Rear suspension of a vehicle with drive wheel borne by an oscillating arm

ES 2 296 902 T3

DESCRIPTION

Rear suspension of a vehicle with a drive wheel supported by a swing arm.

The present invention refers to a rear suspension of a vehicle such as a bicycle, a motorcycle or the like, of the type that comprises a chassis that will be called the frame below, an oscillating arm integral with the frame and that supports the axle of the hub of a frame. rear driving wheel and a shock absorber whose ends are fixed respectively to the frame and the oscillating arm, said suspension providing an "anti-pump" effect and leaving the space between the saddle and the rear wheel freed to allow the fixing of a fender, a luggage rack or the like.

In the field of the all-terrain bicycle called MTB, rear suspensions are well known which comprise an articulated oscillating arm in the lower part of the seat tube cooperating with a shock absorber. This is the case, for example, of the “XC FULL” bicycle marketed by the LAPIERRE company; the swing arm pivots about a fixed axis parallel to the axis of the drive pinion which is supported by the pedal box positioned at the intersection of the oblique tube and the seat tube. In addition, the ends of the shock absorber are integral with the oscillating arm and respectively with the horizontal tube that joins the seat tube to the bicycle fork or with an intermediate tube that extends globally from the pedal box to the horizontal tube, said tube being of the saddle interrupted to give way to the shock absorber.

This type of rear suspension has the drawback of occupying the rear of the bicycle, that is, the space between the rear wheel and the saddle, so that it is not possible to install a rear fender, thus causing various projections of mud, water, etc., on the cyclist's back in the event of rain, for example. On the other hand, a rear suspension of this type causes, under the action of an energetic pedal stroke, such as a pedal stroke to accelerate the bicycle or when the cyclist adopts the position called "in dancer", standing on the pedals. , when going up a hill, etc., an effect called "pumping" that results in a cyclical collapse of the suspension even on well-leveled ground. Thus, in addition to the unpleasantness of driving the bicycle, a part of the motor torque provided by the cyclist is dissipated in the shock absorber instead of participating in the motor skills of the bicycle.

Indeed, in this type of rear suspension, the upper tensioned branch of the transmission chain that extends between the driving pinion, supported by the pedal box, and the driven pinion, integral with the driving rear wheel, extends above the axis of rotation of the swing arm with respect to the frame thus creating a torque proportional to the tension of the upper leg and the distance that separates the upper leg of the chain from the center of rotation of the swing arm that tends to pivot the oscillating arm upwards thus compressing the shock absorber when the cyclist leans on the pedals, the bicycle being in a static equilibrium position, that is to say when it is ridden by a cyclist. When the motor torque applied by the cyclist on the pedals is relatively small and constant, the torque applied to the oscillating arm and consequently the sag of the shock absorber, are also small and constant so that the cyclist does not perceive a pumping effect although a part of the engine torque is dissipated in the shock thus reducing the efficiency of your pedaling. However, when the cyclist gives a pedal stroke to accelerate the bicycle or when the cyclist is in a standing position on the pedals, called "in dancer", the position of the center of gravity of the bicycle / cyclist group varies; This causes a vertical oscillatory movement of the bicycle frame in such a way that the motor torque increases dramatically, causing an increase in the torque applied on the oscillating arm that compresses the shock absorber and then makes the pumping effect appear very quickly perceptible by the cyclist. Thus, when energetic pedaling takes place, the motor torque increases greatly and becomes cyclical, causing each pedal stroke an increase in the torque applied to the oscillating arm that compresses the shock absorber and then makes the pumping effect appear, the latter being characterized by a parasitic alternating compression movement of the front and rear suspension of the bicycle in rhythm with the pedaling frequency that annoys the cyclist.

In order to avoid this drawback, a rear suspension for a bicycle has already been envisaged that provides a so-called "anti-pump" effect; This is the case, for example, of French patent FR 2,774,966 filed by the applicant, which describes a rear bicycle suspension comprising an oscillating arm guided by two connecting rods. The two connecting rods have a defined orientation in such a way that the intersection of their respective axis that passes through the center of their two pivots, said intersection materializing the instantaneous center of rotation of said oscillating arm, is located in the defined upper anterior quadrant of reference. by a horizontal axis and a vertical axis that concur in the center of the pedal box, and are articulated on said oscillating arm at two points remarkably distant from each other. The suspension comprises, on the other hand, a shock absorber whose ends are respectively integral with the oscillating arm and with the seat tube, said shock absorber extending globally parallel to said seat tube at the rear of the latter.

Although this type of suspension provides an anti-pumping effect, it has the drawback of filling the rear of the bicycle in such a way that it is not possible to install a rear fender, a luggage rack or the like. On the other hand, although this type of suspension provides a particularly effective anti-pumping effect, it nevertheless has the drawback of providing insufficient rigidity of the frame / suspension assembly which, when the bicycle is intensively stressed, impairs the general behavior of the bicycle by making it uncomfortable.

One of the objectives of the invention is therefore to avoid these drawbacks by proposing a rear suspension for a bicycle or the like made up of an oscillating arm that joins the rear wheel axle to the frame upright

ES 2 296 902 T3 and a shock absorber whose ends are integral respectively with the frame and the oscillating arm, said frame and / or the oscillating arm comprising means that make it possible to free the space between the saddle and the rear wheel to allow the fixing of a fender rear or a luggage rack for example, while providing an anti-pumping effect.

To this end, and according to the invention, the anti-pumping system of a rear suspension of a vehicle, such as a bicycle, a motorcycle or the like, of the type comprising a chassis, an oscillating arm integral with the chassis that supports the axle of the hub of a driving wheel and a shock absorber whose ends are fixed respectively to the chassis and the oscillating arm, the torque being transmitted to the driving wheel by a chain that extends between a driving pinion integral with the chassis and a driven pinion integral with the axis of the driving wheel hub, said chain forming two branches between the driving and driven pinions, one upper tensioned that transmits the engine torque to the driving wheel and the lower one, called the return wheel, the chassis made up of a globally vertical seat tube, a horizontal tube and an oblique tube, the horizontal tube and the oblique tube being integral with a steering tube that receives a fork and the axis of the driving pinion being positioned at the intersection of the seat tube and the oblique tube and / or the oscillating arm comprising means so that the branch upper part of the transmission chain or the straight line that extends it, pass through the instantaneous center of rotation C of the oscillating arm, when the vehicle is in a position of static balance, and that said upper branch of the chain is located below the instantaneous center of rotation C of the oscillating arm when the hub of the driving wheel is located above its reference position Pr corresponding to the position of the axis of the hub of the driving wheel when the vehicle is in a static equilibrium position. The rear suspension is remarkable because the oscillating arm is attached to at least two articulation means to the chassis whose intersection of the lines D1, D2, that pass through the axes of rotation of each articulation means is located in the upper rear quadrant of a reference defined by a horizontal axis H and a vertical axis V concurrent with the axis of the driving pinion and because the ends of the shock absorber are respectively integral with the oscillating arm or the articulation means that integrates the oscillating arm to the oblique tube and to a leg, said leg extending in the plane containing the chassis tubes, said shock absorber extending in front of the oblique tube, that is to say between the oblique tube and the fork that supports the front wheel, globally parallel to the latter and between the tubes that constitute the chassis in the plane containing the latter.

It is well understood that, when the vehicle rolls on a perfectly level ground, the upper branch of the transmission chain passes through the instantaneous center of rotation of the oscillating arm, that is, the center of rotation of the oscillating arm at every instant t the entire of the engine torque is transmitted to the driving wheel and that, when the cyclist changes pace and accelerates, for example, with the upper branch of the chain located below the instantaneous center of rotation of the oscillating arm, a moment of return is created proportional to the tension of the upper branch of the chain and the distance between the upper branch and the instantaneous center of rotation of the swing arm, which tends to bring the swing arm back to its initial position. This moment of return is created with each energetic pedal stroke of the rider, thus avoiding the appearance of the pumping effect. It is evident that, when an obstacle is crossed, the return moment is added to the return effort of the shock absorber, notably improving traction, on a slope for example. On the other hand, contrary to the teachings of French patent FR 2,774,966 in which the instantaneous center of rotation of the oscillating arm is located in the upper front quadrant of the bicycle, the position of the instantaneous center of rotation in the upper rear quadrant and the position of the shock absorber on the oblique tube of the bicycle provide greater rigidity of the frame / suspension assembly and allow to free the space between the rear wheel and the saddle in order to install a rear fender, a luggage rack or the like.

According to a particularly advantageous characteristic of the rear suspension according to the invention, the instantaneous center of rotation of the oscillating arm moves globally along a line perpendicular to the upper branch of the chain when the axis of the hub of the driving wheel moves, accordingly. such that the moment of return is proportional to the displacement of the drive wheel hub axis.

Other advantages and characteristics will be better highlighted from the description that follows of various embodiment variants, provided by way of non-limiting examples, of the rear suspension according to the invention with reference to the attached drawings, in which:

- figure 1 is a side view of a bicycle equipped with a rear suspension according to the invention,

- figure 2 is a partial side view of a first variant of embodiment of a rear suspension according to the invention that equips a bicycle,

- Figure 3 is a partial side view of a second variant of embodiment of a rear suspension according to the invention that equips a bicycle,

- Figure 4 is a partial side view of a third variant of embodiment of a rear suspension according to the invention that equips a bicycle,

- figure 5 is a partial side view of a fourth and last variant of embodiment of a rear suspension according to the invention that equips a bicycle,

ES 2 296 902 T3

- figure 6 is a partial and schematic representation of a bicycle equipped with a rear suspension according to the invention shown in the empty position,

figure 7 is a partial schematic representation of a bicycle equipped with a rear suspension according to the invention in a position of static balance,

figure 8 is a partial schematic representation of a bicycle comprising a rear suspension according to the invention when the start of a pumping movement takes place.

With reference to the figures, a rear suspension of a bicycle of the all-terrain bicycle type will be described by way of non-limiting example.

To this end, figure 1 shows a general side view of a bicycle comprising a chassis called triangulated frame 1 made up of a globally vertical seat tube 2, by an oblique tube 3 assembled by welding at the lower end of the tube. of the saddle 2 and a horizontal tube 4 assembled at the upper end of the saddle tube 2 and to a globally vertical fork tube 5, the oblique tube 3 being, on the other hand, fixed to said fork tube 5 by welding. The latter supports a fork 6 that includes a suspension 7 of the telescopic type that supports at its lower end the axis of the front wheel hub 8. A handlebar 9 is, in a conventional way, fixed to the upper end of the fork 6 to ensure the direction of the bicycle. Furthermore, the saddle tube 2 is suitable for receiving a saddle stem 10 comprising at its upper end a saddle 11 on which the cyclist is positioned. The lower end of the seat tube 2, and more precisely at the intersection of the oblique tube 3 and the seat tube 2, comprises a pedal box 12 that supports the axis of the driving pinions 13 commonly called plates, whose axes of rotation are coaxial, pedals 14 being integral with said axis of the driving pinions, on either side of the frame 1 of the bicycle.

The bicycle also comprises an oscillating arm 15 made up of two semi-arms 15a and 15b that extend horizontally on either side of the frame 1, said semi-arms 15a and 15b being joined by one or more braces 16. The oscillating arm 15 is connected to the frame 1 by two connecting rods 17 and 18, the connecting rod 17 comprising two axes of rotation 17a and 17b respectively integral with the oblique tube 3 and the oscillating arm 15 and the connecting rod 18 also comprising two axes of rotation 18a and 18b respectively integral with the seat tube 2 and the oscillating arm 15. On the other hand, the oscillating arm 15 supports at its free end the axis of the hub of a rear driving wheel 19 and of a driven pinion 20 integral with said rear wheel 19, the latter being driven in rotation by a transmission chain 21 that is It extends between the driving 13 and the driven pinions 20 forming two branches, an upper one called tensioned 22 that transmits the motor torque to the rear wheel 19 and the other lower one called return 23. In this particular example of embodiment, the connecting rod 18 extends globally vertically and the connecting rod 17 extends globally horizontally, so that the connecting rods 17 and 18 extend substantially perpendicular to each other and the intersection of the line D1 that passes through the axes 17a and 17b of the connecting rod 17 and of the line D2 that passes through the axes 18a and 18b of the connecting rod 18 is located in the upper rear quadrant of a reference defined by a horizontal axis H and a vertical axis V that concur in the axis of the driving pinion 13, that is to say that point C is located above the horizontal axis H and to the right of the vertical axis V. It will be observed, on the other hand, that point C constitutes the instantaneous center of rotation of the oscillating arm 15, being the instantaneous center of rotation C the point around which the pivot arm 15 pivots at every instant t.

Finally, the bicycle comprises a shock absorber 24 whose ends are integral with the remote end of the crank 17, that is to say the end furthest from its axis 17a, and respectively of a leg 25 welded to the oblique tube 3 in the vicinity of the pedal box. 12, said leg 25 extending in the plane containing tubes 2 to 5 of table 1.

Thus, the shock absorber 24 extends in front of the oblique tube 3, that is to say between said oblique tube 3 and the fork that supports the front wheel globally parallel to the latter.

Of course, the shock absorber 24 can be integral with the oscillating arm and a leg welded to one of the tubes of frame 1 and that it can extend between tubes 2, 3 and 4 of frame 1 in the plane containing the latter or behind the frame. seat tube 2 parallel to this, without on the other hand going outside the scope of the invention.

The space between the rear wheel 19 and the saddle, that is, the saddle tube 2, the saddle stem 10 and the saddle 11, is thus freed, making it possible to fix a fender 26, represented in dotted lines, to the saddle tube 2 by a fixing collar 27 positioned between the horizontal tube 4 and the connecting rod 18 in order to avoid the projection of mud, water, gravel, etc ... on the cyclist's back.

Of course, instead and position or in addition to the fenders 26, a luggage rack can be installed behind the saddle 2, 10, 11 above the rear wheel 19.

According to a variant embodiment of the anti-pumping system according to the invention, with reference to FIG. 2, the axis of rotation 17a of the connecting rod 17 that integrates the oscillating arm 15 to the oblique tube 3 is mounted idly on an eccentric 28 that pivots around of an axis 29 parallel to the axis of the driving pinions 13, said eccentric 28 being integral with the oblique tube 3 and the axis of rotation 17b of the connecting rod 17 being integral with the oscillating arm 15. The eccentric 28 comprises, on the other hand, an arm 30 whose free end is secured by any means

ES 2 296 902 T3 known to a tensioned cable 31, which runs parallel to the oblique tube 3 in front of the latter attached to a control box 32 of a gear changer 33 which allows the chain of a first gear 13a called the chainring to pass towards a second pinion 13b called intermediate plate, or towards a third pinion 13c called small plate, said cable 31 passing under the pedal box 12. Thus, the chain 21 being initially on the larger plate 13a corresponding to the position Ci of the instantaneous center of rotation of the oscillating arm 15, the loosening of the cable 31 that allows the passage of the chain 21 from the larger plate 13a towards the intermediate plate 13b causes the rotation of the eccentric 28 in the counterclockwise direction, dragging the connecting rod 17 around its axis. 17b clockwise such that the instantaneous center of rotation C₂, which corresponds to the line D1 that passes through the rotation axes 17a and 17b of the connecting rod 17 and of the line D2 that passes through the rotation axes 18a and 18b of the connecting rod 18, is located on the upper branch 22 of the chain 21 driven by intermediate plate 13b. On the other hand, a new slackening of the cable 31 of the pinion changer 32 that allows the passage of the chain 21 from the intermediate plate 13b towards the small plate 13c causes the rotation of the eccentric 28 in the opposite direction of the needles of a clock. dragging the connecting rod 17 in a clockwise direction around its axis 17b until the instantaneous center of rotation C₃ of the oscillating arm is on the upper branch of the chain 21. The orientation of the connecting rod 18 remains globally unchanged during these chainrings, the positions C₁, C₂ and C₃ of the instantaneous center of rotation of the oscillating arm 15 are located on the line D2 that passes through the axes of rotation 18a and 18b of said connecting rod 18. On the other hand, it is well understood that the tensioning of the cable 31 of the pinion changer 32 allows passage of C positions₃ to C₂ and after C₂ to C₁ by a clockwise rotation of the eccentric 28 that causes the rotation of the connecting rod 17 with respect to its axis 17b in the counterclockwise direction when the passage of the small plate 13c towards the intermediate plate 13b and respectively when the passage of the intermediate plate 13b towards the larger plate 13a takes place.

It is evident that the means for varying the position of the instantaneous center of rotation C described above can be adapted to the axis of rotation 18a of the connecting rod 18 that integrates the oscillating arm 15 to the seat tube 2 without, on the other hand, leaving the framework of the invention .

On the other hand, of course the means for varying the position of the instantaneous center of rotation C of the oscillating arm 15 can be controlled by the control means of the front gear changer 32 and / or of a rear gear changer not shown in the figures. figures. Furthermore, the means for varying the position of the instantaneous center of rotation C of the oscillating arm 15 may consist of means for varying the stiffness of the shock absorber 24, the variation in stiffness causing a variation in the length of the stem of the shock absorber 24 which it causes the rotation of the connecting rods 17 and 18 and consequently the displacement of the instantaneous center of rotation C along the line D2.

On the other hand, and according to a second embodiment variant of the anti-pump suspension according to the invention, with reference to Figure 3, the connecting rod 18 that integrates the oscillating arm 15 to the seat tube 2 can advantageously be replaced by a flexible sheet 34, such as a sheet of steel, carbon fiber composite or the like, whose ends are fixed to the brace 16 of the oscillating arm 15 and to a protuberance 35 of the seat tube 2 positioned between the pedal box 12 and the oscillating arm 15 in front of the rear wheel 19, said sheet 34 then extending globally parallel to the tube of the saddle 2. The flexible sheet 34 is fixed to the strut 16 and to the protrusion 15 by screws 36 for example. Furthermore, it will be noted that the fixing of the sheet 34 to the seat tube 2 being located under the fixing of said sheet 34 to the oscillating arm 15, the frame 1 is suspended under said oscillating arm 15 so that the sheet 34 is only applied to traction.

According to a third variant of embodiment of the rear suspension according to the invention, with reference to Figure 4, the joint that integrates the oscillating arm 15 to the seat tube 2 can advantageously be obtained by a joint of the type with "Silentbloc", which is a registered trademark, consisting of a tubular brace 37 welded to the seat tube 2 in such a way that its axis is parallel to the axis of the driving pinions 13, two oblong "Silentblocs" 38a 38b represented in black, made of rubber, embedded in oblong grooves 39a and 39b respectively made in each semi-arm 15a and 15b of the oscillating arm 15 and a shaft 40 that extends in the "silentblocs" 38a, 38b and in the tubular brace 37 between the half arms 15a and 15b of the oscillating arm 15. The longitudinal axis M of the oblong grooves 39a and 39b extends globally horizontally and the "Silentblocs" 38a, 38b have a maximum elasticity along this same axis M in such a way that the axis 40 can move in the grooves 39a, 39b along this axis. . The instantaneous center of rotation C of the oscillating arm 15 consists of the intersection of the line D'1 that passes through the axes of the means of articulation of the oscillating arm 15 to the oblique tube 3, not represented in this figure, and of the line D '2 orthogonal to the major axis M of the “Silentbloc” type joint that passes through the center of its axis 40.

According to a last variant of embodiment of the rear suspension according to the invention, with reference to figure 5, the means of articulation of the oscillating arm 15 with respect to the frame 1 of the bicycle consist of a tubular brace 41 welded to the seat tube 2 in such a way that its axis is parallel to the axis of the driving pinions 13, two arcuate ports 42a, 42b made in the semi-arms 15a and 15b of the oscillating arm 15, the concavity of the ports 42a being, 42b oriented upwards, that is to say towards the saddle, and its longitudinal axes extending globally horizontally, and an axis 43 extending in the tubular brace 41 and in the ports 42a, 42b, said axis 43 being able to slide in the latter. The instantaneous center of rotation C then consists of the intersection of the line D "1 that passes through the axes of the means of articulation of the oscillating arm 15 to the oblique tube 3 not represented in this figure and of the line D" 2 that passes through one part through axis 42 and secondly through the center Y of the arc of a circle of ports 42a, 42b.

ES 2 296 902 T3

It is evident that the ports 41a and 41b can consist of globally rectilinear ports whose longitudinal axis extends globally horizontally and that the means of articulation of the oscillation arm 15 to the frame 1 of the bicycle can consist of any known equivalent means without thereby leaving the framework of the invention.

The operation of the anti-pumping system according to the invention will now be explained with reference to Figures 6 to 8.

Referring to figure 6 which is a partial and schematic representation of the bicycle represented in the empty position in figure 1, that is to say when the bicycle is resting on the ground without a cyclist, the oscillating arm 15 is fixed to the frame 1 by the two connecting rods 17 and 18 respectively integral with the oblique tube 3 and the seat tube 2 in such a way that the connecting rod 18 is substantially perpendicular to the tensioned branch 22 of the chain 21 and that the instantaneous center of rotation C corresponding to the intersection of the lines D1 and D2 is located in the upper posterior quadrant of the reference defined by a horizontal axis H and a vertical axis V that coincide on the axis of the pinion conductor 13 under the upper branch 22 of chain 21.

When the cyclist rides on the bicycle, that is to say when he leans on the saddle and / or the pedals, with reference to figure 7, the frame 1 sinks with respect to its empty equilibrium position represented by dotted lines causing the rotation of the connecting rod 17 in the opposite direction of the needles of a clock, as indicated by the arrow a, until the instantaneous center of rotation C is located on the upper branch 22 of the chain 21, the characteristics of the shock absorber 24 being defined as a function of the weight of the particular rider so that in this equilibrium position, called static, the upper branch 22 of the chain 21 passes through the instantaneous center of rotation C of the oscillating arm 15. Since the motor torque provided by the pedaling of the cyclist transmitted to the driving wheel 19 by the upper branch 22 passing through the center of rotation of the oscillating arm 15, the moment applied to the oscillating arm 15 is zero, so that the motor torque is fully transmitted to the drive wheel when the rider pedals.

When the cyclist changes his pedaling rhythm by accelerating, for example, with reference to figure 8, the axis of the hub 1 of the rear wheel moves globally along a rectilinear path, that is, along an arc of a circle with a large radius of curvature , upward from a reference position Pr, as indicated by arrow b. The reference position Pr of the rear wheel hub axis corresponds to the position of the rear wheel hub when the bicycle is in a static equilibrium position. The displacement of the axis of the hub of the rear driving wheel causes the rotation of the oscillating arm 15 around the instantaneous center of rotation C which moves globally on the line D2 which, at each moment t, extends globally perpendicular to the tensioned branch 22 of the chain 21, that is to say that its orientation varies little when the oscillating arm 15 rotates. When the hub axis of the rear driving wheel moves up, the instantaneous center of rotation of the swing arm 15 moves up, in such a way that the tensioned upper branch 22 of the chain 21 is located below said instantaneous center of rotation C thus creating a moment of return proportional to the tension of the upper branch 22 of the chain 21 and to the distance Z that separates the upper branch 22 of the instantaneous center of rotation C of the oscillating arm 15 which tends to bring the oscillating arm 15 back to its initial position of static equilibrium. It will be seen that, as the swing arm 15 moves downward, the instantaneous center of rotation of the oscillating arm 15 moves downwards so that the tensioned upper branch 22 of the chain is located above said instantaneous center of rotation C thus creating a moment of return proportional to the tension of the tensioned upper branch 22 and at the distance that separates the latter from the instantaneous center of rotation C of the oscillating arm which tends to bring said oscillating arm 15 back to its position of static equilibrium. Thus, the moment of return of the oscillating arm towards its static equilibrium position opposes, whatever its direction, and at each instant t, to the beginning of the parasitic oscillatory movement called pumping created by the cyclist's pedaling. Furthermore, when the driving wheel returns to its initial position Pr of static equilibrium, the instantaneous center of rotation 6 of the oscillating arm 15 is again positioned on the upper branch 22 of the chain 21 so that the moment applied to the oscillating arm 15 is null.

Of course the center of rotation C of the oscillating arm 15 can be fixed, the chassis and / or the oscillating arm then comprise means so that the upper branch 22 of the transmission chain or the straight line that extends it, passes through the center of swing arm rotation, when the vehicle is in static equilibrium position, and that said upper branch 22 is located below the center of rotation of the oscillating arm when the hub of the driving wheel is located above its reference position.

On the other hand, it is evident that the oscillating arm 15 can consist of a triangulated arm, that is, an arm comprising three tubes welded together to form a triangle, the axis of the rear wheel hub being supported by one of the angles of the rear wheel. triangle, joined by two connecting rods, the axes of which are respectively joined to the seat tube and to the tube of the oscillating arm 15 opposite the rear wheel hub, without, on the other hand, leaving the frame of the invention.

Finally, of course, the anti-pump system according to the invention can be adapted to all types of vehicles of the type comprising a chassis, an oscillating arm integral with the chassis that supports the hub axis of at least one driving wheel and a shock absorber. whose ends are fixed respectively to the chassis and the oscillating arm, such as a motorcycle, a quad, or the like, and that the examples of vehicles that have just been described are only particular illustrations in no way limiting the applications of the anti-pumping system according to the invention.