WO1999031398A1

WO1999031398A1 - Angular contact bearing unit with one piece inner bearing element

Info

Publication number: WO1999031398A1
Application number: PCT/NL1998/000705
Authority: WO
Inventors: Hendrikus Jan Kapaan; Johannes Franciscus Sanden
Original assignee: Skf Engineering And Research Centre B.V.
Priority date: 1997-12-17
Filing date: 1998-12-08
Publication date: 1999-06-24
Also published as: KR20010033245A; EP1038113A1; WO1999031397A1; AU1446699A; AU5348298A; JP2002508485A

Abstract

A double row angular contact rolling element bearing unit comprises an inner bearing element (1) and an outer bearing element (2) having two pairs of opposite races, as well as two rows of rolling elements which are in rolling contact each with a pair of races. The inner bearing element (1) comprises a single inner bearing piece which carries two raceways (15, 16) of equal or different diameters, and the outer bearing element (2) comprises two outer ring pieces (3, 4) each carrying at least one raceway (17, 18), which two outer ring pieces are mutually connected. The outer ring pieces are mutually connected by connecting means (5) providing an axial adjustability of said outer ring pieces (3, 4).

Description

Angular contact bearing unit with one piece inner bearing element

The invention is related to a double row angular contact rolling element bearing unit, comprising an inner bearing element and an outer bearing element having two pairs of opposite races, as well as two rows of rolling elements which are in rolling contact each with a pair of races, said inner bearing element comprising a single inner bearing piece which carries two raceways of equal or different diameters, and said outer bearing element comprising two outer ring pieces each carrying at least one raceway. Such bearing units, which are known from US-A- 1909525, .are widely used in several fields, such as e.g. automotive applications. A bearing unit as used in automotive applications is known from DE-A-4412307.

The known bearing units of this type have an outer ring consisting of one piece, and a split inner ring consisting of two inner ring halves, which may or may not be mutually connected. This layout of the bearing unit with a split inner ring has several disadvantages.

A major disadvantage of said bearings is related to the bearing clearance. For each individual inner ring, the proper width has to be obtained by grinding such that required tolerance is achieved. Another disadvantage concerns the mounting and dismounting from a shaft. As a result of fretting corrosion between the inner rings and shaft under loading conditions, the inner ring halves are difficult to dismount, involving the risk that the connection between these components breaks and the innermost ring stays behind.

At misaligned condition during assembly on the shaft, the connection can be damaged.

These disadvantages have been removed partly by the unit as known from US- A- 1909525, which comprises a single inner bearing piece which carries two raceways, and the outer bearing element of which comprises two outer ring pieces each carrying one raceway, which two outer ring pieces are mutually connected. However, said bearing unit is less suitable for e.g. automative applications. It has the disadvantage that it is difficult to obtain the desired preload or axial clearance. The object of the invention is to provide an angular contact bearing unit which does not have this problem. This object is obtained in that the outer ring pieces are supported with respect to each other by a connecting means providing an axial adjustability of said outer ring pieces. Before connecting the outer ring pieces definitively, the bearing preload or axial preload can be controlled judiciously by axially adjusting the connecting means.

Furthermore, as the inner bearing element now consists of a single inner bearing piece, such as a single ring piece, it is also strong enough to withstand all loadings to which it is subjected, for instance the loadings as occur during removal from a shaft of the bearing in question. Also, an oil injection process can be considered for dismounting the inner ring piece from the shaft. By virtue of this concept small ball/roller guidance in the inner ring piece is no longer required, which allows for optimal manufacturing, e.g. cold forming techniques.

The bearing unit according to the invention can be designed in many ways. For instance, the raceways may be manufactured directly in the inner ring piece and the outer ring pieces. Also, raceway surface modification e.g. by means of laser cladding or coating are feasible. Furthermore, induction hardening or through hardening are possible.

According to a preferred embodiment, the outer ring pieces each carry a separate outer bearing ring provided with a raceway, which outer bearing rings are resting at axial abutments of the outer ring pieces, said abutments facing away from each other.

In this embodiment, different kinds of metallic or non-metallic materials can be used for the inner ring piece and outer ring pieces and the bearing rings including raceways, such as respectively low carbon steel and high carbon steel, cast iron with or without a laser cladded bearing raceway, components made using powder metallizing processes, aluminium for the connecting ring halves.

The outer ring pieces can be connected to each other in many different ways. According to a first possibility, the outer ring pieces at their facing sides may rest against an interposed ring shaped connecting element. In case the ring shaped connecting element comprises two connecting element halves which are mutually connected at their facing ends, such ring shaped element can be applied in a way whereby the appropriate clearance or a preload is established in the bearing. Said halves may be welded together.

In that respect, in a radial cross-section the ring shaped connecting element can be tapered at least at one side, and the outer ring pieces may have a corresponding shape, such that on radial inward compression of the connecting element halves, the outer ring pieces are moved axially providing the required bearing clearance or preload.

The two connecting element halves may be mutually connected in other ways as well, e.g. by means of bolts, an additional clamping ring, or welding. The bearing unit according to the invention has some further advantages, which are related to its adaptability for integrated or additional functions so as to form many different embodiments.

In this respect, at least one of the outer ring pieces may have an outwardly extending mounting flange. Also, at least one of the outer ring pieces may be used as a drive means or act as a support for e.g. a brake disc, or carry a brake disc or brake drum.

Preferably, the brake disc or brake drum is connected to a centring piece which is mounted on one of the ring pieces by means of a close tolerance fit. This embodiment offers very flexible, customized designs for automotive, railway, linear movement actuators, and many other industrial applications for drive and support means with rotating inner ring and/or rotating outer ring pieces.

Furthermore, sensors can be integrated in the bearing unit for controlling and monitoring purposes e.g. rotational speed, pressure, temperature, position etc.

Also, several different types of centring pieces may be applied to a standard ring piece, and different materials may be applied for such components.

The other ring piece carries means for mounting a wheel thereto, which other ring piece and the centring piece engage each other by means of splines. The connection by means of splines which e.g. may be oriented radially or axially, allows for a high torque transfer between the brake disc or brake drum and the wheel to be braked.

In specific embodiments, the inner bearing element may have stepped bore diameters. Such embodiment is in particular suitable for supporting a pinion gear. Furthermore, the inner ring piece may have radially outwardly extending flanges for support of the rolling elements in an "O"-type contact bearing.

Also, at least one row of rolling elements may comprise balls, and at least one row of rolling elements may comprise rollers. A combined application of a row with rollers, and a row with balls, with or without cages, is also feasible. Rows with rollers or balls of mutually different dimensions are possible as well.

The outer ring pieces can be connected in different ways, e.g. by welding such as laser welding. Furthermore, the outer ring pieces and/or the connecting element can also be connected by means of glueing. The inner bearing element may be either constituted by a single inner ring piece, or by a shaft.

The invention will further be explained with reference to the embodiments shown in the figures.

Figure 1 shows a double row angular contact rolling element bearing unit according to the invention.

Figure 2 shows a truck wheel hub unit which incorporates the bearing according to the invention.

Figure 3 shows a second embodiment of a truck wheel hub unit.

Figure 4 shows a third embodiment of a truck wheel hub unit. Figure 5 shows a pinion gear bearing unit incorporating a bearing unit according to the invention.

Figure 6 shows a gear bearing transmission unit.

Figure 7 shows a further variant of the bearing according of the invention.

Figure 8 shows a train wheel bearing unit. Figures 9-11 show further embodiments of the bearing unit.

Figures 12 show an embodiment incorporating a shaft.

Figures 12-20 show the several steps of a method for assembling a bearing unit according to the invention.

The double row angular contact rolling element bearing unit shown in figure 1 comprises an inner ring 1 consisting of a single inner ring piece, and an outer ring 2. The outer ring 2 comprises two outer ring pieces 3, 4, which are mutually connected by the ring shaped connecting element 5. This ring shaped connecting element 5 consists of two or more connecting ring halves 6, 7, which at diametrically opposite locations are welded together; one of the welds 8 is shown in figure 1.

Connecting ring halves 6 have tapered sides 9, 10, which rest against correspondingly tapered sides 11, 12 of the outer ring pieces 3, 4. By pressing the outer connecting ring halves 6, 7 towards one another, outer ring pieces 3, 4 are axially pressed away from each other, thus ensuring the required clearance or preload between the two pairs of rolling elements 13, 14.

The rolling elements 13, 14 in question are in rolling contact with the raceways 15, 16 of the one piece inner ring 1, and raceways 17, 18 of the outer ring pieces 3, 4.

Additionally, the connecting ring halves 6, 7 may be welded to the outer ring pieces 3, 4, e.g. by laser welding.

The bearing unit shown in figure 1 is greased and sealed for life by means of seals 19, 20 which are known per se. The inner ring piece 1 has a screwthreaded bore 162, into which a pipe section

160 may be screwed via a hole 161 in connecting ring 5. Through pipe section 160 pressurized oil can be fed between the engaging faces of the inner ring piece one and a shaft (not shown), for ease of removing the bearing unit.

The embodiment of figure 2 shows a bearing unit according to the invention incorporated in a truck wheel hub unit. In this truck wheel hub unit, an inner ring consisting of a single inner ring piece 1 has been applied as well. The two outer bearing rings 23, 24 are contained in respective outer ring pieces 21, 22. These outer ring pieces 21, 22 are pressed axially outwardly by means of the connecting ring halves 6, 7, which together form connecting ring 5. The outer bearing rings 23, 24 bear against the axial abutments 25, 27 formed on the outer ring pieces 21 respectively 22.

One of the outer ring pieces 21 carries an external flange 27 having wheel bolts 28 for connecting a wheel thereto.

The other outer ring piece 22 has a cylindrical outer surface 29, onto which centring piece 30 has been connected by means of a close tolerance fit. The cylindrical outer surface 29 of the outer ring piece 22 merges into a similar cylindrical outer surface 31 of the connecting ring element 5, and possibly a corresponding surface on the other outer ring piece 21. The centring piece 30 has an inner cylindrical surface 32 which allows a close tolerance fit with the opposing surfaces 30, 31.

The outer ring piece 21 has axially extending splines 33, which engage similar axially oriented splines 34 on the centring piece 30. The centring piece 30 is connected to the outer ring piece 21 by means of bolts 35, screwed in screwthreaded holes 36 in said outer ring piece 21. In the alternative, screwthreaded holes may be provided in centring piece 30, so as to mount the bolts 35 from the side of outer ring piece 21.

The centring piece 30 furthermore carries a brake disc 37 or brake drum. The braking torque exerted by the brake pads on brake disc 37 are transferred via the splines 33, 34 towards the wheel bolts 28 and finally to the wheel connected thereto, for effecting a braking action.

The centring piece 30 may furthermore carry an outer ridge 38, onto which the jaws of a calliper for removing the bearing from a shaft 39 can be applied. The hub unit, in particular in the inner ring 1 thereof, is secured onto the shaft

39 by means of a nut 40, which engages the screwthreaded end 41 of the shaft 39. Although in figure 2 the raceways are formed on outer bearing rings 23, 24, the raceways may alternatively also be formed directly in the outer ring piece 21, 22. Said outer ring pieces 21, 22 may consist of cast iron. By means of a laser cladding process, the desired quality for the raceways may be obtained.

The embodiment of figure 3 comprises to a large extent the same components as the embodiment of figure 2. However, this embodiment is related to a truck hub unit, the outer ring piece 42 of which carries an outer flange 27 with wheel bolts 28, and the other outer ring piece 43 of which carries an outer flange 46, e.g. for connecting a brake drum or brake disc 37 thereto.

The connection between such brake drum or brake disc and the wheel connected to the wheel bolts 28 is now by way of the outer ring pieces 43 and the connecting ring element 5, which is welded by means of e.g. laser welds 47.

The embodiment shown in figure 4 again to a considerable extent corresponds to the embodiments of figures 2 and 3.

The outer ring piece 48 carries an external flange 49, having holes 54 connecting an element thereto, e.g. a brake disc 163 or brake drum, and a flange 164 for connecting a wheel. Also a counter ring 170 for a sensor, e.g. an ABS-sensor, may be provided.

The embodiment shown in figure 5 consists of a bearing unit having a single piece inner ring 51 having stepped portions 52, 53. The outer ring 54 is constituted by two outer ring pieces 55, 56, mutually connected by connecting ring element 57 comprising two halves as according to the preceding embodiments.

The inner ring 51 and the outer ring 54 are mutually supported by two rows of rollers 58, 59. The rollers 59 are of a bigger size than the rollers 58, which makes this bearing particularly suitable for taking up the drive torque of a pinion bearing unit.

Rollers 58 are contained in a cage 101.

The inner ring 51 is clamped between the abutment 63 of the shaft 60, and the nut 62 which co-operates with the screwthreaded portion 64 of the shaft 60. Figure 6 shows a further embodiment which is suitable for a bearing transmission unit. By means of full complement rollers 59 and rollers 58 which are separated by cage 101, the inner ring 51 co-operates with two outer rings 102, 103 which are also rotatable with respect to each other. To that end, a bearing 104, having balls or rollers 105 separated by a cage 106, co-operates with raceways 107, 108 of respectively the outer ring 102 and a thrust bearing ring 109. The thrust bearing ring 109 in turn engages connecting element 110, which by means of wedge-shaped surfaces 111 engages outer ring 103.

The outer ring 103 includes an integrated gear 112. Outer ring 102 furthermore comprises a mounting flange 113.

The inner bore of the inner ring 51 may comprise splines or a thread for connecting purposes. Instead of balls 10, 8, rollers or needles may be used.

Figure 7 shows an embodiment having an inner ring 81 consisting of one piece, and an outer ring 82 comprising a connecting means carried out as a sleeve 83 and outer bearing rings 84, 85. The rolling elements 86, 87 in question, held by means of cages 88, 89, are adjusted in axial direction away from each other by means of lips 90, 91. These lips 90, 91 have been pressed inwardly out of the sleeve 83, leaving a hole 92. The lips 90, 91 and holes 92 have been formed at regular intervals along the circumference of the sleeve 83. By controlling their formation, the required axial clearance or preload is obtained in the bearing unit. By means of seals 19, 20, the bearing is sealed. The inner bore of the inner ring 81 may comprise a screw or ball thread for engagement with a ball screw or roller screw of a linear motion transmission.

The embodiment of figure 8 shows a railway wheel bearing unit 120 by means of which shaft 121 is rotatably supported in support 122 of a railway bogey. The inner ring 1 is mounted on stub 123 of the axle 121. By means of cap 124 and bolts 125, and screwthreaded holes 126 in axle stub 123, the inner ring 1 is pressed onto the shoulder 127 of the axle 121, through rings 128, 129.

The rollers 13, 14 each engage an outer bearing ring 23, 24, which bearing rings are supported with respect to each other by means of connecting element 5. A bore 130 respectively 131 extends through connecting element 5 and inner ring 1. Through bore 130, an oil feed pipe may be connected to hole 131, for supplying oil under pressure in between the axle stub 123 and the inner ring 1. Thereby, the inner ring 1 can be dismounted easily.

The embodiment of figure 9 shows a double row angular contact bearing having a series of balls 65 and a series of tapered rollers 66. The single inner ring piece 67 of the bearing has corresponding raceways 68, 69. The opposite raceways 70, 71 have been formed in the outer ring pieces 72, 73, which are mutually connected by connecting ring element 74.

By means of cages 75, 76, the elements 65, 66 are held at the proper mutual distance. Figure 10 shows an embodiment having an inner ring piece 1 and two outer bearing rings 23, 24, which engage each other by means of spherical rollers 141, 142. The rows of rollers 141, 142 are separated by means of cages 143. Figure 10A shows one pocket 144 of a plastic snap cage 143. This pocket 144 is enclosed between two prongs 145, 146, each provided with a cavity 147 for providing some resilience. As a result of this resilience, the prongs 145, 146 can be slid sideways onto the rolling elements 141. Moreover, the inner diameter of the cages 143 is greater than the outer diameter of the supports 148 which border the raceways of the rolling elements 141, 142, such that a correct mounting of the cages 143 is ensured. The embodiment of figure 1 1 shows an inner ring piece and outer bearing rings having rolling elements 151 which are shaped according to a hollow curve.

Figure 12 shows a bearing unit wherein the inner bearing piece is constituted by a solid shaft 160 e.g. for a pinion bearing unit. Said shaft has two raceways 161, 162 directly manufactured in its outer surface. The outer ring of the bearing unit is constituted by outer ring pieces 3, 4, mutually connected by connecting ring halves 7 (only one is shown), welded together by means of a weld 8.

Onto the shaft 160, a flange 163 and bevel gear 164 have been mounted respectively by means of a weld 165 and a key/spline connection 166 together with a bolt 167.

The shaft may also be carried out with two flanges at its opposite ends, either integrally or with a separate mounting piece.

The assembly procedure shown in figures 13-20 provides a further method for manufacturing a bearing according to the invention. The inner ring 1 is in an upright position, whereafter the rolling elements 13 and corresponding cage 44 are applied on the raceway 15. Said cage 44 has an inner diameter which is larger than the outer diameter of the end flanges 176.

Subsequently, as shown in figure 14, one of the outer rings 3 is applied around the rolling elements 13. As shown in figure 4, the second outer ring 4 is positioned onto the first outer ring 3. Subsequently, as shown in figure 16, the second set of rolling elements 14 with corresponding cage 45 is applied onto the raceway 16.

By means of lifting tool 177, the outer ring 4 is lifted so as to obtain the phase of figure 17 (after tilting the components of 90° towards a horizontal position). A connecting element 170, comprising an inner flexible, e.g. rubber, ring 170 with transverse, convexly shaped lips or plates 174 bonded thereto, is placed around the assembly. Initially, the connecting element 170 is kept in a stretched position by means of tool 177.

After removal of the tool 177, the connecting element reaches a position between the two outer rings 3, 4: see figure 18. In particular, it presses against the facing grooves 171, 172 in the outer rings 3, 4. Finally, by means of a tool (not shown) the convexly curved lips or plates are deformed towards a concave shape, as shown in figure 19, whereafter the assembly of the bearing in question has been completed.

As shown in figure 20, a flange 180 may finally be connected onto the outside of the bearing unit, between the outer rings 3, 4.

Claims

1. Double row angular contact rolling element bearing unit, comprising an inner bearing element (1, 51, 160) and an outer bearing element (2, 54, 82) having two pairs of opposite raceways (15, 16; 17, 18; 68-71), as well as two rows of rolling elements (13, 14; 58, 59; 65, 66) which are in rolling contact each with a pair of raceways (15, 16; 17, 18, 68-71), said inner bearing element comprising a single inner bearing piece (15, 51, 160) which carries two raceways of equal or different diameters, and said outer bearing element (2, 54, 82) comprising two outer ring pieces (3, 4; 23, 24; 55, 56; 72, 73; 84, 85) each carrying at least one raceway, characterized in that the outer ring pieces (3, 4; 23,24; 55, 56; 72, 73; 84, 85) are supported with respect to each other by a connecting means (5) providing an axial adjustability of said outer ring pieces for adjusting the bearing clearance, said connection means (5) being permanently and unreleasably connected.

2. Bearing unit according to claim 1, wherein the outer ring pieces (21, 22; 42, 43) each carry a separate outer bearing ring (23, 24) provided with a raceway, which outer bearing rings (23, 24) are resting against axial or radial (1) abutments (25, 26) of the outer ring pieces (21, 22; 42, 43), said abutments (25, 26) facing away from each other.

3. Bearing unit according to claim 1 or 2, wherein the outer ring pieces (21, 22; 42, 43) at their facing sides rest against an interposed ring shaped connecting element (5).

4. Bearing unit according to claim 3, wherein the ring shaped connecting element (5) comprises at least two connecting element halves (6, 7) which are mutually connected at their facing ends.

5. Bearing unit according to claim 3, wherein the ring shaped connecting element (5) comprises a ring with at least one slit.

6. Bearing unit according to any of claim 1-5, wherein in a radial cross-section the ring shaped connecting element (5) is tapered at least at one side, and the outer ring pieces (21, 22; 42, 43) have a corresponding shape, such that on radial inward compression of the connecting element (5), the outer ring pieces (21, 22; 42, 43) reduce the axial clearance between raceways and rolling elements.

7. Bearing unit according to claim 4, 5 or 6, wherein the connecting element (5) is connected to the adjoining outer ring pieces (21, 2; 42, 43) by means of welding.

8. Bearing unit according to claim 4, 5 or 6, wherein the connecting element (5) is connected to the adjoining outer ring pieces by means of glueing.

9. Bearing unit according to claim 4, 5 or 6, wherein the connecting element (5) is connected to the adjoining outer ring pieces (21, 2; 42, 43) by means of a mechanical connecting means, e.g. a bolted connection, cold deformed connection ring, etc.

10. Bearing unit according to any of the preceding claims, wherein at least one of the outer ring pieces (21, 42, 43, 48) has an outwardly extending mounting flange

(27, 46, 49).

11. Bearing unit according to any of the preceding claims, wherein at least one of the outer ring pieces (22, 43) carries a brake disc (37) or brake drum.

12. Bearing unit according to claim 11, wherein the brake disc (37) or brake drum is connected to a centring piece (30) which is mounted on one of the ring pieces (22) by means of a close tolerance fit.

13. Bearing unit according to claim 12, wherein the other ring piece (21) carries means (27, 28) for mounting a wheel thereto, which other ring piece (21) and the centring piece (30) engage each other by means of splines (33, 34).

14. Bearing unit according to any of the preceding claims, wherein the inner bearing element (51) has stepped bore diameters (52, 53).

15. Bearing unit according to any of the preceding claims, wherein the inner ring piece comprises at least one hole for passing through a gas, or a liquid, or electrical/electronic wires.

16. Bearing unit according to any of the preceding claims, wherein the inner bearing element has radially outwardly extending flanges for support of the rolling elements in an "O"-type contact bearing configuration.

17. Bearing unit according to any of the preceding claims, wherein at least one row of rolling elements comprises balls (65).

18. Bearing unit according to any of the preceding claims, wherein at least one row of rolling elements comprises cylindrical rollers (13, 14, 66).

19. Bearing unit according to any of the preceding claims, wherein at least one row of rolling elements comprises spherically shaped rollers.

20. Bearing unit according to any of the preceding claims, wherein at least one row of rolling elements comprises tapered rollers.

21. Bearing unit according to any of the preceding claims, wherein the outer ring pieces (3, 4; 21, 22; 42, 43; 55, 56; 72, 73) and/or the connecting element (5) are connected by means of welding, e.g. laser welding.

22. Bearing unit according to any of claims 1-18, wherein the outer ring pieces and/or the connecting element are connected by means of glueing.

23. Bearing unit according to any of the preceding claims, wherein the rolling elements of at least one row are separated by means of a cage (75, 76; 88, 89; 143).

24. Bearing unit according to any of the preceding claims, wherein the rolling elements of at least one row are arranged according to a full complement layout.

25. Bearing unit according to any of the preceding claims, wherein the single inner bearing piece is a ring piece (15, 51).

26. Bearing unit according to any of the claims 1-23, wherein the single inner bearing piece is a solid shaft (160).

27. Bearing unit according to any of the preceding claims, comprising integrated sensors or associated components (e.g. counter ring) for performing controlling/monitoring functions, e.g. rotational speed or speed difference, pressure, temperature, position etc.

28. Bearing unit according to any of the preceding claims, wherein the inner bearing element has an aperture for feeding gas or oil to its inner surface, or for passing electric wires.

29. Bearing unit according to any of the preceding claims, wherein different components, such as rings and ring pieces, comprise different metals/non-metals.

30. Bearing unit according to any of the preceding claims, wherein the connection means (5) are welded.

31. Bearing unit according to any of the preceding claims, wherein the connection means (5) are glued.

32. Bearing unit according to claim 1 or 2, wherein the ring-shaped element comprises a multitude of spacer elements (174).

33. Bearing unit according to claim 32, wherein the spacer elements comprise sheet elements, e.g. strips or plates (174).

34. Bearing unit according to claim 33, wherein the sheet metal elements (174) are accommodated in facing grooves (171, 172) in the outer rings.

35. Bearing unit according to claim 32, 33, 34, wherein the spacer elements (174) are before assembly mutually connected, e.g. on a flexible membrane (170) by glueing, vulcanising etcetera.

36. Bearing unit according to claim 35, wherein the flexible membrane (170) is a non-metallic shaped ring, e.g. rubber ring.

37. Bearing unit according to claim 30, wherein the flexible membrane (170) is sealingly connected to the outer rings (3, 4).

38. Bearing unit according to any of the preceding claims, wherein the bearing clearance can be positive (play), zero or negative (preload).

39. Method for assembling a double row angular contact rolling element bearing unit according to any of the preceding claims, said bearing unit, comprising an inner bearing element and an outer bearing element having two pairs of opposite raceways, as well as two rows of rolling elements which are in rolling contact each with a pair of raceways, said inner bearing element comprising a single inner bearing piece which carries two raceways of equal or different diameters, as well as radially outwardly extending end flanges and said outer bearing element comprising two outer ring pieces each carrying at least one raceway, characterized by the steps of: - adjusting the bearing clearance by means of the connecting means,

- measuring the resistance against relative rotational movements (friction torque) of inner bearing element and outer bearing element, during adjusting the bearing clearance,

- adjusting the bearing clearance exerted by the connecting means until resistance against relative rotational movements is obtained,

- permanently connecting the connecting means.

40. Method according to claim 39, wherein the connecting means are permanently and non-releasably connected by means of welding, glueing etcetera.

41. Method according to claim 40, wherein the spacer elements are initially curved convexly on the outside of the ring, comprising the step of cold rolling said spacer elements 50 as to obtain a concave curved outside of the ring

42. Truck wheel hub unit, comprising a bearing unit according to any of the preceding claims.

43. Pinion bearing unit, comprising a bearing unit according to any of claims 1-38.

44. Railway bearing unit, comprising a bearing unit according to any of claims 1-38.

45. Transmission bearing unit, comprising a bearing unit according to any of claims 1-38.

46. Actuator bearing unit, comprising a bearing unit according to any of claims

1-38.

47. Drill bit bearing unit, comprising a bearing unit according to any of claims 1-38.