Truck joint assembly for ground engaging trucks including truck pin having enlarged center section

Abstract

To cope with an abrasion phenomenon of a machine truck.SOLUTION: A ground engaging truck system (18) includes a track roller frame (24) and ground engaging trucks (20 and 22) including a first truck chain (30) and second truck chain (32) respectively, which include truck links (40 and 42) respectively and share truck pins (34) that join the first truck chain (30) and second truck chain (32). A center section (66) of the truck pin (34) is partly positioned in inward link straps (52 and 54) respectively, with respect to a first pin end (62) and second pin end (64), in the first truck chain (30) and second truck chain (32) respectively. The center section of the truck pin has an enlarged diameter to form an outside abrasion surface (68) exposed to a truck guide space (86).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure generally relates to track joint assemblies, and more specifically to track pins having a central section with an enlarged diameter relative to the ends of the track pins.

Background Art

[0002] Various machines used in off-highway environments utilize tracks as ground-engaging propulsion elements, particularly track-type shovels and track-type tractors. Such tracks typically include rotatable track-engaging elements, and each of the two tracks on either side of the machine forms an endless loop that moves around the rotating element during operation. Two parallel chains of linkages with bolted track shoes are a typical configuration for each individual track. The requirements for such machines and associated tracks can be quite substantial depending on the operating environment and specific work applications. For example, machine tracks used in so-called production dozing are typically designed with the machine's more or less continuous movement and severe underfoot conditions in mind, since the machine is driven to dig, push, and distribute material more or less continuously while in service. For other applications, including shovel applications, tracks are often designed for softer or less severe underfoot conditions and for only intermittent operation of the machine, since many excavation operations are performed while the machine is stationary.

[0003] In recent years, the understanding and handling of the wear phenomenon of machine tracks have received engineering attention. The various wear phenomena and wear rates experienced by a machine track are typically the result of how the machine is used as described above, the skill and experience of the operator, and the specific underfoot conditions and substrate materials encountered in the operating environment. The field service life of a machine track can vary based on these and other factors. Machine track components, needless to say the negative side of machine downtime, can be relatively costly to maintain and replace, so engineering efforts in this field often focus on reducing and managing wear between and among components. U.S. Patent No. 4,150,856 to Hakkenburg et al. discloses one known example of a machine track design that includes a one-piece track pin.

Summary of the Invention

[0004] In one aspect, a track joint assembly includes a first track chain and a second track chain having a track link having an outer link strap each having an outer pin bore and an inner link strap having an inner pin bore. The track joint assembly also includes a track pin defining a longitudinal axis and having a first pin end, a second pin end, and a central section extending from the first pin end to the second pin end and having an outer wear surface. The track joint assembly also includes a first track joint including an outer link strap within the track link within the first track chain, the first pin end, within each outer pin bore, and a first interference fit insert supporting the first pin end for rotation and having a first bearing surface extending circumferentially about the longitudinal axis. The first track joint further includes an inner link strap within the track link within the first track chain and a first portion of the central section located within each inner pin bore. The track joint assembly further includes a second track joint including an outer link strap to the track link within the second track chain, the second pin end, within each outer pin bore, and a second interference fit insert supporting the second pin end for rotation and having a second bearing surface extending circumferentially about the longitudinal axis. The second track joint further includes an inner link strap within the track link within the second track chain and a second portion of the central section located within each inner pin bore. A track guide space extends between the first track chain and the second track chain. The central section of the track pin has a diameter enlarged relative to the first pin end and the second pin end, and the outer wear surface is exposed to the track guide space.

[0005] In another aspect, the ground-engaging track system includes a track roller frame, a first track chain and a second track chain each including a track link, and a ground-engaging track having a track pin connecting the first track chain and the second track chain. Each track link includes an outer link strap and an inner link strap. Each track pin includes a first pin end extending and supported for rotation within the outer link strap of the track link within the first track chain, a second pin end extending and supported for rotation within the outer link strap of the track link within the second track chain, and a central section extending from the first pin end to the second pin end. A track guide space extends between the first track chain and the second track chain. Each central section of the track pin includes an enlarged diameter that is positioned at least partially within the inner link strap in each of the first track chain and the second track chain relative to the first pin end and the second pin end, forming an outer wear surface exposed to the track guide space.

[0006] In yet another aspect, a track pin for a track joint assembly in a ground engaging track system includes a solid pin body defining a longitudinal axis extending between a first pin end having a first terminal surface, a second pin end having a second terminal surface, and a central section extending between the first pin end and the second pin end. The central section includes a first lead-in chamfer and a second lead-in chamfer formed adjacent to the first pin end and the second pin end, respectively, for interference fitting with a first portion and a second portion of the central section having inner link straps in a first track chain and a second track chain, respectively. The solid pin body has an overall axial length, and the first pin end and the second pin end each have a pin end axial length. The central section has an enlarged diameter and a central section axial length with respect to the first pin end and the second pin end. The enlarged diameter is greater than the pin end axial length. The axial length of the central section is 60% - 63% of the overall axial length and 314% - 318% of the pin end axial length.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0008] Referring to FIG. 1, a machine 10 is shown according to one embodiment, including a frame 12, an operator cab 14, and a work implement system 16. The machine 10 further includes a ground-engaging track system 18 for moving the machine 10 around a work area. The machine 10 is shown in the context of a shovel where the cab 14 and the implement system 16 can rotate around the ground-engaging track system 18. The ground-engaging track system 18 includes a first track 20 and a second track 22 located on opposite sides of the frame 12. The description and discussion of the features and functions of the track 20 and associated components can be understood by referring to the track 22 as an analog since each track is typically substantially identical. The track system 18 is also configured to support a plurality of rotatable track-engaging elements, including a drive sprocket 26 visible in the view of FIG. 1, typically an idler located at the opposite end of the track roller frame 24 from the sprocket 26, track rollers configured to support a majority of the weight of the machine 10 and distributed between the idler and the drive sprocket 26, and carrier rollers that support the track 20 above the track roller frame 24. The track 20 also includes a first track chain 30 and a second track chain 32, as well as a plurality of track pins 34 that couple the first track chain 30 and the second track chain 32 together. In FIG. 1, the drive sprocket 26 is shown in contact with the track pins 34 and can advance the track 20 in an endless loop around the various rotatable track-engaging elements to move the machine 10 around the work area. A plurality of track shoes 36 can be attached to the first track chain 30 and the second track chain 32, generally by bolting in a conventional manner. As will be further apparent from the following description, the ground-engaging track system 18 can be uniquely configured for improved resistance to component degradation or failure and longer life compared to known systems.

[0009] Referring also to FIG. 2, the ground engagement track system 18 may include a plurality of track joint assemblies 38, one of which is shown in partial cross-section. The track joint assembly 38 includes a first track chain 30 and a second track chain 32, each including track links 40 and 42, respectively, each having outer link straps 44 and 46, respectively, each having outer pin bores 48 and 50. The track links 40 and 42 also each include inner link straps 52 and 54, each having inner pin bores 56 and 58. In the illustrated embodiment, the track links 40 and 42 are mirror images of each other and have an offset configuration in which the outer link straps 44 and 46 are laterally offset with respect to the inner link straps 52 and 54.

[0010] The track joint assembly 38 further includes a plurality of track pins 34, each including a solid pin body 35 and each defining a longitudinal axis 60. Hereinafter, the plurality of track pins 34 referred to in the singular each include a first pin end 62, a second pin end 64, and a central section 66 extending from the first pin end 62 to the second pin end 64, and have an outer wear surface 68 that contacts a drive sprocket 26 within a sprocket pocket alternating with sprocket teeth. The first track chain 30 includes a first track rail 55, and the second track chain 32 includes a second track rail 57. Idlers and track rollers (not shown) may generally ride on the track rails 55 and 57 in a conventional manner. The first pin end 62 includes a first terminal surface 88, and the second pin end 64 includes a second terminal surface 90.

[0011] The track joint assembly 38 includes a first track joint 70 that includes an outer link strap 44 on a track link 40 of the first track chain 30, a first pin end 62, a first interference fit insert 72 that is within each outer pin bore 48 and supports the first pin end 62 for rotation, and a first bearing surface 74. The first bearing surface 74 extends circumferentially about the longitudinal axis 60 and is radially positioned between the first pin end 62 and the outer link strap 44. The first track joint 70 further includes an inner link strap 52 within the track link 40 in the first track chain 30 and a first portion 76 of a central section 66 that is positioned within each inner pin bore 56. The track joint assembly 38 also includes a second track joint 78 that includes an outer link strap 46 of a track link 42 of the second track chain 32, a second pin end 64, and a second interference fit insert 80 that is within each outer pin bore 50 and supports the second pin end 64 for rotation. The second track joint 78 also includes a second bearing surface 82 that extends circumferentially about the longitudinal axis 60 and is radially positioned between the second pin end 64 and the outer link strap 46. The second track joint 78 further includes an inner link strap 54 within the track link 42 in the second track chain 32 and a second portion 84 of the central section 66 that is positioned within each inner pin bore 58.

[0012] In the illustrated embodiment, the first portion 76 and the second portion 84 of the central section 66 are interference fit into the respective inner pin bores 56 and 58. Also in the illustrated embodiment, each of the first interference fit insert 72 and the second interference fit insert 74 extends axially through the respective outer pin bores 48 and 50. Each of the first track joint 70 and the second track joint 78 may further include rotatable bushings 94 and 95 having respective bearing surfaces 74 and 82 formed thereon.

[0013] As described above, the first pin end 62 and the second pin end 64 are supported for rotation by the first interference fit insert 72 and the second interference fit insert 80. Each of the first interference fit insert 72 and the second interference fit insert 80 may include inwardly extending flange portions 96 and 97, respectively, and the rotatable bushings 94 and 95 are axially confined between the central section 66 of the track pin 34 and the respective inwardly extending flange portions 96 and 97. Each of the first track joint 70 and the second track joint 78 may further include pin retainers 98 and 99 that are located outwardly of and adjacent to the respective inwardly extending flange portions 96 and 97. The track pin 34 may also form a first circumferential groove 41 on the first pin end 62 and a second circumferential groove 43 on the second pin end 64. Each of the pin retainers 98 and 99 may include snap rings that are fitted into the corresponding grooves 41 and 43 and contacted by the respective inward flange portions 96 and 97 to maintain the desired relative axial positioning of the first pin end 62 and the second pin end 64 of the outer link straps 44 and 46. In an alternative embodiment, the joined plates may be attached to the first pin ends 62 and 64 instead of snap rings in the grooves, or some other pin retention strategy may be used.

[0014] Also, in the seals of the illustrated embodiments, seals such as lip seals may be positioned at a first track joint 70 and a second track joint 78 that include a first seal 91 at an inner position of the track joint 70 and a second seal 96 at an outer position. Another seal 93 may be positioned at an inner position of the track joint 78, and yet another seal 92 may be positioned at an outer position of the track joint 78. Bushings 94 and 95 may be self-lubricating bushings or bearings to which internal lubricant is not supplied. Each of the track joint 70 and the track joint 78 may also be grease lubricated. In the implementation of the shovel, a relatively low proportion of the tram time, and other service conditions that are normally expected, may be consistent with the ground-engaging track system 18 being a dry track system or being lubricated by self-lubricating or greased bearings. The track system 18 is different from the track systems used in many shovels in that, in contrast to certain other track systems, especially other systems, the outer portions of the track joints 70 and 78 are rotary pin joint connections where the track pins are interference fitted and thus do not rotate relative to the outer link strap. Also, in contrast to certain known track systems and track joint assemblies, no bushing is positioned on the track pin 34. Instead, the contact with the sprocket 26 is direct contact between the outer wear surface 68 and the sprocket 26.

[0015] It is recalled that the first portion 76 of the central section 66 and the second portion 84 of the central section 66 can be interference-fitted within the inner link straps 52 and 54, respectively. Thus, the inner link straps 52 and 54 do not rotate with respect to the pin 34 in such an implementation for the track 20 to advance around the various rotatable track engagement elements. The track guiding space 86 extends between the first track chain 30 and the second track chain 32. The central section 66 of the track pin 34 has an enlarged diameter with respect to the first pin end 62 and the second pin end 64, and the outer wear surface 68 is exposed to the track guiding space 86. It can further be noted that the track pin 34 has a stepped profile within each of the first track joint 70 and the second track joint 78. In addition to omitting the central bushing, the track joint assembly 38 contemplated herein, and other track joint assemblies, differ from certain known designs in that the relatively enlarged diameter of the track pin 34 provides a sacrificial wear material of the track pin 34 itself that can gradually wear during the service life of the ground engaging track system 18.

[0016] Referring now to FIG. 3, a track joint assembly 138 is shown, which uses certain reference numbers to identify features that may be the same or identical to those described in connection with the foregoing embodiments, according to another embodiment. The track joint assembly 138 includes a first track joint 170 and a second track joint 178, including track chains 130 and 132 each having track rails 155 and 157. The track guiding space 186 extends between the track chains 130 and 132. The track shoe 36 is attached to the track chains 130 and 132. The track joint assembly 138 also includes a track pin 34 having an outer wear surface 68, which is potentially substantially identical to the track pins discussed in connection with the preceding embodiments. The track joint assembly 138 differs from the foregoing embodiments in that, rather than an interference fit insert and bushing system to support both ends of the track pin 34, only a single inserted element is provided at each track joint to support the track pin 34 for rotation. The track pin 34 includes an outer bearing surface 134 formed directly thereon and is rotatable within an interference fit bushing 172. Another bearing surface 182 is shown at both ends of the track pin 34. The track pin 34 can interference fit with the inner track links of the track chains 130 and 132 in a manner generally similar to that of the preceding embodiments.

[0017] Referring now to FIG. 4, a track joint assembly 238 is shown that includes a first track chain 230 and a second track chain 232, according to another embodiment. A first track joint is indicated at 270 and a second track joint is indicated at 278. The retention of the track pin 234 in the outer link strap 244 can be generally similar to the embodiment of FIG. 2 in which a first pin end 262 of the track pin 234 is supported for rotation. A second pin end 264 can be similarly configured and supported. The track pin 234 also includes a central section 266 having an enlarged diameter with respect to the first pin end 262 and the second pin end 264. A track guide space 286 extends between the track chain 230 and the track chain 232. Reference numeral 246 identifies an inner link strap within the track chain 230. Rather than interference fitting with the inner link strap, the track pin 234 and the central section 266 may be rotatably supported, and the track joint assembly 238 may thus include bearing surfaces (one of which is labeled 277) that rotatably support the central section 266 within each of the respective inner link straps of interest.

[0018] Next, referring to FIG. 5, the track pin 34 can be sized and coordinated in a manner that enables the desired configuration and function of at least certain embodiments of the first track joint 70 and the second track joint 78. The first lead chamfer 100 and the second lead chamfer 102 are formed on the central section 66 adjacent to the first pin end 62 and the second pin end 64, respectively, for interference fitting with the first portion 76 and the second portion 84 of the central section 66 having the inner link straps 52 and 54 within the first track chain 30 and the second track chain 32. The track pin 34, including the solid pin body 35, has an overall axial length 400 extending between a first end 88 and a second end 90. The first pin end 62 and the second pin end 64 may each have a pin end axial length 430, and the pin end axial length 430 is equal for each of the first pin end 62 and the second pin end 64. Also, recall that the central section 66 has an enlarged diameter indicated by reference numeral 410 in FIG. 5. The enlarged diameter 410 is greater than the pin end axial length 430. The central section 66 also has a central section axial length 420. The central section axial length 420 is 60% - 63% of the overall axial length 400, and 314% - 318% of the pin end axial length 430. Specifically, the enlarged diameter 410 is 50% - 51% of the central section axial length 420, and 61% of the overall axial length 400. Also specifically, the axial length 420 of the central section is 318% of the pin end axial length 430. The pin end diameter is shown as 440 in FIG. 5 and may be approximately equal to the pin end axial length 430. In further detail, the overall axial length 400 is about 200 millimeters, more specifically 207 millimeters. In further detail, the pin end axial length 430 is about 40 millimeters. In further detail, the enlarged diameter 410 is about 60 millimeters, more specifically 63 millimeters. In further detail, the central section axial length 420 is about 130 millimeters, more specifically 127 millimeters.As used herein, the term "about" is generally or broadly understood to use conventional rounding such that, for example, "about 127 millimeters" means from 126.5 millimeters to 127.4 millimeters within the measurement error. In other instances, the term "about" may have a meaning different from conventional rounding methods or a broader meaning to one of ordinary skill in the art, depending on the context.

Industrial Applicability

[0019] As discussed above, the ground-engaging track system 18 and other track systems contemplated herein deviate from conventional designs in various ways. Track systems are often built specifically for a particular type of machine and / or a particular type of work application. For these and other reasons, track configurations that provide a fixed interface between certain components and a rotational interface between other components often do not readily adapt to other configurations without affecting the wear or other relationship patterns and degrees between components or among them. In this example, the ground-engaging track system 18, and particularly the track pin 34, is configured in a manner that can be expected to be attached to and operated on a machine such as a shovel without giving the track system significant changes or modifications or undesirable changes to the expected wear pattern or service life. In other words, the ground-engaging track system 18 can be very easily installed on an existing shovel platform. This is due, at least in part, to the design of the track pin 34, including its dimensions and ratios, which do not change factors such as pitch or track width compared to previous strategies and do not require bushings or additional additional components on the track pin.

[0020] This specification is for illustrative purposes only and should not be construed to narrow the scope of the disclosure. Accordingly, those skilled in the art will understand that various modifications can be made to the embodiments of the disclosure without departing from the full and fair scope and spirit of the disclosure. Other aspects, features, and advantages will be 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". When only one item is intended, "1" or similar language is used. Also, as used herein, the terms "having", "have", "has", or the like are intended to be open terms. Further, the phrase "based on" is intended to mean "at least partially based on" unless otherwise expressly stated.

Claims

1. A track roller frame (24); a ground engaging track (20, 22) having a first track chain (30, 230) and a second track chain (32, 232), each including track links (40, 42) and track pins (34, 234) coupling said first track chain (30, 230) and said second track chain (32, 232) together; each of the track links (40, 42) includes an outer link strap (44, 46, 244) and an inner link strap (52, 54, 246); each of the track pins (34, 234) includes a first pin end (62, 262) extending for rotation and supported within an outer link strap (44, 244) in a track link (40) in the first track chain (30, 230), a second pin end (64, 264) extending for rotation and supported within an outer link strap (46) in a track link (42) in the second track chain (32, 232), and a central section (66, 266) extending from the first pin end (62, 262) to the second pin end (64, 264); a track guide space (86, 186, 286) extends between the first track chain (30, 230) and the second track chain (32, 232); a ground engaging track system (18) including an enlarged diameter such that the central section (66, 266) of each of the track pins (34, 234) is positioned partially within an inner link strap (52, 54, 246) of each of the first track chains (30, 230) and second track chains (32, 232) relative to the first pin end (62, 262) and the second pin end (64, 264) and defines an outer wear surface (68) exposed to the track guide space (86, 186, 286).

2. a sprocket (26) contacting the outer wear surfaces (68) of a plurality of the track pins (34, 234) within the track guide spaces (86, 186, 286); 2. The ground engaging track system (18) of claim 1, further comprising: an interference fit insert (72, 80) each extending through one of the outer link straps (44, 46, 244); and a bearing surface (74, 82, 174, 182, 277) located between one of the interference fit inserts (72, 80) and the first pin end (62, 262) or second pin end (64, 264) of the respective track pin (34, 234).

3. the central section (66) of each of the track pins (34) is an interference fit with the respective inner link strap (52, 54); Each of the track pins (34) defines a longitudinal axis; the center section (66) having a center section axial length, the track pin (34) having a total axial length, The ground engaging track system (18) of claim 1 or 2, wherein the center section axial length is between 60% and 63% of the total axial length and between 314% and 318% of the pin end axial length.

4. a solid pin body (35) defining a longitudinal axis extending between a first pin end (62) having a first end surface (88), a second pin end (64) having a second end surface (90), and a central section (66) extending between said first pin end (62) and said second pin end (64); the central section (66) includes first and second lead-in chamfers (100) and (102) formed adjacent the first and second pin ends (62) and (64), respectively, for interference fitting first and second portions (76) and (84) of the central section (66) having inner link straps (52, 54) to the first and second track chains (30) and (32), respectively; the solid pin body (35) having a total axial length; the first pin end (62) and the second pin end (64) each have a pin end axial length; the central section (66) has an enlarged diameter and central section axial length relative to the first pin end (62) and the second pin end (64); the enlarged diameter is greater than the pin end axial length; and A track pin (34) for a track joint assembly (38, 138) in a ground engaging track system (18), wherein the center section axial length is between 60% and 63% of the total axial length and between 314% and 318% of the pin end axial length.

5. the enlarged diameter is 50% of the central section axial length; the central section axial length is 61% of the total axial length; The track pin (34) of claim 4, wherein the center section axial length is 318% of the pin end axial length.

6. said total axial length is 207 millimeters; The pin end axial length is 40 mm; the expanded diameter is 63 millimeters; The track pin of claim 4 or 5, wherein the central section axial length is 127 millimeters.

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