DE102017202330A1 - Radial bearing arrangement, in particular for a balance shaft - Google Patents

Abstract

The invention relates to a radial bearing arrangement (1) having an outer part (3) and an inner part (4), wherein the parts (3, 4) are rotatable with respect to each other about a common longitudinal axis (X1), and with rolling elements (5), which are arranged radially between the outer part (3) and the inner part (4). The radial bearing assembly (1) is provided with a bearing seat (8) formed on either the inner or the outer part (4), the rolling elements (5) rolling on the bearing seat (8) with line contact. The bearing seat (8) is provided with at least two rolling surfaces (12a, 12b; 14a, 14b) extending transversely and separated longitudinally from one another by a recess (13), the rolling elements (5) being in line contact with each of the rolling surfaces (12). 12a, 12b, 14a, 14b).

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a radial bearing assembly for supporting an outer part with respect to an inner part, in particular for supporting a balance shaft in a housing which is intended to be used in a motor vehicle. The invention also relates to a balance shaft which is supported by such a radial bearing arrangement.

BACKGROUND OF THE INVENTION

A radial bearing arrangement for supporting an outer part with respect to an inner part is known from the prior art, for example from US Pat EP-A1-2014935 , This reference describes an arrangement in which the outer part and the inner part rotate with respect to each other about a common longitudinal axis. A bearing seat is formed on the outer portion or on the inner portion of the bearing assembly, the bearing seat having a load zone exposed to a radial load applied substantially stationary relative to the bearing seat. In particular, load zones of this type are created on bearing seats of balance shafts, more specifically on shafts having a center of gravity that is not rotationally symmetric relative to the longitudinal axis about which the shaft rotates in a housing.

It has been recognized that in conventional wheel bearings, the bearing seat is subjected to a significantly lower load or no mechanical load outside the load zone at all. It has therefore been proposed to provide a bearing seat having a width which varies over its circumference, the bearing seat being significantly tapered outside the load zone. A radial needle bearing of this kind is for example from the EP-A2-1775484 known. This design results in a great weight saving. In addition, the rolling elements cantilever locally and temporarily over the width of the bearing seat, so that lubricant can be fed directly to the rolling elements to improve the Wälzkörperschmierung.

Nevertheless, this arrangement has the disadvantage that the rolling elements, here the needle rollers, are not adequately supported in the strongly tapered region. In addition, parts of some rolling elements are constantly covered by the bearing seat and can not be adequately supplied with lubricant.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the above-mentioned problems. It is proposed a radial bearing assembly, which is particularly suitable for supporting a balance shaft in a housing which is reduced in weight, and which allows improved bearing lubrication, but at the same time prevents rolling elements to leave their predetermined position when the bearing is not rotating.

To this end, the invention relates to a radial bearing assembly having an outer part and an inner part, wherein the parts are rotatable with respect to each other about a common longitudinal axis, and rolling elements, which are arranged radially between the outer part and the inner part. The radial bearing assembly is equipped with a bearing seat which is formed on either the inner or the outer part, wherein the rolling elements roll with line contact on the bearing seat.

According to the invention, the bearing seat is provided with at least two rolling surfaces which extend transversely and which are separated longitudinally from each other by a recess, the rolling elements being in line contact with each of the rolling surfaces.

According to a preferred embodiment of the invention, at least one of the rolling surfaces is provided with at least one interruption, which forms a lubricant channel over the longitudinal width of the rolling surface and which is open to the rolling surface, wherein the lubricant channel forms an angle with the contact line of the rolling elements with the bearing seat and so is formed such that parts of the rolling surface on each side of the lubricant channel facing each other longitudinally along a transversely overlapping length, so as to enable the rolling elements are supported by the rolling surfaces in the region of the lubricant channel.

Thanks to the invention, the rolling elements are efficiently supported by a plurality of rolling surfaces, even if with a very reduced axial length. The rolling elements each contact the bearing seat by a plurality of contact lines over the bearing seat width. This makes it possible to improve the stability of the radial bearing arrangement and greatly reduces the weight of the parts with the possibility of greatly reducing the rolling surface width.

The rolling elements are supported by the bearing seat over the entire circumference of the radial bearing arrangement, so that the rolling elements are prevented from falling out or from shifting during a stopping or releasing process.

Another advantage of the present invention is improved lubrication of the rolling elements by means of the lubricant channel provided on at least one of the rolling surfaces of the bearing seat. The contact line between the Rolling elements and the rolling surface is supplied with lubricant, and the recess between two longitudinally adjacent rolling surfaces forms a lubricant reservoir. The lubricant can thus reach all areas of the rolling elements.

Moreover, the lubricant passage is set at an angle relative to both the rotational axis of the radial bearing assembly and a transverse rolling movement direction of the rolling elements. It allows the rolling elements to always be supported by the rolling surface along at least part of the contact line.

• - Die Wälzkörper sind Nadelrollen.
• - Die Wälzkörper sind umfänglich in einem Käfig gehalten.
• - Der äußere Teil ist ein äußerer Ring, wobei der Lagersitz an einer inneren Bohrung des Rings ausgebildet ist.
• - Der äußere Teil ist ein Gehäuse, wobei der Lagersitz an einer inneren Bohrung des Gehäuses ausgebildet ist.
• - Der innere Teil ist ein Innenring, wobei der Lagersitz an einer äußeren Fläche des Rings ausgebildet ist.
• - Der innere Teil ist ein Abschnitt einer rotierenden Welle, wobei der Lagersitz an einer äußeren Fläche in der Welle ausgebildet ist.
• - Der Schmiermittelkanal ist gerade. Alternativ ist der Schmiermittelkanal gekrümmt oder erstreckt sich in einer gewellten oder gezackten Weise.
• - Der Lagersitz weist zumindest einen Längsabschnitt auf, der sich über die gesamte Breite des Lagersitzes erstreckt, wobei die Abrollflächen sich quer von dem Längsabschnitt erstrecken, wobei die Abrollflächen jeweils eine kleinere Breite als der Längsabschnitt haben. Der zumindest eine Längsabschnitt ist vorzugsweise in der Lastzone angeordnet, in welcher eine Querlast auf die Wälzkörper ausgeübt wird.
• - Der Breitenübergang zwischen dem zumindest einen Längsabschnitt und den Abrollflächen ist graduell. Alternativ ist der Breitenübergang stufenweise.
• - Die Abrollflächen sind an dem Lagersitz außerhalb einer Lastzone angeordnet, in der eine Querlast auf die Wälzkörper ausgeübt wird.
• - Zumindest eine der Abrollflächen erstreckt sich quer und senkrecht hinsichtlich der Längsachse.
• - Zumindest eine der Abrollflächen erstreckt sich quer und winklig, wobei ein Winkel mit einer Ebene senkrecht zu der Längsachse gebildet wird.
• - Der Lagersitz weist zwei Abrollflächen auf, die sich jeweils quer und winklig erstrecken, aber in entgegengesetzte Richtungen, um so eine im wesentlichen X-Form mit einer Kreuzung zu definieren.
• - Zumindest ein Schmiermittelkanal ist an der Kreuzung zwischen den zwei winkligen Abrollflächen bereitgestellt, wobei der Schmiermittelkanal sich parallel sich hinsichtlich einer der Abrollflächen erstreckt, um so die Abrollflächen voneinander zu separieren.

According to further aspects of the invention, which are advantageous but not necessarily, such a radial bearing arrangement may have one or more of the following characteristics:

• - The rolling elements are needle rollers.
• - The rolling elements are circumferentially held in a cage.
• - The outer part is an outer ring, wherein the bearing seat is formed on an inner bore of the ring.
• - The outer part is a housing, wherein the bearing seat is formed on an inner bore of the housing.
• - The inner part is an inner ring, wherein the bearing seat is formed on an outer surface of the ring.
• - The inner part is a portion of a rotating shaft, wherein the bearing seat is formed on an outer surface in the shaft.
• - The lubricant channel is straight. Alternatively, the lubricant channel is curved or extends in a wavy or serrated manner.
• - The bearing seat has at least one longitudinal portion which extends over the entire width of the bearing seat, wherein the rolling surfaces extend transversely from the longitudinal portion, wherein the rolling surfaces each have a smaller width than the longitudinal portion. The at least one longitudinal section is preferably arranged in the load zone, in which a transverse load is exerted on the rolling elements.
• The width transition between the at least one longitudinal section and the rolling surfaces is gradual. Alternatively, the width transition is gradual.
• - The rolling surfaces are arranged on the bearing seat outside a load zone in which a transverse load is exerted on the rolling elements.
• - At least one of the rolling surfaces extends transversely and perpendicularly with respect to the longitudinal axis.
• - At least one of the rolling surfaces extends transversely and at an angle, wherein an angle is formed with a plane perpendicular to the longitudinal axis.
• - The bearing seat has two rolling surfaces, each extending transversely and angularly, but in opposite directions, so as to define a substantially X-shape with an intersection.
• - At least one lubricant channel is provided at the intersection between the two angular rolling surfaces, wherein the lubricant channel extends in parallel with respect to one of the rolling surfaces, so as to separate the rolling surfaces from each other.

The invention also relates to a balance shaft which is supported by a radial bearing assembly according to one of the previous embodiments, wherein a portion of the balance shaft is the inner part of the radial bearing assembly, and wherein a bearing seat is formed on an outer surface of the portion of the balance shaft.

list of figures

• 1 ist eine schematische Draufsicht auf einen Teil einer Radiallageranordnung gemäß einem ersten beispielhaften Ausführungsbeispiel der Erfindung,
• 2 ist eine schematische Draufsicht auf einen Teil einer Radiallageranordnung gemäß einem zweiten beispielhaften Ausführungsbeispiel der Erfindung,
• 3a bis 3c sind detaillierte Ansichten von Schmiermittelkanälen, mit denen die Radiallageranordnung von 2 ausgestattet sein kann, gemäß drei Ausführungsbeispielen,
• 4 ist eine schematische Draufsicht auf einen Teil einer Radiallageranordnung gemäß einem dritten beispielhaften Ausführungsbeispiel der Erfindung,
• 5 ist eine schematische Draufsicht auf einen Teil einer Radiallageranordnung gemäß einem vierten beispielhaften Ausführungsbeispiel der Erfindung, und
• 6 ist eine schematische Draufsicht auf einen Teil einer Radiallageranordnung gemäß einem fünften beispielhaften Ausführungsbeispiel der Erfindung.

The invention will now be explained in conjunction with the appended figures as illustrative examples, without limiting the subject matter of the invention. In the attached figures:

• 1 is a schematic plan view of a portion of a radial bearing assembly according to a first exemplary embodiment of the invention,
• 2 is a schematic plan view of a part of a radial bearing assembly according to a second exemplary embodiment of the invention,
• 3a to 3c are detailed views of lubricant channels with which the radial bearing assembly of 2 may be equipped according to three embodiments,
• 4 is a schematic plan view of a part of a radial bearing assembly according to a third exemplary embodiment of the invention,
• 5 is a schematic plan view of a portion of a radial bearing assembly according to a fourth exemplary embodiment of the invention, and
• 6 is a schematic plan view of a portion of a radial bearing assembly according to a fifth exemplary embodiment of the invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The radial bearing arrangement 1 , in the 1 is illustrated, is designed a shaft 2 in particular a balance shaft in a piston engine of a motor vehicle, the shaft being an eccentrically weighted shaft which shifts vibrations into the engine.

The order 1 has an outer part 3 , here an outer ring, an inner part 4, here a section of the shaft 2 , and several rolling elements 5 on, which are arranged between the inner and the outer part. The outer part 3 and the inner part 4 are centered about a common longitudinal axis X1 and are in relative rotation about this axis. In the embodiment of the balance shaft application, the outer part is 3 stationary and the inner part 4 rotates with the shaft about its longitudinal axis X1.

In the following, the specific identifications of the arrangement 1 for this figure and the following, defining the adjectives "longitudinal" and "transverse" and the adverbs "longitudinal" and "transverse" relative to the axis X1. Thus, a longitudinal portion or longitudinal portion is parallel to the axis X1, while a transverse portion or transverse portion perpendicular to this axis is X1.

The outer part 3 has an inner bore 6 on which is a rolling surface for the rolling elements 5 along a contact line 7 forms. The inner part 4 has a bearing seat 8th on, a rolling surface for the rolling elements 5 along a contact line 9 forms. Here you can see the rolling elements 5 have a cylindrical shape, such as the needle rollers, as in 1 shown. Alternatively, it is also possible to use frustoconical or toroidal rolling elements. Alternatively, the Wälzlagerausgestaltung may also have a double row bearing, such as a double row needle roller bearing. Nevertheless, only ball bearings, ie bearings with punctiform contact with the rolling surfaces are not to be regarded as a radial bearing arrangement with line contact and are not encompassed by the present invention.

The rolling elements 5 move along the inner part 4 in the transverse direction Y1.

The rolling elements, for example, circumferentially equidistant from each other and from a Kä 10 added. Alternatively, the rolling bearing spacings may include a variation in cage pocket spacing, such as axial cage splitting.

With further reference to 1 includes the bearing seat 8th of the inner part 4 a longitudinal section 11 with an axial width substantially equal to that of the inner part 4 , The longitudinal section supports the rolling elements 5 along a major part of the rolling element width. The longitudinal section 11 is advantageously provided in a load zone in which a transverse load on the rolling elements 5 is exercised. The load is exerted in the load zone and can efficiently from the outer part 4 the wave 2 on the rolling elements 5 along a contact line 9 be transmitted with maximum width.

According to the invention, the bearing seat 8th of the inner part 4 continue two rolling surfaces 12a and 12b on, extending across the longitudinal section 11 extend in a circumferential direction. The width of the rolling surfaces 12a . 12b each is smaller than the width of the longitudinal section 11 , The sum of the widths of the rolling surfaces 12a . 12b is smaller than the width of the longitudinal section 11 ,

In the first embodiment of the invention, as in FIG 1 illustrated, the rolling surfaces extend 12a . 12b transverse and perpendicular with respect to the longitudinal axis X1, that is parallel to the rolling direction Y1der rolling elements. The rolling surfaces 12a . 12b are parallel to each other and are longitudinally through a recess 13 separated from each other. The rolling elements 5 are in line contact with each of the rolling surfaces 12a . 12b ,

The rolling surfaces 12a . 12b are advantageously on the bearing seat 8th outside a load zone in which a shear load on the rolling elements 5 is exercised. There is neither a load on the rolling elements 5 exercised still transferred, making it the sole purpose of the rolling surfaces 12a . 12b is, the displacement of the rolling elements 5 to support. The widths of the rolling surfaces 12a . 12b are very reduced compared to the longitudinal section. The recess 13 in between allows the use of less material and then greatly reduces the weight of the inner part.

The two rolling surfaces 12a . 12b define two contact lines with a rolling element 5 along the longitudinal direction. This allows it. the stability of the radial bearing assembly 1 to improve. In the embodiment of 1 two rolling surfaces 12a, 12b extend transversely at both longitudinal end sides of the inner part so as to improve the stability of the rolling elements.

The bearing seat 8th supports the rolling elements 5 over the entire circumference of the radial bearing assembly, in the load zone through the longitudinal section 11 and in the no-load zone through the surfaces 12a . 12b , Thereby, a sliding or sliding of the rolling elements can be reliably prevented.

A second embodiment of the invention is in 2 , wherein like elements have the same reference numerals, and differs from the first embodiment of the 1 in that the rolling surfaces 12a . 12b of the bearing seat 8th lubricant channels 13a . 13b exhibit.

Each of the rolling surfaces 12a . 12b has an interruption along its transverse surface. This break consists in recesses or grooves, the lubricant channels 13a , 13b over the entire longitudinal width of the rolling surfaces 12a . 12b form and are open to the rolling surfaces. Lubricant can then from both longitudinal sides of the rolling elements 5 be guided. In addition, the channels 13a . 13b open, allowing lubricant between the rolling surfaces 12a . 12b and the rolling elements 5 can be distributed in the contact line.

In addition, the lubricant channels 13a . 13b not parallel to the longitudinal axis of rotation X1 and are not perpendicular to the transverse movement direction Yl, but the channels are more angled to it. The channels 13a . 13b form an angle with the contact line of the rolling elements 5 with the rolling surfaces 12a . 12b , The channels 13a . 13b are designed to have sections of the rolling surfaces 12a . 12b on each side of the lubricant channels 13a, 13b are opposed to each other along a transverse overlapping length O1. As a result, the rolling elements 5 always through the rolling surfaces 12a . 12b over the entire circumference of the bearing seat 8th supports, even in the area of the lubricant channels 13a, 13b. The angular orientation of the channels 13a . 13b generates a preferred pumping direction of the lubricant with respect to the transverse movement direction Y1 of the rolling elements 5 , allowing lubricant through the channels and thus to all regions of the rolling elements 5 to be led.

In the embodiment of 2 have the channels 13a . 13b the same width, same orientation and are aligned longitudinally. Alternatively, the channels may have different widths and orientations. The channels can not be aligned longitudinally. According to another embodiment, only one of the two rolling surfaces 12a . 12b equipped with a lubricant channel.

In the embodiment of 2 are the lubricant channels 13a . 13b just. Alternatively, the lubricant channels may be curved or extend in a wavy or serrated manner.

Furthermore, the recess 13 between the two rolling surfaces 12a . 12b Define a lubricant reservoir to a sufficient amount of lubricant for the rolling elements 5 sure.

The 3a to 3c disclose three alternative embodiments of the lubricant channels 13 that are in the rolling surfaces 12a . 12b the bearing seat of the inner part 4 are provided.

In 3a has the lubricant channel 13 a width L1 forms an angle A1 with the longitudinal direction and defines an overlap length O1.

As in 3b illustrated, it is possible the orientation of the lubricant channel 13 to change, wherein an angle A2 is smaller than A1. The consequence is an overlap length O2 which is smaller than O1.

In another embodiment, the width L3 of the lubricant channel 13 be enlarged. If the orientation angle A1 remains the same, the overlap length decreases. In turn, when the rolling surface is adapted to have a first portion on a first side of the channel 13 which is longitudinal about a width D3 with respect to a second part on a second side of the channel 13 is shifted, the overlap length O1 can remain the same.

These configurations of the lubricant channels may be used, among other things depending on the application, the required amount of lubricant to be supplied to the rolling elements, the movement of the rolling elements.

A third embodiment of the invention is in 4 illustrated in which the same elements have the same reference numerals, and differs from the second embodiment of the 2 in that the rolling surfaces 12a . 12b two lubricant channels each 13a and 13c respectively. 13b and 13d exhibit.

The channels 13a . 13b . 13c and 13d are oriented in the same direction, forming a similar angle with the axis X1 and the direction Y1. Alternatively, the channels may have different directions and widths.

The channels 13a and 13d the rolling surfaces 12a respectively. 12b are aligned longitudinally. The channels 13c and 13b the rolling surfaces 12a respectively. 12b are also aligned longitudinally. Alternatively, the channels may be transversely offset.

A fourth embodiment of the invention is in 5 illustrated in which like elements have the same reference numerals, and differs from the second embodiment of the 2 in that the bearing seat 8th rolling surfaces 14a . 14b in angled direction.

The rolling surface 14a extends from the longitudinal section 11 transverse and angular, forming an angle with the direction Y1. The rolling surface 14a extends from a longitudinal side of the bearing seat 8th of the inner part 4 toward the opposite side of the bearing seat 8th ,

The rolling surface 14a extends from the longitudinal section 11 transverse and angular, forming an angle with the direction Y1. The rolling surface 14b extends from the opposite longitudinal side of the bearing seat in the direction of the rolling surface 14a towards the opposite side of the bearing seat 8th , The rolling surfaces 14a and 14b extend angled in opposite directions so as to define a substantially X-shape.

The rolling surface 14b is with lubricant channels 15a . 15b at the intersection between the two angled rolling surfaces 14a . 14b fitted. The lubricant channels 14a . 14b are angled and extend parallel with respect to the other rolling surface 14a so the rolling surfaces 14a . 14b to separate from each other. Every channel 15a . 15b is between the rolling surfaces 14a and a portion of the rolling surface 14b provided.

A first section of the rolling surface 14b on one side of the lubricant channel 15a lies along the rolling surface 14a opposite to the support of the rolling elements 5 in this area of the canal 15a sure. Similarly, there is a second section of the rolling surface 14b on one side of the lubricant channel 15b along the rolling surface 14a opposite to the support of the rolling elements 5 in the area of the canal 15b sure. Furthermore, the rolling surface 14b and channels 15a . 15b designed such that both sections of the rolling surface 14b on both sides of the lubricant channels 15a . 15b longitudinally opposed to each other along a transverse overlap length O4. Then the rolling elements 5 always from the rolling surface 14a and the two sections of the rolling surface 14b in the area of the lubricant channels 15a . 15b supported. In the embodiment of 5 is the rolling surface 14a in the middle and the rolling surface 14b is longitudinal on both sides of the rolling surface 14a divided into two sections, so as to improve the stability of the rolling elements 5.

The angled direction of the rolling surfaces 14a . 14b It also allows lubricant over the entire longitudinal width of the rolling elements 5 is distributed, which prevents the emergence of a situation in which too little or absolutely no lubricant to the rolling elements 5 is provided, in particular in the central region of the rolling elements. No area of the rolling elements is not exposed to a recess or a lubricant.

A fifth embodiment of the invention is in 6 illustrated in which like elements have the same reference numerals, and differs from the fourth embodiment of the 5 in that the rolling surface 14b additionally angled lubricant channels 15c . 15d having.

The lubricant channels 15c . 15d are still designed to support the rolling elements 5 sure.

As an alternative, not shown, more lubricant channels may be provided on the rolling surfaces 14b, or may be on the other rolling surface 14a , or on both rolling surfaces 14a . 14b be provided.

Representative, non-limiting examples of the invention have been described above in detail with reference to the attached drawings. This detailed description is merely intended to teach one skilled in the art further details in order to practice preferred aspects of the present teachings and is not intended to limit the scope of the invention. Moreover, each of the additional features and teachings disclosed above may be used separately or in conjunction with other features and teachings to provide improved radial bearing arrangements.

In addition, various features of the representative examples described above, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly listed to provide additional useful embodiments of the present teachings.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2014935 A1 [0002]
• EP 1775484 A2 [0003]

Claims (9)

A radial bearing assembly (1) having an outer part (3) and an inner part (4), said parts (3, 4) being rotatable with respect to each other about a common longitudinal axis (X1), and with rolling elements (5) radially in between outer part (3) and the inner part (4) are arranged, wherein the radial bearing assembly (1) is provided with a bearing seat (8) formed on either the inner or the outer part (4), wherein the rolling bodies (5 Rolling with line contact on the bearing seat (8), characterized in that the bearing seat (8) with at least two rolling surfaces (12a, 12b, 14a, 14b) is provided, which extend transversely and longitudinally separated by a recess (13) wherein the rolling elements (5) are in line contact with each of the rolling surfaces (12a, 12b; 14a, 14b). Arrangement according to Claim 1 wherein at least one of the rolling surfaces (12a, 12b; 14a, 14b) is provided with at least one interruption having a lubricant passage (13a, 13b; 13c, 13d; 15a, 15b; 15c, 15d) across the longitudinal width of the rolling surface (12a, 12b, 14a, 14b) and is open to the rolling surface (12a, 12b; 14a, 14b), the lubricant channel (13a, 13b; 13c, 13d; 15a, 15b; 15c, 15d) forming an angle (A1, A2). formed with the contact line (9) of the rolling elements (5) with the bearing seat (8) and is designed such that portions of the rolling surface (12a, 12b, 14a, 14b) on both sides of the lubricant channel (13a, 13b, 13c, 13d; 15a, 15b, 15c, 15d) face each other along a transverse overlap length (O1, O2, O3) so as to allow the rolling elements (5) from the rolling surface (12a, 12b; 14a, 14b) in the region of the lubricant channel (13a, 13b, 13c, 13d, 15a, 15b, 15c, 15d) to be supported. Arrangement according to one of the preceding claims, wherein the rolling elements (5) are needle rollers. Arrangement according to one of the preceding claims, wherein the inner part (4) is a portion of a rotating shaft (2), wherein the bearing seat (8) on an outer surface of the shaft (2) is formed. Arrangement according to one of the preceding claims, wherein the bearing seat (8) has at least one longitudinal section (11) which extends over the entire width of the bearing seat (8), wherein the rolling surfaces (12a, 12b; 14a, 14b) extend transversely from the Each longitudinal portion (11) and the rolling surfaces (12a, 12b, 14a, 14b) each have a smaller width than the longitudinal portion (11). Arrangement according to one of the preceding claims, wherein at least one of the rolling surfaces (12a, 12b) extends transversely and perpendicularly with respect to the longitudinal axis (X1). Arrangement according to one of Claims 1 to 5 , wherein at least one of the rolling surfaces (14a, 14b) extends transversely and angularly, forming an angle with a plane (Y1) perpendicular to the longitudinal axis (X1). Arrangement according to Claim 7 wherein the bearing seat (8) has at least two rolling surfaces (14a, 14b) each extending transversely and angularly but in opposite directions so as to substantially define an X-shape. Arrangement according to Claim 8 wherein at least one lubricant channel is provided at the intersection between the two angular rolling surfaces, the lubricant channel (15a, 15b) extending parallel to one of the rolling surfaces (14a, 14b) so as to separate the rolling surfaces (14a, 14b) from each other.

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