Air cushion measuring device

Abstract

Air cushion measuring device. Measuring device (3) for a motor vehicle (1), comprising a chassis (9) and a fastening means (10) intended to be fixed to a wheel hub (4A, 4B) of the vehicle, the fastening means being supported by the chassis, characterized in that it comprises at least one air cushion (13) fixed to an underside (14) of the chassis and intended to cooperate with a horizontal surface (S) to move the measuring device along the horizontal surface. Figure for the abbreviation: Figure 3

Description

Title of the invention: Air cushion measuring device Technical field of the invention

[0001] The invention relates to a measuring device intended to be fixed to a wheel hub of a motor vehicle. The invention also relates to a test bench comprising such a measuring device. The invention further relates to a method of installing and a method of uninstalling such a measuring device. State of the prior art

[0002] To characterize the performance of a motor vehicle, test benches are known that are equipped with measuring devices intended to be fixed to a wheel hub of the vehicle. These test benches make it possible to carry out measurements in a very reproducible manner, and without using the vehicle in an external environment. Each measuring device generally comprises a chassis resting on the ground and supporting a fixing means intended to be fixed to a wheel hub of the vehicle. Each device may further comprise a means for generating a resistive torque such as an electric motor, and a sensor such as a dynamometric sensor. The fixing means is generally supported by the chassis in a rotational connection about the axis of rotation of the wheel hub. Said dynamometric sensor is configured to measure a torque transmitted between the wheel hub and the means for generating a resistive torque.To characterize the performance of a vehicle, such a measuring device is coupled to each drive wheel hub of the vehicle.

[0003] To install a vehicle on such a test bench, the procedure is generally as follows. First, the vehicle, equipped with its wheels, is brought into a test chamber. Then, the vehicle is raised with a lifting means so that it no longer rests on the ground via its wheels. Next, the drive wheels are removed from the vehicle so as to gain access to the drive wheel hubs. Next, the fixing means of a measuring device is coupled to each drive wheel hub. This is generally done by using the fixing holes in the wheel hub provided for fixing the vehicle wheel. Fixing screws are passed through each of the fixing holes in the wheel hub and into fixing holes provided in the fixing means for this purpose. The fixing screws are then tightened so as to firmly fix each drive wheel hub to a fixing means of a measuring device.Once the drive wheel hubs are fixed to the fixing means, the lifting means is gradually removed so that the weight of the vehicle, or at least the weight of one axle of the vehicle, rests on the measuring devices. The vehicle is thus carried by means of its wheel hubs, which allows . to obtain test conditions that are highly representative of the actual conditions of use of the vehicle.

[0004] The operation of coupling a wheel hub with the fixing means is a long and complex operation. Indeed, if the fixing holes of the wheel hub and the corresponding fixing means are not well aligned, it is not possible to insert the fixing screw and / or there is a risk of damaging the wheel hub and / or the fixing means. In addition, when this operation is poorly performed, the assembly formed by the vehicle and the measuring device may include residual stresses and / or geometric alignment defects which distort the measurements taken. The coupling operation thus requires horizontal movements of the measuring devices combined with vertical movements of the vehicle. Large masses must therefore be moved with great precision.

[0005] To position a measuring device relative to a vehicle, it is known to mount the measuring device on guide rails. The guide rails are configured to move the measuring device horizontally, either along a longitudinal axis or along a transverse axis of the vehicle. The use of guide rails, however, requires heavy infrastructure. In addition, the measuring device mounted on guide rails has limited mobility. In particular, the measuring device cannot be moved between different test chambers. Publication EP3325937A1 discloses, for example, such a measuring device.

[0006] A measuring device mounted on casters is also known. Such a measuring device can be moved manually on a flat floor, then stabilized with removable stabilizing feet. Publication US8505374B1 discloses, for example, such a measuring device.

[0007] The measuring devices known from the state of the art are nevertheless not satisfactory and do not allow coupling to be carried out with a vehicle wheel hub in a simple and precise manner.

[0008] After characterizing the vehicle's performance, the measuring device is uninstalled, and in particular the fixing means and the wheel hub are separated. The uncoupling operation is also a particularly delicate operation. Indeed, during this operation, the vehicle's lifting means are used again and the load exerted by the vehicle is gradually transferred from the measuring device to the lifting means. If the vehicle is insufficiently lifted or lifted too much, stresses remain at the interface between the wheel hub and the fixing means. Unscrewing the fixing screws connecting the wheel hub and the fixing means then causes a sudden release of the residual stresses, which leads to damage to the fixing means and / or the wheel hub. Presentation of the invention

[0009] The aim of the invention is to provide a measuring device, a method of installing and a method of uninstalling such a measuring device which overcomes the above drawbacks and improves the measuring devices and their installation methods known from the prior art.

[0010] More specifically, a first object of the invention is a measuring device which can be coupled simply and precisely to a vehicle wheel hub. Summary of the invention

[0011] The invention relates to a measuring device for a motor vehicle, comprising a chassis and a fixing means intended to be fixed to a wheel hub of the vehicle, the fixing means being supported by the chassis, the measuring device comprising at least one air cushion fixed on a lower face of the chassis and intended to cooperate with a horizontal surface to move the measuring device on the horizontal surface.

[0012] The at least one air cushion may comprise at least three air cushions. The at least one air cushion may be configured such that the measuring device rests on the ground exclusively via the at least one air cushion when the at least one air cushion is active.

[0013] The measuring device may comprise means for varying an air pressure in the at least one air cushion to vary the position of the fixing means relative to a vertical axis.

[0014] The measuring device may comprise a source of compressed air attached to the chassis and at least one pneumatic conduit connecting the source of compressed air to the at least one air cushion.

[0015] The at least one air cushion may comprise at least two air cushions, and the measuring device may comprise an automatic pressure distributor configured to adjust a pneumatic pressure between the at least two air cushions to maintain the measuring device in lift during a load transfer from a lifting means of the vehicle to the measuring device.

[0016] The fixing means can be articulated in rotation relative to the chassis around a transverse axis, perpendicular to an axis of rotation of the wheel hub.

[0017] The measuring device may comprise a means for generating a resistive torque, in particular an electric motor, supported by the chassis, a transmission means connecting said means for generating a resistive torque to the fixing means, and a dynamometric sensor configured to measure a torque transmitted between said means for generating a resistive torque and the fixing means.

[0018] The transmission means may comprise a homokinetic means comprising a single center of rotation positioned on said transverse axis.

[0019] The measuring device may comprise at least one foot fixed to the chassis, the at least one foot being distinct from the at least one air cushion, the at least one foot being intended to rest on the horizontal surface and to support the chassis when the at least one air cushion is inactive, the at least one foot being intended to take position above ground level when the at least one air cushion is active.

[0020] The invention also relates to a test bench comprising two measuring devices as defined above, the two measuring devices being independent of each other, the fixing means of a first measuring device being intended to be fixed to a first wheel hub of the vehicle, the fixing means of a second measuring device being intended to be fixed to a second wheel hub of the vehicle.

[0021] The invention also relates to a method of installing a measuring device as defined above, the method comprising: - a detachment from the ground of the measuring device by activation of at least one air cushion, then - a movement of the measuring device by horizontal translation and / or by rotation around a vertical axis so as to make the fixing means coincide with a wheel hub of a vehicle or with an adapter fixed to a wheel hub of a vehicle, then - the attachment of the measuring device attachment means to the vehicle wheel hub or to the adapter attached to the vehicle wheel hub.

[0022] The invention also relates to a method of uninstalling a measuring device as defined above, the method comprising: - the transfer of the vehicle's weight from the measuring device to a means of lifting the vehicle, then - adjusting the position of the fixing means along a vertical axis by varying the air pressure in the at least one air cushion, then - the detection of an absence of constraint at the interface between the fixing means and the wheel hub or between the fixing means and the adapter fixed to the wheel hub, then - the separation of the means of fixing the measuring device to the vehicle wheel hub or to the adapter fixed to the vehicle wheel hub. Presentation of figures

[0023] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the attached figures among which:

[0024] [Fig.l] is a schematic front view of a motor vehicle installed on a test bench equipped with two measuring devices according to one embodiment of the invention.

[0025] [Fig.2] is a perspective view from above of a measuring device according to a embodiment of the invention.

[0026] [Fig.3] is a perspective view from below of the measuring device of [Fig.2]

[0027] [Fig.4] is a schematic sectional view of an air cushion of the device measure. Detailed description

[0028] [Fig.l] schematically illustrates in front view a motor vehicle 1 installed on a test bench 2 according to an embodiment of the invention. The vehicle 1 can be of any type. It can be, for example, a private vehicle, a utility vehicle, a truck or even a bus. The test bench 2, which supports the vehicle 1, rests on a horizontal surface S, in particular on the ground.

[0029] An orthogonal XYZ reference frame is defined as follows: The Y axis designates the longitudinal axis of the vehicle. When moving forward and in a straight line, the vehicle moves from rear to front in a direction parallel to its longitudinal Y axis. The X axis is a horizontal axis, perpendicular to the Y axis. The X axis is oriented from right to left, with left and right being defined according to the point of view of a driver of the vehicle. The Z axis is parallel to a vertical axis and oriented from bottom to top.

[0030] According to the embodiment presented, the test bench 2 is equipped with two measuring devices 3 connected respectively to a right hub 4A and to a left hub 4B of two drive wheels of the vehicle. Each measuring device 3 comprises a fixing means 10 by means of which it is fixed to a hub 4A, 4B of the vehicle, after the wheel fixed to this hub has been removed.

[0031] The weight of the vehicle is supported at least partially by the measuring devices 3. More precisely, for a vehicle comprising four wheels, if four measuring devices 3 are used, fixed to the four hubs of the vehicle, the weight of the vehicle 1 is entirely supported by the measuring devices 3. If only two measuring devices 3 are used, fixed to the two hubs of two driving wheels of the vehicle, only the weight of a first axle (front or rear) of the vehicle 1 is supported by the measuring devices, while the weight of a second axle of the vehicle can be supported by its wheels resting on the horizontal surface S.

[0032] The two measuring devices 3 fixed to the hubs 4A and 4B may be globally identical. We will now therefore describe a particular measuring device 3.

[0033] The measuring device 3 comprises a means for generating a resistive torque such than an electric motor 6. The fixing means 10 is connected to the electric motor 6 via a transmission means 7. The measuring device 3 further comprises a means for measuring a rotational torque 8 or dynamometric sensor 8. This dynamometric sensor 8 is arranged so as to measure the torque transmitted between the electric motor 6 and the fixing means 10. This torque is also equal to the torque transmitted by the hub 4A, 4B to the fixing means 10. The dynamometric sensor 8 may comprise, for example, at least one strain gauge capable of translating the deformation of a part into a variation in an electrical resistance. A computer connected to the measuring device may be configured to record the electrical signals from the dynamometric sensor 8. Furthermore, the measuring device 3 also comprises a chassis 9, supporting the fixing means 10, the electric motor 6, the transmission means 7 and the dynamometric sensor 8.As we will see in more detail later, the measuring device is configured to be moved on the horizontal surface S and then stabilized at a chosen position.

[0034] Alternatively, the measuring device 3 could be intended to measure other characteristics of the vehicle 1, for example characteristics of a steering system, a suspension system or even a braking system. Thus, according to certain variant embodiments, the fixing means 10 could not be rotatably mounted around the axis of rotation of the hub.

[0035] The fixing means 10 (better visible in [Fig.2]) may be in the form of a flange of generally circular shape. The fixing means 10 is intended to be fixed to a wheel hub of the vehicle, in particular by means of an adapter. The fixing means 10 may comprise holes 11 and possibly fixing screws 12 predisposed in the holes 11 for fixing the wheel hub or the adapter. The adapter makes it possible to fix the fixing means 10 to any shape of hub 4A. On the one hand, it comprises holes intended to cooperate with the fixing screws 12 and the position of which corresponds to the position of the holes 11 of the fixing means 10. On the other hand, it comprises a fixing interface specifically adapted to the hub 4A of the vehicle to be tested, for example holes capable of being positioned opposite holes in the hub provided for fixing a wheel.

[0036] The vehicle 1 has a camber angle Al, shown in an exaggerated manner in [Fig.l]. The camber angle Al designates the angle formed by the plane of rotation of the wheel with the Z axis. It can typically be between 0° and 3°, or even more than 3° for certain vehicles. The camber angle can be indifferently negative (as shown in [Fig.l]) or positive. As shown schematically in [Fig.l], the fixing means 10 of each measuring device 3 is tiltable relative to the chassis 9 around a transverse axis Y1 parallel to the Y axis.

[0037] The transmission means 7 comprises a first shaft and a second connected shaft to the first shaft by a homokinetic means. The first shaft is coupled to the electric motor 6, in particular to a rotor of the electric motor 6, and is rotatable relative to the chassis 9 around a first axis XI, parallel to the axis X. The second shaft is fixed to the fixing means 10 and is rotatable relative to the chassis 9 around a second axis X2. The fixing means 10 is therefore rotatable relative to the chassis 9 around the second axis X2. The axis X2 coincides with an axis of rotation of the wheel hub 4A, 4B to which the fixing means is coupled. The angle formed between the two axes XI and X2 is substantially equal to the camber angle AL. The axes XI and X2 are perpendicular to the transverse axis Yl. When the camber angle Al is zero, the two axes XI and X2 can be coincident and parallel to the X axis. When the camber angle Al is non-zero, the two axes XI and X2 extend in a plane parallel to the X axis and the Z axis.

[0038] The homokinetic means, also called a homokinetic joint or transmission joint, is a ball joint connecting means ensuring the connection between the first shaft and the second shaft so that the speeds of the first shaft and the second shaft are the same at all times, even if the two axes XI and X2 are not aligned. The homokinetic means may for example be of the finger ball joint type. The homokinetic means preferably comprises a single center of rotation or ball joint center positioned on the axis YL. This positioning of the center of rotation makes it possible to obtain a more compact, lighter measuring device which also has a lower resistive torque when the fixing means 10 is tilted. The measuring device 3 is therefore particularly ergonomic and simple to use. Alternatively, the measuring device 3 could be simplified and not comprise any homokinetic means.

[0039] The chassis 9 forms a rigid structure supporting the various components of the measuring device. It may, for example, comprise a metal frame. As can also be seen in [Fig. 2], the chassis 9 may comprise a base of generally rectangular shape. The chassis 9 may further be equipped with handles enabling an operator to manually move the measuring device 3 on the horizontal surface S by pulling and / or pushing.

[0040] The measuring device 3 comprises a set of air cushions 13 arranged on a lower face 14 of the chassis 9. The lower face 14 designates a face of the chassis 9 facing the horizontal surface S. When they are activated, the air cushions 13 are configured to place the measuring device 3 in suspension above the horizontal surface S. In particular, the air cushions 13 are supplied by a source of compressed air 15 generating an air flow allowing the measuring device 3 to be slightly detached from the horizontal surface S. Advantageously, the source of compressed air 15 is mounted on the measuring device 3, in particular fixed to the chassis 9, and connected to the air cushions 13 by pneumatic conduits 16. The source of compressed air 15 can, for example, include a pump and an ambient air suction outlet and be supplied with electrical energy by an electricity distribution network. Advantageously, the compressed air source comprises means for varying the air pressure and a control box for adjusting the air pressure in at least one air cushion or in each of the air cushions. Alternatively, the measuring device 3 could not include a compressed air source 15 and the air cushions 13 could be supplied by a compressed air distribution network separate from the measuring device 3. The distribution network could nevertheless include means for varying the air pressure and a control box for adjusting the air pressure in at least one air cushion or in each of the air cushions.

[0041] [Fig. 4] schematically illustrates an embodiment of an air cushion 13. The air cushion 13 comprises a base 17 on which is fixed a skirt 18, for example annular in shape and / or for example made of leather. The base 17 is fixed to the lower face 14 of the chassis 9. The skirt 18 is provided with an air inlet 19 connected to the compressed air source 15 and an air outlet 20 arranged substantially towards a center of the skirt 18 and oriented towards the horizontal surface S. When the air cushion 13 is supplied with an air flow, pressurized air enters the skirt 18 through its air inlet 19 and exits through the air outlet 20. An air gap 21 is then formed between the skirt 18 and the horizontal surface S, which causes the air cushion to detach. The skirt is preferably flexible but, alternatively, it could also be rigid.

[0042] Advantageously, the dimension of the skirt 18 and / or of the air blade 21 along the Z axis can vary as a function of the air pressure in the air cushion 13. It is thus possible to adjust the position of the fixing means 10 along the Z axis over a range of a few millimeters, or even a few centimeters, by varying the air pressure circulating in the air cushions 13. Advantageously, the air cushion(s) 13 are configured so that the position of the fixing means 10 along the vertical axis Z can vary by at least 5 mm as a function of the air pressure in the air cushion, preferably at least 10 mm, or even at least 20 mm. The control box for adjusting the air pressure in the air cushion(s) can be used for this purpose.

[0043] The horizontal surface must be sufficiently smooth and clean to allow the air cushions 13 to function properly. In particular, it must be free of cracks or holes through which pressurized air could escape.

[0044] As can be clearly seen in [Fig. 3], the measuring device 3 comprises three air cushions fixed to the lower face 14 of the chassis 9. In particular, the measuring device 3 comprises two air cushions arranged on the side of the chassis under the fixing means 10 and one air cushion on the side of the chassis 9 opposite the fixing means 10. The center of gravity of the triangle formed by the center of the three air cushions can be substantially aligned with the center of gravity of the measuring device 3.

[0045] Alternatively, the number of air cushions 13 could be different, for example one, two, four or even more air cushions. By using at least three air cushions, the entire chassis can be supported exclusively by means of the air cushions 13. According to an alternative embodiment, the measuring device 3 could comprise one or more casters resting on the ground and supporting the measuring device in cooperation with at least one air cushion 13. The number of air cushions 13 that the measuring device comprises can be adapted according to the mass of the measuring device.

[0046] In addition, the measuring device 3 also comprises a set of feet 22 fixed to the lower face 14 of the chassis 9. The feet 22 are distinct from the air cushions 13. They may be, for example, rubber pads. As can be seen in [Fig. 1], the feet 22 are intended to rest on the horizontal surface S, to support and stabilize the chassis 9 when the air cushions are inactive, that is to say when they are not supplied with pressurized air. The feet 22 are intended to take position above ground level, and therefore to be without contact with the ground, when the air cushions are active, that is to say when they are supplied with pressurized air.

[0047] To install the vehicle 1 on the test bench 2, the following procedure can be used. First, the vehicle 1 is brought into a test chamber. Then, the vehicle is raised with a lifting means so as to lift the wheels off the ground, and then the drive wheels are removed so as to gain access to the wheel hubs 4A and 4B. Adapters can then be fixed to the wheel hubs 4A and 4B in place of the wheels.

[0048] In parallel, two independent measuring devices 3 are also brought into the test chamber. For this, the air cushions 13 are activated by supplying them with pressurized air. Each measuring device 3 then comes into suspension above the horizontal surface 3. Each measuring device 3 can then be moved effortlessly on the horizontal surface S. In particular, each measuring device can be freely translated along the X and Y axes and pivoted around the Z axis. Effortless movement not only relieves the person handling the measuring device but also allows the measuring device to be positioned with great precision. Indeed, the absence of friction between the measuring device and the horizontal surface makes it possible to envisage very small movements of the measuring device 3, for example of the order of a centimeter or a millimeter.Such movements are very difficult to achieve with measuring devices mounted on casters because their movement requires overcoming adhesion forces. The adhesion forces are generally greater than the forces required to roll these measuring devices. Therefore, to move a measuring device mounted on casters on . a short distance, it is necessary to apply a significant force in one direction and then as soon as the measuring device begins to move, apply a retaining force in the opposite direction. In addition, the initial orientation of the rollers tends to impose a direction of movement of the measuring device which does not necessarily correspond to the desired direction of movement. Such manipulations require a great deal of force and are very tedious. On the contrary, thanks to the invention, it is easy to move each measuring device 3 so as to make the fixing means 10 coincide with the wheel hub 4A, 4B or with an adapter fixed to the wheel hub.

[0049] Advantageously, the air cushions also allow the measuring device to be moved along the vertical Z axis. To do this, it is sufficient to vary the air pressure in each air cushion. A certain inclination relative to the ground can also be obtained by individually adjusting the air pressure level of each air cushion.

[0050] Then, it is sufficient to put the fixing means 10 in contact with the adapter fixed to the wheel hub 4A, 4B so that the fixing means 10 automatically adapts to the camber angle of the vehicle. The fixing means pivots freely around the transverse axis Yl. An angle is then established between the first axis XI and the second axis X2 whose value is equal to the camber angle Al of the vehicle. The first axis XI remains parallel to the axis X, while the second axis X2 is inclined in the plane comprising the axes X and Z. When the fixing means 10 is brought into contact with the adapter fixed to the corresponding wheel hub 4A, 4B, it is easy to make adjustments to the position or orientation of the measuring device 3 by moving it on the air cushions 13. When the fixing means 10 coincides perfectly with the adapter fixed to the wheel hub 4A or 4B, these two elements can be secured together with the fixing screws 12.

[0051] The two measuring devices 3 can be assembled successively to the two wheel hubs 4A, 4B or simultaneously.

[0052] Then, when the two measuring devices 3 are respectively fixed to the two wheel hubs 4A and 4B, the lifting means can be deactivated so as to gradually rest the weight of the vehicle, or at least the weight of an axle of the vehicle, on the measuring devices 3. When the lifting means is deactivated, a load transfer therefore occurs from the lifting means to the measuring devices. During this load transfer, the air cushions remain activated so as to allow adjustments to the position and orientation of each measuring device. Advantageously, the air cushions are sized so as to support the weight of the measuring device 3 as such plus the weight exerted by the vehicle 1 on the fixing means 10. Due to the very low adhesion of the measuring device to the horizontal surface, each measuring device is naturally positioned in a position of less stress during this load transfer.

[0053] Advantageously, the measuring device 3 comprises an automatic pressure distributor configured to adjust a pneumatic pressure between the air cushions to maintain the measuring device in lift during the transfer of load from the lifting means to the measuring devices. Indeed, the attachment of a wheel hub to the attachment means 10 leads to moving the center of gravity of the measuring device 3 in the direction of the attachment means 10. In [Fig.l], a first arrow F1 represents the force exerted by the measuring device not coupled to the vehicle. A second arrow F2 represents the force exerted by the measuring device after coupling with a hub of the vehicle and load transfer. In the absence of a pressure distributor, the displacement of the center of gravity could lead to greater crushing of the air cushions 13 arranged on the side of the attachment means 10.This greater crushing could lead to some feet 22 of the measuring device coming into contact with the horizontal surface S which would cause the measuring device to lose mobility. Thanks to the pressure distributor, the measuring device remains horizontal or substantially horizontal during the load transfer. Consequently, the measuring device does not land on the ground before the complete load transfer from the vehicle to the measuring device. As it remains in lift throughout the load transfer, it can naturally position itself in a position of less stress.

[0054] Thanks to the invention, it is not necessary to position the vehicle precisely to couple each measuring device. The invention makes it possible to envisage the design of a test center of smaller dimensions, without a test chamber dedicated to the measurements carried out with the measuring devices 3. Each measuring device can be easily moved between different test chambers. The measuring device allows alignment without added stress with the vehicle tested, regardless of the position of the vehicle in the test chamber.

[0055] In addition, the measuring device can be moved effortlessly on horizontal ground. The movement of the measuring device is particularly ergonomic. The invention thus makes it possible to envisage measuring devices that are both more massive while remaining manually mobile.

[0056] To dissociate the test device 3 from the vehicle, the lifting means can be activated to gradually transfer the weight of the vehicle from the measuring devices to the lifting means. Advantageously, the air pressure in each air cushion can be varied to more finely adjust the position along the vertical axis Z of each fixing means 10 until an absence of stress is observed at the interface between the fixing means 10 and the wheel hub 4A, 4B or between the fixing means 10 and the adapter fixed to the wheel hub 4A, 4B. This absence of stress can be detected by visually observing the interface between the fastening means 10 and the wheel hub 4A, 4B or between the fastening means 10 and the adapter fixed to the wheel hub 4A, 4B. A slight movement may occur at this interface when the absence of constraint is obtained. This movement may be more easily perceptible if the fastening screws 12 are partially loosened during this operation. Advantageously, the means for varying the air pressure in the air cushion(s) is positioned so that it can be controlled by an operator while visually observing the interface between the fastening means 10 and the wheel hub 4A, 4B or between the fastening means 10 and the adapter fixed to the wheel hub 4A, 4B. This makes it possible to position the fastening means 10 in a position in which the wheel hub no longer exerts any constraint or minimal constraint on the fastening means 10.In this position, the fixing screws 12 can be completely removed without risk of damage to the vehicle and / or the measuring device.

Claims

Claims

1. Measuring device (3) for a motor vehicle (1), comprising a chassis (9), a fixing means (10) intended to be fixed to a wheel hub (4A, 4B) of the vehicle, a means for generating a resistive torque, in particular an electric motor (6), a transmission means (7) connecting said means for generating a resistive torque to the fixing means (10), and a dynamometric sensor (8) configured to measure a torque transmitted between said means for generating a resistive torque and the fixing means (10), the fixing means and the means for generating a resistive torque being supported by the chassis, characterized in that it comprises at least one air cushion (13) fixed on a lower face (14) of the chassis and intended to cooperate with a horizontal surface (S) to move the measuring device on the horizontal surface.

2. Measuring device (3) according to the preceding claim, characterized in that the at least one air cushion (13) comprises at least three air cushions, and / or in that the at least one air cushion is configured so that the measuring device rests on the ground exclusively via the at least one air cushion when the at least one air cushion is active.

3. Measuring device (3) according to one of the preceding claims, characterized in that it comprises means for varying an air pressure in the at least one air cushion to vary the position of the fixing means (10) relative to a vertical axis (Z).

4. Measuring device (3) according to one of the preceding claims, characterized in that it comprises a source of compressed air (15) fixed to the chassis (9) and at least one pneumatic conduit (16) connecting the source of compressed air to the at least one air cushion (13).

5. Measuring device (3) according to one of the preceding claims, characterized in that the at least one air cushion (13) comprises at least two air cushions, and that it comprises an automatic pressure distributor configured to adjust a pneumatic pressure between the at least two air cushions to maintain the measuring device in lift during a load transfer from a lifting means of the vehicle (1) to the measuring device.

6. Measuring device (3) according to one of the preceding claims, characterized in that the fixing means (10) is articulated in rotation by relative to the chassis (9) around a transverse axis (Y 1), perpendicular to an axis of rotation (XI) of the wheel hub (4A, 4B).

7. Measuring device (3) according to the preceding claim, characterized in that the transmission means (7) comprises a homokinetic means comprising a single center of rotation positioned on said transverse axis (Yl).

8. Measuring device (3) according to one of the preceding claims, characterized in that it comprises at least one foot (22) fixed to the chassis (9), the at least one foot being distinct from the at least one air cushion (13), the at least one foot being intended to bear on the horizontal surface (S) and to support the chassis when the at least one air cushion is inactive, the at least one foot being intended to take position above ground level when the at least one air cushion is active.

9. Test bench (2) comprising two measuring devices (3) according to one of the preceding claims, the two measuring devices being independent of each other, the fixing means (10) of a first measuring device being intended to be fixed to a first wheel hub (4A) of the vehicle, the fixing means (10) of a second measuring device being intended to be fixed to a second wheel hub (4B) of the vehicle.

10. Method for installing a measuring device (3) according to one of claims 1 to 8, characterized in that it comprises: - a detachment from the ground of the measuring device by activation of the at least one air cushion (13), then - a displacement of the measuring device by horizontal translation and / or by rotation around a vertical axis so as to make the fixing means (10) coincide with a wheel hub (4A, 4B) of a vehicle or with an adapter fixed to a wheel hub of a vehicle, then - the fixing of the fixing means (10) of the measuring device to the wheel hub of the vehicle or to the adapter fixed to the wheel hub of the vehicle.

11. Method for uninstalling a measuring device (3) according to one of claims 1 to 8, characterized in that it comprises: - transferring the weight of the vehicle from the measuring device to a means for lifting the vehicle, then - adjusting the position of the fixing means (10) along a vertical axis (Z) by varying the air pressure in the at least one air cushion, then - detecting an absence of stress at the interface between the means of attachment and the wheel hub or between the attachment means and the adapter attached to the wheel hub, then - the separation of the means of fixing the measuring device to the vehicle wheel hub or to the adapter fixed to the vehicle wheel hub.

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