Rolling bearing and axle bearing for railway vehicle

Abstract

To provide a rolling bearing and an axle bearing for a railway vehicle which can rigidly attach a sealing device to a bearing side with an attachable / detachable configuration, which has a high sealing property, and which can be stably and continuously used even in a harsh environment.SOLUTION: A bearing includes an inner ring, an outer ring, a plurality of rolling elements, and a sealing device for sealing between the inner ring and the outer ring. The sealing device includes: a seal case fitted at a shoulder part of the outer ring; and a seal member. The seal case includes: a case outer ring part internally fitted with the shoulder part of the outer ring; and a case inner ring part internally fitted with the case outer ring part. The case inner ring part includes an expanded diameter part with a larger outer diameter at a tip end part in an axial direction. The case outer ring part includes a deformation part which deforms in a diameter expansion direction by the expanded diameter part of the internally fitted case inner ring part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing and an axle bearing for a railway vehicle. [Background technology]

[0002] Generally, a railway vehicle bearing unit is rotatably attached to the end of an axle of a railway vehicle, supporting the axle rotatably and supporting the weight of the vehicle.

[0003] This type of railway vehicle bearing unit generally includes a double-row tapered roller bearing or cylindrical roller bearing (hereinafter simply referred to as a bearing), which is an example of a railway vehicle bearing, and supports the railway vehicle axle. This bearing includes a single outer ring and two inner rings, each divided into a separate row, and a sealing device is arranged between the two rows of raceway surfaces of the outer ring and the inner ring.

[0004] Bearings with the above-described structure, for example those used in railway vehicle bogies, are important components, and so are disassembled and inspected during regular vehicle inspections, and bearings that are found to be faulty are reassembled and used again. However, due to the impact of the decline in society's productive labor force in recent years, measures such as extending the interval between regular railway vehicle inspections are required. Therefore, there is a demand for railway vehicle bearings that offer even greater reliability and longer life.

[0005] Patent Document 1 discloses a sealing device having at least one protruding claw portion on the outer diameter surface of a seal case having a short cylindrical portion for installation fitted into the open end of an outer ring, a radial through hole formed in the axial open end of the outer ring, and a configuration in which the protruding claw portion is engaged with the through hole. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-167999 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the rolling bearing of Patent Document 1, the sealing device can be prevented from slipping out of the outer ring by engaging the protruding claws with through holes formed in the outer ring, but there are problems in that the outer diameter surface of the outer ring is deformed when the sealing device is pushed into the open end of the outer ring, and when the sealing device is removed from the outer ring, the protruding claws get caught on the open end of the outer ring, causing burrs in the sealing device. There is also the problem that the sealing device itself cannot be reused.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to provide a rolling bearing and an axle bearing for railway vehicles that can firmly attach a sealing device to the bearing side in a detachable configuration without deforming or damaging the outer ring, that provides stable sealing performance, and that can be used stably and continuously even in harsh environments. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following configuration [1].

[0010] [1] A bearing comprising an inner ring, an outer ring, a plurality of rolling elements arranged to be able to roll between the inner ring and the outer ring, and a sealing device that seals the gap between the inner ring and the outer ring, the sealing device includes a seal case fitted onto an axial end of the outer ring and extending axially outward from the outer ring, and a seal member provided on an inner diameter portion of the seal case to seal between the inner ring and the outer ring, the seal case has a case outer ring portion fitted inside the outer ring, and a case inner ring portion fitted inside the case outer ring portion, The case inner annular portion is formed with an expanded diameter portion having an increased outer diameter at a tip end in the axial direction, the case outer ring portion has a deformation portion that is deformed in a diameter-expanding direction by the expanded diameter portion of the case inner ring portion fitted therein; Rolling bearing. [2] A railway vehicle axle bearing in which the rolling bearing according to [1] is used, A pair of the inner rings is provided, Tapered rollers are used as the rolling elements, A front cover is provided on one axial end side of the pair of inner rings, and a rear cover is provided on the other axial end of the pair of inner rings. Axle bearings for railway vehicles. [3] A railway vehicle axle bearing using the rolling bearing according to [1], The inner ring is provided. Cylindrical rollers are used as the rolling elements, A front cover is provided on one axial end side of the inner ring, and a rear cover is provided on the other axial end of the inner ring. Axle bearings for railway vehicles. [Effects of the Invention]

[0011] According to the present invention, by fitting the inner annular portion of the case into the outer annular portion of the case fitted inside the outer ring, the deformed portion is deformed in the radially expanding direction and can act as a locking piece, so that the sealing device can be firmly and smoothly attached to the outer ring. Because the sealing device can be firmly attached without damaging the outer ring or the sealing device, it can maintain high sealing performance for a long period of time even when used continuously in a harsh environment. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a bearing unit for a railway vehicle. [Figure 2] FIG. 2 shows a sealing device attached to a bearing. [Figure 3A] FIG. 3A is a diagram showing the seal case in a temporarily fastened state. [Figure 3B] FIG. 3B is a diagram showing a temporarily attached state of the seal case. [Figure 3C] FIG. 3C is a diagram showing the fixed state of the seal case. [Figure 4A] FIG. 4A shows the sealing device in a state ready for removal. [Figure 4B] FIG. 4B is a diagram showing the sealing device in a separated state. [Figure 4C] FIG. 4C is a diagram showing the sealing device in a completely removed state. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment in which the rolling bearing of the present invention is applied to a railway vehicle bearing unit will now be described in detail with reference to the drawings, in which: Figure 1 is a schematic cross-sectional view showing a railway vehicle bearing unit;

[0014] 1, using a tapered roller bearing as an example, the railway vehicle bearing unit 10 includes a double-row tapered roller bearing (hereinafter also simply referred to as a bearing) 20 as a railway vehicle axle bearing, and an axle 100 of the railway vehicle is rotatably supported by this bearing 20. A wheel (not shown) of the railway vehicle is attached to the outer end of the axle 100 (the right end in FIG. 1). The double-row tapered roller bearing 20 comprises a single outer ring 21, two inner rings 22, 22 divided individually into each row, tapered rollers (rolling elements) 23 arranged so as to roll freely between two rows of raceway surfaces formed between the outer ring 21 and the inner rings 22, 22, and a cage 24 that holds the multiple tapered rollers 23.

[0015] A front cover 30 and a rear cover 31 are disposed around the axle 100 at both axial ends of the inner rings 22, 22 so as to abut against the axial end face of the inner ring 22. The inner rings 22, 22, the front cover 30, and the rear cover 31 are sandwiched between a stepped portion 101 on the outer peripheral surface of the axle 100 and a nut 11, and are fixed with bolts 13 from the axial end 102 side of the axle 100. The outer ring 21 is also positioned in the axial direction by being fixed to a housing (not shown).

[0016] Contact-type sealing devices 40 are attached to both sides of double-row tapered roller bearing 20, and these sealing devices 40 prevent foreign matter from entering double-row tapered roller bearing 20 and lubricant (grease) from leaking from inside the bearing. Note that sealing devices 40 may also be of a non-contact type.

[0017] 1, in the railway vehicle bearing unit 10 of this embodiment configured as described above, the double row tapered roller bearing 20, front cover 30, rear cover 31, and sealing devices 40, 40 are unitized and inserted from the shaft end 102 side of the axle 100 and press-fitted onto the outer circumferential surface of the axle 100. In addition, a lubricant is applied near the entrance of the bearing press-fit portion of the axle 100 to prevent damage to the fitting surface between the axle 100 and the inner circumferential surfaces of the inner rings 22, 22 when the double row tapered roller bearing 20 is press-fitted onto the axle 100.

[0018] Next, a specific configuration of the sealing device 40 will be described with reference to Fig. 2 and Fig. 3A. Fig. 2 is a diagram showing the sealing device of the present invention attached to a bearing. Fig. 3A is a diagram showing the sealing device and bearing before attachment, and is a diagram showing a state in which a seal case, which will be described later, is temporarily fastened. The sealing device 40 has a seal case 50 that is detachably attached and fixed to a shoulder portion 21b formed on the axial end of the inner diameter portion of the outer ring 21, and a seal member 60 that is attached and fixed to the seal case 50 and that comes into contact (sliding contact) with sliding contact surfaces 34 formed on the outer diameter portions of the front cover 30 and the rear cover 31. The seal member 60 may be configured not to come into sliding contact with the sliding contact surfaces 34. Shoulder portion 21b of outer ring 21 is a surface parallel to the axial direction that is formed with a larger diameter than raceway surface 21a of outer ring 21, and is connected to the axial end of raceway surface 21a via a step portion 21c extending in the radial direction. Additionally, shoulder portion 21b of outer ring 21 has an annular relief groove 21d cut out radially outward at the end on the step portion 21c side. This configuration can be seen in FIG. 3A. As shown in Fig. 2, a step 35 that forms a labyrinth between the rear cover 31 and the seal case 50 is formed on the axially outer side of the sliding contact surface 34 of the rear cover 31. A similar step 35 is also formed on the front cover 30. What is shown in Fig. 2 is just one example, and for example, the rear cover 31 may not have a step 35 that forms a labyrinth.

[0019] The seal case 50 has a case outer ring portion 51 that fits inside the shoulder portion 21b of the outer ring 21 and extends axially outward from the shoulder portion 21b of the outer ring 21, and a case inner ring portion 52 that fits inside the inner surface of the case outer ring portion 51.

[0020] The case inner ring portion 52 is a metal member formed in a ring shape along the case outer ring portion 51, and has a case inner ring cylindrical portion 52a formed along the shoulder portion 21b of the outer ring 21 (the case outer ring portion 51 that fits inside it), and a case inner ring circular portion 52b bent from the axial outer end of the case inner ring cylindrical portion 52a toward the inner ring 22 side, and is formed in an L-shaped cross section.

[0021] The case inner annular cylindrical portion 52a has an inner end in the axial direction bent radially outward to form an annular inner annular expanded portion 52a1, which serves as a tightening margin when the case inner annular portion 52 is pressed into the case outer annular portion 51.

[0022] The case outer ring portion 51 is a member formed along the shoulder portion 21b of the outer ring 21, and has a first case outer ring cylindrical portion 51a that fits inside the shoulder portion 21b of the outer ring 21, a first case outer ring circular portion 51b that is bent from the axial outer end of the first case outer ring cylindrical portion 51a toward the inner ring 22 side, a second case outer ring cylindrical portion 51c that extends axially outward from the radial inner end of the first case outer ring circular portion 51b, a second case outer ring circular portion 51d that is bent from the axial outer end of the second case outer ring cylindrical portion 51c toward the inner ring 22 side, and a third case outer ring cylindrical portion 51e that extends axially outward from the radial inner end of the second case outer ring circular portion 51d, and has a cross section formed in a two-stage crank shape.

[0023] The first case outer ring cylindrical portion 51a has, at its axial inner end, an annular deforming portion 51a1 that is deformed in the diameter-expanding direction by the inner ring diameter-expanding portion 52a1. At least the deforming portion 51a1 of the case outer ring portion 51 is formed of an elastic material. The portion of the case outer ring portion 51 excluding the deforming portion 51a1 may be formed of metal. The deformed portion 51a1 is deformed so as to be pushed out in the diameter-expanding direction by the inner ring expanded diameter portion 52a1 when the case inner ring portion 52 is pressed into the case outer ring portion 51. At this time, the deformed portion 51a1 deformed in the diameter-expanding direction enters the relief groove 21d formed in the shoulder portion 21b of the outer ring 21, thereby functioning as a locking piece that prevents the seal case 50 from coming off the outer ring 21.

[0024] The first case outer ring portion 51b is formed with a threaded hole 55 that penetrates in the axial direction. The threaded hole 55 is threaded so that a removal bolt 56, which will be described later, can be threaded therein. The screw hole 55 may be formed in one place, or in a plurality of places at predetermined intervals along the first case outer ring portion 51b.

[0025] The third case outer annular cylindrical portion 51e extends parallel to the step portion 35 formed on the front cover 30 and the rear cover 31 (the rear cover 31 in the illustrated example), and is formed with a diameter slightly larger than that of the step portion 35. This forms a labyrinth between the third case outer annular cylindrical portion 51e and the step portion 35. This configuration can be seen in FIGS. 1 and 2.

[0026] The sealing member 60 has a slinger 61 fitted into the case outer ring portion 51, a core 62 fitted into the slinger 61, and an elastic sealing material 63 attached and fixed to the core 62 and in contact with the sliding surface 34. The elastic sealing material 63 is an elastic body, but is not limited to this and may be a metal that forms a labyrinth as shown in the slinger protrusion 61c.

[0027] The slinger 61 is a metal member formed in an annular shape along the case outer ring portion 51, and has a crank-shaped cross section, including a slinger cylindrical portion 61a formed to fit inside the second case outer ring cylindrical portion 51c, a slinger ring portion 61b bent from the axial inner end of the slinger cylindrical portion 61a toward the inner ring 22, and a cylindrical slinger protrusion 61c extending axially inward from the radial inner end of the slinger ring portion 61b. This configuration can be seen in Figure 3A.

[0028] The core 62 is a metal member formed in a ring shape along the slinger 61, and has a core cylindrical portion 62a formed to fit inside the slinger cylindrical portion 61a, a core circular ring portion 62b bent from the axial outer end of the core cylindrical portion 62a toward the inner ring 22, and a seal support portion 62c extending from the radial inner end of the core circular ring portion 62b toward the inner ring 22 side, to which the elastic sealing material 63 is fixed. The seal support portion 62c has a cylindrical portion extending axially inward from the core metal ring portion 62b and a ring portion bent from the inner end of the cylindrical portion toward the sliding contact surface 34, and is formed with an L-shaped cross section. This configuration can be seen in Figure 3A.

[0029] The elastic seal material 63 is an annular elastic member that is attached and fixed to the seal support portion 62c, and has a base end portion 63a with an L-shaped cross section that is fixed to the seal support portion 62c, a first lip portion 63b that protrudes toward the inner diameter side from the base end portion 63a, and a second lip portion 63c. The first lip portion 63b is disposed axially inward relative to the seal support portion 62c, and the second lip portion 63c is disposed axially outward relative to the seal support portion 62c. This configuration can be seen in FIG.

[0030] According to the sealing device 40 described above, the elastic seal material 63 comes into contact with the sliding surface 34 of the rear cover 31 arranged adjacent to the inner ring, thereby sealing the space formed between the outer ring 21 and the inner ring 22. Furthermore, according to the sealing device 40, a labyrinth is formed on the axially outer side of the elastic seal material 63. Specifically, the labyrinth is formed between the third case outer ring cylindrical portion 51e of the case outer ring portion 51 and the step portion 35 of the rear cover 31. This makes it possible to more efficiently prevent foreign matter, such as rainwater or cleaning liquid, from entering the inside of the bearing 20 from the outside. Furthermore, according to the sealing device 40, the slinger protrusion 61c of the slinger 61 is formed axially inside the elastic seal member 63. This makes it possible to more efficiently prevent the lubricant inside the bearing 20 from leaking out of the bearing 20.

[0031] (Sealing device installation method) Next, a method for attaching the sealing device 40 will be described with reference to Figures 3A to 3C. Figure 3A is a diagram showing a temporarily fixed state of the seal case. Figure 3B is a diagram showing a temporarily attached state of the seal case. Figure 3C is a diagram showing a fixed state of the seal case. First, as shown in FIG. 3A, a part of the case inner ring portion 52 is fitted into the inner peripheral surface of the case outer ring portion 51, thereby bringing the seal case 50 into a temporarily fixed state. Specifically, the temporarily fastened state of the seal case 50 refers to a state in which the outer peripheral surface of the case inner ring cylindrical portion 52a is partially fitted into the inner peripheral surface of the first case outer ring cylindrical portion 51a. At this time, the inner ring expanded diameter portion 52a1, which is an interference formed at the tip of the case inner ring cylindrical portion 52a, is not fitted into the first case outer ring cylindrical portion 51a, and the deformed portion 51a1 of the first case outer ring cylindrical portion 51a is not deformed.

[0032] Next, as shown in FIG. 3B, the temporarily fixed seal case 50 is fitted into the shoulder portion 21b of the outer ring 21 to bring it into a temporarily attached state. Specifically, by inserting the first case outer annular cylindrical portion 51a into the shoulder portion 21b of the outer ring 21, the tip half of the first case outer annular cylindrical portion 51a is fitted into the shoulder portion 21b of the outer ring 21. This changes the seal case 50 from a temporarily fastened state to a temporarily attached state. At this time, the seal case 50 in the temporarily fastened state can be inserted to a position where the tip of the case inner annular cylindrical portion 52a abuts against the step portion 21c of the outer ring 21.

[0033] Next, as shown in FIG. 3C, a portion of the temporarily attached seal case 50 is deformed to fix the seal case 50 to the outer ring 21 so that the seal case 50 does not come off. Specifically, by pushing the case outer ring portion 51 axially inward, the first case outer ring portion 51b of the case outer ring portion 51 and the case inner ring portion 52b of the case inner ring portion 52 are brought into tight contact with each other. At this time, the inner ring expanded diameter portion 52a1 of the case inner ring cylindrical portion 52a causes the deformed portion 51a1 of the first case outer ring cylindrical portion 51a to deform radially outward toward the inside of the escape groove 21d of the outer ring 21 disposed radially outward.

[0034] According to this configuration, the deformed portion 51a1 that is deformed into the relief groove 21d acts as a locking piece for the seal case 50 that is fitted into the shoulder portion 21b. Therefore, the sealing device 40 can be firmly attached and fixed to the outer ring 21 side by a simple and easy attachment method.

[0035] (How to remove the sealing device) Next, a method for removing the sealing device 40 will be described with reference to Figures 4A to 4C. Figure 4A is a diagram showing a state in which the sealing device is being prepared for removal. Figure 4B is a diagram showing a state in which the sealing device is separated. Figure 4C is a diagram showing a state in which removal of the sealing device has been completed. First, as shown in FIG. 4A, removal bolt 56 is screwed into threaded hole 55 formed in first case outer ring portion 51b (removal preparation state).

[0036] Next, as shown in FIG. 4B, by tightening the removal bolt 56, the axial end of the removal bolt 56 pushes the case inner ring portion 52 (the case inner annular ring portion 52b) in the axial direction, so that the case outer ring portion 51 and the case inner ring portion 52, which had been in close contact with each other, separate in the axial direction (separated state). Along with this, the deformation of the deformed portion 51a1 formed by the elastic body toward the outside in the radial direction is also naturally restored to its original state.

[0037] Next, as shown in FIG. 4C, since the deformed portion 51a1 no longer functions as a locking piece, the worker can easily remove the seal case 50 by pulling it off the shoulder portion 21b of the outer ring 21 (removal completed state).

[0038] According to this configuration, the sealing device 40, which is firmly attached and fixed, can be removed from the outer ring 21 with a simple operation, so that maintenance work and the like can be carried out smoothly.

[0039] The present invention is not limited to the above-described embodiment, and modifications and improvements can be made as appropriate.

[0040] As described above, the present specification discloses the following: (1) A bearing comprising an inner ring, an outer ring, a plurality of rolling elements arranged to be able to roll between the inner ring and the outer ring, and a sealing device that seals the gap between the inner ring and the outer ring, the sealing device includes a seal case fitted onto an axial end of the outer ring and extending axially outward from the outer ring, and a seal member provided on an inner diameter portion of the seal case to seal between the inner ring and the outer ring, the seal case has a case outer ring portion fitted inside the outer ring, and a case inner ring portion fitted inside the case outer ring portion, The case inner annular portion is formed with an expanded diameter portion having an increased outer diameter at a tip end in the axial direction, the case outer ring portion has a deformation portion that is deformed in a diameter-expanding direction by the expanded diameter portion of the case inner ring portion fitted therein; Rolling bearing. According to this configuration, by fitting the inner annular portion of the case into the outer annular portion of the case fitted inside the outer ring, the deformed portion is deformed in the radially expanding direction and can act as a locking piece, so that the sealing device can be firmly and smoothly attached to the outer ring. Because the sealing device can be firmly attached without damaging the outer ring, it can maintain high sealing performance for a long period of time even when used continuously in a harsh environment.

[0041] (2) The deformation portion is formed of an elastic body. The rolling bearing according to (1). According to this configuration, the deforming portion is elastically deformed, so that the sealing device can be smoothly removed from the outer ring without damaging the outer ring with the deforming portion.

[0042] (3) The outer ring portion and the inner ring portion have annular portions that are in close contact with each other in the axial direction, A screw hole is provided in the axially outer circular ring portion, A rolling bearing according to (1) or (2). According to this configuration, the outer ring portion and the inner ring portion of the case, which are in close contact with each other in the axial direction, can be separated by threading a bolt into the screw hole, which makes it easy to remove the sealing device.

[0043] (4) A railway vehicle axle bearing using the rolling bearing according to any one of (1) to (3), A pair of the inner rings is provided, Tapered rollers are used as the rolling elements, A front cover is provided on one axial end side of the pair of inner rings, and a rear cover is provided on the other axial end of the pair of inner rings. Axle bearings for railway vehicles. According to this configuration, the sealing device is firmly attached to the outer ring by the deformed portion deformed by the enlarged diameter portion, so that high sealing performance can be maintained for a long period of time even when used continuously in harsh environments.

[0044] (5) A railway vehicle axle bearing using the rolling bearing according to any one of (1) to (3), The inner ring is provided. Cylindrical rollers are used as the rolling elements, A front cover is provided on one axial end side of the inner ring, and a rear cover is provided on the other axial end of the inner ring. Axle bearings for railway vehicles. According to this configuration, the sealing device is firmly attached to the outer ring by the deformed portion deformed by the enlarged diameter portion, so that high sealing performance can be maintained for a long period of time even when used continuously in harsh environments. [Explanation of symbols]

[0045] 10. Bearing units for railway vehicles 11 Nut 13 volts 20 Bearings 21 outer ring 21a Raceway surface 21b Shoulder 21c Stepped section 21d Relief groove 22 Inner Circle 24 Cage 30 Front lid 31 Rear lid 34 Sliding surface 35 Step part 40 Sealing device 50 Seal Case 51 Case outer ring 51a First case outer cylindrical ring portion 51a1 Deformed part 51b First case outer ring 51c Second case outer cylindrical ring 51d Second case outer ring 51e Third case outer cylindrical ring 52 Case inner ring 52a Case inner cylindrical ring 52a1 Inner ring expanded diameter part (expanded diameter part) 52b Case inner ring 55 screw hole 56 Removal bolt 60 Sealing material 61 Slinger 61a Slinger cylindrical part 61b Slinger ring part 61c Slinger protrusion 62 Core 62a Core cylindrical part 62b Core metal ring part 62c Seal support 63 Elastic sealing material 63a Proximal end 63b First lip 63c Second lip 100 axles 101 Outer surface step

Claims

1. an inner ring, an outer ring, a plurality of rolling elements arranged to be free to roll between the inner ring and the outer ring, and a sealing device that seals the gap between the inner ring and the outer ring, the sealing device includes a seal case fitted onto an axial end of the outer ring and extending axially outward from the outer ring, and a seal member provided on an inner diameter portion of the seal case to seal between the inner ring and the outer ring, the seal case has a case outer ring portion fitted inside the outer ring, and a case inner ring portion fitted inside the case outer ring portion, The case inner annular portion is formed with an expanded diameter portion having an increased outer diameter at a tip end in the axial direction, the case outer ring portion has a deformation portion that is deformed in a diameter-expanding direction by the expanded diameter portion of the case inner ring portion fitted therein; Rolling bearing.

2. The deformation portion is formed of an elastic body.

2. The rolling bearing according to claim 1.

3. the case outer ring portion and the case inner ring portion have circular ring portions that are in close contact with each other in the axial direction, A screw hole is provided in the axially outer circular ring portion, 2. The rolling bearing according to claim 1.

4. A railway vehicle axle bearing using the rolling bearing according to any one of claims 1 to 3, A pair of the inner rings is provided, Tapered rollers are used as the rolling elements, A front cover is provided on one axial end side of the pair of inner rings, and a rear cover is provided on the other axial end of the pair of inner rings. Axle bearings for railway vehicles.

5. A railway vehicle axle bearing using the rolling bearing according to any one of claims 1 to 3, The inner ring is provided. Cylindrical rollers are used as the rolling elements, A front cover is provided on one axial end side of the inner ring, and a rear cover is provided on the other axial end of the inner ring. Axle bearings for railway vehicles.

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