Technical field of the invention

This invention relates to a centre pivot liner, more particularly a railway bogie centre pivot liner.

Background to the invention

Materials having a relatively low coefficient of friction (CoF) value tend to have relatively low impact and/or mechanical strength, thus while suitable to promote slidable displacement between moving parts, on the downside tend to not having the required degree of impact and/or mechanical strength required.

Railway bogie centre pivot liners manufactured from synthetic materials are well known in the art. The bearing surfaces of these kind of liners are currently manufactured from a synthetic material having relatively high mechanical strength, coupled with acceptable, but not optimal, CoF values.

The applicant having considered the above proposes a railway bogie centre pivot liner comprising of at least two types of materials so as to yield a liner having improved friction reduction properties, while at the same time having a certain minimum degree of impact and/or mechanical strength.

Summary of the invention

According to a first aspect of the invention there is provided a centre pivot liner which includes a body; and a bearing formation mountable about the body for in use, defining a bearing surface of the centre pivot liner; wherein the bearing formation has a coefficient of friction value less than that of the body. The body may be disc shaped in plan view.

The body may include elongate grooves arranged in a spaced apart manner about the body and further radiating centrally away from the body.

The bearing formation may have a coefficient of friction value less than that of the flange.

The bearing formation may be mountable about a receiving formation defined in the body and/or flange.

The receiving formation may be shaped and sized for complementarily receiving the bearing formation therein.

The receiving formation may include a recess and/or an aperture.

The receiving formation may include a plurality of recesses and/or apertures defined in a spaced apart relationship about the body and/or flange. The recesses and/or apertures may be evenly spaced apart.

The bearing formation may have a thickness dimension such that when located in the receiving formation, the bearing formation protrudes about an inner and/or outer facing surface of the body and/or flange, the inner and/or outer protruding surface defining the bearing surface.

The bearing formation may have a thickness dimension such that when located in the receiving formation, the bearing formation is flush with the inner and/or outer facing surface of the body and/or flange.

The bearing formation may be kept in place in the receiving formation by incorporating a suitable adhesive.

The bearing formation may be shaped and sized to, in use, fit into the receiving formation in a friction fit manner. The receiving formation and bearing formation may be distinctively dimensioned so as to define a retaining arrangement for, in use, retaining the bearing formation in the receiving formation in a fixed manner.

The receiving formation and bearing formation may be distinctively dimensioned so as to define a retaining arrangement for, in use, releasably retaining the bearing formation in the receiving formation.

The retaining arrangement may include a female type formation defined circumferentially about, and preferably centrally, an outer surface of the bearing formation.

The female type formation may take the form of a groove defined circumferentially about and centrally an outer surface of the bearing formation.

The retaining arrangement may further include a male type formation defined circumferentially about, and preferably centrally, an inner facing surface of the receiving formation for mating with the female type formation to retain the bearing formation therein.

The male type formation may take the form of a ridge extending circumferentially about an inner facing surface of the receiving formation.

The retaining arrangement may be configured to retain the bearing formation in the receiving formation in an interlocking manner.

The bearing formation may have a maximum coefficient of friction value of typically less than about 0.2 when employing the internationally recognised formula as set out in document ASTM D3702 - 94(2019) entitled “Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self- Lubricated Rubbing Contact Using a Thrust Washer Testing Machine”.

Abovementioned international standard was developed in accordance with internationally recognised principles on standardisation established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organisation Technical Barriers to Trade (TBT) Committee.

In another form of the invention the body may, in use, further include a flange extending upwardly away from a peripheral region of and circumferentially about the body.

In use, the flange facilitates rotation of the bogie about the centre pivot as well as reduce wear to the centre pivot.

The body and/or flange may be manufactured from a synthetic or metallic material.

The synthetic material may include a polymer material, or a mixture wherein the mixture includes a polymer material.

The body and / or flange may be manufactured from a material having resiliently deformable properties.

According to a second aspect of the invention there is provided a centre pivot liner which includes a body for in use, defining a bearing surface of the centre pivot liner, wherein the body has a coefficient of friction value of typically less than about 0.2.

In this form of the invention the centre pivot liner may further include a flange extending circumferentially about and extending upward away from a peripheral region thereof for facilitating rotation of the bogie about the centre pivot as well as reduce wear to the centre pivot.

The coefficient of friction value of typically less than 0.2 will be established when employing the internationally recognised formula as set out in document ASTM D3702 - 94(2019) entitled “Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine”.

The flange may be manufactured from a synthetic or metallic material.

The synthetic material may include a polymer material, or a mixture wherein the mixture includes a polymer material.

The flange may be manufactured from a material having resiliently deformable properties.

Brief Description of the Drawings

The invention will now be described by way of the following, non-limiting example with reference to the accompanying drawings. In the drawings: -

Figures 1 depicts a first embodiment;

Figures 2 depicts the centre pivot liner shown in figure 1, including the flange;

Figure 3 is a cross sectional side view of figure 2; Figure 4 is a top perspective of the first embodiment illustrating the bearing formations arranged flush with inner surface of the body;

Figure 5 is a cross sectional side view of figure 4;

Figure 6 is a bottom perspective illustrating the receiving formation in the form of a plurality of apertures; Figure 7 is an enlarged view of a section of figure 6 more clearly depicting the male type formation of the receiving formation;

Figure 8 is a top perspective depicting the receiving formation in the form of a plurality of recesses; Figure 9 is a top perspective of the bearing formation;

Figure 10 is a cross sectional side view of figure 9;

Figure 11 is a top perspective of a second embodiment; and

Figure 12 is top perspective of the second embodiment including a flange, in accordance with the invention.

Detailed description of the drawings

Figures 1 to 8 depict a first embodiment of the centre pivot liner 10 which includes a body 12 and a bearing formation 14 mountable about the body 12 for in use, defining a bearing surface 16 of the centre pivot liner 10, wherein the bearing formation 14 has a coefficient of friction value less than that of the body 12.

Body 12 further includes elongate grooves 13 arranged in a spaced apart manner about the body 12 and further radiating centrally away from the body 12.

Body 12 can also include a flange 18, shown in figure 2, extending upwardly away from a peripheral region of and, circumferentially about the body 12 for in use, facilitating rotation of the bogie about the centre pivot as well as reduce wear to the centre pivot.

The bearing formation 14 will typically also have a coefficient of friction value less than the flange 18.

Bearing formation 14 is typically mountable about a receiving formation defined in the body 12 and/or flange (the latter not shown).

The receiving formation will preferably be shaped and sized for complementarily receiving the bearing formation 14 therein and can be in the form of a recess 19, see figure 7, or an aperture 21 as depicted in figure 6, defined about the body 12 and/or flange 18 and will preferably be presented as a plurality of recesses 19 and/or apertures 21 spaced apart, more preferably evenly spaced apart, about the body 12 and/or flange 18 (the latter not shown).

Figures 1, 2 and 3 depict bearing formation 14 having a thickness dimension such that when located in the receiving formation, the bearing formation 14 protrudes about an inner facing surface 20 of the body 12, the inner protruding surface defining bearing surface 16.

Figures 4 and 5 depict bearing formation 14 having a thickness dimension such that when located in the receiving formation, the bearing formation is flush with the inner facing surface 20 of the body 12.

It is to be appreciated that the bearing formation 14 can also be arranged about an inner surface 22 of flange 18.

The receiving formation and bearing formation 14 will typically be distinctively dimensioned so as to define a retaining arrangement for, in use, retaining the bearing formation 14 in the receiving formation in a releasable, or, fixed manner.

Figures 3, 5, 9 and 10 more clearly illustrates the retaining arrangement which includes a female type formation in the form of a groove 24 defined circumferentially about, and preferably centrally, an outer surface of the bearing formation 14.

The retaining arrangement further also includes a male type formation in the form of a ridge 26, more clearly shown in figures 3, 5 and 7, defined circumferentially about, and preferably centrally, an inner facing surface of the receiving formation for complementarily mating with the female type formation to retain the bearing formation 14 therein.

Bearing formation 14 will preferably have a maximum coefficient of friction value of typically less than 0.2 when employing the internationally recognised formula as set out in document ASTM D3702 - 94(2019) entitled “Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine”.

Abovementioned international standard was developed in accordance with internationally recognised principles on standardisation established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organisation Technical Barriers to Trade (TBT) Committee.

Body 12 and/or flange 18 can further be manufactured from a synthetic or metallic material which can include a polymer material, or a mixture wherein the mixture includes a polymer material.

The body 12 and / or flange 18 can further be manufactured from a material having resiliently deformable properties.

Figures 11 and 12 depict a second embodiment of the invention 110 of the invention, wherein the body 112 has a coefficient of friction value less than that of the flange 114.

The body will typically have a coefficient of friction value of typically less than 0.2 when employing the internationally recognised formula as set out in document ASTM D3702 - 94(2019) entitled “Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine”.

Body 112 further includes elongate grooves 113 arranged in a spaced apart manner about the body 112 and further radiating centrally away from the body 112.

Flange 114 can further be manufactured from a synthetic or metallic material which can include a polymer material, or a mixture wherein the mixture includes a polymer material. Flange 114 can further be manufactured from a material having resiliently deformable properties.

The Applicant considers the invention advantageous in that a railway bogie centre pivot liner is disclosed which is manufactured from two types of material yielding a liner with improved bearing characteristics wherein the bearing formations defining the bearing surfaces are manufactured from a material having a coefficient of friction (CoF) value lower than that of the remaining structure.

This combination of use of materials yields a bogie centre pivot liner of relatively high mechanical strength to endure high impacts and mechanical stresses, while at the same time having improved bearing characteristics. The thickness dimension of the bearing formations may further be such as to define the bearing surface flush with inner and/or outer facing surfaces of the body and/or flange, or such as to allow the bearing surfaces to protrude above the inner and/or outer facing surfaces of the body and/or flange.

It shall be understood that the examples are provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.