FR2987020A1 - Device for adjusting parallelism of rear axle of wheels of car, has tool allowing adjustment of longitudinal position of support relative to plate, where position variation of articulations allows parallelism adjustment of wheels - Google Patents

Abstract

The device has an adjustment tool including an eccentric end and co-operating with a traversing hole of a central support (200) and an oblong hole (405) placed in a zone of a center structure of a vehicle or a plate (400) integral to the structure. The tool allows adjustment of longitudinal position of the support relative to the plate by actuation of the tool. Variation of position of two articulations (105, 106) embedded in the support allows an adjustment of parallelism of wheels at two sides of the vehicle, simultaneously. An independent claim is also included for a method for adjusting parallelism of wheels of a car.

Description

FIELD OF THE INVENTION The present invention relates to the general technical field of motor vehicle equipment. In particular, the present invention relates to a device for adjusting the parallelism of the wheels, a method of adjusting the parallelism of the wheels and a motor vehicle comprising such a device. State of the art The suspensions on a vehicle, are the elements allowing to connect the unsprung masses, typically the wheel, the braking and wheel drive systems, to the suspended masses, typically the chassis, the engine and all the vehicle components attached to the chassis. Thus, the suspension consists of a connecting device between the "unsprung masses" and the "suspended masses", a spring and possibly a damper.

Suspension geometry refers to the set of dimensional and kinematic characteristics of the mechanical linkage system between the suspended part (the body) and the wheel of a vehicle. This also defines the degrees of freedom of the suspension. Each type of vehicle has rules of geometry to respect during an intervention or an adjustment. They are determined by the manufacturer according to very precise criteria and thus make it possible to meet the road stability requirements of steering precision and protection against abnormal wear of the tires. More precisely, the geometry of the running gear is defined by characteristic angles: the inclination of the pivots, the hunting, the camber and the parallelism. Some motor vehicles are equipped with suspensions comprising a trailing arm with the axis is transverse or oblique.

A rear axle of a motor vehicle of the oblique trailing arm type is shown in FIG. 1. This type of rear axle comprises an arm (or triangle) drawn with a right oblique axis 102 and an arm (or triangle) drawn with a left oblique axis 101. symmetrical and often coupled to each other by an anti-roll bar 107. Each pulled arm 101, 102 comprises a rear portion to which are secured a wheel 100, a fluid damper and a spring. This rear portion is extended towards the front of the vehicle by two end portions, one being oblique with respect to the longitudinal direction of the vehicle and having a first end and the other being substantially parallel to the longitudinal direction of the vehicle and having a second end. These first and second ends are placed at different levels with respect to the longitudinal direction of the vehicle. In other words, they are offset with respect to each other and therefore the direction which joins them is oblique with respect to the transverse direction of the vehicle, which is perpendicular to the longitudinal direction. The first end is provided with an element which constitutes an inner hinge 105, 106 which is secured to the inner body part in an adjustable position.

The second end is provided with an element which constitutes another external articulation 103, 104 which is fixedly secured to the outer body part. One of the known solutions for adjusting the parallelism of the wheels is an eccentric system of bolts comprising an eccentric screw, an eccentric and indexed washer, and an eccentric nut. This type of solution is used on motor vehicles in which the fasteners of each arm are substantially horizontal and open (screwing Y). However, the wheel alignment adjusters of the prior art only allow to act wheel by wheel (left or right).

The disadvantage of acting on one side of the vehicle at a time is that it disrupts the direction of travel of the vehicle, including the bisector of the directions of advance of each wheel, which leads to "roll in crab".

DISCLOSURE OF THE INVENTION The object of the present invention is to solve all or part of the disadvantages of the devices proposed by the prior art, in particular those set out above, by proposing an adjustment device which makes it possible to act identically simultaneously. on each of the wheels. For this purpose, according to a first aspect, the present invention aims a device for adjusting the parallelism of a rear axle of a motor vehicle, said vehicle being of the pull-arm type, each arm comprising at each end of its front part a suitable articulation. to be connected to the structure 10 of the vehicle. The device comprises: - a central support receiving the joints of the rear axle arms adapted to be present in the center of the vehicle, said support comprising a through hole; an area of the structure of the center of the vehicle or a plate adapted to be secured to the structure of the center of the vehicle; means for fixing the support to the structure or to the plate; and an adjusting tool comprising a eccentric pin, said tool cooperating with the through hole of the support and an oblong hole 20 formed in the zone of the structure or the plate integral with the structure of the center of the vehicle, said tool allowing by its actuation the adjustment of the longitudinal position of the support central to the plate, this variation of the position of the two joints embedded in the support allowing a simultaneous adjustment of the parallelism of the wheels on both sides of the vehicle. The device according to the invention is suitable for adjusting the parallelism of the wheels of a rear axle of a motor vehicle of the trailing arm type with transverse or oblique axis known to those skilled in the art. Each pulled arm comprises a rear portion to which a wheel, a fluid damper and a spring are secured. This rear portion is extended towards the front of the vehicle by two end portions, one being oblique with respect to the longitudinal direction of the vehicle and having a first end and the other being substantially parallel to the longitudinal direction of the vehicle and having a second end. The first end is provided with an element which constitutes an articulation called "inner articulation" which is secured to the body part in an adjustable position. The second end is provided with an element which constitutes a second articulation called "external articulation" which is fixedly secured to the body part. The parallelism adjusting device according to the invention comprises a central support in which are embedded the two inner joints right and left side. The central support is made of any suitable material giving it the properties of shape and necessary strength in a manner known to those skilled in the art. It can be formed in one or more parts which assemble so as to embed or allow the attachment of the two inner joints of the ends of the arms drawn from the rear axle. The common support is intended to be fixed to a plate or zone secured to the suspended part of the vehicle, in particular to the vehicle body by fastening means The central support also comprises a through hole from one side to the support. The parallelism adjusting device according to the invention further comprises an adjustment tool that can be introduced into the hole through the support receiving the two inner hinges. The tool has a shape complementary to that of the through hole. It can be full or hollow. The adjustment tool comprises a body, which constitutes the guide zone of the tool, and two end faces, called "upper end face" and "lower end face", located at the two opposite end portions of the tool. The adjustment tool comprises on its upper end face a pin integral with the end face eccentrically with respect to the median longitudinal axis of the tool. Preferably the stud is substantially perpendicular to the surface on which it is fixed.

By pin is meant a small projection, for example cylindrical and / or conical, of diameter less than the diameter of the adjusting tool. When positioning the tool in the hole through the support, the eccentric pin is introduced into an oblong hole formed in the plate or zone integral with the body The rotation of the tool around its axis of revolution, in the through hole the support receiving the two inner hinges causes, thanks to the eccentric pin cooperating with the oblong hole of the plate, a relative longitudinal movement between the integral plate of the vehicle body and the support. Thus, thanks to a setting performed simultaneously on the two inner joints, the two arms pulled whose second ends are fixed to the body by the outer joints, are driven slightly in rotation about a substantially vertical axis, which varies the parallelism of the two rear wheels together. In other words, the device according to the invention allows the adjustment of the parallelism of the wheels by the rotation of a single tool.

An advantage of the device according to the invention is that it allows to act simultaneously on the parallelism of the wheels on both sides of the vehicle. Another advantage of the device according to the invention is its ease of use. The simultaneous action on the two inner hinges advantageously allows after sale to maintain the direction of advancement of the vehicle when it leaves the factory. According to preferred embodiments, the invention also satisfies the following characteristics, implemented separately or in each of their technically operating combinations. According to particular features, the central support comprises a substantially central and cylindrical through-hole. In a particular embodiment, the means for fixing the support to the zone of the structure of the vehicle center or to the plate comprise a prism stretched in a longitudinal direction on the structure 30 cooperating with its complement on the central support. In another embodiment, the means for fixing the support to the zone of the vehicle center structure or the plate comprise an oblong hole cooperating with a pilot, said driver being intended to be inserted in said oblong hole. By pilot is meant a small protuberance integral with a surface. For example, the pilot may have a cylindrical or conical shape, substantially perpendicular to the surface on which it is attached. The oblong hole adapted to receive a pilot makes it possible to limit the lateral movement between the support and the plate while allowing a slight longitudinal movement when adjusting the parallelism of the wheels. According to particular characteristics, the oblong hole is oblong along a longitudinal axis to the vehicle. It advantageously serves as a guide leading to a longitudinal displacement of the central support. Preferably the central support has on its upper face two drivers intended to be inserted in two oblong holes formed in the plate. In an alternative embodiment, the region of the structure of the center of the vehicle or the central plate has on its upper face two studs for insertion into two oblong holes formed in the support. The maneuvering device represented by a hexagon operable with a key could be a simple hole substantially perpendicular to the axis of the guide zone and the maneuver can be carried out using a simple cylindrical rod introduced in said hole. In a preferred embodiment, the adjusting tool comprises three parts, - a guiding zone of substantially cylindrical shape, - an upper end face and a lower end face, the upper end face having a solidarity pin eccentric relative to the axis of revolution of the middle part, and - a lower part having a shape adapted for gripping and clamping. The guide zone allows guiding in the hole through the support. According to particular features, the guide zone has a substantially cylindrical shape. The lower part is the part accessible to the technician to carry out the actuation of the tool in the adjustment device. Advantageously, the lower part of the tool has a shape that facilitates handling of the tool when it is inserted into the through hole of the central support. In one embodiment, the lower portion is hexagonal in shape.

Advantageously, this shape of the lower part of the tool facilitates its manipulation by a gripping tool, for example a key. In another embodiment, the lower portion of the adjusting tool comprises a hole substantially perpendicular to the median axis of the guide zone.

The hole provided on the lower part advantageously allows the operation of the tool with the aid of a simple cylindrical bar introduced into said hole. The adjustment tool is advantageously easy to manufacture and manipulate. Indeed, a mechanic a little bit equipped can achieve it himself. A second aspect of the invention relates to a method of adjusting the parallelism of the wheels of a motor vehicle comprising a trailing arm type rear train. The method according to the invention implements a device for adjusting the parallelism of the wheels according to the invention and comprises: a step of fixing the adjustment device by fixing a central support around the joints of the arms of the train rear axle present in the center of the vehicle, and the attachment of the central support to an area of the structure of the center of the vehicle or a plate integral with the structure of the center of the vehicle by fixing means, - a step of introduction of a adjusting tool comprising an eccentric stud with respect to its axis of revolution, in a through hole in the central support, said tool cooperating with the through hole of the central support and an oblong hole in the area of the structure or plate integral with the structure of the center of the vehicle, and - a step of actuating the tool for adjusting the longitudinal position of the central support allowing adjustment of the simultaneously parallelism of the wheels on both sides of the vehicle In a first step, for example, when mounting the motor vehicle in the factory, a parallelism adjusting device according to the invention is fixed on the rear axle of the vehicle. Specifically, the central support of the device is mounted to embed the two inner joints of each of the two trailing arms oblique axis of the rear axle. The support is also attached to an area of the structure of the center of the vehicle or a plate connected to the suspended part of the vehicle by fastening means provided on the central support and the plate. The following steps can be performed whenever it is necessary to adjust the parallelism of the wheels of the motor vehicle, at the time of assembly of the vehicle or after sale of the vehicle for example.

In a second step, the tool of the adjusting device is introduced into the through hole from one side to the central support. The eccentric end secured to one of the end portions of the tool is introduced into a substantially transverse oblong hole formed on the plate integral with the structure of the center of the vehicle.

In a third step, the tool is actuated inside the device, that is to say that it is rotated on itself. This rotation causes a rotation of the eccentric end, which causes cooperating with the transverse oblong hole of the plate integral with the body a slight longitudinal movement of the central support. The amplitude of this longitudinal movement is limited by the length of the longitudinal oblong holes as well as the value of the eccentricity of the nipple of the adjusting tool. A third aspect of the invention relates to a motor vehicle comprising a device for adjusting the parallelism of the wheels object of the invention.

The advantages, aims and characteristics of this mounting method and this motor vehicle being similar to those of the cable guiding device, they are not repeated here.

PRESENTATION OF THE FIGURES Other advantages, aims and features of the present invention will become apparent from the description which follows, for the purpose of explaining and in no way limiting with reference to the accompanying drawings, in which: FIG. 1 represents, schematically, a view in perspective of a rear axle with trailing arms with oblique axis according to a prior art, - Figure 2 shows, schematically, a perspective view of a rear axle with trailing arms oblique axis comprising a device for adjusting the parallelism of the wheels According to the invention in one embodiment, - Figure 3 shows, schematically, a perspective view of the central support of the device according to the invention receiving the two internal joints of the trailing arms of the rear train in a particular embodiment FIG. 4 schematically represents a perspective view of the central support fixed to a plate secured to the central portion; In a particular embodiment, FIG. 5 schematically represents a perspective view of an adjustment tool of the device for adjusting the parallelism of the wheels in a particular embodiment. FIG. , a perspective view of an adjustment tool introduced into the central support of the device forming the subject of the invention in one embodiment, - FIG. 7 is a schematic representation of a perspective view of the adjustment device which is the subject of the invention. in one embodiment, and - Figure 8 shows, schematically, in the form of a logic diagram steps of realization of the wheel parallelism adjustment method of a motor vehicle implementing a device object of the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for adjusting the parallelism of a rear axle of a motor vehicle, said vehicle being of the pull-arm type, each arm comprising at each end of its front part a hinge adapted to be connected. to the structure of the vehicle. The device comprises: - a central support 200 receiving the joints 105, 106 of the rear axle arms 101, 102 adapted to be present in the center of the vehicle, said support 200 comprising a through hole 303; an area of the structure of the center of the vehicle or a plate 400 adapted to be secured to the structure of the center of the vehicle; means for fixing the support to the zone of the structure of the center of the vehicle or to the plate 400; and an adjustment tool 500 comprising an eccentric end 503, said tool 500 cooperating with the through hole 303 of the support 200 and an oblong hole 405 formed in the zone of the structure or the plate 400 integral with the structure of the center of the vehicle, said tool 500 allowing by its actuation the adjustment of the longitudinal position of the central support 200 relative to the plate 400, this variation of the position of the two joints 105, 106 embedded in the support allowing adjustment of the parallelism of the wheels 100 simultaneous of the two sides of the vehicle.

An oblique or transverse axis trailing arm type rear axle 101, 102 known to those skilled in the art is illustrated in FIG. 1 and has already been previously described. The device according to the invention is particularly suitable for adjusting the parallelism of the wheels 100 of a motor vehicle equipped with such a rear gear. Each pulled arm 101, 102 comprises a rear portion to which a wheel 100, a damper (for example fluid without excluding another type of damper) and a spring (for example metal without excluding another type) are secured. This rear part is extended towards the front of the vehicle by two end parts, one being oblique with respect to the longitudinal direction of the vehicle and having a first end and the other being substantially parallel to the longitudinal direction of the vehicle and comprising a second end. The first end is provided with an element which constitutes a hinge 105, 106 called "inner hinge" which is secured to the body portion in an adjustable position. The second end is provided with an element which constitutes a second articulation 103, 104 called "external articulation" which is fixedly secured to the body part. Referring to Figures 2 to 7 we will describe a particular embodiment of the adjustment device object of the invention. The parallelism adjusting device according to the invention comprises a central support 200 in which are embedded the two inner joints 105, 106 right and left side as shown schematically in Figure 2. The central support 200 may be made of any known material by the skilled person adapted to confer the necessary form and strength. It can be formed in one or more parts which assemble so as to embed the two inner joints 105, 106 of the ends of the arms drawn from the rear axle. Figure 3 shows in detail the central support 200 of the device object of the invention. In this embodiment, the central support 200 is formed of two parts 304, 305 assembled together so as to encase the two inner joints 105, 106. These two parts 304, 305 are held together by screwing screws into through holes 306. correspondents provided for this purpose in each of the parts of the support. The central support 200 also comprises a through hole 303 from one side to the support. This through hole 303 is substantially central, transverse and cylindrical in this embodiment.

The common support 200 is intended to be fixed to a plate 400 secured to the suspended part of the vehicle, in particular to the vehicle body by fixing means as shown in FIG. 4. In the embodiment represented here, the means of fixing the support 200 to the plate 400 comprise two oblong holes 403, 404 formed in the plate cooperating with two drivers 301, 302 integral with the part 304 of the support 200 intended to be fixed to the plate 400.

In this embodiment, the drivers 301, 302 are of conical shape, substantially perpendicular to the surface on which it is fixed. The oblong holes 403, 404 advantageously make it possible to limit the lateral movement between the support 200 and the plate while allowing a slight longitudinal movement when adjusting the parallelism of the wheels. In an alternative embodiment, the plate 400 comprises on its face intended to be fixed to the central support 200 two drivers intended to be inserted into two oblong holes formed in the support 200.

The parallelism adjusting device according to the invention further comprises a setting tool 500 shown schematically in FIG. 5. The adjustment tool 500 is adapted to be introduced into the through hole 303 of the support 200 common to the two inner hinges 105, 106. In one embodiment, the adjustment tool 500 comprises: a guiding zone 504 of substantially cylindrical shape, an upper end face 501 and a lower end face 502, the upper end face 501 comprising a fixed lug 503. eccentric to the axis of revolution 506 of the middle portion 504, and - a lower portion 505 having a shape adapted for gripping and clamping. The guide zone 504 allows the insertion of the tool 500 into the through-hole 303 of the support 200. The lower portion 505 is the part accessible to the technician for effecting the actuation of the tool 500 in the adjustment device. This lower portion 505 has a shape that facilitates handling of the tool when it is inserted into the hole through the central support. Preferably the lower portion 505 is of hexagonal shape. Thus the lower part allows the operation of the tool 500 with a key. This part may alternatively comprise a simple hole substantially perpendicular to the axis 506 of the guide zone 504. In this embodiment, the operation of the tool can be done with a simple cylindrical bar introduced into said hole.

The adjustment tool is easy to manufacture and handle. The adjustment tool comprises on its upper end face 501 a stud 503 integral with the end face eccentrically with respect to the median longitudinal axis 506 of the tool, which corresponds to the axis of revolution of the tool 500 .

In this embodiment, the eccentric stud 503 is a small cylindrical protuberance having and / or conical, of diameter smaller than the diameter of the adjusting tool 500. FIG. 6 shows schematically the tool 500 introduced into the through hole 303 of the 200. The eccentric stud 503 is introduced into an oblong hole 405 formed in the plate 400 integral with the body of the vehicle as shown in FIG. 7. A second aspect of the invention concerns a method for adjusting the parallelism of the wheels 100. a motor vehicle comprising a trailing arm type trailing arm with oblique axis.

FIG. 8 represents in the form of a logic diagram the steps of the method which is the subject of the invention. The method according to the invention implements a device for adjusting the parallelism of the wheels according to the invention and comprises: a step 800 for fixing the adjustment device by fixing a central support 200 around the joints 105, 106 rear axle arms 101, 102 present in the center of the vehicle, and the fixing of the central support 200 to a zone of the structure of the center of the vehicle or a plate 400 secured to the structure of the center of the vehicle by fastening means 301, 302, 403, 404, a step 810 of introduction of an adjustment tool 500 comprising an eccentric pin 503 with respect to its axis of revolution 506 in a through hole 303 formed in the central support 200, said tool 500 cooperating with the through hole 303 of the central support 200 and an oblong hole 405 formed in the zone of the structure or the plate 400 secured to the structure of the center of the vehicle, and a step 820 of actuating the tool 500 permitting the adjustment of the longitudinal position of the central support 200 relative to the plate 400, this variation of the position of the joints 105, 106 allowing adjustment of the parallelism of the wheels 100 simultaneous of both sides of the vehicle. In a first step 800, performed for example, during assembly of the motor vehicle in the factory, a parallelism adjusting device according to the invention is fixed on the rear axle of the vehicle. More specifically, the central support 200 of the device is mounted so as to embed the inner hinges 105, 106 of each of the two trailing arms with oblique axis 101, 102 of the rear axle. The support 200 is also attached to an area of the structure of the center of the vehicle or a plate 400 connected to the suspended part of the vehicle by fixing means provided on the central support and the plate 301, 302, 403, 404. The steps 810, 820 can be made each time it is necessary to adjust the parallelism of the wheels of the motor vehicle, 15 at the time of assembly of the vehicle or after sale of the vehicle for example. In a second step 810, the tool 500 is introduced into the through hole 303 from one end to the central support 200. The eccentric end 503 secured to the upper end face 501 of the tool 500 is introduced into an oblong hole 405. arranged on the zone of the structure or the plate 400 integral with the structure of the center of the vehicle. In a third step 820, the tool 500 is actuated inside the device, that is to say that it is rotated on itself about its axis of revolution 506. This rotation causes a rotation the eccentric end 25 503, which causes cooperating with the oblong hole 405 of the plate 400 integral with the body a slight longitudinal movement of the central support 500. The amplitude of this longitudinal movement is limited by the length of the longitudinal holes and by The second ends fixed to the body by the external joints 103, 104 are driven slightly in rotation about an axis which is perpendicular to the body part (and therefore parallel to the axial direction), which varies the parallelism of the two wheels 100 rear between them.

Thus, the adjustment of the position of the two inner joints 105, 106 is performed simultaneously on the trailing arms 101, 102. The above description clearly illustrates that by its different characteristics and their advantages, the present invention achieves the objectives that she had fixed herself. The device according to the invention solves the problem of simultaneous adjustment of the parallelism of the wheels on both sides of the vehicle, causing a longitudinal displacement of a central assembly with the help of tooling for making and using simple and with an eccentric. The simultaneous action on the two inner hinges advantageously allows after sale to maintain the direction of advancement of the vehicle when it leaves the factory.

Claims (10)

CLAIMS1 - Device for adjusting the parallelism of a motor vehicle rear axle, said vehicle being of the pull-arm type (101, 102), each arm (101, 102) having at each end of its front part a hinge (103, 104, 105, 106) adapted to be connected to the structure of the vehicle, the device comprising: - a central support (200) receiving the articulations (105, 106) of the rear axle arms (101, 102) adapted to be present at the center of the vehicle, said support (200) including a through hole (303); an area of the structure of the center of the vehicle or a plate (400) adapted to be secured to the structure of the center of the vehicle; means for fixing the support to the zone of the structure of the center of the vehicle or to the plate (400); and an adjusting tool (500) comprising an eccentric end (503), said tool (500) cooperating with the through hole (303) of the support (200) and an oblong hole (405) formed in the region of the structure of the center of the vehicle or the plate (400) integral with the structure of the center of the vehicle, said tool (500) allowing by its actuation the adjustment of the longitudinal position of the central support (200) relative to the plate (400), this variation the position of the two joints (105, 106) embedded in the support allowing adjustment of the parallelism of the wheels (100) simultaneous of both sides of the vehicle. 2 - Device according to claim 1, characterized in that the support (200) central comprises a through hole (303) substantially central and cylindrical. 3 - Device according to claim 1 or 2, characterized in that the means for fixing the support (200) to the region of the vehicle center structure or the plate (400) comprise an oblong hole (403, 404) cooperating with a pilot (301, 302), said driver (301, 302) being adapted to be inserted into said oblong hole (403, 404). 4 - Device according to one of claims 1 to 3, characterized in that the central support (200) has on its upper face two drivers (301, 302) for insertion into two oblong holes (403, 404) formed in the area of the center structure of the vehicle or the plate (400). 5 - Device according to one of claims 1 to 4, characterized in that the area of the vehicle center structure or the central plate (400) has on its upper face two drivers (301, 302) intended to be inserted. in two oblong holes (403, 404) formed in the support (200). 6 - Device according to one of claims 1 to 5, characterized in that the tool (500) for adjusting comprises: - a guide zone (504) of substantially cylindrical shape; an upper end face (501) and a lower end face (502), the upper end face (501) comprising a stud (503) integral eccentrically with respect to the axis of revolution (506) of the middle part (504); ; and - a lower portion (505) having a shape adapted for gripping and clamping. 7 - Device according to claim 6, characterized in that the lower portion (505) of the adjusting tool (500) is hexagonal. 8 - Device according to claim 6, characterized in that the lower portion (505) of the adjusting tool (500) comprises a hole substantially perpendicular to the axis (506) of the guide zone (504). 9 - A method for adjusting the parallelism of the wheels (100) of a motor vehicle comprising a trailing arm type rear axle (101, 102), said method being characterized in that it implements a device for adjusting the parallelism of the Wheels according to any one of claims 1 to 8 and in that it comprises: - a step (800) for fixing the adjusting device by fixing a central support (200) around the joints (105, 106) rear axle arms (101, 102) present in the center of the vehicle, and fixing the central support (200) to an area of the vehicle center structure or a plate (400) integral with the vehicle center structure by fastening means (301, 302, 403, 404); a step (810) of introduction of an adjustment tool 500 comprising an eccentric pin (503) with respect to its axis of revolution (506) in a through-hole (303) formed in the central support (200), said tool (500) cooperating with the through hole (303) of the central support (200) and an oblong hole (405) formed in the area of the vehicle center structure or the plate (400) integral with the structure of the center of the vehicle ; and a step (820) for actuating the tool (500) for adjusting the longitudinal position of the central support (200) relative to the plate (400), this variation in the position of the articulations (105, 106). ) allowing adjustment of the parallelism of the wheels (100) simultaneously on both sides of the vehicle. 10 - Motor vehicle comprising a device for adjusting the parallelism of the wheels according to one of claims 1 to 8.