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Title:
WHEEL FOR A TRACK SYSTEM
Document Type and Number:
WIPO Patent Application WO/2020/252583
Kind Code:
A1
Abstract:
A wheel for a track system for traction of a vehicle, in which the wheel may be designed to enhance its lubrication while facilitating its manufacturing (e.g., by eliminating one or more welds and/or reducing its number of parts).

Inventors:
LUSSIER ALAIN (CA)
Application Number:
PCT/CA2020/050847
Publication Date:
December 24, 2020
Filing Date:
June 18, 2020
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
CAMSO INC (CA)
International Classes:
B62D55/08; B62D55/092
Domestic Patent References:
WO2016131140A12016-08-25
Foreign References:
US6364438B12002-04-02
JP2015020608A2015-02-02
Attorney, Agent or Firm:
SMART & BIGGAR LLP (CA)
Download PDF:
Claims:
CLAIMS

1. A wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track- engaging assembly, the wheel comprising a body that comprises:

- a circumferential surface configured to contact the track; and

- a cavity comprising:

- a lubricant chamber configured to contain a lubricant for the wheel; and

- a bushing-engaging portion configured to engage a bushing;

wherein a diameter of the bushing-engaging portion of the cavity corresponds to a majority of a radius of the wheel.

2. The wheel of claim 1 , wherein the diameter of the bushing-engaging portion of the cavity corresponds to at least 60% of the radius of the wheel.

3. The wheel of claim 1 , wherein the diameter of the bushing-engaging portion of the cavity corresponds to at least 70% of the radius of the wheel.

4. The wheel of claim 1 , wherein the bushing-engaging portion of the cavity has a circular cross-section.

5. The wheel of claim 1 , wherein the bushing-engaging portion of the cavity has a noncircular cross-section.

6. The wheel of claim 5, wherein the noncircular cross-section of the bushing- engaging portion of the cavity is a polygonal cross-section.

7. The wheel of claim 1 , wherein the cavity includes a machined internal surface.

8. The wheel of claim 1 , wherein the cavity includes a polished internal surface.

9. The wheel of claim 1 , wherein: the cavity includes an internal surface; and a surface roughness of the internal surface of the cavity is no more than 6.3 pm.

10. The wheel of claim 1 , wherein: the cavity includes an internal surface; and a surface roughness of the internal surface of the cavity is no more than 3.2 pm.

11. The wheel of claim 1 , wherein: the cavity includes an internal surface; and a surface roughness of the internal surface of the cavity is no more than 0.4 pm.

12. The wheel of claim 1 , wherein a dimension of the lubricant chamber in a radial direction of the wheel varies in an axial direction of the wheel.

13. The wheel of claim 12, wherein the dimension of the lubricant chamber in the radial direction of the wheel is less in lateral portions of the lubricant chamber than in a central portion of the lubricant chamber that is disposed between the lateral portions of the lubricant chamber in the axial direction of the wheel.

14. The wheel of claim 1 , wherein the body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel.

15. The wheel of claim 14, wherein the circular members are integrally cast with one another.

16. The wheel of claim 14, wherein the circular members of the body of the wheel comprises at least two circular members.

17. The wheel of claim 14, wherein the circular members of the body of the wheel comprises at least three circular members.

18. The wheel of claim 14, wherein each of a first lateral one of the wheel members and a second lateral one of the wheel members is wider in an axial direction of the wheel than a central one of the wheel members that is disposed between the first lateral one of the wheel members and the second lateral one of the wheel members in the axial direction of the wheel.

19. The wheel of claim 18, wherein the central one of the wheel members is larger in diameter than the first lateral one of the wheel members and the second lateral one of the wheel members.

20. The wheel of claim 1 , wherein the bushing comprises a metallic material.

21. The wheel of claim 20, wherein the metallic material is a first metallic material and the bushing comprises a second metallic material.

22. The wheel of claim 20, wherein the metallic material comprises an alloy.

23. The wheel of claim 1 , wherein the bushing comprises a polymeric material.

24. The wheel of claim 23, wherein the polymeric material is fiber-reinforced polymeric material.

25. The wheel of claim 1 , wherein: the bushing is an outer bushing; and the outer bushing is configured to engage an inner bushing extending within the outer bushing.

26. The wheel of claim 1 , wherein the cavity comprises a seal-engaging portion configured to engage a seal.

27. The wheel of claim 26, wherein a diameter of the seal-engaging portion of the cavity is greater than the diameter of the bushing-engaging portion of the cavity.

28. The wheel of claim 1 , comprising a hub secured to the body of the wheel.

29. The wheel of claim 28, wherein the hub comprises a lubricant cap operable to allow access to the lubricant.

30. A track system comprising the wheel of claim 1.

31. A wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track- engaging assembly, the wheel comprising a body that comprises:

- a circumferential surface configured to contact the track; and

- a cavity comprising:

- a lubricant chamber configured to contain a lubricant for the wheel; and

- a bushing-engaging portion configured to engage a bushing;

wherein: the body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel; and the cavity includes a machined internal surface.

32. The wheel of claim 31 , wherein the machined internal surface of the cavity is a polished internal surface.

33. The wheel of claim 31 , wherein a surface roughness of the internal surface of the cavity is no more than 6.3 pm.

34. The wheel of claim 31 , wherein a surface roughness of the internal surface of the cavity is no more than 3.2 pm.

35. The wheel of claim 31 , wherein a surface roughness of the internal surface of the cavity is no more than 0.4 pm.

36. The wheel of claim 31 , wherein a diameter of the bushing-engaging portion of the cavity corresponds to a majority of a radius of the wheel.

37. The wheel of claim 36, wherein the diameter of the bushing-engaging portion of the cavity corresponds to at least 60% of the radius of the wheel.

38. The wheel of claim 36, wherein the diameter of the bushing-engaging portion of the cavity corresponds to at least 70% of the radius of the wheel.

39. The wheel of claim 31 , wherein the bushing-engaging portion of the cavity has a circular cross-section.

40. The wheel of claim 31 , wherein the bushing-engaging portion of the cavity has a noncircular cross-section.

41. The wheel of claim 31 , wherein the noncircular cross-section of the bushing- engaging portion of the cavity is a polygonal cross-section.

42. The wheel of claim 31 , wherein a dimension of the lubricant chamber in a radial direction of the wheel varies in an axial direction of the wheel.

43. The wheel of claim 42, wherein the dimension of the lubricant chamber in the radial direction of the wheel is less in lateral portions of the lubricant chamber than in a central portion of the lubricant chamber that is disposed between the lateral portions of the lubricant chamber in the axial direction of the wheel.

44. The wheel of claim 31 , wherein the circular members are integrally cast with one another.

45. The wheel of claim 31 , wherein the circular members of the body of the wheel comprises at least two circular members.

46. The wheel of claim 31 , wherein the circular members of the body of the wheel comprises at least three circular members.

47. The wheel of claim 31 , wherein each of a first lateral one of the wheel members and a second lateral one of the wheel members is wider in an axial direction of the wheel than a central one of the wheel members that is disposed between the first lateral one of the wheel members and the second lateral one of the wheel members in the axial direction of the wheel.

48. The wheel of claim 47, wherein the central one of the wheel members is larger in diameter than the first lateral one of the wheel members and the second lateral one of the wheel members.

49. The wheel of claim 31 , wherein the bushing comprises a metallic material.

50. The wheel of claim 49, wherein the metallic material is a first metallic material and the bushing comprises a second metallic material.

51. The wheel of claim 49, wherein the metallic material comprises an alloy.

52. The wheel of claim 31 , wherein the bushing comprises a polymeric material.

53. The wheel of claim 52, wherein the polymeric material is fiber-reinforced polymeric material.

54. The wheel of claim 31 , wherein: the bushing is an outer bushing; and the outer bushing is configured to engage an inner bushing extending within the outer bushing.

55. The wheel of claim 31 , wherein the cavity comprises a seal-engaging portion configured to engage a seal.

56. The wheel of claim 55, wherein a diameter of the seal-engaging portion of the cavity is greater than the diameter of the bushing-engaging portion of the cavity.

57. The wheel of claim 31 , comprising a hub secured to the body of the wheel.

58. The wheel of claim 57, wherein the hub comprises a lubricant cap operable to allow access to the lubricant.

59. A track system comprising the wheel of claim 31.

60. A wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track- engaging assembly, the wheel comprising a body that comprises:

- a circumferential surface configured to contact the track; and

- a cavity comprising:

- a lubricant chamber configured to contain a lubricant for the wheel; and

- a bushing-engaging portion configured to engage a bushing;

wherein: the body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel; and the cavity includes a polished internal surface.

61. A wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track- engaging assembly, the wheel comprising a body that comprises:

- a circumferential surface configured to contact the track; and

- a cavity comprising:

- a lubricant chamber configured to contain a lubricant for the wheel; and

- a bushing-engaging portion configured to engage a bushing; wherein: the body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel; the cavity includes an internal surface; and a surface roughness of the internal surface of the cavity is no more than 6.3 pm.

Description:
WHEEL FOR A TRACK SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Patent Application 62/862,741 filed on June 18, 2019 and incorporated by reference herein.

FIELD

This disclosure relates generally to off-road vehicles and, more particularly, to off-road vehicles comprising tracks.

BACKGROUND

Certain off-road vehicles, including industrial vehicles such as construction vehicles (e.g., loaders, bulldozers, excavators, etc.), agricultural vehicles (e.g., harvesters, combines, tractors, etc.), and forestry vehicles (e.g., feller-bunchers, tree chippers, knuckleboom loaders, etc.), as well as military vehicles (e.g., combat engineering vehicles (CEVs), etc.), to name a few, may be equipped with track systems comprising tracks (e.g. elastomeric tracks, steel tracks, etc.) which enhance their traction and floatation on soft, slippery and/or irregular grounds (e.g., soil, mud, sand, ice, snow, etc.) on which they operate.

Track systems may be constructed in various ways, often comprising a plurality of wheels. For example, a track system may comprise a track-engaging assembly comprising a plurality of wheels which interact with the track. The wheels may comprise a plurality of wheels, for example a drive wheel, idler wheels (e.g. front idler wheels, rear idler wheels, etc.), roller wheels, etc., which interact with the track. Roller and idler wheels often comprise two or three circular members spaced apart in a widthwise direction of the track system, each circular member comprising a part of a circumferential surface of the respective roller or idler wheel which engages a rolling path of the track. In addition, the spacing between the circular members may interact with projections of the track to ensure that the track-engaging assembly and the track are aligned.

Roller and idler wheels also often comprise a cavity where an axle can be inserted.

In some cases, the circular members are integrally made with one another, i.e. , are made of one piece. However, notably because the width of the circular members is relatively great, because a diameter of an axle supporting the idler wheel is relatively low and because a radial dimension of the internal cavity is therefore also relatively low, an internal surface of the cavity cannot be machined, resulting in poor surface finish of the cavity. Over time and use, this causes erosion of the internal surface and contamination of a lubricant inside the roller or idler wheels, thereby diminishing durability of the roller or idler wheels.

To remedy this, other roller or idler wheels have circular members that are rather distinct from one another, i.e., that are not integral with one another. Each circular member is then separately manufactured and has an internal surface which can be machined because the width of each circular member is sufficiently small. However, manufacturing costs for manufacturing two or three separate pieces instead of one are much higher. Moreover, the distinct circular members need to be welded to one another to form each roller or idler wheel, which also brings additional manufacturing costs and other durability and performance issues.

For these and other reasons, there is a need for improvements relating to off-road vehicles comprising tracks. SUMMARY

In accordance with various aspects, this disclosure relates to a wheel for a track system for traction of a vehicle, in which the wheel may be designed to enhance its lubrication while facilitating its manufacturing (e.g., by eliminating one or more welds and/or reducing its number of parts).

According to an aspect, this disclosure relates to a wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track-engaging assembly, the wheel comprising a body that comprises: a circumferential surface configured to contact the track; and a cavity. The cavity comprises: a lubricant chamber configured to contain a lubricant for the wheel; and a bushing-engaging portion configured to engage a bushing. A diameter of the bushing-engaging portion of the cavity corresponds to a majority of a radius of the wheel.

According to another aspect, this disclosure relates to a wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track-engaging assembly, the wheel comprising a body that comprises: a circumferential surface configured to contact the track; and a cavity. The cavity comprises: a lubricant chamber configured to contain a lubricant for the wheel; and a bushing-engaging portion configured to engage a bushing. The body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel. The cavity includes a machined internal surface.

According to another aspect, this disclosure relates to a wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track-engaging assembly, the wheel comprising a body that comprises: a circumferential surface configured to contact the track; and a cavity. The cavity comprises: a lubricant chamber configured to contain a lubricant for the wheel; and a bushing-engaging portion configured to engage a bushing. The body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel. The cavity includes a polished internal surface.

According to another aspect, this disclosure relates to a wheel for a track system for traction of a vehicle, the track system comprising a track and a track-engaging assembly for moving the track around the track-engaging assembly, the wheel comprising a body that comprises: a circumferential surface configured to contact the track; and a cavity. The cavity comprises: a lubricant chamber configured to contain a lubricant for the wheel; and a bushing-engaging portion configured to engage a bushing. The body of the wheel comprises a plurality of circular members that are spaced from one another, integrally formed with one another, and include respective parts of the circumferential surface of the wheel. The cavity includes an internal surface. A surface roughness of the internal surface of the cavity is no more than 6.3 pm.

These and other aspects of this disclosure will now become apparent to those of ordinary skill in the art upon review of a description of embodiments in conjunction with accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

A detailed description of embodiments is provided below, by way of example only, with reference to accompanying drawings, in which:

Figure 1 shows an example of an off-road vehicle comprising a track in accordance with an embodiment;

Figures 2 and 3 show a perspective view and a side view of a track system of the vehicle that includes the track; Figures 4 and 5 show an inner plan view and a cross-sectional view of the track;

Figure 6 shows a core of the track in accordance with an embodiment;

Figure 7 shows an example of roller wheels of the track system in relation to the track;

Figure 8 shows an example of idler wheels of the track system in relation to the track;

Figure 9 shows another example of roller wheels of the track system in relation to the track;

Figure 10 shows a cross-sectional view of a given one of the idler wheels;

Figure 11 shows a cross-sectional view of a variant of the idler wheel;

Figure 12 shows the cross-sectioned idler wheel of Figure 11 in a perspective view; Figure 13 shows a bushing of the idler wheel of Figure 11 ;

Figure 14 shows an elevation view of a body of the idler wheel of Figure 11 with the bushings;

Figure 15 shows a cross-sectional view of another variant of the idler wheel;

Figure 16 shows a cross-sectional view of another variant of the idler wheel; and

Figure 17 shows a cross-sectional view of a variant of the roller wheel of the track system. It is to be expressly understood that the description and drawings are only for purposes of illustrating embodiments and are an aid for understanding. They are not limiting.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows an example of an embodiment of a vehicle 10 comprising track systems 16i, I 62. Each of the track systems 161 , 162 comprises a track 22 to engage the ground. In this embodiment, the vehicle 10 is a heavy-duty work vehicle for performing construction, agricultural, or other industrial work or military work. More particularly, in this embodiment, the vehicle 10 is a construction vehicle. Specifically, in this example, the construction vehicle 10 is a compact track loader. The vehicle 10 comprises a frame 12, a powertrain 15, and an operator cabin 20 for an operator to move the vehicle 10 on the ground to perform work using a work implement 18.

As further discussed below, in this embodiment, a machinability of the track systems 161 , I62 may be enhanced, a lubrication system of the track systems 161 , 162 may be improved, and a manufacturing cost of the track systems 161 , 162 may be reduced, including by modifying geometry of a cavity of wheels of the track systems 161 , 162, etc.

The powertrain 15 is configured to generate motive power for the track systems 161 , 162 to propel the vehicle 10 on the ground. To that end, the powertrain 15 comprises a prime mover 14 which is a source of motive power that comprises one or more motors. For example, in this embodiment, the prime mover 14 comprises an internal combustion engine. In other embodiments, the prime mover 14 may comprise another type of motor (e.g., an electric motor) or a combination of different types of motor (e.g., an internal combustion engine and an electric motor). Motive power generated by the prime mover 14 is applied to the track systems 161 , 162. In some embodiments, the powertrain 15 may transmit power from the prime mover 14 to the track systems 161 , 162 (e.g., via a transmission, a differential, and/or any other suitable mechanism). In other embodiments, at least part of the powertrain 15 (e.g., a motor and/or a transmission) may be part of one or more of the track systems 161 , 162. The operator cabin 20 comprises a user interface 1 1 that allow the operator to interact with the vehicle 10, including to steer the vehicle 10 on the ground, use the work implement 18, and control other aspects of the vehicle 10. For example, the user interface 11 comprises an accelerator, a brake control, and a steering device that can be used by the operator to control motion of the vehicle 10 on the ground, as well as controls to operate the work implement 18. The user interface 11 may also comprise an instrument panel (e.g., a dashboard) which provides indicators (e.g., a speedometer indicator, a tachometer indicator, etc.) to convey information to the operator.

The work implement 18 is operable to perform work. In this embodiment, the work implement 18 comprises a bucket for moving soil, debris or other material. In this example, the vehicle 10 comprises support arms 19i, 192 carrying the work implement 18 and mounted to a rear part 21 of the frame 12 so that they extend forwardly pass the operator cabin 20. In other embodiments, the work implement 18 may comprise a dozer blade, a backhoe, a fork, a grapple, a scraper pan, an auger, a saw, a ripper, a material handling arm, or any other type of work implement.

The track systems 16i , 162 engage the ground to propel the vehicle 10. With additional reference to Figures 2 and 3, each track system 16i comprises a track-engaging assembly 21 and the track 22 disposed around the track-engaging assembly 21. In this embodiment, the track-engaging assembly 21 comprises a plurality of wheels which, in this example, includes a drive wheel 24 and a plurality of idler wheels that includes a front (i.e. , leading) idler wheel 23, a rear (i.e. , trailing) idler wheel 25, and roller wheels 28i-28io. The track system 16i also comprises a frame 13 which supports various components of the track system 16i, including the wheels 24, 23, 25, 28i-28io. In this embodiment, the vehicle 10 can be steered by operating the track systems 161 , 162 differently, such as by moving their tracks 22 at different speeds and/or in different directions. The track system 16i has a longitudinal direction and a front longitudinal end 57 and a rear longitudinal end 59 that define a length of the track system 16i along a longitudinal axis 61 that defines the longitudinal direction of the track system 16i. The track system 16i has a widthwise direction and a width that is defined by a width WT of the track 22. The track system 16i also has a heightwise direction that is normal to its longitudinal and widthwise directions.

The drive wheel 24 may be rotatable by power derived from the prime mover 14 for imparting movement of the track 22 in order to propel the vehicle 10 on the ground. The idler wheels 23, 25 and the roller wheels 28i-28io may not convert power supplied by the prime mover 14 to motive force, but rather guide the track 22 and/or maintain it under tension as it is driven by the drive wheel 24. The frame 12 supports components of the track system 16i, including the idler wheels 23, 25 and the roller wheels 28i-28io. As the track 22 is driven by the drive wheel 24, the roller wheels 28i-28io may be configured to roll on a bottom run 66 of the track 22 to apply it on the ground for traction.

In this embodiment, the track system 16i has a generally triangular configuration in which an axis of rotation 27 of the drive wheel 24 is spaced from axes of rotation 81 , 83 of the front and rear idler wheels 23, 25. More particularly, in this embodiment, the axis of rotation 27 of the drive wheel 24 is spaced from the axes of rotation 81 , 83 of the front and rear idler wheels 23, 25 in the height direction of the track system 16i and in the longitudinal direction of the track system 16i. In this example, a distance between the axis of rotation 27 of the drive wheel 24 and the axis of rotation 81 of the front idler wheel 23 is different from a distance between the axis of rotation 27 of the drive wheel 24 and the axis of rotation 83 of the rear idler wheel 25. More specifically, in this example, the distance between the axis of rotation 27 of the drive wheel 24 and the axis of rotation 81 of the front idler wheel 23 is greater than the distance between the axis of rotation 27 of the drive wheel 24 and the axis of rotation 83 of the rear idler wheel 25. Thus, the axis of rotation 27 of the drive wheel 24 is closer to a given one of the axes of rotation 81 , 83 of the front and rear idler wheels 23, 25 in the longitudinal direction of the track system 16i than to the other one of the axes of rotation 81 , 83 of the front and rear idler wheels 23, 25. Specifically, in this case, the axis of rotation 27 of the drive wheel 24 is closer to the axis of rotation 83 of the rear idler wheel 25 in the longitudinal direction of the track system 16i than to the axis of rotation 81 of the front idler wheel 23. The drive wheel 24 is therefore elevated and asymmetrically disposed longitudinally relative to the front and rear idler wheels 23, 25.

The track 22 engages the ground to provide traction to the vehicle 10. A length of the track 22 allows the track 22 to be mounted around the track-engaging assembly 21 . In view of its closed configuration without ends that allows it to be disposed and moved around the track-engaging assembly 21 , the track 22 can be referred to as an“endless” track. With additional reference to Figures 4 to 6, the track 22 comprises an inner side 45, a ground-engaging outer side 47, and lateral edges 49i , 492. The inner side 45 faces the wheels 24, 23, 25, 28i-28io, while the ground-engaging outer side 47 engages the ground. A top run 65 of the track 22 extends between the longitudinal ends 57, 59 of the track system 16i and over the wheels 24, 23, 25, 28i-28io, whereas the bottom run 66 of the track 22 extends between the longitudinal ends 57, 59 of the track system 16i and under the wheels 24, 23, 25, 28i-28io. The bottom run 66 of the track 22 defines an area of contact 63 of the track 22 with the ground which generates traction and bears a majority of a load on the track system 16i, and which will be referred to as a“contact patch” of the track 22 with the ground. The track 22 has a longitudinal axis 19 which defines a longitudinal direction of the track 22 (i.e. , a direction generally parallel to its longitudinal axis) and transversal directions of the track 22 (i.e., directions transverse to its longitudinal axis), including a widthwise direction of the track 22 (i.e., a lateral direction generally perpendicular to its longitudinal axis). The track 22 has a thicknesswise direction normal to its longitudinal and widthwise directions.

In this embodiment, the track 22 is elastomeric, i.e., comprises elastomeric material 32, to be flexible around the track-engaging assembly 21. The elastomeric material 32 of the track 22 can include any polymeric material with suitable elasticity. In this embodiment, the elastomeric material of the track 22 includes rubber. Various rubber compounds may be used and, in some cases, different rubber compounds may be present in different areas of the track 22. In other embodiments, the elastomeric material 32 of the track 22 may include another elastomer in addition to or instead of rubber (e.g., polyurethane elastomer). In other embodiments, the track 22 may be metallic, i.e. , may comprise a metallic material (e.g. steel).

More particularly, the track 22 comprises an endless body 36 underlying its inner side 45 and ground-engaging outer side 47. In view of its underlying nature, the body 36 will be referred to as a “carcass”. The carcass 36 is elastomeric in that it comprises elastomeric material 38 which allows the carcass 36 to elastically change in shape and thus the track 22 to flex as it is in motion around the track-engaging assembly 21.

In this embodiment, the track 22 comprises internal reinforcements disposed in its elastomeric material 32, including the elastomeric material 38 of the carcass 36.

For instance, in this embodiment, a plurality of cores 44I -44N are disposed (e.g. partially or entirely embedded) in the elastomeric material 38 of the carcass 36. The cores 44i- 44N, which may in some cases also be referred to as“inserts”, are distributed along and extend transversally to the longitudinal direction of the track 22 to impart transverse rigidity to the track 22. The cores 44I -44N may also help to drive the track 22 by engagement with the drive wheel 24 and/or guide the track 22 by contacting the wheels 23, 25, 28i-28io as the track 22 is driven by the drive wheel 24.

More particularly, in this embodiment, the core 44i comprises a pair of wings 511 , 512 (i.e., extensions) and a wheel engager 53 disposed between the wings 511 , 512.

The wings 511 , 512 may be elongated along a longitudinal axis of the core 44i to impart transverse rigidity to the track 22. In this embodiment, each of the wings 511 , 512 has an inner surface 33 oriented towards the inner side 45 of the track 22 and an outer surface 34 oriented towards the ground-engaging outer side 47 of the track 22. In this embodiment, each of the wings 511 , 512 has a tapered shape whereby its inner surface 33 and its outer surface 34 converge towards one another toward a given one of the longitudinal ends 48i , 482 of the core 44i. The wings 511 , 512 may have any other shape in other embodiments.

The wheel engager 53 is configured to engage respective ones of the wheels 23, 25, 28i-28io as the track 22 is driven by the drive wheel 24. More particularly, in this embodiment, the wheel engager 53 comprises a drive portion 52 for engaging the drive wheel 24 to drive the track 22 and a wheel guide 54 that projects on the inner side 55 of the track 22 for contacting the roller wheels 28i-28io to help guide the track 22. In this example, the wheel guide 54 comprises a pair of guide projections 57i , 572 that project on the inner side 55 of the track 22. Each guide projection 57i comprises a top end 60, a base 61 , and a pair of wheel-facing sides 62i , 622 opposite one another and extending from its base 61 to its top end 60. The wheel engager 53 may be configured in various other ways in other embodiments (e.g., it may comprise only one guide projection or more than two (2) guide projections, etc.).

In some embodiments, the wheel engager 53 and the wings 511 , 512 may be integrally made with one another, i.e. , may be one unitary component.

In other embodiments, the wheel engager 53 and the wings 511 , 512 are distinct components and are secured to one another (e.g. by being mechanically interlocked at an interface of the wheel engager 53, by being bonded to one another by a chemical bond and/or an adhesive, by being fastened using mechanical fasteners (e.g., bolts, screws, etc.), by welding, by being crimped onto one another, by being fastened to one another through a combination of two or more fastening methods, such as welding, crimping, a mechanical fastener, an adhesive, etc.).

In this embodiment, the carcass 36 comprises a layer of reinforcing cables 37I -37M that are adjacent to one another and extend generally in the longitudinal direction of the track 22 to enhance strength in tension of the track 22 along its longitudinal direction. In this case, each of the reinforcing cables 37I -37M is a cord including a plurality of strands (e.g., textile fibers or metallic wires). In other cases, each of the reinforcing cables 37i- 37M may be another type of cable and may be made of any material suitably flexible along the cable’s longitudinal axis (e.g., fibers or wires of metal, plastic or composite material).

Also, in this embodiment, the carcass 36 comprises a layer of reinforcing fabric 43. The reinforcing fabric 43 comprises thin pliable material made usually by weaving, felting, knitting, interlacing, or otherwise crossing natural or synthetic elongated fabric elements, such as fibers, filaments, strands and/or others, such that some elongated fabric elements extend transversally to the longitudinal direction of the track 22 to have a reinforcing effect in a transversal direction of the track 22. For instance, the reinforcing fabric 43 may comprise a ply of reinforcing woven fibers (e.g., nylon fibers or other synthetic fibers).

The carcass 36 may be molded into shape in a molding process during which the rubber 38 is cured. For example, in this embodiment, a mold may be used to consolidate layers of rubber providing the rubber 38 of the carcass 36, the cores 44i- 44N, the reinforcing cables 37I -37M, and the layer of reinforcing fabric 43.

The inner side 45 of the track 22 comprises an inner surface 55 of the carcass 36 and a plurality of wheel-contacting projections 48I -48N that project from the inner surface 55 and are positioned to contact respective ones of the wheels 23, 25, 28i-28io to do at least one of guiding the track 22 and driving (i.e. , imparting motion to) the track 22. Since each of them is used to do at least one of guiding the track 22 and driving the track 22, the wheel-contacting projections 48I -48N can be referred to as“guide/drive projections”. In this embodiment, each guide/drive projection 48i interacts with respective ones of the idler wheels 23, 25, 28i-28io to guide the track 22 to maintain proper track alignment and prevent de-tracking without being used to drive the track 22, in which case the guide/drive projection 48i is a guide projection. In other embodiments, a guide/drive projection 48i may interact with the drive wheel 24 to drive the track 22, in which case the guide/drive projection 48i is a drive projection. In yet other embodiments, a guide/drive projection 48i may both (i) interact with the drive wheel 24 to drive the track and (ii) interact with respective ones of the idler wheels 23, 25, 28i-28io to guide the track 22 to maintain proper track alignment and prevent de-tracking, in which case the guide/drive projection 48i is both a drive projection and a guide projection.

In this embodiment, each guide projection 48i comprises elastomeric material 67 overlying a given one of the cores 44I -44N. The elastomeric material 67 can be any polymeric material with suitable elasticity. More particularly, in this embodiment, the elastomeric material 67 includes rubber. Various rubber compounds may be used and, in some cases, different rubber compounds may be present in different areas of the drive/guide projection 48i. The elastomeric material 67 of the guide projection 48i may be provided on the inner side 45 of the track 22 in various ways. For example, in this embodiment, the elastomeric material 67 of the guide projection 48i is provided by being molded with the carcass 36.

The inner side 45 of the track 22 comprises rolling paths 30i , 302 on which the roller wheels 28i-28io roll to apply the bottom run 66 of the track 22 onto the ground. For example, a peripheral surface 75 of each roller wheel 28i between an outer lateral surface 35 and an inner lateral surface 49 of the roller wheel 28i is in rolling contact with a given one of the rolling paths 30i , 302 of the track 22. Each of the rolling paths 30i , 302 of the track 22 comprises an inner lateral edge 56i and an outer lateral edge 562 that define a width W rp of that rolling path.

The ground-engaging outer side 47 of the track 22 comprises a ground-engaging outer surface 31 of the carcass 36 and a tread pattern 40 to enhance traction on the ground. The tread pattern 40 comprises a plurality of traction projections 58I -58T projecting from the ground-engaging outer surface 31 , spaced apart in the longitudinal direction of the track 22 and engaging the ground to enhance traction. The traction projections 58I -58T may be referred to as“tread projections” or“traction lugs”. The traction lugs 58I -58T may have any suitable shape (e.g., curved shapes, shapes with straight parts and curved parts, etc.). In this embodiment, each traction lug 58i is an elastomeric traction lug in that it comprises elastomeric material 41. The elastomeric material 41 can be any polymeric material with suitable elasticity. More particularly, in this embodiment, the elastomeric material 41 includes rubber. Various rubber compounds may be used and, in some cases, different rubber compounds may be present in different areas of the traction lug 58i. In other embodiments, the elastomeric material 41 may include another elastomer in addition to or instead of rubber (e.g., polyurethane elastomer).

The traction lugs 58I -58T may be provided on the ground-engaging outer side 47 of the track 22 in various ways. For example, in this embodiment, the traction lugs 58I -58T are provided on the ground-engaging outer side 47 of the track 22 by being molded with the carcass 36.

The drive wheel 24 is rotatable by power derived from the powertrain 15 to drive the track 22. In this embodiment, the drive wheel 24 is a drive sprocket comprising a plurality of drive members 29I -29D spaced apart circumferentially to engage the drive portion 52 of each of the cores 44I -44N in order to drive the track 22 (e.g., a“positive drive” arrangement). In this example, the track 22 comprises drive voids 39i-39v (e.g., recesses or holes) to receive the drive members 29I -29D of the drive wheel 24.

The idler wheels 23, 25, 28i-28io are not driven by power supplied by the powertrain 15, but are rather used to do at least one of supporting part of a weight of the vehicle 10 on the ground via the track 22, guiding the track 22 as it is driven by the drive wheel 24, and tensioning the track 22. More particularly, in this embodiment, the front and rear idler wheel 23, 25 maintain the track 22 in tension and help to support part of the weight of the vehicle 10 on the ground via the track 22. The roller wheels 28i-28io roll on the rolling paths 30i , 302 of the track 22 along the bottom run 66 of the track 22 to apply it onto the ground.

In this embodiment, a machinability and durability of the wheels 23, 25 may be enhanced, a lubrication system of the wheels 23, 25 may be improved, and a manufacturing cost of the wheels 23, 25 may be reduced, including by modifying geometry of a cavity of wheels of the track systems 16i , 1 62, etc.

More specifically, in this embodiment, each of the wheels 23, 25 comprises lateral sides 130i, 1302 opposite one another and defining an inboard side and an outboard side, and a circumferential surface 132 disposed between the sides 130i , 1302 and configured to roll on the inner side 45 of the track 22. Each of the wheels 23, 25 has a widthwise direction defining a width W w , a radial direction, and a circumferential direction.

Each of the wheels 23, 25 comprises a circumferential portion 156, a hub portion 155, and a radially-extending portion 154 between the circumferential portion 156 and the hub portion 155. The hub portion 155 is an inner portion of the wheels 23, 25 which is associated with a hub 119 receiving an axle 158 with two additional hubs 159i, 1592 affixed (e.g. press-fitted, fastened, screwed, etc.) at each end of the axle 158, for each one of the wheels 23, 25. For instance, this may be done by fitting or press-fitting the bearings 176i , 1 762 into an internal cavity of the hub portion 155 of the respective one of the wheels 23, 25 and fitting or press-fitting the hubs 159i , 1592 over the axle 158 such that the hubs 159i , 1592 respectively engage the bearings 176i , 1 762 or by any suitable means. The circumferential portion 156 is an outer portion of each wheel 23, 25 which rolls on the rolling path 31 i of the inner side 45 of the track 22. The radially- extending portion 154 is an intermediate portion of the wheel 23, 25 which extends radially between the hub portion 155 and the circumferential portion 156.

More specifically, in this embodiment, each of the wheels 23, 25 comprises a body 160 that comprises a circumferential surface 132 configured to contact the track 22 and a cavity 170. The cavity may comprise a lubricant chamber 172 configured to contain a lubricant for the respective one of the wheels 23, 25; and a bushing-engaging portion174 configured to engage at least one of a plurality of bushings 180i-180t >. The bushing-engaging portion 174 of the cavity 170 is the portion of the cavity 170 which engages, i.e. , contacts, at least one of the bushings 180i-180t > . In this embodiment, the bushing-engaging portion 174 of the cavity 170 may have a circular cross-section. The bushing-engaging portion 174 of the cavity 170 may have a diameter Db (i.e., a dimension of the bushing-engaging portion 174 of the cavity 170 measured across a cross-section of the bushing-engaging portion 174 of the cavity 170 by passing through a center of the cross-section of the bushing-engaging portion 174 of the cavity 170) corresponding to a majority (i.e. at least 50%) of a radius of the respective one of the wheels 23, 25. For example, in some embodiments, the diameter Db of the bushing- engaging portion 174 of the cavity 170 may correspond to at least 60% of the radius of the respective one of the wheels 23, 25, in some embodiments at least 70%, and in some embodiments even more.

In this embodiment, the radii of the wheels 23, 25 are substantially constant along the widths of the wheels 23, 25. In other embodiments, the radii of the wheels 23, 25 may vary in the axial direction of the wheels 23, 25. In this case, the bushing-engaging portion 174 of the cavity 170 may have a diameter Db corresponding to a majority of a minimum value of the radius of the respective one of the wheels 23, 25. For example, in some embodiments, the diameter Db of the bushing-engaging portion 174 of the cavity 170 may correspond to at least 60% of the minimum value of the radius of the respective one of the wheels 23, 25, in some embodiments at least 70%, and in some embodiments even more.

The cavity 170 may be defined by an internal surface 178 of the cavity. In this embodiment, the internal surface 178 of the cavity 170 is machined, i.e., reduced or finished by turning, shaping, planning, milling, polishing, and/or otherwise having material removed (i.e., substractive manufacturing) by a machine-operated tool. In particular, the geometry (e.g., diameter) of the cavity 170 enables the internal surface 178 of the cavity 170 of the body 160 to be machined. In addition, in this embodiment, the internal surface 178 may be also polished (e.g. hand-polished, machine-polished, chemically-polished, etc.). The internal surface 178 may have any suitable surface finish to prevent erosion of the internal surface 178, thus preventing contamination of the lubricant and improving a durability of the wheels 23, 25. For example, in some embodiments, the internal surface 178 of the cavity 170 may have a surface roughness of no more than 6.3 pm, in some embodiments of no more than 3.2 pm, in some embodiments of no more than 0.4 pm and in some embodiments of even less.

In the embodiment, a dimension DL of the lubricant chamber 172 in a radial direction of the wheels 23, 25 may vary in an axial direction of the wheels 23, 25. More specifically, the dimension DL of the lubricant chamber 172 may be less less in lateral portions 190, 192 of the lubricant chamber 172 than in a central portion 194 of the lubricant chamber 172 that is disposed between the lateral portions 190, 192 of the lubricant chamber in the axial direction of the respective one of the wheels 23, 25, in order to increase an internal volume (i.e. capacity) of the lubricant chamber 172.

In this embodiment, the body 160 of the wheels 23, 25 comprises a plurality of circular members 162i-162b that are spaced from one another and integrally formed with one another. That is, the circular members 162i-162b are manufactured separately and then affixed to one another (e.g. by welding). The body 160 of the wheels 23, 25 may include respective parts of the circumferential surface 132 of each one of the wheels 23, 25. In particular, the geometry (e.g., diameter) of the cavity 170 enables the body 160 of the wheels 23, 25 to have more than one circular member while also comprising the machined internal surface 178 of the cavity 170. More specifically, in this embodiment, the circular members 162i-162b are integrally cast with one another.

In particular, in this embodiment, the body 160 of the wheels 23, 25 comprises two lateral circular members 162i , 1622 and a central circular member 1623 disposed between and spaced from the lateral circular members 162i , 1622 of the body 160 in the axial direction of the wheel. In operation, the guide projections 57i , 572 of the track 22 may occasionally occupy the space between the circular members 162I -1623 and may in some occasions engage the circular members 162I -1623 to guide the track around the track-engaging assembly 21 . Each one of the lateral circular members 162i , 1622 may be wider in an axial direction of respective one of the wheels 23, 25 than the central circular member 1623, while the central circular member 1623 may by larger in diameter than each one of the lateral circular members 162i, 1622. In this embodiment, each one of the circular members 162I -1623 comprises part of the circumferential surface 132 of the respective one of the wheels 23, 25.

The bushings 180i-180b comprise an inner bushing 180i and an outer bushing I 8O2 configured to engage the inner bushing I 8O1 extending within the outer bushing I 8O2. Each one of the bushings I 8O1 , I 8O2 may have a bearing pad function and/or a spacing function. In this embodiment, the inner bushing I 8O1 as a bearing pad function and a spacing function, while the outer bushing I 8O2 mainly serves as a spacer.

In some embodiments, the bushings I 8O1 , I8O2 may comprise a metallic material. In addition, in some embodiments, the bushings I 8O1, I 8O2 comprise two different metallic materials and/or comprise an alloy. In addition or alternatively, in some embodiments, the bushing 174 may comprise polymeric material. For example, the polymeric material may be fiber-reinforced polymeric material.

In this embodiment the cavity 170 comprises a seal-engaging portion 196 configured to engage a seal 198. More specifically, in this embodiment, each bearing 176i constitutes a seal. A diameter D s of the seal-engaging portion of the cavity 170 may be greater than the diameter Db of the bushing-engaging portion 174 of the cavity 174.

In this embodiment, as the hubs 159i , 1592 are affixed (e.g. press-fitted, fastened, screwed, etc.) at each end of the axle 158, they are also secured to the body 160 of respective one of the wheels 23, 25. Each hub 159i may comprise a lubricant cap 161 operable to allow access to the cavity to remove, replace or add lubricant.

The track, including the cores 44I -44N, may be implemented in various other ways in other embodiments. For example, in some embodiments, as shown in Figures 11 to 14, each bushing- engaging portion 174 may enclose only one bushing 180 serving as a spacer and bearing pad.

As another example, as shown in Figure 15, in some embodiments, the dimension DL of the lubricant chamber 172 in a radial direction of the wheels 23, 25 may be constant in the axial direction of the wheels 23, 25 to facilitate machining the lubricant chamber 172. More specifically, the dimension DL of the lubricant chamber 172 may be substantially the same in the lateral portions 190, 192 and in the central portion 194 of the lubricant chamber 172.

As another example, in some embodiments, as shown in Figure 16, the cross-section of the bushing-engaging portion 174 of the cavity 170 may be noncircular, such as polygonal like rectangular (e.g., square) or hexagonal. In this case, the bushing- engaging portion 174 of the cavity 170 may have a diameter Db corresponding to a majority of a minimum value of the radius of the respective one of the wheels 23, 25. For example, in some embodiments, the diameter Db of the bushing-engaging portion 174 of the cavity 170 may correspond to at least 60% of the minimum value of the radius of the respective one of the wheels 23, 25, in some embodiments at least 70%, and in some embodiments even more.

While in the embodiments considered above the wheels 23, 25 are idler wheels, in other embodiments, other wheels (e.g. the drive wheel 24, the roller wheels 28i-28io, etc.) may benefit from the features discussed above with regards to front and idler wheels 23, 25.

For example, in some embodiments, as shown in Figure 17, the roller wheels 28i-28io may have a construction similar to the idler wheels 23, 25, and may comprise a body 160 comprising two lateral circular members 162i, 1622, but without any central circular member disposed between and spaced from the lateral circular members 162i , 1622 of the body 160 in the axial direction of the wheel. While in embodiments considered above the off-road vehicle 10 is a construction vehicle, in other embodiments, the vehicle 10 may be another type of work vehicle such as an agricultural vehicle (e.g., a combine harvester, another type of harvester, a tractor, etc.) for performing agricultural work, a forestry vehicle (e.g., a feller-buncher, a tree chipper, a knuckleboom loader, etc.) for performing forestry work, or a military vehicle (e.g., a combat engineering vehicle (CEV), etc.) for performing military work, or may be any other type of vehicle operable off paved roads. Although operable off paved roads, the vehicle 10 may also be operable on paved roads in some cases. Also, while in embodiments considered above the off-road vehicle 10 is driven by a human operator in the vehicle 10, in other embodiments, the vehicle 10 may be an unmanned ground vehicle (e.g., a teleoperated or autonomous unmanned ground vehicle).

Any feature of any embodiment discussed herein may be combined with any feature of any other embodiment discussed herein in some examples of implementation.

Certain additional elements that may be needed for operation of certain embodiments have not been described or illustrated as they are assumed to be within the purview of those of ordinary skill in the art. Moreover, certain embodiments may be free of, may lack and/or may function without any element that is not specifically disclosed herein.

Although various embodiments and examples have been presented, this was for purposes of description, but should not be limiting. Various modifications and enhancements will become apparent to those of ordinary skill in the art.