AU784026B2

AU784026B2 - Axle box sealing system

Info

Publication number: AU784026B2
Application number: AU23187/02A
Authority: AU
Inventors: Malcolm Rowcliffe
Original assignee: SKF Australia Pty Ltd
Current assignee: SKF Australia Pty Ltd
Priority date: 1999-07-06
Filing date: 2002-03-08
Publication date: 2006-01-19
Anticipated expiration: 2019-07-06
Also published as: AU2318702A

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) APPLICATION NO:

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COMPLETE SPECIFICATION LODGED:

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RELATED ART: NAME OF APPLICANT: ACTUAL INVENTOR: ADDRESS FOR SERVICE: ROLLING STOCK SUPPLY SERVICE PTY LTD MALCOLM ROWCLIFFE LORD COMPANY, Patent Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA.

"AXLE BOX SEALING SYSTEM" INVENTION TITLE: DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO'S: Australian Provisional Patent Application Number PR3627 filed on March 9, 2001.

The following Statement is a full description of this invention including the best method of performing it known to us:

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 10 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 when 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.

S 15 Australian Patent Application Number 37980/99 describes an axle box sealing system including an labyrinth seal having an inner labyrinth ring and an outer back plate, and **including a resilient annulus and a low friction annulus of similar cross sectional dimension disposed within a groove in the labyrinth ring. In some circumstances it is not possible to apply the invention of Australian Patent Application Number 37980/99, as the invention requires the cutting of a relatively deep groove within the labyrinth ring. This can result in the presence of stress concentrations about the groove and lead to failure of the sealing system.

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

In accordance with one aspect of the present invention there is provided an axle box sealing system comprising a labyrinth seal, the labyrinth seal being formed by an inner labyrinth ring and an outer back plate, the labyrinth ring being arranged to rotate relative to the back plate, wherein a low friction annulus is arranged between the labyrinth ring and the back plate, the low friction annulus being arranged to engage with a resilient annulus, such that the resilient annulus and the low friction annulus combine to provide a seal between the labyrinth ring and the back plate, and whereby the resilient annulus has a cross sectional dimension substantially smaller than a cross sectional dimension of the low friction annulus.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross sectional view of an axle box sealing system in accordance with a first embodiment of the present invention; and Figure la is an enlarged view of a portion of the axle box sealing system of Figure 1.

Figure 2 is a cross sectional view of an axle box sealing system in accordance with a second embodiment of the present invention.

Figure 2a is an enlarged view of a portion of the axle box sealing system of Figure 2.

Referring to the Figures, there is shown an axle box sealing system 10 including an axle 12, an inner labyrinth ring 14, and an outer back plate 16. The axle 12 is supported by bearings (not shown), and is arranged to rotate relative to the outer back plate 16. The inner labyrinth ring 14 is rigidly connected to the axle 12, and is arranged to rotate together with axle 12 relative to the back plate 16.

The labyrinth ring 14 has a first portion 18 adjacent the bearings. The first portion 18 has an outer diameter which varies in a step wise manner along the first portion 18.

The back plate 16 has a first portion 20 corresponding with the first portion 18 of the labyrinth ring 14. The first portion 20 of the back plate 16 has an inner diameter which varies in a step wise manner along the first portion 20. The variations in the inner diameter of the first portion 20 of the back plate 16 are complementary to the variations in outer diameter of the first portion 18 of the labyrinth ring 14. The first !'"'"portion 18 of the labyrinth ring 14 is adjacent, in use, the first portion 20 of the back 1 plate 16. A labyrinth seal 22 is thus formed between the first portions 18, 20 of the labyrinth ring 14 and the back plate 16.

The back plate 16 has a second portion 21 which extends away from the first portion in an axial direction. The second portion 21 has a substantially constant inner diameter.

The labyrinth ring 14 has a second portion 19 which extends away from the first portion 18 in an axial direction. The second portion 19 has a substantially constant :*:external diameter, and is arranged, in use, adjacent the second portion 21 of the back plate 16.

The labyrinth ring 14 has a third portion 23 which extends away from the second portion 19 in an axial direction. The outer diameter of the third portion 23 is tapered, and decreases away from the second portion 19. A wedge shaped (in cross section) gap 25 is therefore evidenced between the third portion 23 of the labyrinth ring 14 and the second portion 21 of the back plate 16.

The labyrinth ring 14 includes a circumferential recessed groove 24. The circumferential recessed groove 24 is located in the second portion 19 of the labyrinth ring 14. The circumferential recessed groove 24 includes two substantially parallel vertical walls 26 interconnected by a floor 28 which extends laterally between the vertical walls 26.

The axle box sealing system 10 further includes a low friction annulus 30 and at least one resilient annulus 32.

The low friction annulus 30 is manufactured from a friction reducing material, preferably Teflon or a graphite-filled material. The low friction annulus 30 has an !'"'"inner circumferential surface 34 having a diameter slightly greater than that of the i circumferential recessed groove 24, and an outer circumferential surface 36 having a diameter substantially the same as the second portion 21 of the back plate 16. A distance between the inner circumferential surface 34 and the outer circumferential surface 36 is substantially shorter than the diameter of the inner circumferential surface 34. In other words, the thickness of the low friction annulus 30 is small relative to the size of the low friction annulus The low friction annulus 30 has a first side surface 38 and a second opposed side :surface 40. The distance between the inner circumferential surface 34 and the outer circumferential surface 36 is substantially of the same order as the distance between the first side surface 38 and the second side surface 40 of the low friction annulus In other words, the depth of the low friction annulus 30 is substantially the same as the thickness of the low friction annulus Preferably, a cross sectional area of the low friction annulus 30 defined by the inner circumferential surface 34, the outer circumferential surface 36, and the first and second side surfaces 38, 40 is substantially square.

The distance between the first and second side surfaces 38, 40 of the low friction annulus 30 is marginally smaller than the distance between the two walls 26 of the recessed groove 24. The distance between the inner circumferential surface 34 and the outer circumferential surface 36 is greater than the depth of the walls 26 of the recessed groove 24. The low friction annulus 30 thus fits snugly within, and protruding from, the recessed groove 24.

The or each resilient annulus 32 is preferably manufactured from rubber or a synthetic plastics material. The or each resilient annulus 32 has an outer diameter substantially equal to the inner diameter of the low friction annulus 30. The or each resilient 10 annulus 32 is substantially circular in cross section, with a cross sectional diameter substantially smaller than the outer diameter of the resilient annulus 32. The or each resilient annulus 32 has a cross sectional area substantially smaller than that of the low friction annulus 30. Preferably, the or each resilient annulus 32 is an O-ring.

In use, the or each resilient annulus 32 is housed within the circumferential recessed groove 24 located in the second portion 19 of the labyrinth ring 14. The low friction annulus 30 is placed over the resilient annulus or annuli 32 such that an inner portion of the low fiction annulus 30 is housed in the circumferential recessed groove 24 and an outer portion thereof projects outwardly from the circumferential recessed groove 24.

The low friction annulus 30 provides a seal between the second portion 19 of the labyrinth ring 14 and the second portion 21 of the back plate 16. Any relative movement between the back plate 16 and the labyrinth ring 14 is compensated for by the resilience of the resilient annulus or annuli 32. On the other hand the low friction annulus 30 does not cause a high level of wear on the resilient annulus or annuli 32 relative to other materials.

In the embodiment shown in Figure 1, the low friction annulus 30 has a small groove arranged to partially engage a single resilient annulus 32 therewithin. The effect of the s engagement of the resilient annulus within this groove is to secure the location of the low friction annulus 30 relative to the floor 28 of the recessed groove 24.

In the embodiment shown in Figure 2, two resilient annuli 32 are used. The resilient i annuli 32 are located parallel to each other, spaced across the floor 28 of the recessed groove 24.

.#oooi 10 In use, the outer circumferential surface 36 of the of the low friction annulus 30 acts against the second portion 21 of the back plate 16, and prevents passage of lubricant between the low friction annulus 30 and the back plate 16 from the axle box to the labyrinth seal 22. Similarly, the resilient annulus or annuli 32 prevents passage of lubricant between the low friction annulus 30 and the labyrinth ring 14 from the axle box to the labyrinth seal 22.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims

1. An axle box sealing system comprising a labyrinth seal, the labyrinth seal being formed by an inner labyrinth ring and an outer back plate, the labyrinth ring being arranged to rotate relative to the back plate, wherein a low friction annulus is arranged between the labyrinth ring and the back plate, the low friction annulus being arranged to engage with a resilient annulus, such that the resilient annulus and the low friction annulus combine to provide a seal between the labyrinth ring and the back plate, and whereby the resilient annulus has a cross sectional dimension substantially S. smaller than a cross sectional dimension of the low friction annulus. 0o :o 15 2. An axle box sealing system as claimed in Claim 1, wherein a circumferential groove is provided in a facing surface of the labyrinth ring or the back plate, the low friction annulus being at least partially arranged within the groove.

3. An axle box sealing system as claimed in Claim 2, wherein the resilient annulus is located within the groove.

4. An axle box sealing system as claimed in Claim 3, wherein the resilient annulus is located between a floor of the groove and the low friction annulus. An axle box sealing system as claimed in any one of Claims 2 to 4, wherein the groove is within the labyrinth ring.

6. An axle box sealing system as claimed in any one of the above claims, wherein the low friction annulus has a groove within which the resilient annulus is at least partially engaged.

7. An axle box sealing system as claimed in any one of the above claims, S°wherein the resilient annulus is made of rubber or a synthetic plastics material. o.o.oi S S"8. An axle box sealing system as claimed in any one of the aove claims, wherein the resilient annulus is an O-ring.

9. An axle box sealing system as claimed in any one of the above claims, wherein the low friction annulus is made of polytetrafluoroethylene or a graphite material, or a material having low friction properties. An axle box sealing system substantially as herein above described with reference to, and as shown in, accompanying Figure 1.

11. An axle box sealing system substantially as herein above described with reference to, and as shown in, accompanying Figure 2. DATED THIS 8TH DAY OF MARCH 2002 RO LL INC S %TOC GK 9 UP I SR VICE9 P TY1 1 TD By their Patent Attorneys LORD COMPANY PERTH, WESTERN AUSTRALIA. .06 .0.00. 0 sole 0 6000