WO2008037009A1

WO2008037009A1 - Chain drive pin assembly

Info

Publication number: WO2008037009A1
Application number: PCT/AU2007/001427
Authority: WO
Inventors: Colin Michael Piacentini; Clayton Hyder
Original assignee: Super Track Enterprises Pty Ltd
Priority date: 2006-09-29
Filing date: 2007-09-26
Publication date: 2008-04-03

Abstract

A pin assembly (16) of a chain assembly (12) comprising pivotally interconnected set of links (13 A, 13B and 14 A, 14B), the pin assembly comprising a pin (18) fixed with respect to one link (13A, 14A) of each set, a first bush (22) rotatably received over the pin and fixed with respect to the other link (13B, 14B) of each set, a second bush (25) rotatably received over the first bush and located between the links, a first lubricant reservoir (26) provided within the pin and connected to the zone defined between the opposed faces of the pin and the first bush, a first sealing means (24) between the pin and the first bush, a second lubricant reservoir (33) formed in the opposed faces of the first and/or second push, said second reservoir being configured such that substantially the full surface of the other opposed faces of the first and second bush will pass over the reservoir with at least one full rotation of one bush relative to the other bush, a second sealing means (30) between the first and second bush.

Description

"Chain Drive Pin Assembly"

Field of the Invention

The present invention relates to a chain drive for a chain and sprocket assembly.

Throughout this specification, the term "chain and sprocket assembly" will be taken to include any arrangement wherein a chain drives, or is driven by, a sprocket and where the chain comprises two sets of links held in a parallel spaced relationship with respect to each other where the links of each set are interconnected by a pin assembly and where the pin assembly provides the engagement surface for the sprocket. One particular application of such an assembly, the chain supports an endless track for a tracked vehicle, for example a bulldozer, grader or shovel.

Throughout this specification and claim, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention

According to a first aspect of the invention, there is provided a pin assembly for the chain of a chain assembly comprising a pair of chains each comprising a set of links, in which adjacent links of each set are pivotally interconnected, the chains being held in spaced relationship by the pin assemblies, the pin assembly comprising a pin adapted to be fixed with respect to one link of each set, a first bush concentrically and rotatably received over the pin and adapted to be fixed with respect to the other link of each set, and a second bush rotatably and concentrically received over the first bush and located between the links, a first lubricant reservoir provided within the pin and connected to the zone defined between the opposed faces of the pin and the first bush, a first sealing means between the pin and the first bush to prevent the escape of lubricant from between the opposed faces of the pin and the first bush, a second lubricant reservoir formed in f the opposed faces of the first and/or second bush, said second reservoir being configured such that substantially the full surface of the other opposed faces of the first and second bush will pass over the reservoir with at least one full rotation of one bush relative to the other bush, a second sealing means between the first and second bush to prevent the escape of lubricant from between the opposed faces of the first bush and second bush.

According to a preferred feature of the invention the second reservoir comprises a first recess formed in the one opposed face, said recess having the form of a convoluted groove in the one opposed face. According to a preferred feature of the invention the reservoir comprises at least one annular second recess formed in the one opposed face and located adjacent at least one end of the one opposed face, the first recess opening into each second recess, the second sealing means provided outward of the second reservoir. According to a preferred feature of the invention wherein the second reservoir is provided in the inner face of the second bush.

According to a preferred feature of the invention, the second sealing means comprises a pair of annular seals provided between the first bush and the second bush. According to a preferred feature of the invention, the annular seals are located proximate the ends of the second bush. According to a preferred feature of the invention a pair of annular recesses is provided between the first bush and the second bush, each annular recess accommodating one of the annular seals. According to a preferred feature of the invention the pair of annular recesses is provided on the inner wall of the second bush.

According to a second aspect of the invention, there is provided a chain assembly comprising a pair of chains each comprising a set of links, in which adjacent links of each set are pivotally interconnected, the chains being held in spaced relationship by the pin assemblies and the links of each set are pivotally interconnected by the pin assemblies, wherein the pin assemblies are of the form as claimed at any one of the preceding claims and where the second bush of each pin assembly provides the engagement surfaces for a sprocket According to a preferred feature of the invention the ends of the second bush are received in annular recesses formed in the inner axial face of the other links and a third sealing means is located between the ends of the second bush and the respective annular recesses. According to a preferred feature of the invention the third seal is associated with a dust cover outward of the third seal and supported to lie across the annular recess. According to a preferred feature of the invention a biasing means is located in the annular recess to bear upon the respective end of the second bush, the biasing means providing a biasing force on the end of the second bush away from the inner end of the recess. According to a preferred feature of the invention the third seal comprises an O-ring seal.

According to a preferred feature of the invention the outer end of each end of the inner radial face of the first bush is provided with a slight taper prior to the engagement of the outer end in the other link. According to a preferred feature of the invention the extent of the taper substantially corresponds to the thickness of the other link in which the end is fixed. According to a preferred feature of the invention the variation in radius of the inner face of the first bush as a result of the taper is no more than 0.1mm.

The invention will be more fully understood in the light of the following description of several specific embodiments.

Brief Description of the Drawings

The description is made with reference to the accompanying drawings of which:

Figure 1 is a partial exploded perspective view of a section of a chain and sprocket assembly in accordance with the first embodiment of the invention;

Figure 2 is a sectional elevation view taken through section A-A of Figure 1 ;

Figure 3 is an enlarged sectional side elevation of a region at the end of the second bush according to the first embodiment showing the sealing provided for the second bush; Figure 4 is a sectional side elevation of the second bush according to the first embodiment illustrating the configuration of the reservoir;

Figure 5 is a fragmentary view of an end portion of the first bush according to the first embodiment showing tapers thereon (to an exaggerated extent);

Figure 6 is a fragmentary view of the end portion of the first bush shown in Figure 5 fitted into a link;

Figure 7 is a fragmentary view of an end portion of a first bush of a chain and sprocket assembly in accordance with the second embodiment of the invention, showing in particular a taper thereon (to an exaggerated extent);

Figure 8 is a fragmentary view of the end portion of the first bush shown in Figure 7 fitted into a link; and

Figure 9 is an enlarged sectional side elevation of a region at the end of the second bush according to the third embodiment showing the sealing provided for the second bush.

Detailed Description of the Specific Embodiments

Each of the embodiments relate to a chain which is used to support the track of a tracked vehicle from the drive. A difficulty that has been experienced in relation to such vehicles relates to the wear that takes place on the pin assemblies which support the links at each side of the chain and the sockets of the sprockets which receive the pin assemblies.

The chain drive of the first embodiment as shown at Figures 1 to 6 comprises a chain 12 which has a pair of sets of links 13 and 14 with one set of links 13 located to one side of the chain 12 and the other set of links 14 located to the other side of the chain 12 and the sets of links being interconnected by a set of pin assemblies 16 where the pin assemblies 16 are to be engaged by the tooth spaces 15 of the sprockets 11 of the drive which are provided on the vehicle. AII of the links in a given set are identical, one set of links being the mirror image of the other set of links. In the arrangement shown, there are links 13A and 13B interconnected by one of the pin assemblies 16 and links 14A and 14B also interconnected by that same pin assembly. The links are interconnected such that the adjacent ends of links 13A, 13B and 14A, 14B overlap and are supported from the pin assemblies 16 such that they are capable of relative pivotable movement with respect to each other about the longitudinal axis of the pin assembly 16.

Each link 13 is configured in known manner such that opposed ends thereof are laterally offset with respect to each other. Similarly, each link 14 is configured in known manner such that opposed ends thereof are laterally offset with respect to each other. One end section of each link 13, 14 incorporates a first aperture 19 and the other end section incorporates a second aperture 23.

The chain 12 is adapted to support the track through bored apertures 17 which are provided in the outer edge of each of the links.

The pin assemblies 16 each comprise a pin 18, the ends of which are fixedly received in the first apertures 19 in the axially outermost end section of each two interconnected links . In the interconnected links shown in Figure 2, the pin 18 has one end received in first aperture 19 of link 13A and the other end received in first aperture 19 of link 14A. Each end of the pin 18 is formed with a groove 20 and each groove 20 receives a retaining circlip 21 accommodated in counterbores provided at the outer ends of the first apertures 19.

A cylindrical first bush 22 is concentrically and rotatably received over the pin 18 and the ends of the bush 22 are fixedly received in the second apertures 23 provided in the axially innermost end sections of each two interconnected links. In the interconnected links shown in Figure 2, the first bush 22 has one end received in second aperture 23 of link 13B and the other end received in the second aperture 23 of link 14B. The pin 18 is formed with a hollow core 26 which is open at one end and where the open end is closed by an end cap 27. The core is intended to receive a lubricant before the core is closed by the end cap 27. A radial passage 29 is provided intermediate of the length of the pin 18 between the hollow core 26 and outer radial face of the pin 18 in order that lubricant is able to flow into space between the opposed faces of the pin and the first bush 22. A first sealing means 24 is provided between each end of the first bush 22 and the abutting face of the respective link fixed to the pin 18 (being links 13A and 14A in the arrangement shown in Figure 2) to retain the lubricant between the pin 18 and the first bush 22. The first sealing means 24 comprises a pair of annular seals which are supported and accommodated in counter bores provided at the inner ends of the first apertures 19 of the respective links (being links 13A and 14A in the arrangement shown in Figure 2)

A second bush 25 is rotatably and concentrically received over the first bush 22 between the innermost ends of the links supported by the pin assemblies 16. In the arrangement shown in Figure 2, the second bush 25 is received between the inner end sections of links 13B and 14B. The outer face of the second bush 25 is cylindrical and is of a diameter to be snugly received in the tooth spaces 15 of the sprockets of the vehicle.

The pin assembly 16 also accommodates a lubricant between the first and second bushes 22, 25. A second sealing means 30 is provided between the first bush 22 and the second bush 25. The further sealing means 30 comprises a pair of annular seals 31 supported in annular recesses 32 respectively, provided at each end of the inner radial face of the second bush 25. In addition, a reservoir 33 is provided in the inner face of the second bush 25. The reservoir 33 comprises an annular groove or channel 33A provided at the ends of the second bush 25 and inward of the second sealing means 30 and a serpentine or convoluted channel 33B which extends over the inner radial face of the second bush 25 between the annular grooves or channel 33A and opens into those annular grooves or channels 33A. The reservoir 33 is intended to receive and accommodate a lubricant which can be introduced prior to the assembly of the pin assembly 16. As a result of the configuration of the reservoir 33, the opposing face of the first bush 22 has access to the reservoir on each rotation of the second bush 25 on the first bush. Furthermore because the radial extent of the reservoir 33 into the structure of the second bush 25 is not significant, the strength of the second bush is not compromised. The ends of the second bush 25 are received in a second annular recess 37 which is provided in the opposed axial face of the respective links 13, 14. In the arrangement shown in Figure 2, the second bush 25 is received in the recesses 37 in inner end sections of links 13B and 14B.

As shown at Figure 3 a third seal 39 is provided between the ends of the second bush 25 and the opposed axial face of the second recess 37 together with a resilient spring in the form of a wave spring 41 which bears between the opposed end face and axial face to bias the second bush 25 away from the links. The resultant effect of the resilient springs 41 is to bias the second bush 25 to a central position between the links. In addition, a dust excluder cover 43 is provided between the opposed outer radial faces of the second bush 25 and the second recess 37. The third seal 39 is intended to exclude small particulate matter from the assembly and the dust cover 43 is intended to exclude larger particulate matter.

Owing to the provision of the second bush 25, there is little or no relative motion between the socket of the chain and the exterior of the pin assembly 16 which is provided by the second bush 25 which is able to rotate on the first bush 22. As a result, wear to the second bush 25 and the socket as a result of interface abrasion is significantly reduced.

In this embodiment, the outer end portion of each end of the inner radial face of the first bush 22 is provided with a slight first taper 51 , as shown in Figure 5. The axial extent of the first taper 51 substantially corresponds to the thickness of the link 13, 14 in which the respective end is fixed (such links being links 13B and 14B in the arrangement shown in Figure 2). In this embodiment, the radial extent of the first taper 51 is of the order of 0.1mm. In addition, the outer end portion of each end of the outer radial face of the first bush 22 is provided with a slight second taper 52, as also shown in Figure 5. The axial extent of the second taper 52 substantially corresponds to the thickness of the link 13, 14 in which the respective end is fixed (such links being links 13B and 14B in the arrangement shown in Figure 2). In this embodiment, the radial extent of the second taper 52 is of the order of 0.05mm. The presence of the first taper 51 provides a small amount of clearance between the inner face of the first bush 22 and the outer radial face of the pin 18 whereby when the first bush 22 is driven into engagement with the respective link 13, 14 , the taper 51 will allow for some radial deflection of the end of the first bush 22 to facilitate complete engagement with the link and without creating a binding force between the first bush 22 and the pin 18 in that region. The second taper 52 also assists in this way by providing a clearance space between the first bush 22 and the radially inner face of the aperture 23 in which it is received, the clearance space accommodating an interference fit between the first bush 22 and the aperture 23 without distorting the first bush 22 to an extent that would create a binding force on the pin 18.

Figure 5 illustrates the first and second tapers 51 , 52 on the second bush 22. The tapers 51 , 52 shown in an exaggerated form for the purposes of illustration, as they would otherwise not necessarily be discernible in the drawing. Figure 6 illustrates schematically the second bush 22 installed in the aperture 23, with deflection arising from the interference fit therebetween being limited to ensure that there is no binding force on the pin 18.

There may be applications where the first taper 51 and/or the second taper 52 are not necessary on the first bush 22.

According to a second embodiment of the invention the outer end portion of each end of the outer radial face of the first bush 22 is formed with an outwardly flaring taper 53, as shown in Figure 7. Apart from the configuration of the outer end portions of the first bush 22, the chain drive according to the second embodiment is the same as that of the first embodiment and so corresponding reference numerals are used to identify corresponding parts. In this embodiment, the presence of the taper 53 assists in establishing a binding force between the first bush 22 and the radial inner face of the aperture 23 in which it is received. The flared taper 53 is caused to deflect inwardly and exerts a radially outward binding force on the surrounding aperture 23 in the respective link 14 with which it is engaged, as shown in Figure 8. In accordance with a third embodiment as shown at Figure 9 the annular recess 37 in the link 13 or 14 which receives the end of the second bush is formed to closely receive the end of the second bush. In addition the outer edge 38 of the end of the second bush is bevelled and the third seal 39 takes the form of an O- ring seal 39 which is received between the outer bevelled edge and the annular recess. According to alternative embodiments the O-ring seal can be replaced by other equivalent forms of seal

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiments described above.

Claims

ClaimsThe Claims Defining the Invention are as Follows:

1. A pin assembly for the chain of a chain assembly comprising a pair of chains each comprising a set of links, in which adjacent links of each set are pivotally interconnected, the chains being held in spaced relationship by the pin assemblies, the pin assembly comprising a pin adapted to be fixed with respect to one link of each set, a first bush concentrically and rotatably received over the pin and adapted to be fixed with respect to the other link of each set, and a second bush rotatably and concentrically received over the first bush and located between the links, a first lubricant reservoir provided within the pin and connected to the zone defined between the opposed faces of the pin and the first bush, a first sealing means between the pin and the first bush to prevent the escape of lubricant from between the opposed faces of the pin and the first bush, a second lubricant reservoir formed in the opposed faces of the first and/or second bush, said second reservoir being configured such that substantially the full surface of the other opposed faces of the first and second bush will pass over the reservoir with at least one full rotation of one bush relative to the other bush, a second sealing means between the first and second bush to prevent the escape of lubricant from between the opposed faces of the first bush and second bush.

2. A pin assembly as claimed at claim 1 wherein, the second reservoir comprises a first recess formed in the one opposed face, said recess having the form of a convoluted groove in the one opposed face.

3. A pin assembly as claimed at claim 2 wherein the reservoir comprises at least one annular second recess formed in the one opposed face and located adjacent to at least one end of the one opposed face, the first recess opening into each second recess, the second sealing means provided outward of the second reservoir.

4. A pin assembly as claimed at claim 3 wherein the second reservoir is provided in the inner face of the second bush.

5. A pin assembly as claimed at any one of the preceding claims wherein, the second sealing means comprises a pair of annular seals provided between the first bush and the second bush.

6. A pin assembly as claimed at claim 5 wherein, the annular seals are located proximate the ends of the second bush.

7. A pin assembly as claimed at claim 6 wherein, a pair of annular recesses is provided between the first bush and the second bush, each annular recess accommodating one of the annular seals.

8. A pin assembly as claimed at claim 7 wherein, the pair of annular recesses is provided on the inner wall of the second bush.

9. A pin assembly substantially as herein describe with reference to the accompanying drawings.

10. A chain assembly comprising a pair of chains each comprising a set of links, in which adjacent links of each set are pivotally interconnected, the chains being held in spaced relationship by the pin assemblies and the links of each set are pivotally interconnected by the pin assemblies, wherein the pin assemblies are of the form as claimed at any one of the preceding claims and where the second bush of each pin assembly provides the engagement surfaces for a sprocket

11. A chain as claimed at claim 10 wherein, the ends of the second bush are received in annular recesses formed in the inner axial face of the other links and a third sealing means is located between the ends of the second bush and the respective annular recesses.

12. A pin assembly as claimed at claim 11 wherein the third seal is associated with a dust cover outward of the third seal and supported to lie across the annular recess.

13. A chain as claimed at claim 11 or 12 wherein a biasing means is located in the annular recess to bear upon the respective end of the second bush, the biasing means providing a biasing force on the end of the second bush away from the inner end of the recess.

14. A chain as claimed at claim 11 or 12 or 13 wherein the third seal comprises an O-ring seal.

15. A chain as claimed at any one of claims 10 to 14 wherein the outer end of each end of the inner radial face of the first bush is provided with a slight taper prior to the engagement of the outer end in the other link.

16. A chain as claimed at claim 15 wherein the extent of the taper substantially corresponds to the thickness of the other link in which the end is fixed.

17. A chain as claimed at claim 15 or 16 wherein the variation in radius of the inner face of the first bush as a result of the taper is no more than 0.1 mm.

18. A chain substantially as herein described with reference to the accompanying drawings.