AU760432B2

AU760432B2 - Axle box sealing system

Info

Publication number: AU760432B2
Application number: AU37980/99A
Authority: AU
Inventors: Malcolm Rowcliffe
Original assignee: ROLLING STOCK SUPPLY AND SERVI
Current assignee: SKF Australia Pty Ltd
Priority date: 1998-07-06
Filing date: 1999-07-06
Publication date: 2003-05-15
Anticipated expiration: 2019-07-06
Also published as: AU3798099A

Description

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TITLE

"AXLE BOX SEALING SYSTEM" The present invention relates to an axle box sealing system.

Bearing failures in railway systems regularly result in disruption of rail traffic. The cost of repair to rail track and wagons is high, as is the economic cost due to delays in rolling stock delivery. The major suspected cause of bearing failure is loss of grease from axle boxes which are fitted with labyrinth sealing systems. Labyrinth seals are designed to "minimise leakage by offering resistance to fluid flow. Nevertheless, labyrinth seals do not completely seal the axle boxes, and axle grease leakages occur where the viscosity of the axle grease is decreased by high ambient temperatures.

*The loss of axle grease from axle boxes which are fitted with labyrinth sealing systems has been a long recognised problem for which solutions have been sought for the past twenty to thirty years.

It is known to provide felt seals which are disposed intermediate a labyrinth ring and a 1 5 complementary back plate of a labyrinth seal, in a recessed groove of the complementary back plate. The cost of fitting such seals is high, however, due to the requirement for a newly modified complementary back plate to provide a recessed groove in which to house the felt seal.

The present invention seeks to overcome at least in part some of the aforementioned disadvantages.

In accordance with one aspect of the invention there is provided an axle box sealing system, including a labyrinth seal having an inner labyrinth ring and an outer back plate, interengaged with one another wherein there is provided a circumferential groove in a

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3 facing surface of the labyrinth ring or the back plate, which groove comprises a first resilient annulus and a second low friction annulus extending around the first annulus, the second annulus having an outer circumferential surface in engagement with the opposing member.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a top plan view of two components of an axle box sealing system, in accordance with the present invention including a first annulus and a second annulus; Figure 1A is a cross-sectional view of two components of an axle box sealing system in S 10 accordance with the present invention, including a first annulus and a second annulus; Figure 2 is a cross sectional view of an axle box sealing system in accordance with the present invention; and Figure 3 is a cross sectional view of an axle box assembly which incorporates an axle box sealing system in accordance with the present invention.

In Figure 1 of the accompanying drawings there is shown a first inner annulus 20 and a second outer annulus 30. The first annulus 20 is manufactured from a resilient material, preferably rubber or a synthetic plastics material. The first annulus 20 has an inner circumferential surface 22 and an outer circumferential surface 24. A distance between the inner circumferential surface 22 and the outer circumferential surface 24 of the first annulus 20 is substantially shorter than an inner diameter of the first annulus 20. In other words, the thickness of the first annulus 20 is narrow relative to the size of the first annulus 4 The second annulus 30 is manufactured from a friction reducing material, preferably Teflon or a graphite-filled material. The second annulus 30 has an inner circumferential surface 32 and an outer circumferential surface 34. A distance between the inner circumferential surface 32 and the outer circumferential surface 34 of the second annulus 30 is substantially shorter than an inner diameter of the second annulus 30. In other words, the thickness of the second annulus 30 is narrow relative to the size of the second annulus In use, the first annulus 20 is located in the area defined by the second annulus Referring to Figure 1A of the accompanying drawings there is shown the first annulus jo nested within the second annulus 30. The first annulus 20 has a first side surface 26 and a second opposed side surface 28. The distance between the inner circumferential surface S"22 and the outer circumferential surface 24 of the first annulus 20 is substantially of the same order as a distance between the first surface 26 and the second surface 28 of the first annulus. In other words, the depth of the first annulus 20 is substantially the same as the thickness of the first annulus It is preferable that a cross-sectional area 29 of the first annulus 20 defined by the inner circumferential surface 22, the outer circumferential surface 24, the first surface 26 and the second surface 28 is quadrangular.

The second annulus 30 has a first side surface 36 and a second opposed side surface 38.

The distance between the inner circumferential surface 32 and the outer circumferential surface 34 of the second annulus 30 is substantially of the same order as a distance between the first surface 36 and the second surface 38 of the second annulus. In other words, the depth of the second annulus 30 is substantially the same as the thickness of the second annulus It is preferably that a cross-sectional area 39 of the second annulus 30 defined by the inner circumferential surface 32, the outer circumferential surface 34, the first surface 36 and the second surface 38 is quadrangular.

It is preferable that the cross-sectional area 29 of the first annulus 20 is substantially of the same size as the cross-sectional area 39 of the second annulus It will be appreciated that the size of the first annulus 20 and the size of the second annulus 30 will be determined by axle diameter and class of axle box for which the axle S 10 box sealing system is arranged to be fitted.

In Figure 2 of the accompanying drawings there is shown an axle box sealing system including the first annulus 20, the second annulus 30, a circumferential recessed groove V 40, a labyrinth ring 50, a back plate 60 and an axle The circumferential recessed groove 40 includes two substantially parallel vertical walls 42 interconnected by a flat floor 44 which extends laterally between the vertical walls 42, wherein a distance between the two walls 42 of the circumferential recessed groove 40 is marginally greater than the depth of the first annulus 20 or the depth of the second annulus 30. Thus, the first annulus 20 and the second annulus 30 snugly fit within the circumferential recessed groove A depth of the two walls 42 of the circumferential recessed groove 40 is less than the sum of the thickness of the first annulus 20 and the thickness of the second annulus 30. The depth of the two walls 42 of the circumferential recessed groove 40 is greater than the thickness of the first annulus 20 or the thickness of the second annulus The circumferential recessed groove 40 is arranged in use, to house the first annulus and an inner portion of the second annulus 30 within the area defined by the flat floor 44 and the walls 42 of the circumferential recessed groove 40. The inner circumferential surface 22 of the first annulus 20 is contiguous and parallel with respect to the flat floor 44 of the circumferential recessed groove 40, and the first surface 26 and second surface 28 of the first annulus 20 are adjacent and parallel with the respective walls 42 of the circumferential recessed groove 40. The inner circumferential surface 32 of the second annulus 30 is contiguous and parallel with respect to the outer circumferential surface 24 of the first annulus 20. A portion of the first surface 36 and a portion of the second surface 38 of the second annulus 30, located proximal with respect to the first annulus are adjacent and parallel with the respective walls 42 of the circumferential recessed groove The circumferential recessed groove 40 is located in a lateral surface 52 of the labyrinth ring 50, proximal a circumferential, outwardly expanding lug 54 of the labyrinth ring Further, there is provided on the back plate 60 an inwardly extending circumferential lug 62 which is located inwardly of and adjacent the lug 54. The circumferential recessed groove 40 is located such that it is aligned with the lug 62 of the back plate In use, the lug 62 of the back plate 60 is located at a distance from the flat floor 44 of the circumferential recessed groove 40 which is marginally less than the sum of the thickness of the first annulus 20 and the thickness of the second annulus 30. Thus, the first annulus and the second annulus 30 fit snugly between the flat floor 44 of the circumferential recessed groove 40 and the inwardly extending circumferential lug 62 of the back plate A close fitting seal is effected between the back plate 60 and the labyrinth ring 7 when the first annulus 20 and the second annulus 30 are housed within the circumferential recessed groove It will be appreciated that the lug 62 of the back plate 60 may be machined to standardise a bore such that the bore is an appropriate diameter for the class of axle box to be used.

In use, the outer circumferential surface 34 of the second annulus 30 is contiguous to the lug 62 of the back plate In Figure 3 of the accompanying drawings there is shown an axle box assembly 100 which incorporates an axle box sealing system The axle box assembly 100 includes an axle 70, a series of spherical bearings units 110 t which are press fitted onto the axle 70 and located in a housing 120. Individual spherical bearings units 110 are separated by a spacer 130. Axle grease is distributed in an area 140 o defined by the spacer 130, the spherical bearings units 110 and the housing 120, where the axle grease acts as a lubricant for the spherical bearings units 110. The axle box sealing system 10 is located adjacent a dust guard area 72 of the axle In use, the axle box sealing system is assembled by initially fitting the first annulus and the second annulus 30 into the circumferential recessed groove 40. The labyrinth ring is then shrunk or press fitted onto the axle 70. The back plate 60 is then engaged with the labyrinth ring 50 and locked with set screws, and finally the housing 120 of the axle box assembly is slide fitted over the back plate 60 and locked into place with nuts and spring washers.

In use, the first annulus 20 is housed in the circumferential recessed groove 40 located in the labyrinth ring 50. The second annulus 30 is placed over the annulus 20 such that an inner portion of the second annulus 30 is housed in the circumferential recessed groove 8 and an outer portion thereof projects outwardly from the circumferential recessed groove The second annulus 30 in conjunction with the first annulus 20 provides a seal between the back plate 60 and the labyrinth ring 50. As the first annulus 20 is resilient any relative movement between the back plate 60 and the labyrinth ring 50 is compensated for by the resilience of the first annulus 20. On the other hand the second annulus 30 is formed of a low friction material so that wear of the first annulus 20 is kept at a relatively low level S. compared to other materials.

*e* In use, the resiliency of the first annulus 20 effectively compensates for misalignment of Sio 0 the lug 62 of the back plate 60 and the lateral surface 52 of the labyrinth ring 50 due to wear movement between the spherical bearing units 110 and the housing 120 when the axle is in motion. The use of Teflon or graphite filled material on the second annulus reduces the friction between the second annulus 30 and the back plate 60 minimising metal wear on the back plate 60, thereby maintaining an acceptable iron content in the 15 grease particularly after an initial polishing or running in stage. Secondly heat generation is minimised which in turn assists the maintenance of a desirable viscosity of the axle grease. The second annulus 30 also maintains minimum wear on the first annulus thereby decreasing costs for replacement and maintenance of axle box seals. The first annulus 20 and the second annulus 30 work in combination to provide an effective barrier against flow of low viscosity axle grease through the labyrinth seal, thus preventing leakages, and ultimately bearing failures which result from inadequate lubrication.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. For example, the circumferential recessed groove 40 could be located in the back plate

Claims

1. An axle box sealing system, including a labyrinth seal having an inner labyrinth ring and an outer back plate interengaged with one another, wherein there is provided a circumferential groove in a facing surface of the labyrinth ring, which groove is arranged, in use, to house a first resilient annulus and an inner portion of a second low friction annulus extending around the first annulus, the second annulus having an outer circumferential surface in engagement with the outer back plate.

2. An axle box sealing system according to claim 2, in which the first resilient Sannulus is made of rubber or a synthetic plastics material.

3. An axle box sealing system according to claim 2 or 3, in which the second low friction annulus is made of polytetrafluorethylene or a graphite-filled material, or oooo .another material having low friction properties. 20

4. An axle box sealing system according to any one of claims 2 to 4, in which the back plate is provided with an inwardly extending circumferential lug, wherein the outer circumferential surface of the second low friction annulus is contiguous with the lug.

5. An axle box sealing system according to any one of claims 2 to 5, in which a portion of the second annulus projects outwardly from the circumferential groove. 11

6. An axle box sealing system substantially as hereinbefore described with reference to any one of the accompanying Figures 1 to 3. DATED THIS 17TH DAY OF SEPTEMBER 2002. ROLLING STOCK SUPPLY SERVICE PTY LTD By their Patent Attorneys LORD COMPANY PERTH, WESTERN AUSTRALIA.