Roller assemblies for ground engaging track systems

Abstract

A roller assembly (32) for a ground engaging track system (24) includes a roller (34) defining a shaft bore (42) and a roller shaft (52) having a circumferentially inclined surface (60) within the shaft bore (42). A roller retention system (83) of the roller assembly (32) includes a roller retention collar (84) having an outer circumferential surface (96) and an inner peripheral surface (98) that may include a wedge surface (98) structured to frictionally fit the retention collar (84) within the collar bore (44) of the roller (34) on the circumferentially inclined surface (60) to limit axial displacement of the roller (34) on the roller shaft (52). The roller assembly (32) may include two roller retention collars (84, 86) that support the roller (34) against axial displacement and secure the roller (34) and roller shaft (52) for rotation together relative to the track roller frame (26) without the use of thrust washers or the like.

Description

[Technical Field]

[0001] The present disclosure relates generally to ground engaging track systems, and more particularly to roller assemblies for ground engaging track systems having roller retention collars that fasten to the rollers and limit axial displacement of the rollers on shafts fixed for rotation therewith. [Background technology]

[0002] Various machines utilize tracks as ground-engaging propulsion elements. Such tracks typically include multiple rotatable track-engaging elements, such as a drive sprocket, one or more idlers, carrier rollers, and track rollers. The tracks form an endless loop that travels around the rotating elements during operation. Ground-engaging track systems typically operate in harsh off-highway environments. To optimize the service life of track system components and avoid unscheduled machine downtime, components in such track systems are typically constructed to be extremely robust. Contact between components is often affected by the presence and / or type of substrate, which tends to cause component wear over time. Most machine applications require traveling up and down inclines, traveling over hard and uneven substrates, pushing or pulling loads, and other activities, resulting in track system components experiencing various types of loads during service. Managing and mitigating loads on ground-engaging track systems has been the subject of considerable engineering effort over the years.

[0003] In the case of idlers in track systems, for example, certain known designs use thrust washers, bearings, or plates that contact the idler while it rotates on a shaft to react to side loads generally oriented along or parallel to the idler's axis of rotation. The use of thrust washers and the like is usually successful in reacting to side loads that could cause excessive wear, damage, or performance degradation of the equipment. Nevertheless, thrust washers, plates, and the like, especially when in direct contact with the idler, can add complexity and number to the track system and create service and replacement challenges. One known ground-engaging track system using idler groups is described in U.S. Patent No. 9,550,536 to Johannsen et al. While the strategy set forth in Johannsen undoubtedly has a variety of applications, there is always room for improvement, development of alternative strategies, and adaptation to different types of machines or off-highway environments. Summary of the Invention

[0004] In one aspect, a roller assembly for a ground-engaging track system includes a roller defining a roller central axis and having an outer tread surface and an inner roller surface forming a shaft bore and a collar bore extending axially outward from the shaft bore. The roller assembly further includes a roller shaft having a first shaft end, a second shaft end, an intermediate roller support section, and a circumferentially inclined surface transitioning between the first shaft end and the intermediate roller support section and enlarging in diameter toward the intermediate roller support section. The roller assembly further includes a roller retaining collar having an inner surface facing the roller, an outer surface, and a bolt hole extending between the inner and outer surfaces facing the roller for fastening the roller retaining collar to the roller. The roller retaining collar further includes an outer peripheral surface sized to fit the retaining collar within the collar bore and an inner peripheral wedge surface forming a shaft hole for positioning the roller retaining collar on the roller shaft. The shaft hole enlarges in diameter toward the inner surface facing the roller to limit axial displacement of the roller on the roller shaft, and is sized to frictionally fit the roller retaining collar on the circumferentially inclined surface.

[0005] In another aspect, a ground-engaging track system includes a roller assembly having a roller defining a roller center axis and a shaft bore extending between first and second axial sides of the roller, and a roller shaft. The roller shaft includes a first circumferentially inclined surface, a second circumferentially inclined surface, and an intermediate roller support section positioned within the shaft bore, extending between the first and second circumferentially inclined surfaces. The track system further includes a roller retention system including a first retention collar positioned around the roller shaft on the first axial side and having a first inner circumferential wedge surface, and a second retention collar positioned on the roller shaft on the second axial side and having a second inner circumferential wedge surface. The first retention collar is clamped to the first axial side of the roller and frictionally fits onto the first circumferentially inclined surface due to clamped contact between the first inner circumferential wedge surface and the first circumferential inclined surface. A second retaining collar is clamped against a second axial side of the roller and frictionally fits onto the second circumferential inclined surface based on clamped contact between the second inner circumferential wedge surface and the second circumferential inclined surface.

[0006] In yet another aspect, a roller assembly for a ground-engaging track system includes a roller defining a roller central axis and including an outer tread surface and an inner roller surface forming a shaft bore extending between a first axial side of the roller having a first side and a second axial side of the roller having a second side. The roller assembly further includes a roller shaft having a first shaft end, a second shaft end, and an intermediate roller support section enlarged relative to the first and second shaft ends and positioned within the shaft bore. The intermediate roller support section, together with the roller, forms a keyed roller-shaft joint that secures the roller and roller shaft against relative rotation. The roller assembly further includes a first retaining collar coaxially disposed around the roller shaft and in axial-facing contact with both the first side and the intermediate roller support section and clamped against the first axial side of the roller such that the roller is secured against axial displacement on the roller shaft in a first direction. The roller assembly further includes a second retaining collar coaxially disposed about the roller shaft and clamped to a second axial side of the roller in contact with both the second side and the intermediate roller support section such that the roller is fixed against axial displacement on the roller shaft in a second direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a side view of a machine, according to one embodiment. [Figure 2] FIG. 2 is a side view of a ground engaging track system, according to one embodiment. [Figure 3] FIG. 3 is another view of a ground engaging track system, according to one embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a ground engaging track system, according to one embodiment. [Figure 5] FIG. 5 is a perspective, cross-sectional view of a ground engaging track system, according to one embodiment. [Figure 6]FIG. 6 is a side view of a portion of a roller assembly for a ground engaging track system, according to one embodiment. [Figure 7] FIG. 7 is a cross-sectional view of a portion of a roller assembly for a ground engaging track system, according to one embodiment. [Figure 8] FIG. 8 is a cross-sectional view of a ground engaging track system according to another embodiment. [Figure 9] FIG. 9 is a cross-sectional view of a ground engaging track system according to yet another embodiment. [Figure 10] FIG. 10 is a diagram of a roller shaft for a roller assembly in a ground engaging track system such as that shown in FIG. [Figure 11] FIG. 11 is a diagram of a portion of a roller assembly in a ground engaging track system as shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Referring to FIG. 1 , a machine 10 according to one embodiment is shown and includes a frame 12, an upper machinery assembly 13 supported on the frame 12, and a lower machinery assembly 23. The machine 10 includes a boom 16, a dip 18 rotatably supported by the boom 16, and a loading system 14 having a bucket 20. The machine 10 is illustrated in the context of a rope shovel having a cable system 22 operable to a front-loading bucket 20, such as may be used to load material on a mine working face. The machine 10 may alternatively be a different type of machine, such as a hydraulic front shovel, a track-type tractor, a track-type loader, a shovel, or various other types of tracked equipment. The lower machinery assembly 23 includes a ground-engaging track system 24 having a track roller frame 26, tracks 28, a drive sprocket 30, and idler rollers 34. Another track associated with substantially identical components is hidden from view in FIG. 1 . The track 28 typically includes a plurality of interconnected track links attached to or integrally formed with a track shoe, forming an endless loop extending around a rotatable element. Also, in the illustrated embodiment, the track 28 has an oval configuration, but it should be understood that in some embodiments, a so-called "high drive" configuration having a high drive sprocket and both a front and a back idler may be used. The idler rollers 34 are supported by the track roller frame 26 and are part of a roller assembly 32 that includes a roller shaft 52. The ground-engaging track system 24 and roller assembly 32 may include a roller retention system 83 that secures the idler rollers 34 and roller shaft 52 together for rotation during operation of the ground-engaging track system 24 in contact with the idler rollers 34 without the use of thrust washers, thrust bearings, plates, or the like, as discussed further herein. While the implementation of the present disclosure in the context of an idler is a practical strategy, in other examples, the idler roller 34 (hereinafter "roller 34") may be a different type of roller in a ground-engaging track system within a machine.

[0009] 2-4 , the track roller frame 26 may have a first window 48 and a second window 50 formed therein. The windows 48 and 50 provide support for the roller assembly 32 and associated components, and further provide access for maintenance or replacement, as discussed herein. The roller 34 defines a roller central axis 36 and includes an outer tread surface 38 configured to contact the track 28 during operation, and an inner roller surface 40. The inner roller surface 40 extends circumferentially around and is centered on the roller central axis 36, forming a shaft bore 42, a first collar bore 44, and a second collar bore 46. The collar bores 44 and 46 communicate with the shaft bore 42 and extend axially outward of the shaft bore 42 to a first axial side 61 of the roller 34 and a second axial side 65 of the roller 34, respectively. First axial side 61 includes a first axial side surface 63, and second axial side 65 includes a second axial side surface 67. Roller shaft 52 includes a first shaft end 54, a second shaft end 56, and an intermediate roller support section 58 extending between first shaft end 54 and second shaft end 56. It will be understood that roller shaft 52 also defines a longitudinal axis numbered identically to central axis 36 and is coaxially disposed with rollers 34 with intermediate roller support sections 58 positioned within shaft bores 42.

[0010] The ground-engaging track system 24 (hereinafter "track system 24") further includes a first bearing block 64 that supports the first shaft end 54 for rotation within the window 48 and a first end retainer 68 attached to the first shaft end 54 at a location axially outward of the first bearing block 64. The track system 24 further includes a second bearing block 66 that supports the second shaft end 56 for rotation within the window 50 and a second end retainer 70 attached to the second shaft end 56 at a location axially outward of the second bearing block 66. "Axially outward" means in a direction away from the center point of the central axis 36 and along or parallel to the central axis 36. "Axially inward" has the opposite meaning. In the illustrated embodiment, the first end retainer 68 and the second end retainer 70 each include a multi-piece split end retainer that is fastened to the respective shaft end by bolts or the like and seats in circumferential grooves 67 and 71 on the first shaft end 54 and the second shaft end 56, respectively. To react thrust loads on the roller assembly 34 to the bearing blocks 64 and 66 and the track roller frame 26, a first plate 76 is sandwiched between the first end retainer 68 and the first bearing block 64, and a second plate 78 is sandwiched between the second end retainer 70 and the second bearing block 66. One or more journal bearings 80 are positioned within the first bearing block 64, and one or more journal bearings 82 are positioned within the second bearing block 66 to rotatably journal the respective first and second shaft ends 54 and 56. The first bearing block 64 may have an outer rectangular shape, and the second bearing block 66 may also have an outer rectangular shape, with each bearing block positioned within the windows 48 and 50 having an appropriate complementary or corresponding rectangular shape. A first cover 72 may be coupled to the first bearing block 64, and a second cover 74 may be coupled to the second bearing block 66.

[0011] 5 , the roller shaft 52 further includes a first circumferential beveled surface 60 transitioning between the first shaft end 54 and the intermediate roller support section 58. The circumferential beveled surface 60 is circumferential about the central axis 36 and expands in diameter in an axially inward direction of the intermediate roller support section 58. The roller shaft 52 may also include a second circumferential beveled surface 62 transitioning between the second shaft end 56 and the intermediate roller support section 58. The second circumferential beveled surface 62 is also circumferential about the central axis 36 and expands in diameter in an axially inward direction of the intermediate roller support section 58. In some embodiments, the first circumferential beveled surface 60 and the second circumferential beveled surface 62 each have a conical shape. Thus, the first shaft end 54 and the second shaft end 56 may each be cylindrical, and the intermediate roller support section 58 may also be cylindrical. The first circumferential inclined surface 60 and the second circumferential inclined surface 62 have a conical shape that transitions from the respective cylindrical shaft ends 54 and 56 to the cylindrical enlarged intermediate roller support section 58 .

[0012] The track system 24 and roller assembly 32 further include a roller retention system 83, as described above. The roller retention system 83 includes a first roller retention collar 84 and a second roller retention collar 86. The first roller retention collar 84 and the second roller retention collar 86 may be substantially identical, and therefore, a description of one herein may be understood as referring by analogy to the other. A practical mounting strategy uses two roller retention collars. However, in some embodiments, a single roller retention collar may be used. The roller retention collar 84 includes an inner axial surface 88 (inner surface 88) facing the rollers, an outer axial surface 90 (outer surface 90), and bolt holes 92 extending between the inner surface 88 and the outer surface 90. As shown in the drawings, a first set of bolts 94 fastens the roller retention collar 84 to the rollers 34, and a second set of bolts 95 fastens the roller retention collar 86 to the rollers 34. Bolt holes 92 can be shaped so that the heads of bolts 94 (and 95) are recessed therein during installation, so that bolt holes 92 and the corresponding bolt holes in roller retaining collar 86 define an axially inward bolt connection direction. Roller retaining collar 84 is positioned on first axial side 61 and tightened in contact with first axial side surface 63. Roller retaining collar 86 is positioned on second axial side 65 and tightened in contact with second axial side surface 67. In the manner described above, tightening roller retaining collars 84 and 86 and friction-fitting onto roller shaft 52 captures roller 34 between collars 84 and 86 against axial displacement on roller shaft 52, and secures roller shaft 34 and roller shaft 52 for rotation together, such that roller shaft 52 is a live shaft relative to track roller frame 26.

[0013] The roller retaining collar 84 further includes an outer peripheral surface 96 sized to fit the roller retaining collar 84 within the collar bore 44. In practical implementations, the roller retaining collar 84 may be sized to have a clearance fit with the inner roller surface 40 within the collar bore 44 prior to tightening during installation. As discussed further herein, installation and tightening of the roller retaining collar 84, and similarly installation of the roller retaining collar 86, creates a wedge effect of the roller retaining collar 84 on the roller shaft 52, resulting in the desired secure coupling of the roller 34 and the roller shaft 52. To this end, the roller retaining collar 84 further includes an inner peripheral wedge surface 98 extending circumferentially about the central axis 36 and forming a shaft hole 100 for locating the roller retaining collar 84 on the roller shaft 52. The roller retaining collar 86 also includes an inner peripheral wedge surface 99 forming a shaft hole (not numbered) for locating the roller retaining collar 86 on the roller shaft 52. Shaft bore 100 is enlarged in diameter toward inner surface 88 so as to limit axial displacement of roller 34 on roller shaft 52, and is sized to friction-fit roller retaining collar 84 onto circumferentially inclined surface 60. Roller retaining collar 84 and roller retaining collar 86 are each coaxially disposed around roller shaft 52, secured to respective axial sides 61 and 65, and may friction-fit onto respective first and second circumferentially inclined surfaces 60 and 62 based on the clamped contact between first inner circumferential wedge surface 98 and circumferentially inclined surface 60 and the clamped contact between inner circumferential wedge surface 99 and circumferentially inclined surface 62. As mentioned above, shaft bore 100 is enlarged in diameter in the axially inward direction of inner surface 88 in the assembled configuration of the drawings. The term "sized" as opposed to friction fit means that the shaft bore 100 is neither too small to fit the first shaft end 54 relative to the roller retaining collar 84 nor too large to fit the intermediate roller support section 58 relative to the roller retaining collar 84.It will thus be appreciated that when roller retaining collar 84 is installed within roller assembly 32, first set of bolts 94 can be tightened to clamp roller retaining collar 84 against first axial side 61 while simultaneously bringing inner peripheral wedge surface 98 into contact with inner roller surface 40 and engaging circumferential ramp surface 60 and outer peripheral surface 96. It will be further appreciated that by tightening both roller retaining collar 84 and roller retaining collar 86 onto roller 34 in this manner, roller retaining collars 84 and 86 are drawn axially inward toward one another while simultaneously being compressed both axially and radially against intermediate roller support section 58, creating a friction fit that secures roller 34 and roller shaft 52 together in the manner described.

[0014] Referring again to FIG. 6 , the roller retention collar 84 is shown as it appears in side view bolted to the roller 34 and positioned about the roller shaft 52. The roller retention collar 84 defines a collar central axis collinear with the roller central axis 36 and may include at least one relief channel 104, again indicated by reference numeral 36. The at least one relief channel 104 extends axially from the outer surface 90, into the plane of the page of FIG. 6 , to the inner surface 88. The at least one relief channel 104 further extends radially between the outer circumferential surface 96 and the inner circumferential wedge surface 98. In the illustrated embodiment, the roller retention collar 84 comprises a multi-piece collar having a plurality of arcuate collar segments 102 and a plurality of relief channels 104 formed between adjacent ones of the plurality of arcuate collar segments 102. Each relief channel 104 may extend completely axially through the roller retention collar 84 and completely radially through the roller retention collar 84. However, embodiments are contemplated in which the relief channel 104 extends only partially radially through the roller retention collar 84. During assembly and tightening of the roller retention collar 84, the relief channel or channels 104 allow some relative movement between the collar segments 102, allowing the roller retention collar 84 to bear against the circumferentially inclined surface 60 and the inner roller surface 40.

[0015] Also illustrated in FIG. 6 are contact points 106 between the collar segments 102 and the roller shaft 52. The interior contour of the inner circumferential wedge surface 98 may vary circumferentially about the axis 36, varying from a radially inward contact point 106 to a radially outward clearance location 108, as can be seen in FIG. 6. The points 106 may define a circle with the clearance location 108 representing a radially outward deviation from the circle defined by the contact points 106. The circumferentially varying contour of the inner circumferential wedge surface 98 can help make the clamping force relatively more uniform circumferentially about the circumferentially inclined surface 60 as the roller retaining collar 84 clamps into engagement with the roller 34 and roller shaft 52 and the inner circumferential wedge surface 98 deforms, for example, into a more conical shape.

[0016] 7, a diagram of the longitudinal profile of the inner circumferential wedge surface 98 in contact with the circumferential ramp surface 60 is shown in a cross-sectional plane containing the central axis 36. From FIG. 7, it can be seen that the inner circumferential wedge surface 98 has a profile that varies longitudinally along the central axis 36. In other words, the inner circumferential wedge surface 98 does not extend strictly parallel to the circumferential ramp surface 60 throughout its entirety, but instead includes a relieved surface or section 112 that transitions into a conical section 113 at a transition point 114. The transition point 114 may be located approximately at the midpoint of the length of the longitudinal circumferential ramp surface 60. The relief surface 112 may be a longitudinally radiused, arcuate surface that is spaced radially outward from the conical surface 113. The contour of the inner circumferential wedge surface 98 varying longitudinally along the central axis 36 can help make the clamping force at the interface of the circumferential ramp surface 60 and the inner circumferential wedge surface 98 relatively more uniform longitudinally.

[0017] Referring now to FIG. 8 , a ground-engaging track system 124 is shown including a roller assembly 132 according to another embodiment. The roller assembly 132 includes a roller 134, which may be an idler roller having an outer tread surface not visible in FIG. 8 , and a roller shaft 152. The bearing blocks and retainers and other structures shown in FIG. 8 are not specifically numbered but may be substantially identical to those described in connection with the previous embodiment. The roller shaft 152 may similarly, at least in some instances, be identical to the roller shaft 52 described above. The roller assembly 132 includes a first retaining collar 184 and a second retaining collar 186 having inner circumferential wedge surfaces 198 and 199, respectively. The outer circumferential surfaces of the roller retaining collars 84 and 86 described above may be cylindrical or substantially cylindrical, and the roller retaining collars 184 and 186 may be conical or at least partially conical, including outer circumferential wedge surfaces 196 and 197 that expand in diameter toward the outer surface of the respective roller retaining collars 184 and 186. Roller 134 has first collar bore 144 and second collar bore 146 within which roller retention collars 184 and 186 are disposed that contact the inner roller surface of roller 134 and are clamped to roller 134 to provide double wedge retention of roller 134 on roller shaft 152.

[0018] 9-11, a ground-engaging track system 224 including a roller assembly 232 according to another embodiment is shown. The roller assembly 232 includes a roller 234, which may be an idler roller, defining a central axis 236 and an inner roller surface 240. A roller shaft 252 extends through the roller 234 and includes a first shaft end 254, a second shaft end 256, and an intermediate roller support section 258. It will be understood that the roller 234 includes an outer tread surface, an inner roller surface 240 that defines a shaft bore, and certain other features that are the same or similar to those described in connection with the previous embodiment. The first and second bearing blocks 264 and 266, as well as other components that support the roller assembly 232, may also be the same or substantially the same as those described in connection with the previous embodiment. The roller 234 includes a first axial side 261 having a first side 263 and a second axial side 265 having a second side 267. A first retaining collar 284 is coaxially disposed around roller shaft 252 and is fastened to first axial side 261 in axial-facing contact with both first side 263 and intermediate roller support section 258 so that rollers 234 are fixed against axial displacement on roller shaft 252 in a first direction. A second retaining collar 286 is coaxially disposed around roller shaft 252 and is fastened to second axial side 265 in contact with both second side 267 and intermediate roller support section 258 so that rollers 234 are fixed against axial displacement on roller shaft 252 in a second direction opposite the first direction.

[0019] The first retaining collar 284 includes a roller-facing inner surface 295 that contacts the first side surface 263 and that contacts the intermediate roller support section 258. The second retaining collar 286 may be substantially identical to the first retaining collar 284. Bolt holes 269 are formed in the roller 234 to receive bolts 275 that tighten the first retaining collar against the first axial side surface 261. Additional bolt holes (not numbered) may be formed in the second axial side surface 265 to tighten the second retaining collar 286 in a similar manner. The inner roller surface 240 may include a flat inner surface 277 and an arcuate inner surface 279, and the intermediate roller support section 258 may include a flat outer surface 281 and an arcuate outer surface 283 in facing relationship to the flat inner surface 277 and the arcuate inner surface 285, respectively. The intermediate roller support section 258, together with the rollers 234, forms a keyed roller-shaft joint 259 that secures the rollers 234 and roller shaft 252 against relative rotation such that the roller shaft 252 is a live shaft within the associated track roller frame and bearing blocks 264 and 266. The inner roller surface 240 may further include a second flat inner surface 285 and a second arcuate inner surface 287, and the intermediate roller support section 258 may further include a second flat outer surface 289 and a second arcuate outer surface 291 in facing relationship to the flat inner surface 285 and the arcuate inner surface 287, respectively. A first groove 267 may be formed on the first shaft end 254, and a second groove 271 may be formed on the second shaft end 256, to receive an end retainer.

[0020] A phantom line 284 representing the contact footprint of the retaining collar 284 against the roller shaft 252 and roller 234 is shown in FIG. 11. When the retaining collar 284 is installed for service, it can be seen that its inner surface 295 abuts against both the intermediate roller support section 258 and the roller 234. A second retaining collar 286 can be similarly configured such that both the retaining collar 284 and the retaining collar 286 contact the intermediate roller support section 258 with arcuate inner surfaces 279 and 287 and arcuate outer surfaces 283 and 291 at locations circumferentially and angularly aligned about the central axis 236, and with first and second side surfaces 263, 267 at locations circumferentially and angularly aligned about the central axis 263 with flat inner surfaces 277 and 285 and flat outer surfaces 281 and 289, respectively. [Industrial Applicability]

[0021] With reference to the drawings generally, it will be recalled that roller assemblies according to the present disclosure may be installed for service in a ground-engaging track system and supported for rotation without the use of thrust washers, thrust bearings, or plates positioned to contact the subject rollers. It will also be recalled that windows formed in the track roller frame provide access to the roller assemblies for maintenance or replacement. In one practical application, roller assemblies according to the present disclosure may be provided as retrofit assemblies installed on machines in place of existing roller assemblies. For certain machine types, such as shovels used in mining applications, simplified service and retrofit applications that can be performed in the field, minimizing downtime, are often welcomed by the industry. One challenge to field serviceability of these and other ground-engaging track systems is the need to fit certain pieces and components of the equipment through windows formed in the track roller frame. According to the present disclosure, new idler rollers can be replaced with existing idler rollers, with the components necessary to mount and support the idler rollers within the track roller frame passing through windows in the track roller frame. By eliminating the use of thrust washers and the like located within the track roller frame, assembly can be simplified using fewer components compared to certain designs as well as a more robust overall ground engaging track system.

[0022] This specification is for illustrative purposes only and should not be construed to limit the scope of the present disclosure in any way. Accordingly, those skilled in the art will understand that various modifications can be made to the embodiments of the present disclosure without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features, and advantages will become apparent upon review of the accompanying drawings and the appended claims. As used herein, the articles "a" and "an" are intended to include one or more items and may be used interchangeably with "one or more." Where only one item is intended, "one" or similar language is used. Also, as used herein, the terms "has," "have," "having," or similar terms are intended to be open-ended terms. Furthermore, the phrase "based on" is intended to mean "based at least in part on," unless expressly stated otherwise.

Claims

1. A roller assembly (32, 132) for a ground engaging track system (24, 124), comprising: a roller (34, 134) defining a roller central axis and including an outer tread surface (38), an inner roller surface (40) forming a shaft bore (42), and a collar bore (44, 144) extending axially outward of said shaft bore (42); a roller shaft (52, 152) including a first shaft end (54), a second shaft end (56), an intermediate roller support section (58), and a first circumferential inclined surface (60) transitioning between the first shaft end (54) and the intermediate roller support section (58) and expanding in diameter in the direction of the intermediate roller support section (58); a first roller retaining collar (84, 184) for fastening the roller (34, 134), the first roller retaining collar (84, 184) to the roller (34, 134), the first roller retaining collar (84, 184) including an inner surface (88) facing the roller, an outer surface (90), and a bolt hole (92) extending between the inner surface (88) facing the roller and the outer surface (90); the first roller retaining collar (84, 184) further including an outer peripheral surface (96) sized to fit within the collar bore (44, 144) over the first roller retaining collar (84, 184), and an inner peripheral wedge surface (198) forming a shaft hole (100) for locating the first roller retaining collar (84, 184) on the roller shaft (52, 152); the shaft hole (100) expands in diameter in an axial direction from its outer surface (90) to its inner surface (88) facing the rollers so as to limit axial displacement of the rollers (34, 134) on the roller shafts (52, 152), and is sized to frictionally fit the first roller retaining collar (84, 184) onto the first circumferentially inclined surface (60); the roller shaft (52, 152) further includes a second circumferential inclined surface (62) transitioning between the second shaft end (56) and the intermediate roller support section (58); the roller assembly (32, 132) further includes a second roller retention collar (86, 186) on the second circumferential inclined surface (62), the second roller retention collar (86, 186) having an inner circumferential wedge surface (199) sized to frictionally fit the second roller retention collar (86, 186); the first roller retaining collar (84, 184) defines a collar central axis, extends axially from the outer surface (90) to the roller-facing inner surface (88), and includes at least one relief channel (104) extending radially between the outer circumferential surface (96) and the inner circumferential wedge surface (198); the rollers (34, 134) include idlers (34, 134); A roller assembly wherein said circumferentially inclined surfaces (60, 62) have a conical shape.

2. 2. The roller assembly (132) of claim 1, wherein said outer peripheral surface (96) defines a peripheral wedge surface (196, 197) that expands in diameter in the direction of said outer surface (90).

3. a first set of bolts (94) that tighten the first roller retaining collar (84, 184) against the first axial side (61) of the roller (34, 134) and frictionally fit the first roller retaining collar (84, 184) onto the first circumferentially inclined surface (60); 3. The roller assembly (32, 132) of claim 1 or 2, further comprising: a second set of bolts (95) that tighten the second roller retaining collar (86, 186) against the second axial side (65) of the roller (34, 134) and frictionally fit the second roller retaining collar (86, 186) onto the second circumferentially inclined surface (62).

4. a first bearing block (64) that supports the first shaft end (54) for rotation; and a first end retainer (68) that is attached to the first shaft end (54) at a position axially outward of the first bearing block (64); 4. The roller assembly (32, 132) of claim 1, further comprising: a second bearing block (66) that supports the second shaft end (56) for rotation; and a second end retainer (70) that is attached to the second shaft end (56) at a location axially outward of the second bearing block (66).

5. 5. The roller assembly (32, 132) of claim 1, wherein the first roller retention collar (84, 184) comprises a multi-piece collar (84, 184) having a plurality of arcuate collar segments (102) and a plurality of relief channels (104) formed between adjacent ones of the plurality of arcuate collar segments (102).

6. 5. The roller assembly (32, 132) of claim 1, wherein the inner circumferential wedge surface (198) has a profile that varies circumferentially about the collar central axis and longitudinally along the collar central axis.

7. A ground engaging track system (24, 124) comprising: a roller (34, 134) having a shaft bore (42) defining a roller central axis and extending between a first axial side (61) and a second axial side (65) of the roller; and a roller shaft (52, 152); a roller assembly (32, 132) in which the roller shaft (52, 152) includes a first circumferential inclined surface (60), a second circumferential inclined surface (62), and an intermediate roller support section (58) extending between the first circumferential inclined surface (60) and the second circumferential inclined surface (62) and positioned within the shaft bore (42); a first retaining collar (84, 184) positioned around the roller shaft (52, 152) on the first axial side (61) and having a first inner circumferential wedge surface (198); and a second retaining collar (86, 186) positioned around the roller shaft (52, 152) on the second axial side (65) and having a second inner circumferential wedge surface (199), the first retaining collar (84, 184) is clamped against the first axial side (61) of the roller (34, 134) and frictionally fits onto the first circumferential inclined surface (60) based on clamped contact between the first inner circumferential wedge surface (198) and the first circumferential inclined surface (60); a roller retention system (83) in which the second retention collar (86, 186) is clamped to the second axial side (65) of the roller (34, 134) and frictionally fits onto the second circumferential inclined surface (62) based on clamped contact between the second inner circumferential wedge surface (199) and the second circumferential inclined surface (62); the rollers (34, 134) include idlers (34, 134) that are captured against axial displacement on the roller shafts (52, 152) between the first and second retention collars (86, 186) and are fixed for rotation with the roller shafts (52, 152) based on the friction fit between the first and second retention collars (84, 184), at least one of the first retention collar (84, 184) or the second retention collar (86, 186) has a relief channel (104) formed therein; at least one of the first retention collar (84, 184) or the second retention collar (86, 186) comprises a multi-piece collar (84, 86, 184, 186) having a plurality of arcuate collar segments (102); the roller (34, 134) includes an inner roller surface (40) that defines a shaft bore (42), a first collar bore (44, 144) that extends axially outward of the shaft bore (42) to the first axial side surface (61), and a second collar bore (46, 146) that extends axially outward of the shaft bore (42) to the second axial side surface (65); the first retaining collar (84, 184) is within the first collar bore (44, 144), and the second retaining collar (86, 186) is within the second collar bore (46, 146); each of the first and second retaining collars (84, 184, 86, 186) is cylindrical and includes an outer peripheral surface (96) that contacts the inner roller surface (40) within the respective first and second collar bores (44, 144, 46, 146).

8. A roller assembly (232) for a ground engaging track system (224), comprising: a roller (234) defining a roller central axis and including an outer tread surface and an inner roller surface (240) forming a shaft bore extending between a first axial side (261) of said roller (234) having a first side (263) and a second axial side (265) of said roller (234) having a second side (257); a roller shaft (252) having a first shaft end (254), a second shaft end (256), and an intermediate roller support section (258) enlarged relative to the first shaft end (254) and the second shaft end (256) and positioned within the shaft bore, the intermediate roller support section (258) forming, with the roller (234), a keyed roller-shaft joint (259) that secures the roller (234) and roller shaft (252) against relative rotation; a first retaining collar (284) arranged coaxially around the roller shaft (252) and fastened to the first axial side surface (261) of the roller (234) in axially facing contact with both the first side surface (263) and the intermediate roller support section (258) so that the roller (234) is fixed against axial displacement on the roller shaft (252) in a first direction; a second retaining collar (286) arranged coaxially around the roller shaft (252) and fastened to the second axial side surface (265) of the roller (234) in contact with both the second side surface (257) and the intermediate roller support section (258) so that the roller (234) is fixed against axial displacement on the roller shaft (252) in a second direction; the inner roller surface (240) includes a flat inner surface (277) and an arcuate inner surface (279), and the intermediate roller support section (258) includes a flat outer surface (281) and an arcuate outer surface (283) facing the flat inner surface (277) and the arcuate inner surface (279), respectively; the first retaining collar (284) and the second retaining collar (286) contact the intermediate roller support section (258) at positions angularly aligned circumferentially about the roller central axis with the arcuate inner surface (279) and the arcuate outer surface (283), and contact the first side surface (263) and the second side surface (257), respectively, at positions angularly aligned circumferentially about the roller central axis with the flat inner surface (277) and the flat outer surface (281).

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