AU2009353348A1

AU2009353348A1 - Railway bearing backing ring

Info

Publication number: AU2009353348A1
Application number: AU2009353348A
Authority: AU
Inventors: Paul A. Hubbard
Original assignee: Amsted Rail Co Inc
Current assignee: Amsted Rail Co Inc
Priority date: 2009-10-01
Filing date: 2009-10-01
Publication date: 2012-05-24
Also published as: RU2518789C2; WO2011040896A1; RU2011148968A; UA101896C2; MX360414B; CA2764184A1; BRPI1004357B1; CN102333967A; MX2010010724A; ZA201005921B; CA2764184C; BRPI1004357A2

Abstract

A novel method and apparatus are presented for press fitting a bearing assembly onto a journal in a single press fit operation. A compressible, adhesive gasket affixes the backing ring to the bearing cone of a bearing assembly, facilitating the press fit of the bearing assembly onto a journal. Despite the introduction of the compressible gasket, the bearing stack compressive preload is maintained on the bearing assembly regardless of any degradation in the gasket.

Description

WO 2011/040896 PCT/US2009/005403 RAILWAY BEARING BACKING RING Field of the Invention [00011 This invention relates to anti-friction bearings and more particularly, in one embodiment, to tapered roller bearings. Background of the Invention [0002] Anti-friction bearings (also commonly known as rolling-contact bearings), such as ball bearings and tapered roller bearings, are commonly used in various industrial applications. Like any other moving mechanical component, bearings eventually experience wear related degradation. Because bearings are a high-value item, it is general practice to recondition worn bearing assemblies. Bearing assemblies removed from service for reconditioning are cleaned, inspected for defects, and i-epaired as required. The bearing is reassembled and prior to release, undergoes a quality-control inspection. Bearing assemblies passing quality-control inspection are ready to be pressed onto a shaft (e.g., a railcar axle). [00031 Certain types of bearing assemblies, however, lack a means for retaining the backing ring to the bearing assembly. As it is desirable to press fit the bearing assembly and the backing ring onto the journal as a unit, the absence of a retaining means to affix these two components can prove problematic for their efficient installation. Summary of the Invention [00041 A bearing assembly is presented having a compressible, adhesive gasket to affix the bearing backing ring to the bearing cone of a bearing assembly. The adhesive gasket facilitates the press fit of the bearing assembly and backing ring, as a unit, onto the journal of a shaft (e.g., a railcar axle) in a single operation. 1 WO 2011/040896 PCT/US2009/005403 [0005] The compressible, adhesive gasket has a body formed, in one embodiment, with a compressible, closed cell, polymer foam. In this embodiment, the body of the gasket is coated with a pressure sensitive adhesive. [0006] The adhesive gasket, in one embodiment, has an annular shape to fit around part of the backing ring and into a gap between the backing ring and the bearing cone. The compressible nature of the adhesive gasket helps ensure uniform gasket contact over potentially rough, nonparallel, and uneven surfaces presented between the backing ring and the bearing cone. Disposing the adhesive gasket in the gap allows the bearing assembly to have a series of abutting solid metal components from the backing ring to the retaining cap, allowing the preload compression on the bearing assembly exerted by the retaining cap to remain isolated and unaffected by any deterioration in the adhesive gasket. Brief Description of the Figures [0007] Various embodiments of a bearing assembly with a novel compressible, adhesive gasket are described and illustrated in the accompanying figures. The figures are provided as examples only and are not intended to be considered as limitations to the invention. Consequently, the bearing assembly and gasket are illustrated by way of example and not by limitation in the accompanying figures in which: [0008] FIG. I is a sectional view of one embodiment of the bearing assembly; [00091 FIG. 2 is an enlarged sectional view of the bearing assembly illustrated in FIG. 1; [00101 FIG. 3 is a detailed sectional view of one embodiment of the adhesive gasket depicted in the bearing assembly embodiment illustrated in FIG. 1; and [0011] FIG. 4 is a sectional view of the installation of a bearing assembly onto a journal with a bearing press. 2 WO 2011/040896 PCT/US2009/005403 Detailed Description [0012] Referring to FIG. 1, an exemplary bearing assembly 10 is illustrated. In this embodiment, the bearing assembly 10 is a tapered roller bearing of the type commonly used in railway applications to support a railcar wheel. The bearing assembly 10 described in the following embodiments, however, may be adapted for use in many other common industrial applications. Consequently, the bearing assembly 10 illustrated and described below in relation to a tapered roller bearing assembly for a railcar wheel is for convenience only. [00131 The bearing assembly 10 is typically preassembled before being mounted on a shaft 11 (e.g., a railcar axle). At the free end of the shaft 11, a journal 12 terminates in a slightly conical, tapered guide 13 to facilitate installation of the bearing assembly 10 onto the journal 12. The bearing assembly 10, in one embodiment, is press fit on the journal 12 which is machined to very close tolerances to accurately accommodate the press fit. [00141 The journal 12 terminates at its inboard end in a contoured fillet 18 leading to a shoulder 19 on the shaft 11. A dust guard 14 having a cylindrical surface extends axially inward from the shoulder 19. A backing ring 22 having a contoured inner surface is affixed to a complementary surface of the fillet 18. The fillet 18 and the adjacent shoulder 19 affix the bearing assembly 10 against axially inward displacement. [00151 The backing ring 22, in some embodiments, also has a collar 26 extending axially inward and concentrically over the outer cylindrical surface 15 of the dust guard 14. The collar 26, in some embodiments, develops an interference fit with the outer cylindrical surface 15 of the dust guard 14. [00161 A bearing retaining cap 20 having a plurality of threaded bores is mounted at the free end of the shaft 11 to the journal 12 with threaded cap screws or bolts 21. The bearing retaining WO 2011/040896 PCT/US2009/005403 cap 20 and the backing ring 22 cooperatively clamp the bearing assembly 10 into position on the journal 12. The bearing retaining cap 20 directly abuts the bearing cone 38 of the bearing assembly 10 and develops a compressive preload on the bearing assembly. [0017] The bearing assembly 10 is preassembled from a number of individual components. The bearing assembly 10 includes a bearing cup 31 having raceways 32, 34 formed on the inner surface of the bearing cup. The raceways 32, 34 cooperate with bearing cones 38, 40 to capture and support two rows of tapered rollers 42, 44 respectively. In some embodiments, cages 46, 48 maintain the spatial position of the rollers 42, 44 within the raceways 32, 34. A center spacer 47 is positioned between the bearing cones 38, 40 to maintain the cones in accurately spaced position relative to one another and allow for proper bearing lateral clearance. [0018] Bearing seal cases 50, 52 cover the ends of the bearing assembly 10, protecting the bearing from external contaminants and sealing the lubricant within the bearing assembly. The bearing seal cases 50, 52 depicted in FIG. 1 are a type of cone riding bearing seal which is mounted on the bearing cone 38, 40 and the bearing cup 31. [0019] Referring to FIG. 2, the inboard end of the bearing assembly 10 of FIG. 1 and in particular, the bearing seal case 52 is illustrated in a detailed sectional view. The bearing seal cases 50, 52 are identical, consequently, in the following discussion, all references to the bearing seal case 52 on the inboard side of the bearing assembly 10 can be applied to the outboard bearing seal case 50. [00201 The bearing seal 52 comprise two components: an outer seal case 54 and an inner seal case 56. The outer seal case 54 is affixed to the bearing cup 31. In one embodiment, the outer seal case 54 may be affixed to the bearing cup 31 with an interference fit between the large diameter open end section 51 and the counterbore 33 in the bearing cup 31. 4 WO 2011/040896 PCT/US2009/005403 [0021] Alternatively, in another embodiment, the outer seal case 54 may have a retaining lip 53 adapted to snap into an undercut retaining groove 37 in the bearing cup 31. This design allows the outer seal case 54 to be releaseably retained on the bearing assembly 10. [0022] The inner seal case 56 is a generally cylindrical housing affixed to the bearing cone 40 on the standout 43 of the bearing cone. The inner seal case 56 has a wear surface 57 to provide a similar functionality as wear rings found in other types of bearing assemblies. [0023] A seal body 60 (typically of elastomeric construction) is attached to the outer seal case 54 and is urged against the wear surface 57 of the inner seal case 56 to form a dynamic seal between the stationary and moving bearing assembly components. [00241 Tapered roller bearing assemblies and backing rings for railcar axles are generally pressed onto the journal of the rail car axle. As noted above, the backing ring 22 is a separate and loose component from the bearing assembly 10, particularly in many short design, such as Class K, bearings. These bearing assemblies are reconditioned often today and, the lack of an attachment means has proven problematic for their reassembly onto railcar axles after reconditioning. [00251 A novel method and apparatus are presented to facilitate, in a single press fit operation, the installation of a bearing assembly onto a journal. To prevent the disengagement of the backing ring 22 from the bearing assembly 10, a special adhesive gasket 90 is positioned between the backing ring 22 and the bearing cone 40 in a manner preventing loss of compressive preload on the bearing assembly. [0026] The adhesive gasket 90 may take any shape, but an annular shaped gasket covers the greatest available surface area between the bearing cone 40 and the backing ring 22, maximizing the adhesive force connecting the bearing assembly with the backing ring. The annular shape 5 WO 2011/040896 PCT/US2009/005403 also facilitates the placement of the adhesive gasket 90 between the backing ring 22 and the bearing cone 40 to avoid interruption of the solid metal bearing stack between the bearing retaining cap 20 and the backing ring 22. This isolates the gasket 90 from the bearing stack, preventing any gasket degradation from affecting the preload compression on the bearing stack. [00271 In this embodiment, the bearing stack is a series of abutting metallic components including: the bearing retaining cap, bearing cones, the center spacer, and the backing ring. Any compressible material interposed in this solid metal bearing stack may degrade, resulting in the loss or reduction of the clamping force (i.e., compressive preload) exerted by the retaining cap on the bearing assembly and backing ring. A loss of bearing stack compressive preload loosens the bearing assembly and the backing ring; which in turn accelerates wear related degradation and can eventually lead to bearing, shaft, or backing ring failure. [00281 To preclude this possible loss of compression, the annular adhesive gasket 90 is placed over and radially outward of the annular boss 23 of the backing ring 22. The annular boss 23 extends from the axially outward directed surface of the backing ring 22 and directly abuts the bearing cone 40, maintaining the metal to metal series of contacts between the bearing retaining cap and the backing ring. The annular boss 23 projecting from the backing ring 22 has an outer cylindrical surface having an outer diameter smaller than the outer diameter of the cone back face 41. As a result, a circumferential gap 25 is created between the cone back face 41 and the backing ring 22. [0029] The adhesive gasket 90 is disposed in gap 25. The outside diameter of the adhesive gasket 90, in one embodiment, is radially inward from the outside diameter of the cone back face 41 to prevent overlap and adhesion to the bearing seal 52. The adhesive gasket 90, in one embodiment, may abut the outer cylindrical surface of the annular boss 23. 6 WO 2011/040896 PCT/US2009/005403 [00301 Referring to FIG. 3, the adhesive gasket 90 is depicted in detail. In one embodiment, the adhesive gasket 90 comprises a compressible polymeric annular gasket body 92 with an adhesive 94 (e.g., an acrylic adhesive or epoxy resin) applied to the inboard and outboard directed end surfaces. [00311 The annular gasket body 92, in one embodiment, may comprise any number of polymeric foam materials, open or closed cell. In one embodiment, the compressible annular gasket body 92 is a closed cell polyethylene material (e.g., Ethafoam @). Other types of polymer foams may also be used, including cross-linked polyethylene and polyurethane foams depending upon the tensile strength requirements of the bearing assembly components. 100321 Because the gasket body 92 is formed from a compressible polymeric material, in one embodiment, the thickness of the adhesive gasket 90 may be dimensionally oversized to ensure full contact with both the backing ring and the bearing cone. Any voids formed from the rough or uneven surfaces between the backing ring and the bearing cone are filled by the adhesive gasket as the bearing retaining cap compresses the bearing stack, allowing the gasket to make full contact with both the backing ring and the bearing cone. [0033] A variety of different adhesives 94 may be employed on the adhesive gasket 90. In one embodiment, the inward and outward directed surfaces of the gasket body 92 are coated with an adhesive 94, such as a pressure sensitive adhesive (e.g., an acrylic resin adhesive). Other types of adhesives 94 may also be used such as epoxy resins. [0034] Certain adhesives 94 may require protection from activation (e.g., pressure activation) and protection from contamination. An acrylic resin adhesive applied to the gasket surfaces may be protected prior to its application, with a releasable liner 96 (e.g., paper backing). The releasable liner 96 may comprise both a release coating (e.g., silicone) (not shown) and the liner 7 WO 2011/040896 PCT/US2009/005403 (e.g., paper). The releasable liner 96 is removed immediately prior to its application to the bearing assembly. [00351 In one embodiment, the annular shape of the adhesive gasket 90 establishes a continuous, circumferential boundary between the backing ring 22 and the bearing cone 40. In one embodiment, the polymeric materials used in the construction of the adhesive gasket 90 (both the body 92 and the adhesive 94) are moisture resistant, providing a moisture resistant boundary around the outer circumferential joint produced by the abutment of the annular boss to the cone back face. [00361 A number of different procedures may be used in conjunction with the adhesive gasket to facilitate the press fit of a bearing assembly onto a shaft with a bearing press. Referring to FIG. 4, a typical bearing press 100 for press fitting a bearing assembly 10 is illustrated. [00371 The first step, in one embodiment, of the press fit procedure is to attach the adhesive gasket 90 around the annular boss 23 of the backing ring 22. The adhesive gasket 90 should not overlap the axially outward directed surface of the annular boss 23 to insure preload compression can be maintained after installation on the bearing assembly 10. [00381 In one embodiment of the process, the bearing assembly 10 and the backing ring 22 are pressed together to activate the pressure sensitive adhesive on the gasket 90 and affix these bearing components together. The bearing assembly unit (i.e., bearing assembly 10 and backing ring 22) may now be placed over a pilot sleeve 130 which is part of the bearing press 100. The pilot sleeve 130 holds the bearing assembly 10 by the internal diameter of the bearing cones 38, 40 and backing ring 22 while the bearing assembly unit is pressed onto the journal 12. 8 WO 2011/040896 PCT/US2009/005403 100391 In another embodiment of the press fit process, the bearing assembly 10 and the backing ring 22 (with the adhesive gasket attached) are separately placed onto a pilot sleeve 130. Sufficient pressure is then exerted between the backing ring 22 and the bearing assembly 10 while on the pilot sleeve 130 to activate the pressure sensitive adhesive and affix the components together. [00401 The bearing press 100 with its pilot sleeve 130 (including the bearing assembly and backing ring) is then aligned concentrically with the end of the journal 12. The journal is now ready to receive the bearing assembly 10 and backing ring 22. The bearing press 100 has a press ram 110 for applying force to the assembly sleeve 120 (another component of the bearing press 100) which telescopes over the pilot sleeve 130 and pushes the bearing assembly 10 and the backing ring 22 off the pilot sleeve and onto the journal 12. The bearing assembly 10 and the backing ring 22 are pressed axially inward onto the journal 12 until the contour surface 27 of the backing ring 22 is in complementary relation with the fillet 18. The installation process is then complete and the bearing press 100 is removed from the journal. [00411 Typically the press ram 110 of the bearing press 100 is hydraulically driven. The press fit developed between the bearing assembly 10 and the journal 12 is predetermined by the dimensional tolerances of the axle and the bearing components pressed onto the axle. To ensure the integrity of the press fit, certain technical specifications must be met related to the peak pressure and force achieved during the press fit operation to ensure a tight fit. The satisfaction of these technical specifications is typically verified using measurements taken from pressure gauges attached to the bearing press. [00421 While the invention has been illustrated with respect to several specific embodiments, these embodiments are illustrative rather than limiting. Various modifications and additions 9 WO 2011/040896 PCT/US2009/005403 could be made to each of these embodiments as will be apparent to those skilled in the art. Accordingly, the invention should not be limited by the above description or of the specific embodiments provided as examples. Rather, the invention should be defined only by the following claims. 10

Claims

1. A bearing assembly affixed to a shaft, the shaft having a shoulder spaced from a free end, a journal of smaller diameter than the shaft between the shoulder and the free end, and a fillet leading from the journal to the shoulder, the bearing assembly adapted to be fitted onto the journal, the bearing assembly comprising: a bearing cup having a raceway directed radially inward; a bearing cone affixed to the journal; a plurality of rollers captured between the raceway of the bearing cup and the bearing cone; an inner seal case affixed to the bearing cone; an outer seal case affixed to the bearing cup, the outer seal case having a seal body extending to the inner seal case; a backing ring affixed to the fillet of the journal and abutting the bearing cone; and an adhesive gasket disposed between the backing ring and the bearing cone, the adhesive gasket affixing the backing ring to the bearing cone.

2. The bearing assembly of claim 1, wherein the backing ring includes an annular boss extending axially outward, the boss abutting the bearing cone, the backing ring and the bearing cone forming a gap radially outward from the boss.

3. The bearing assembly of claim 2, further comprising a bearing retaining cap affixed to the free end of the journal.

4. The bearing assembly of claim 3, further comprising a cage for separating the plurality of rollers. 11 WO 2011/040896 PCT/US2009/005403

5. The bearing assembly of claim 2, wherein the adhesive gasket is disposed in the gap.

6. The bearing assembly of claim 5, wherein the adhesive gasket is compressible.

7. The bearing assembly of claim 5, wherein the adhesive gasket is annular.

8. The bearing assembly of claim 5, wherein the adhesive gasket comprises: a gasket body having an axially inwardly directed surface and an axially outwardly directed surface, wherein the gasket body is a polymer; and an adhesive on the axially inward directed surface and the axially outward directed surface.

9. The bearing assembly of claim 8, wherein the polymer is a closed cell foam.

10. The bearing assembly of claim 8, wherein the polymer is polyethylene.

11. The bearing assembly of claim 8, wherein the adhesive is an acrylic resin.

12. A method for pressing a bearing assembly and backing ring onto a shaft with a bearing press, the shaft having a shoulder spaced from a free end, a journal of smaller diameter than the shaft between the shoulder and the free end, and a fillet leading from the journal to the shoulder, the method comprising: mounting an adhesive gasket between a backing ring and a bearing cone of the bearing assembly to affix the backing ring to the bearing cone; capturing the backing ring and the bearing cone on a pilot sleeve of the bearing press; affixing the bearing press to the free end of the journal; and forcing a press ram against a telescoping assembly sleeve, the assembly sleeve abutted against the bearing cone to slide the bearing assembly and backing ring axially inward on the journal. 12 WO 2011/040896 PCT/US2009/005403

13. The method of claim 12, wherein the backing ring includes an annular boss extending axially outward, the boss abutting the bearing cone, the backing ring and the bearing cone forming a gap radially outward from the boss.

14. The method of claim 13, wherein the adhesive gasket is disposed in the gap.

15. The method of claim 14, wherein the adhesive gasket is annular.

16. The method of claim 14, wherein the adhesive gasket is compressible.

17. The method of claim 14, further comprising attaching a bearing retaining cap to the free end of the journal.

18. The method of claim 14, wherein the adhesive gasket comprises: a gasket body having an axially inwardly directed surface and an axially outwardly directed surface, wherein the gasket body is a polymer; and an adhesive applied on the axially inward directed surface and the axially outward directed surface.

19. The method of claim 18, wherein the adhesive is an acrylic resin.

20. The method of claim 18, wherein the polymer is a polyethylene foam. 13