Pneumatic system for inflating a wheel, integrated to a driven axle

The invention relates to a system for pneumatically powering a wheel comprising a bearing support (10), a shaft (20) comprising a hub-forming end (21) which extends radially (Y), at least one set of rolling bearings (30), wherein the system further comprises a chamber (C) formed by the hub-forming end (21), the bearing support (10), a rolling bearing seal (40) and a chamber seal (50), a primary channel (60) crossing the bearing support (10) and opening into the chamber (C), a secondary channel (70) crossing the hub-forming end (21) and opening into the chamber (C), wherein seals seal the cavity (C) in order to let air pass from the primary channel to the secondary channel via the cavity (C).

GENERAL TECHNICAL FIELD

The invention relates to pneumatic supply systems for controlling the inflation condition of wheels of vehicles and inflating them.

More particularly, the invention relates to such systems within the scope of a wheel locally driven by a hydraulic machine with a rotating shaft.

STATE OF THE ART

The adjustment of the inflation of wheels is frequent on agricultural machines or building site machines for increasing or reducing the contact surface area with the ground.

On conventional axles, without any hydraulic machine, the supply of compressed air is accomplished through the fixed axis of the wheel spindle.

Within the scope of a wheel locally driven by a hydraulic machine with a rotating shaft, the wheel is driven into rotation by the shaft of the hydraulic machine, the shaft being borne by a rolling bearing. Therefore, for supplying compressed air as far as into the wheel, a connection between a fixed portion and a rotating connection is required.

Because of the conditions of use of such vehicles, the system has to be integrated.

Existing solutions imply architecture modifications which shift the wheel outwards or else weaken the existing components, notably by creating channels in the axle which may weaken the structure because of corrosion produced by compressed air (humidity, etc.).

PRESENTATION OF THE INVENTION

The presented invention aims at overcoming these different drawbacks, by proposing a system for pneumatically supplying a wheel comprising:a bearing support,a shaft extending along a longitudinal axis inside the bearing support and comprising a hub-forming end which extends radially, the shaft being configured so as to be driven into rotation by a hydraulic machine,at least one set of rolling bearings, positioned between the bearing support and the shaft for the rotation of said shaft in the bearing support around the longitudinal axis,
wherein the system further comprises:a chamber formed by the hub-forming end, the bearing support, a rolling bearing seal and a chamber seal,a primary channel crossing the bearing support and opening into the chamber,a secondary channel crossing the hub-forming end and opening into the chamber,
wherein:the rolling bearing seal, positioned longitudinally between the set of rolling bearings and the chamber, is in contact with the bearing support and the shaft for ensuring the seal between the shaft configured so as to be movable in rotation and the bearing support configured so as to be fixed,the chamber seal is in contact with the bearing support and with the hub-forming end for ensuring the seal between the hub-forming end configured so as to be movable in rotation and the bearing support configured so as to be fixed.

The invention is directed to giving the possibility of supplying a tire mounted on a vehicle wheel rim with compressed air. The chamber allows fluidic communication between the rotating parts and the fixed parts. The seals give the possibility of creating such a sealed chamber. Both channels have the role of transmitting the compressed air from the fixed bearing support as far as the rotating rim.

The invention also comprises the following features, taken alone or as a combination:the hub-forming end comprises a longitudinal extension which faces an end of the bearing support, said end of the bearing support thus being radially located between the shaft and the longitudinal extension,the chamber seal is radially positioned between the end of the bearing support and the longitudinal extension,the rolling bearing seal and the chamber seal are located in a same radial plane,the primary channel comprises a rectilinear channel portion longitudinally extending in the end of the bearing support and opening into the chamber,the system comprising a second channel portion extending parallel to the channel portion, so as to have portions with smaller sections,the secondary channel longitudinally crosses in the hub-forming end,the hub-forming end comprises an attachment area and the secondary channel connects the chamber to said attachment area,the secondary channel opens into the attachment area by forming an angle comprised between 30 and 60° with respect to the longitudinal axis,the secondary channel comprises a first portion longitudinally extending from the attachment area and a second portion connecting the chamber to the first portion,further comprising a protection seal radially positioned between the bearing support and the longitudinal extension for protecting the chamber seal, said chamber seal thus being located longitudinally between the chamber and the additional seal,the rolling bearings are lubricated with grease,the system comprises a second set of rolling bearings separated from the other set of bearings by a seal,the second set of bearings is lubricated with oil.

The invention also proposes an assembly comprising:a system as described earlier,means for supplying compressed air with a pipe, in order to provide compressed air,a wheel rim,
wherein:the wheel rim is secured to the hub-forming end,the pipe provides compressed air to the first channel,the wheel rim is supplied with air through the second channel, via the chamber.

The invention proposes a vehicle comprising an assembly as described earlier.

Said vehicles may be road machinery, but also agricultural machines or public works machines, and in the broadest sense, all the machines having a wheel (for example trucks, etc.) and which include supply of compressed air for a tire mounted on a wheel rim.

The invention finally proposes a method for assembling a system as described earlier, comprising steps:for fitting out a bearing support,for fitting out a shaft,for mounting the bearing support and the shaft,for assembling the bearing support and the shaft.

The method may comprise the following sub-steps:the step for fitting out the bearing support comprises the setting into place of a rolling track of a metal seal of a protection seal,the step for fitting out the shaft comprises the setting into place of a chamber seal and of a rolling bearing seal, the setting into place of a rolling track and of the corresponding rolling bearing,the step for assembling the bearing support and the shaft comprises the setting into place of a shim and of an elastic ring.

DETAILED DESCRIPTION

In connection withFIGS. 1 to 4, are illustrated a system1comprising a bearing support10as well as a shaft20which extends along a longitudinal axis X and which comprises a hub-forming end21. The bearing support10has a general axisymmetrical shape inside which the shaft20is movable in rotation.

The hub-forming end21gives the possibility of attaching a wheel rim2abearing a tire2b. For this purpose, the hub-forming end21extends radially, i.e. it has a dimension along a radial direction Y, orthogonal to the longitudinal axis X, greater than a dimension of the shaft20(outside the hub-forming end21) along the same direction Y.

The system is mounted on a vehicle, for example an agricultural or building site vehicle, equipped with wheel rims2aeach bearing a tire2b. The tire2bmay be inflated at different pressures. In particular, within the scope of the invention, the inflation of the tire2bis accomplished by arrival of air at the wheel rim. The cooperation between the wheel rim2aand the tire2bis known and will not be described here.

Means for providing compressed air5give the possibility of supplying the system with compressed air, as this will be detailed subsequently.

The Bearing

The shaft20is a rotary shaft along the longitudinal axis X with respect to the bearing support10. The bearing support10is thus defined to be fixed.

By fixed, is therefore meant, relatively to a vehicle reference system. However, even if the bearing support10does not perform any rotation related to the displacement of the vehicle, it may be movable in a reference system bound to the vehicle when it fits out a steered wheel. At least one set of rolling bearings is provided between the bearing support10and the shaft20. The rolling bearing comprises rolling tracks and elements rolling on these tracks, like rollers, balls or any other equivalent means. The rolling elements may be accommodated in cages for maintaining them in position. In the illustrated example of roller bearings with rollers, tapered rollers30are supported on two rolling tracks31,32, one secured to the bearing support10and the other to the shaft20. The roller bearing rollers are typically accommodated in cages33.

The set of rolling bearings30is typically lubricated with grease. Grease allows better lubrication than oil. It operates better at high contact pressures, and allows better lifetime of the rolling bearings for very high loads on the bearings. Alternatively, in order to simplify the architecture of the system, the set of rolling bearings30may be lubricated with oil.

A second set of rolling bearings35may be provided, in order to form an “O” or “X” mounting. This set35also has its own rolling tracks. An inter-rolling bearing seal36may separate both sets of rolling bearings30,35in order to allow each of them to have its own lubrication. For example, the second set35may be lubricated with oil from a hydraulic machine. Generally, the rolling bearings may be lubricated with oil, or with grease, or in a mixed way, some with oil and some with grease in the same machine.

Whatever the case, the rolling bearings which are lubricated with grease have to be separated from the oil contained in a case of the hydraulic machine96(seeFIG. 1, 13) by a seal.

Alternatively, the tracks of the rollers30or35may be made in one piece with the bearing support10or the shaft20.

Longitudinally, these elements are laid out in the following order: hub-forming end21, set of rolling bearings30, inter-rolling bearing seal36, second set of rolling bearings35, and then the hydraulic machine3.

The shaft20is preferably driven into rotation by a hydraulic machine3.

The hydraulic machine3will be presented at the end of the description.

The Chamber

In order to be able to supply the wheel rim2awith compressed air in order to allow inflation of the tire2b, the system1further comprises a chamber C formed by the hub-forming end21, the bearing support10and two seals: a rolling bearing seal40and a chamber seal50(FIGS. 2, 3).

This chamber C, formed between rotating parts and fixed (non-rotating) parts, gives the possibility of producing the interface in the system for transmitting compressed air from the compressed air supply means5to the wheel rim2a(FIG. 1).

Indeed, a primary channel60is provided, which crosses the bearing support10in order to open into the chamber C. This primary channel60comprises an admission orifice60a, opening into the outer radial surface of the bearing support10, on which is connected a pipe4connected to the compressed air supply means5(FIG. 1). Given that the admission orifice60ais on the bearing support10, it is fixed and may therefore be supplied with compressed air without any difficulty. The compressed air is thereby injected into the sealed chamber C by means of the seals40,50.

A secondary channel70is also provided, which crosses the hub-forming end21for opening into the chamber C. This secondary channel70comprises an outlet orifice70aconfigured for opening into the portion of the hub-forming end21, which is substantially located at the center or in the central portion of the wheel rim2a(FIG. 1). The outlet orifice70acontains in a known way sealing and attachment surfaces, typically a threading, for receiving a connector towards the tire2bvia the wheel rim. Given that the outlet orifice70ais on the hub-forming end21which is rotating, the function of the chamber C is to provide a fluidic connection between the fixed elements of the system and the rotating elements.

A valve system for controlling the inflation (not shown in the figures) may be attached on the outlet orifice70ain order to control the air flow rate intended to enter the tire.

An inflation orifice (not shown in the figures) present in the wheel rim, allows the inside of the tire to be put into communication with the outlet orifice70a, notably via the inflation control valve, for example by means of a pipe (not shown in the figures). This pipe may be rigid and formed according to its trajectory, or flexible, or include a rigid portion and a flexible portion.

More generally, the control valve may be positioned anywhere on the air transmission chain between the outlet orifice70aof the secondary channel70and the inflation orifice. The fluidic communications are then ensured by direct secured attachment, or through flexible pipes.

The seal is ensured by means of the seals40,50which close the chamber C. Both seals40,50have the shape of a circular seal.

The chamber C has a section along a plane orthogonal to the longitudinal axis X with the shape of a ring, or according to the selected plane, several concentric rings.

The Seals

The rolling bearing seal40ensures the seal of the cavity C at the shaft20and at the bearing support10. It is located:radially between the bearing support10and the shaft20andlongitudinally between the hub-forming end21and the rolling bearing30.

The rolling bearing seal40is in contact both with the bearing support10and the shaft20, for ensuring the seal of the cavity C during rotation of the shaft20.

The chamber seal50ensures the seal of the cavity C at the hub-forming end21and at the bearing support10.

In a preferred embodiment, the bearing support10comprises an end11and the hub-forming end21comprises a longitudinal extension22which longitudinally faces the end11of the bearing support10. In this way one obtains that the end11of the bearing support10is radially located between the shaft20and the longitudinal extension22of the hub-forming end21.

The end11of the bearing support20has the shape of a cylindrical barrel which will be accommodated inside a circular groove formed in the hub-forming end11. The groove, which comprises an internal radial face21a, an axial face22band an external radial face21c, opens onto the bearing support20.

In this configuration, the chamber seal50is advantageously positioned between the end11of the bearing support10, i.e. on the external radial face21cand the longitudinal extension22. It ensures the seal of the cavity C between the rotary longitudinal extension22and the end11of the fixed (non-rotary) bearing support10.

Advantageously, both seals40,50are located in a same radial plane or substantially in a same radial plane, i.e. in a same, or substantially in a same, plane orthogonal to the longitudinal axis.

According to a sectional view of the system shown inFIG. 5(a figure not to scale) the shaft20, the rolling bearing seal40, the end11of the bearing support10, the chamber seal50and the longitudinal extension22are again found in a same plane, orthogonal to the longitudinal axis X. The seals40,50are radially framed by the shaft20and the bearing support10, or the shaft20and the longitudinal extension22.

By substantially in a same plane, is meant that there exists a radial sectional plane in which both seals are visible.

A seal support44of the fret type may be positioned between the rolling bearing seal40and the bearing support10and a blocking support45may be positioned between said seal40and the shaft20(internal radial face21a).

A shim46may be positioned in the chamber C, in contact with the chamber seal C, in order to block it longitudinally.

These arrangements of supports44,45and of shim46are only required insofar that the device is not specially designed for having the chamber C and the seals40,50.

In particular, as illustrated inFIG. 3, the seal support44is positioned between the rolling bearing seal40and the bearing support10. Such a support44allows implementation of a standard seal on specific architectures, themselves also stemming from a standard system without any pneumatic supply.

Preferentially, as illustrated inFIG. 4, the seals40,50are of the lip ring type, which are adapted for rotary parts. In an embodiment, the seals40,50each comprise a trim41,51, in fixed contact with the shaft20and the hub-forming end21(or the seal support41if necessary) respectively, and a sealed lip42,52, which is in friction with the bearing support10(or the seal support41if necessary) and allows the sealing of the cavity C in spite of the rotation. Both seals40,50are secured to the rotary portions and are therefore in rotation with respect to the bearing support10. This embodiment is practical for assembling and mounting the machine.

Nevertheless, one of the two seals40,50may not be rotary (seeFIG. 2for example) and may be secured to the bearing support10.

The trim and the sealed lip are connected together by a thinner intermediate offset portion on one of the edges of the trim and of the lip, thereby defining a recessed portion at the opposite edge between the trim and the lip. This recessed portion forms, in a sectional plane illustrated in the figures, a C. According to an embodiment, the recessed portion faces the chamber C, according to another embodiment, the recessed portion faces the rolling bearings.

Additionally, a protection ring may be combined with each lip seal.

Primary Channel

According to a preferred embodiment, the primary channel60comprises a rectilinear channel portion61which extends longitudinally or substantially longitudinally with respect to the longitudinal axis X in the end11of the bearing support10. The channel portion61opens into the chamber C.

In order to be able to connect the channel portion61to the admission orifice60a, a rectilinear conduit62is provided. The latter extends radially, or substantially radially, i.e. orthogonal or substantially orthogonal to the longitudinal axis X.

The admission orifice60acontains attachment means not shown, for example a threading and sealing means, for connecting it to the pipe4in a known way.

The layout of the primary channel60in a rectilinear channel portion61and a rectilinear conduit62which overlap in the bearing support10allows them to be formed in the bearing support10by simple drilling. In order to limit the shrinkage of material of the bearing support, the length of the primary channel60is preferably a minimum.

By resorting to drilling, it is thus not necessary to modify the foundry molds.

According to an embodiment shown inFIG. 6, the primary channel60may comprise a second channel portion63fluidically in parallel with the one mentioned earlier. Both channel portions61,63open into the cavity C and are then separated by a distance of less than the diameter of the conduit62, so as to be able to also open into the conduit62. As illustrated inFIG. 6, communication is accomplished by intersection of several cylinders corresponding to the portions61,63and to the conduit62. In the case shown inFIG. 6, both portions61,63are geometrically parallel.

By having two channel portions61,63, it is possible to reduce their diameter comparatively to a single portion61, for constant air flow. The bearing support10is a part subject to strong stresses (it notably bears the weight of the vehicle) and it may be desirable to minimize the volume of each recess.

Alternatively, it is possible to provide a conduit62for each of the respective portions61,63, but then a duplication of the pipe4has to be provided, which complicates the making of the system and increases the amount of material to be scooped out. Nevertheless, by having two channel portions61,63, it is possible to limit the scooping out of material radially. This gives the possibility of having a more resistant or thinner, bearing supporting part10, in order to let through the required air flow.

The Secondary Channel

Several embodiments of the secondary channel will now be described. An attachment area23is defined on the hub-forming end21(seeFIG. 1). This area corresponds to a radial planar area (with respect to the longitudinal axis X) of the hub on which the wheel rim2ais secured. Generally, it gives the possibility of receiving a set of bolts24regularly distributed in a ring crossed in its center by the longitudinal axis X.

As illustrated inFIG. 2for example, the secondary channel70may be made as a rectilinear channel longitudinally extending or substantially longitudinally extending along the longitudinal axis X. By the architecture of the hub-forming end21and of the attachment area23which is radially further away than the chamber C, the outlet orifice70aof the channel70is radially found between the longitudinal axis X and the attachment area23.

As illustrated inFIGS. 7 and 8, the secondary channel70may be made as a rectilinear channel obliquely extending by radially diverging with respect to the longitudinal axis X in order to open at the attachment area23, i.e. the outlet orifice70ais found in this area23. A recess25is formed in the attachment area23so as to allow the outlet orifice70ato be in the extension of the rectilinear channel70without however being in the planar area of the attachment area23.

By “obliquely”, is meant that in a sectional plane comprising the longitudinal axis X, the channel extends along an angle comprised between 10 and 80°, and more specifically between 30 and 60°.

Alternatively, as illustrated inFIGS. 9, 10 and 11, 12, the secondary channel70may comprise a first portion71longitudinally extending from the attachment area23. The outlet orifice70ais in the radial planar area of the attachment area. The secondary channel70also comprises a second portion72which connects the first portion71to the chamber C.

For design reasons, the second portion72crosses the hub-forming end21as far as the chamber C, by joining the first portion71in said hub-forming end21. An internal radial end of said portion72thus opens into the chamber C and an external radial end of said portion72opens onto an external radial surface of the hub-forming end11, said second portion72being secant with the first portion71. Indeed, the portions are preferably made by drilling, and not by foundry molding. The portions are preferably rectilinear. The second portion72may be oblique with respect to the longitudinal X or orthogonal extension.

A plug73is provided at the external radial end of the second portion72for sealing the secondary channel70and allowing compressed air from the chamber C to attain the outlet orifice70a.

The primary and secondary channels are preferably never aligned, so as to avoid direct circulation of the air and to maintain a buffering role of the cavity C, for possibly absorbing temporary overpressures. In this way, when the channel portion61and the secondary channel70extend rectilinearly parallel to the longitudinal axis X, the latter are positioned at different radial distances.

Other Elements

In order to protect the chamber seal50, a protection seal80may be provided. When it is positioned, the chamber seal50is located between the chamber C and the protection seal80which prevents water, dust, etc. from coming into contact with said chamber seal50.

More specifically, according to an embodiment, the protection seal80is positioned radially between the bearing support10and the longitudinal extension22for protecting the chamber seal50(FIG. 2).

This is typically a lip ring seal, already used in the bearings for protecting them from the outside environment.

The protection seal80is fixed.

Further, a metal seal as a metal sheet81is positioned radially outside on the bearing support10and extends towards the extension22so as to partly overlap it, without touching it. This metal sheet81gives the possibility of protecting the protection seal from a direct burst.

It is possible that the seals40,50have a few leaks, promoted when the means for providing compressed air5malfunction and cause overpressures in the chamber C. These seals may then jump out of their accommodation or be torn, thus allowing dirt to pass into the grease. In particular, if the inter-rolling bearing seal36is damaged, there may then be a risk of a grease leak towards the case of the engine lubricated with oil. Indeed, the inter-rolling bearing seal36is in fluidic communication with the volume between the rolling bearing seal40and the first set of rolling bearings30.

In order to find a remedy to this, a device is provided for giving the possibility of setting the spaces around the seals40,50to atmospheric pressure, as well as the space around the rolling bearings30,35. As illustrated inFIGS. 11, 12, a first drill hole82may be provided in the longitudinal extension22. This drill hole82, from an outer surface to the hub-forming end21opens between the chamber seal50and the protection seal80. A second drill hole83may be provided in the end11of the bearing support10, and also if necessary, the seal support44of the fret type, in order to open into the region around the rolling bearings30. Fluidic communication82,83is then provided between this region and the outside which is at atmospheric pressure, via both drill holes82,83. A discharge chamber is thereby defined which allows discharge of the overpressures of the chamber C.

The drill hole83in the bearing support10and in the fret44is not necessarily rectilinear, i.e. there may be a shift, for example if a space exists as a circular groove, or groove, between the fret44and the bearing support10. Said groove may be made in the fret or in the bearing support10. In a known way, this groove may allow communication between the end11of the bearing support10and the drill hole in the fret44, even if they are not facing each other radially, and to a lesser extent axially.

A valve84, which acts as an anti-return valve, obturates the first drill hole82so as to both allow discharge of the overpressures but also prevent dirt from penetrating through the first drill hole82. The valve84is tared to the intended pressure. In particular, the taring of the valve84is sufficiently low so that the pressure for deterioration of the seals, notably the inter-rolling bearing seal36, is not attained.

In order to avoid interferences with the portion61of the primary channel60, the second drill hole83is made in another plane than the portion, so that there is no fluidic communication between the primary channel60and the second drill hole83.FIG. 11illustrates a sectional view in the plane of the primary channel60, therefore, the second drill hole83is not visible.FIG. 12illustrates a sectional view of the bearing support10in the plane of the drill hole83.

The Compressed Air Supply Means

They may assume several forms.

Notably, these means5may be made with:a compressor dimensioned for providing the air flow and the pressure required for inflating a tire2bborne by the wheel rim2a. It is generally powered by a motor (not shown in the figures),a compressed air tank.

Such pieces of equipment for providing compressed air are very common on wheeled machines and vehicles. They may be used in a known way for varying the pressure of the tires depending on the nature of the ground, or of a height of the vehicle. They may be dedicated to inflation of the wheels, or be shared with other pieces of pneumatic equipment, such as a suspension system with air cushions. They may be mechanically connected to the main motor of the machine or of the vehicle, or be driven by means of a dedicated machine. This dedicated machine may advantageously be an electrical machine and powered by the electric network of the machine or of the vehicle, and be driven by a control unit.

The pipe4allows transfer of compressed air as far as the admission orifice60aof the primary channel60.

The pipe4is preferably flexible since the bearing supports10may be part of a steered wheel (typically the front wheels of a vehicle), or of a movable wheel relatively to the chassis, by means of a suspension system.

The Hydraulic Machine

With reference toFIG. 13, the hydraulic machine3is preferentially a machine with radial pistons90comprising:a lobed cam91, notably a multi-lobed cam,a plurality of pistons92radially positioned in a cylinder block93, the pistons92each comprising a roller94which may roll on the lobed cam91,a machine shaft95, which may be secured to the cylinder block93.

This type of machine may be actuated or disabled by retraction of the pistons92in the block93, or by engagement or disengagement of the block93with respect to the machine shaft95.

Such a machine converts hydraulic energy into mechanical energy by the variation of the cylinder capacities of the pistons when they roll on the lobed cam.

Such a machine, if it is of the type with multilobed cams, has relatively low speeds of rotation but has a high torque.

This machine rotates at the speed of the wheels.

A case (not shown) and a lid protect the assembly. In a known way, the case comprises normally unpressurized oil. The case ensures collection of the leaks of the machine, and this oil flow ensures lubrication and cooling of the machine. However, the case may be set to a low pressure in order to retract the pistons and disable the machine. The machine is connected to a supply line, a return line and a case draining line.

The machine may be of the type when the rolling bearings are in grease, or else of the type when a rolling bearing is in grease, and the other one in oil, or else of the type when both rolling bearings are in grease. If one of the rolling bearings is in grease, the machine includes an isolating seal between grease and oil.

In particular, the machine shaft95may be secured in rotation to the shaft20or else, as this is the case in the figures, forming a single and same part with the shaft20.

The bearing supports10are typically secured to the case and/or to the lid.

A gear reducer may be placed between the block and the output shaft.

In this case, the hydraulic machine is preferentially a so-called rapid hydraulic machine with axial pistons, or a machine with radial pistons and a cam with a single lobe. In this case, the machine rotates faster than the wheels.

Now, an assembling method will be described (FIG. 14).

In a first step for fitting out the bearing, the bearing support10is equipped with a rolling track31secured to the bearing support10. This track31may be maintained in place by the seal support44of the fret type.

In a second step for fitting out the bearing, the metal seal81and the protection seal80are laid, as well as the inter-rolling bearing seal36.

In a step for equipping the shaft20:the rolling bearing seal40is positioned on the shaft20, with or without the seal support44and/or the shim support45,the chamber seal50is laid on the hub-forming end21,the rolling track32of the shaft20is driven onto the shaft,the rolling bearings30and the cage33are laid on the shaft.

Next, the bearing support10is laid on the thereby fitted-out shaft20.

The tracks of the second set of rolling bearing35may then be set into place.

Finally, in a following step, a shim37and an elastic ring38are placed in the ring-shaped groove extending on a periphery of the shaft (not shown) outside the rolling bearings30,35. When the hydraulic machine3is set into place, the shim37and the elastic ring38are longitudinally found between the machine3and the rolling bearings30,35.

The resistance of the machine shaft95, or of the shaft20according to the embodiments, in the hydraulic machine3, is thus improved.

When the shaft20comprises longitudinal splines (“splined shaft”) for achieving transmission of torque between the cylinder block93and the shaft20,90, the groove is machined transversely to these splines.