the resulting force between 0 and a maximum value.

14. A transverse stabilization unit (10) according to claim 12 or claim 13, characterized in that the rotation frequency is between 35 Hz and 45 Hz.

15. A transverse stabilization unit (10) according to any one of claims 12 to 14, characterized in that the rotation frequency is adjustable within a frequency range including the interval between 35 Hz and 45 Hz.

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