US20080085069A1

US20080085069A1 - Railroad bearing with corrosion inhibitor

Info

Publication number: US20080085069A1
Application number: US11/867,942
Authority: US
Inventors: David G. Toth; James R. Callan; Brian M. Hupp; Stephen E. Brister
Original assignee: Timken Co
Current assignee: Timken Co
Priority date: 2006-10-06
Filing date: 2007-10-05
Publication date: 2008-04-10

Abstract

A backing ring that serves to position an antifriction bearing on the journal of an axle for a railcar or locomotive carries a ring containing a corrosion inhibitor. During installation of the bearing on the journal, the backing ring is advanced over the journal followed by the bearing. When the axially directed force that advances the bearing over the journal is transmitted through the bearing to the backing and is resisted at the fillet, the corrosion inhibitor exudes from the backing ring and forms a coating on the fillet to inhibit fretting and other corrosion between the backing ring and the journal.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application derives and claims priority from U.S. provisional application 60/849,892, filed Oct. 6, 2006, and from U.S. provisional application 60/915,156, filed May 1, 2007, both of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF THE INVENTION

This invention relates to bearing assemblies for the axles or railcars and locomotives and, more particularly, to a bearing assembly having a backing ring that carries its own supply of a corrosion inhibitor, to the backing ring itself, and to a process for installing the backing ring over an axle journal.
The typical railcar or locomotive has axles to which its wheels are fitted, and those axles at their ends have journals through which the weight of the car or locomotive is transferred to the wheels. Each bearing is clamped between a backing ring that seats against a fillet at the inboard end of the journal and an end cap that extends across the outboard end of the journal. Sometimes wear rings are interposed between the bearing and backing ring and between the bearing and end cap. Owing to the offset between each bearing and its nearby wheel, the journal around which the bearing fits flexes slightly as the axle revolves. This flexure produces movement between the backing ring and the journal fillet against which the backing ring seats. The movement may lead to fretting corrosion and damage to the journal. To retard fretting corrosion, the installation of a bearing over an axle journal is usually accompanied by the application of a liquid corrosion inhibitor to the fillet of the journal. But this is a manual operation that consumes time and those charged with it sometimes forget to apply the inhibitor.

DESCRIPTION OF THE INVENTION

FIG. 1 is longitudinal sectional view of a bearing assembly fully installed over an axle journal in accordance with the present invention, so that the axle journal is coated with a corrosion inhibitor that is initially carried by the backing ring of the assembly;

FIG. 2 is a half-sectional view of the bearing assembly during its installation over the axel journal;

FIG. 3 is an enlarged sectional view of the segment within the circle of FIG. 2 and showing the ring of inhibitor captured in the backing ring;

FIG. 4. is a half-sectional view of a bearing assembly with an alternative backing ring during its installation over an axle journal;

FIG. 5 is an enlarged sectional view of the segment within the circle of FIG. 4 and showing an inhibitor ring within the large end of the backing ring; and

FIG. 6 is a perspective view of the modified backing ring with the inhibitor ring exposed within it.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings.
Referring now to the drawings (FIG. 1) an axle A for a railcar or locomotive is fitted with a bearing B and a wheel W that is set inwardly from the bearing B. The wheel W rolls along the rail of a railroad track, and as it does the axle A rotates about its longitudinal axis X. The weight of the railcar or locomotive transfers through the bearing B to the axle A and thence through the axle A to the wheel W where it is resisted by the underlying rail. Actually, the axle A is one of several axles A under a railcar or locomotive, with each axle A having two wheels W and two bearings B beyond the wheels W. Owing to the axial offset between the bearings B and the wheels W, the axle A undergoes slight flexures in the regions of offset.
The axle A at each of its ends has a journal 2 which leads to a somewhat larger dust guard segment 4 at a fillet 6 on the journal 2. Inwardly from the dust guard segment 4 the axle A has an even larger wheel seat to which the wheel W is fitted. The journal 2 extends out to an end face 8 out of which threaded holes open. The journal 2 for the most part and the dust guard segment 4 are cylindrical and concentric, with their common center being the axis X. The fillet 6 has a contoured surface that is concave.
The bearing B fits around the journal 2 (FIG. 1) where it is captured between a backing ring 10 that bears against the fillet 6 and an end cap 12 that extends over the end face 8, yet is spaced slightly outwardly from it. The bearing B is separated from the backing ring 10 and from the end cap 12 by wear rings 14, and all are clamped tightly together with cap screws 16 which thread into the holes in the end of the journal 2 and bear against the end cap 12. The wear rings 14 adjacent to the bearing B fit snugly over the journal 2, but remote from the bearing B a clearance exists between each wear ring 14 and the journal B owing to an undercut in the wear ring 14. The bearing B together with the backing ring 10, the end cap 12, and the wear rings 12 form a bearing assembly.
The bearing B includes (FIG. 1) an outer race in the form of a cup 20, an inner race in the form of two cones 22 located within the cup 16, and rolling elements in the form of tapered rollers 24 located between the cup 20 and cones 22. In addition, the bearing B includes a spacer 26 located between the two cones 22 to maintain a prescribed spacing between the cones 22. The ends of the bearing B are closed by seals 28 located between the ends of the cup 20 and the wear rings 14. The cones 22 fit over the journal 2 of the axle A with interference fits, with the spacer 26 between them. The cup 20 fits into an adapter which in turn fits into the truck of a railcar or locomotive. The tapered rollers 24 lie along tapered raceways 30 on the cup 20 and cones 22 where they are organized in two rows—one around the inboard cone 22 and the other around the outboard cone 22. The raceways 30 of the two cones 22 taper in opposite directions and so do the two raceways of the cup 20. This orients the rollers 24 such that the rollers 24 of the inboard row take thrust or axial loads in one direction, and the rollers 24 of the outboard row take thrust in the opposite direction. The rollers 24 of both rows transfer radial loads. The cones 22 at the large ends of their raceways 30 have thrust ribs 32 which confine the rollers 24 to the annular spaces between the raceways 30 of the cup 20 and cones 22. The thrust rib 30 of each cone 22 leads out to back face 34, which is squared off with respect to the axis X. The bearing B transfers thrust loads to the axle A primarily at the back faces 32 of its cones 22.
Actually, the thrust loads transferred through the inboard cone 22 and rollers 24 pass to the journal 2—and axle A—through the inboard wear ring 14 and the backing ring 10 which lie between the back face 34 of the inboard cone 22 and the fillet 6 on the journal 2. The thrust loads transferred through the outboard cone 22 and rollers 24 pass to the journal 2 through the outboard wear ring 14, the end cap 12 and the cap screws 16. The end cap 12 fits over the end of the journal 2 and against the outboard wear ring 14 which in turn is against the back face 34 of the outboard cone 22. The cap screws 16 clamp the two cones 22 and the spacer 26 and the wear rings 14 tightly between the backing ring 10 and the end cap 12 and urge the backing ring 10 firmly against the fillet 6. Radial loads transfer through the bearing B and through the journal 2 and dust guard segment 4 to the nearby wheel W, and owing to the offset, create a moment.
Turning now to the backing ring 10, it has (FIG. 1) a contoured inner surface 36 that seats snugly against the fillet 6. Beyond the larger end of the contoured surface 36, the backing ring 10 has a lip 38 that projects over the dust guard segment 4 when the backing ring 10 is fully seated against the fillet 6. Preferably, a interference fit exists between the lip 38 and the dust guard segment 4 to reduce motion between the backing ring 10 and the fillet 6. At its opposite end the backing ring 10 has a counterbore 40 that opens toward the bearing B and receives the end of the inboard wear ring 14 with an interference fit. The counterbore 40 leads up to and terminates at a shoulder 42. When the bearing B is fully installed over the journal 2, the end of the inboard wear ring 14 for all intents and purpose abuts the shoulder 42. Indeed, the cap screws 16 clamp the inboard wear ring 14 tightly against the shoulder 42.
As the axle A revolves, it will experience some flexure, inasmuch as the bearing B through which weight is transferred to the axle A is offset from the nearby wheel W that transfers the weight to the rail over which the wheel W rolls. The flexure to a large measure is concentrated in the region of the journal 2 around which the inboard wear ring 14 and backing ring 10 are located. The inboard wear ring 14 sees some motion on the cylindrical surface of the journal 2, whereas the backing ring 10 experiences motion on the fillet 6, its contoured inner surface 36 slipping minutely back and forth on the concave surface of the fillet 6. To minimize fretting corrosion along the fillet 6 and journal 2, a coating 44 designed to lubricate and inhibit corrosion covers the fillet 6 and the nearby region of the journal 2.
The coating 44 derives from an inhibitor ring 50 (FIGS. 2 and 3) and is released as the bearing B, the backing ring 10, and the wear rings 14 are installed over the journal 2—indeed, as they are advanced to their final positions over the journal 2. In this regard, the seals 28 at the ends of the cup 20 retain the wear rings 14 in alignment with the cones 22. The remote end of the inboard wear ring 14, that is the end that is offset from the back face 34 of the inboard cone 22, fits into the counterbore 40 of the backing ring 10 where it is retained by the interference fit, but not against the shoulder 42 at the end of the counterbore 40. Hence, a space exists between the end of the inboard wear ring 14 and the shoulder 42. The inhibitor ring 50 occupies that space. Preferably, the inside diameter of the inhibitor ring 50 exceeds the diameter of the cylindrical region of the journal 2.
Thus, the bearing B, wear rings 14, and backing ring 10 form an assembly and are installed over the journal 2 of the axle A as a package. More specifically, the backing ring 10 is aligned with the end of the journal 2, over which it is advanced followed by the inboard wear ring 14 that is captured in the backing ring 10. Due to the interference fits with the journal 2, a force is applied to the outboard wear ring 14 to press the inboard wear ring 14, the two cones 22 along with the spacer 26, and the outboard wear ring 14 over the cylindrical region of the journal 2. Continued advancement brings either the lip 38 into contact with the dust guard segment 4 or the backing ring 10 into contact with the fillet 6 of the journal 2, depending on, whether or not a lip 38 is small enough to interfere with the dust guard segment 4. In any event, the backing ring 10 no longer advances, but not the wear rings 14 and the cones 22 of the bearing B behind it. They continue to advance, driving the inboard wear ring 14 farther into the counterbore 44 of the backing ring 10. The inboard wear ring 14 advances until its end bottoms out against the shoulder 42 at the end of the counterbore 40. Ultimately, the wear rings 14 and bearing B assume their final positions over the journal 2. During the increment of advance that forces the inboard wear ring 14 farther into the counterbore 40 of the backing ring 10, the inhibitor ring 50 collapses and the corrosion inhibitor of which it is formed flows or exudes onto the surface of the fillet 6 and the nearby cylindrical surface of the journal 2, that is to say, the surface over which the inboard wear ring 14 fits. The inhibitor covers those surfaces and works under both the backing ring 10 and the inboard wear ring 14 to provide the coating 44 that lubricates and inhibits fretting corrosion.
The inhibitor ring 50 may be formed from a solid or semi-solid material which will flow and deform under pressure, such as a wax or dense grease having the desired corrosion inhibiting, lubricating, and rust preventative properties. Alternatively, the ring 50 may be formed as a tubular O-ring containing a liquid or viscous corrosion inhibitor. The O-ring has walls preferably formed from a polymer that is no more than a few mills thick. Moreover, the polymer is compatible with the corrosion inhibitor in the sense that the corrosion inhibitor will not react with or otherwise cause deterioration of the polymer. Irrespective of its composition, the inhibitor ring 50 is considerably softer than the steels from which the axle A, the wear rings 14, and the backing 10 are formed, so that when compressed between any two of those components, its corrosion inhibitor will exude onto the fillet 6.
An alternative backing ring 60 (FIGS. 4-6) likewise has a contoured inner surface 62 along which the backing ring 60 seats against the fillet 6 at the inner end of the journal 2. Beyond the large end of the contoured surface 62 the backing ring 60 has a lip 64 that fits over the dust guard segment 4, preferably with an interference fit. At its opposite end the backing ring 60 has a counterbore 66 that receives the end of the inboard wear ring 14 with an interference fit. The fillet 6 and the contoured inner surface 62 along which the backing ring 60 seats against the fillet 6 are covered with a coating 68 that inhibits corrosion, including fretting corrosion.
Initially, that is to say prior to the installation of the bearing B, the wear rings 14, and the backing ring 60, over the journal 2, the backing ring 60 has an inhibitor ring 70 located within its axially directed lip 64. The ring 70 conforms to the inside surface of the lip 64 and may also conform to the adjacent region of the contoured inner surface 62. The diameter of dust guard segment 4 should exceed the inside diameter of the inhibitor ring 70. Anyone of the materials that are suitable for the inhibitor ring 50 may likewise be used for the inhibitor ring 70.
The backing ring 60 and then the bearing B with the wear rings 14 fitted into its seals 28 are installed over the journal 2 in that order, the inboard wear ring 14 having been pressed into the counterbore 66 of the backing ring 60 (FIG. 4). Then the bearing B, along with its wear rings 14 and the backing ring 60 are advanced over the journal 2 with the backing ring 60 leading. As the backing ring 60 moves over the fillet 6, the inhibitor ring 70 will align with and eventually come in contact with the larger end of the fillet 6, that is, the region where the fillet 6 merges into the dust guard segment 4 (FIG. 5). Continued advancement causes the inhibitor ring 70 to compress and exude inhibitor over the fillet 6 and along the contoured surface 62 of the backing ring 60, forming the coating 68 on those surfaces. Ultimately, the end cap 12 is installed on the journal 2 and secured with the cap screws 16.
The end cap 12 retains the bearing B, the wear rings 14, and the backing ring 10 on the journal with the backing ring 60 seated firmly against the fillet 6. The coating 68 inhibits corrosion, including fretting corrosion, between the backing ring 10 and the fillet 6 and between the inboard wear ring 14 and the cylindrical surface of the journal 2.
The backing ring 60 with a slight modification may be installed over a shortened and stiffened journal fitted with a compact bearing of the type disclosed in U.S. Pat. No. 5,462,367. That modification would simply allow the end of the backing ring to abut the back face of the inboard cone. Moreover, the backing ring 10 or 60 need not be united with the inboard wear ring 14 prior to installation over the journal 2, but may be installed over the journal 2 ahead of the bearing B and wear rings 14.

Claims

1. An assembly for installation over an axle journal having a fillet at one end, said assembly comprising:

an antifriction bearing defining an axis of rotation;

a backing ring aligned axially with the antifriction bearing;

a corrosion inhibitor carried by the backing ring for release onto the fillet of the axle journal upon installation of the assembly over the axle journal.

2. An assembly according to claim 1 wherein the backing ring has a contoured inner surface configured to seat against the fillet, with the inner surface having a large end and a small end.

3. An assembly according to claim 2 and further comprising a wear ring located between the bearing and the backing ring and aligned with both; wherein the backing ring at the small end of the contoured inner surface has a counterbore that ends at a shoulder in the backing ring; wherein the wear ring fits into the counterbore; and wherein the corrosion inhibitor also fits into the counterbore between the end of the wear ring and the shoulder.

4. An assembly according to claim 3 wherein the corrosion inhibitor takes the form of a ring.

5. An assembly according to claim 2 wherein the corrosion inhibitor is at the large end of the contoured inner surface on the backing ring.

6. An assembly according to claim 5 wherein the backing ring has a lip that projects axially beyond the large end of the contoured inner surface and the corrosion inhibitor is within the lip.

7. An assembly according to claim 6 wherein the corrosion inhibitor takes the form of a ring.

8. In combination with an axle journal having a cylindrical portion and a fillet at the end of the cylindrical portion, the improvement comprising:

a backing ring that is advanced over the journal to ultimately seat against the fillet and provide a backing for an antifriction bearing, and a corrosion inhibitor carried by the backing ring and configured to exude over the fillet under a force applied to the backing ring when advancement of the backing ring is resisted at the fillet.

9. The combination according to claim 8 wherein the backing ring has a contoured inner surface along which the backing ring will ultimately seat against the fillet, with the surface having a large end and a small end; wherein the backing ring also has a counterbore at the small end of the contoured surface; and wherein the corrosion inhibitor is in the counterbore.

10. The combination according to claim 9 wherein the corrosion inhibitor is the form of a ring.

11. The combination according to claim 8 wherein the backing ring has a contoured inner surface along which the backing ring will ultimately seat against the fillet, with the contoured surface having a small end and a large end; and wherein the corrosion inhibitor is at the large end of the contoured surface.

12. The combination according to claim 11 wherein the backing ring has a lip that projects axially beyond the large end of the contoured surface; and wherein the corrosion inhibitor is within the lip.

13. The combination according to claim 12 wherein the corrosion inhibitor is in the form of a ring.

14. The combination according to claim 8 and further comprising an antifriction bearing around the journal, with the backing ring being between the fillet and the antifriction bearing.

15. A process for installing a backing ring over an axle journal having a cylindrical portion and a fillet at one end of the cylindrical portion, said process comprising:

providing the backing ring with a corrosion inhibitor;

advancing the backing ring over the cylindrical portion of the journal substantially without releasing the corrosion inhibitor; and

releasing the corrosion inhibitor onto the fillet when the backing ring encounters the fillet.

16. The process according to claim 15 wherein the corrosion inhibitor is released by applying an axially directed force to the backing ring.

17. A process according to claim 15 wherein the backing ring has a contoured inner surface with a large end and a small end, and the backing ring also has a counterbore at the small end of the contoured surface and a shoulder at the end of the counterbore, and further comprising:

inserting the corrosion inhibitor into the counterbore;

inserting a wear ring into the counterbore such that the corrosion inhibitor is captured between the wear ring and the shoulder; and

when the backing ring encounters the fillet, forcing the wear ring into the counterbore to cause the corrosion inhibitor to exude from the counterbore onto the fillet.

18. A process according to claim 15 wherein the backing ring has a contoured inner surface with a large end and a small end; and wherein the corrosion inhibitor is at the large end of contoured surface where it will exude over the fillet as the backing ring is forced toward the fillet.