Patent Description:
In many current applications, track chain members such as track links or track shoes are attached to each other using a pin that allows the track chain members to rotate relative to each other while still allowing the chain to remain in tension when installed on the undercarriage of a track type vehicle. If the pin becomes loose or otherwise falls out of the bores of the track chain members, the track chain will fall off the undercarriage of the track type vehicle, requiring maintenance in the field that may be difficult and costly. To help prevent this from happening, different devices have been employed to retain the pin in the bores of the track chain members.

One such device that has been used is a snap ring with a welded plate on a floating plate that blocks the egress of the pin from the bore of the track chain member. This device has had problems. For example, it is difficult to service the pin when needed due to the presence of the welded plate. If the welded plate is not provided, the likelihood of the snap ring twisting out of its retention groove adjacent the pin retaining bore is increased. Therefore, this solution has proven to be unsatisfactory in some applications.

Similarly, another solution has been to use a bolt and nut combination to hold the pin in place. However, it is often necessary to weld the nut to the bolt making servicing the pin difficult. Also, the nut and bolt are often exposed on the side of the track chain member, allowing them to become damaged. This may make disassembly difficult.

In other applications, under uneven mine floor conditions, the track pad or other portion of the track chain member undulates causing high stress on the outer roller path as the surface of a track roller or idler wheel is no longer pressing flat or in a parallel manner onto the pad. The high stresses may cause fracturing or spalling of the track chain member, necessitating unwanted maintenance. Even on flat surfaces or terrain, the high loads encountered by the track chain member created by the weight of the machine may also cause fracturing or spalling over time. This too may lead to maintenance sooner than desired.

Similarly, the shoe member may bend relative to the track pad of the track chain member when subjected to high stress created by the weight and/or payload of the machine as well as movement of the track as it encounters obstacles, etc..

Various previous attempted solutions to withstand the stress concentrations in the track chain member have been to harden the track chain member. However, it has proven difficult to achieve the desired hardening depth of previous track chain members.

<CIT> discloses a track for track laying vehicles.

<CIT> discloses a crawler track link in which a link attachment body is a separate component from a link main body. The link attachment body comprises: a plate section having a tread surface; and two protrusions that are integrated with the plate section and that protrude upward from the tread surface. An attachment pin attaches the link attachment body to the link main body below the plate section on the opposite side from the protrusions.

The present disclosure provides a track chain member in accordance with claim <NUM> a track chain assembly in accordance with claim <NUM>.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure. In the drawings:.

Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. In some cases, a reference number will be indicated in this specification and the drawings will show the reference number followed by a letter for example, 100a, 100b etc. It is to be understood that the use of letters immediately after a reference number indicates that these features are similarly shaped and have similar function as is often the case when geometry is mirrored about a plane of symmetry. For ease of explanation in this specification, letters will often not be included herein but may be shown in the drawings to indicate duplications of features discussed within this written specification.

Various embodiments of the present disclosure include a pin retention design that includes a bolt, washer, nut and spacer that are positioned near the longitudinal end of a track pin. This may prevent the track pin from egressing out of a track pin bore found in a track chain member while the track chain is in used on a machine.

<FIG> illustrate an application of various embodiments of the pin retention device of the present disclosure.

Referring to <FIG>, there is shown a machine <NUM> having a frame <NUM> with a track system <NUM>, including a first track 14a and a second track 14b positioned at opposite sides of frame <NUM>. Machine <NUM> is shown in the context of an excavator having an operator cab <NUM>, a linkage <NUM> and an implement <NUM> coupled with linkage <NUM>. Tracks 14a and 14b are part of a machine undercarriage <NUM> coupled with frame <NUM> in a conventional manner. Each of tracks 14a and 14b include a plurality of coupled together track shoes <NUM> forming endless loops extending about a plurality of rotatable elements. In a typical design, an idler <NUM> and a drive sprocket <NUM> will be associated with each of tracks 14a and 14b and mounted to a track roller frame <NUM>. A plurality of track rollers <NUM> may also be mounted to roller frame <NUM>, and are associated with each of tracks 14a and 14b to support machine <NUM> and guide tracks 14a and 14b in desired paths, as further described herein. One or more carrier rollers <NUM> may also be associated with each of tracks 14a and 14b to support and guide the tracks opposite rollers <NUM> during operation. The unique design of tracks 14a and 14b and the overall track and undercarriage system of which they are a part are contemplated to enable machine <NUM> to operate in certain environments such as soft underfoot conditions without the shortcomings associated with many earlier designs. While use in the machine environment of an excavator is emphasized herein, it should be understood that machine <NUM> might comprise a different type of machine. For instance, track-type tractors or even half-track machines are contemplated herein. Further still, machine <NUM> might consist of a conveyor or other type of machine wherein tracks are used for purposes other than as ground engaging elements. Also, the machine might be some type of hydraulic shovel or rope shovel.

Referring now also to <FIG>, there is shown machine undercarriage <NUM> partially disassembled, showing portions of track roller frame <NUM> and a carbody <NUM>. Each of tracks 14a and 14b may include a first track chain 90a and a second track chain 90b. In one embodiment, each track chain 90a and 90b may be positioned at or close to opposite edges of each track shoe <NUM> making up the respective track. Each of track chains 90a and 90b may consist of alternating inboard links <NUM> and outboard links <NUM>. Referring also to <FIG>, there is shown a segment of track 14a, representative of any portion thereof, and substantially identical to any segment of track 14b. The segment of track 14a shown in <FIG> includes three coupled together track shoes <NUM>, each having one track link of
first track chain 90a and one track link of second track chain 90b coupled therewith. Each of the respective track links may be bolted to the corresponding track shoe with bolts <NUM>. In other embodiments, described herein, integral track links and track shoes may be used.

It will further be noted from the <FIG> illustration that each track link may include opposite ends positioned adjacent ends of successive track links in the corresponding track chain. In particular, each outboard track link <NUM> may include a first end 93a and a second end 93b opposite first end 93a. Each inboard link <NUM> may also include a first end 95a and a second end 95b. The respective track links may be positioned such that their ends are located adjacent ends of adjacent track links in a side-by-side arrangement. Links having their ends arranged in a side-by-side manner could be either straight or S-shaped links, for example. Track pins <NUM> may extend through adjacent track link ends to couple the track links, and in turn adjacent track shoes, together, regardless if the track links and shoes are integral with each other or separate members. Each of inboard links <NUM> may include bores <NUM> in each of ends 95a and 95b wherein a track pin <NUM> is press fitted. Each outboard link <NUM> may include another bore <NUM> in each of its ends 93a and 93b wherein a track pin <NUM> is loose-fitted. Snap-rings, keepers or some other pin retention mechanism according to an embodiment that will be described herein may be used to inhibit pins <NUM> from slipping out of bores <NUM>, etc. End caps <NUM> may be used to seal bores <NUM> to retain lubricating fluid therein and enable access for service, etc. In one embodiment, links <NUM> and <NUM> may be formed with a single forging die, and their respective bores, etc., formed via machining to obtain different sizes for press-fits versus loose fits.

Among other things, the present disclosure provides a track system, one embodiment of which is shown in <FIG>, which differs from known track designs in that the respective track chains 90a and 90b serve only to couple together the sets of track shoes <NUM>. Also in contrast to earlier designs, the track chains do not include rails upon which track rollers ride. Instead, track rollers <NUM> ride directly on portions of track shoes <NUM>. This strategy allows track chains 90a and 90b to be relatively simpler and lighter than conventional track chain designs. Track chains 90a and 90b may also be positioned adjacent a first outboard edge 61a and a second outboard edge 61b of each of track shoes <NUM>. Positioning track chains 90a and 90b close to the respective outboard edges 61a and 61b will enable track chains 90a and 90b to inhibit flexing and separating of track shoes <NUM> during certain operating conditions such as during high vertical loading and in response to certain mechanical stresses. In particular, where one of track shoes <NUM> is positioned upon a relatively hard supporting object such as a stump or stone, chains 90a and 90b can inhibit separating or creation of gaps between track shoes <NUM> due to stresses placed thereon, as described above in relation to earlier track designs.

As mentioned above, track rollers <NUM> ride directly on track shoes <NUM>. Each track shoe <NUM> may include an upper side <NUM> having a pad <NUM> positioned thereon. Pad <NUM> may include a first rail 65a and a second rail 65b, configured to support a track roller during operation. A guide block <NUM> may also be adjoined by each pad <NUM> and may comprise an integral part of, or be positioned upon, each pad <NUM>. Each guide block <NUM> can provide guiding for track rollers as well as drive surfaces for the corresponding track, as further described herein. Each pad <NUM> may extend approximately from a front edge 64a of each track shoe <NUM> to a back edge 64b of the corresponding track shoe. In one embodiment, a pad <NUM> may be formed integrally with each track shoe <NUM>, such as by casting, forging, etc. Each guide block <NUM> may also be formed integrally with a pad <NUM>. Integral pad and block elements could be keyed to and bolted on track shoes <NUM> in certain embodiments. In most versions, each pad <NUM> will provide a thickened region of wear material for wearing against track rollers. In other embodiments, however, pads <NUM> need not include a thickened wear region at all. Although pads <NUM> will typically be rectangular, in other embodiments they might have alternative shapes. Pads <NUM> will typically have a width defined by outboard edges of rails 65a and 65b which is less than one third a width D of the corresponding track shoe. The term pad should thus be understood to refer generally to a region of each track shoe, or a part or region of a part coupled therewith, which provides rails 65a and 65b for track rollers, without limitation as to shape or construction.

It will be further noted that rails 65a and 65b are positioned outboard of each guide block <NUM> and positioned inboard of each track chain 90a and 90b. In one embodiment, each of rails 65a and 65b may have a width, shown via arrows R in <FIG>, which is less than a distance by which the closest outboard track chain 90a, 90b is spaced therefrom. In other words, each of track chains 90a and 90b may be spaced an average distance from rails 65a and 65b, respectively, which is greater than the width R of the corresponding rail. In certain embodiments, track chains 90a and 90b may be spaced an average distance, respectively, from rails 65a and 65b which is more than twice a width of the corresponding rail. The distance whereby track chains 90a and 90b are spaced from rails 65a and 65b is shown in <FIG> via arrows A. Also apparent from the <FIG> illustration are certain of the relative dimensional characteristics of each track shoe <NUM>. It will be noted that each track shoe <NUM> has a length, shown via arrow L, which is less than one half its width, shown via arrow D in <FIG>.

As alluded to above, tracks 14a and 14b are considered to be well suited for work in soft underfoot conditions. To this end, tracks 14a and 14b may be "low ground pressure" tracks, each having track shoes <NUM> with a relatively large ground contact area for distributing pressure from the weight of machine <NUM> across a relatively large surface area. Each of track shoes <NUM> has a footprint defined in part by front and back edges 64a and 64b, and also defined in part by outboard edges 61a and 61b. Each of track shoes <NUM> may further include a ground contact area that is equal to its footprint, or less than its footprint only to an extent that adjacent track shoes overlap one another. Grousers <NUM> are associated with each of track shoes <NUM> and may extend downwardly from a lower side thereof, which is positioned opposite upper side <NUM>.

Though not clearly shown in <FIG> and <FIG>, a pin retention device <NUM> according to an embodiment of the present disclosure may be located at a front 93a or back portion 93b of the rail portion of the track chain member such as the track shoe <NUM> of <FIG>.

<FIG> illustrate another configuration of a track chain member <NUM> in the form of a track shoe <NUM> with integral link members <NUM> that use a pin retention device according <NUM> to an embodiment of the present disclosure. The track chain member <NUM> may be differently configured and work with a differently configured drive sprocket or idler than what is shown in <FIG>. In other embodiments, the track chain member may be a track shoe or track link member that are separate from each other such as when the track shoe is attached to the track link member via fastening, etc..

As best seen in <FIG>, a track chain assembly <NUM> comprises a plurality of track chain segments <NUM>. A track chain segment <NUM> comprises two track chain members <NUM> such as shoes and/or links. The track chain members <NUM> are attached to each other via a track pin <NUM>, allowing the track chain members <NUM> to rotate relative to each other, imparting the track chain assembly <NUM> with enough flexibility so that the chain may alter its shape from flat, such as when the segment <NUM> is contacting flat ground, to curved such as when the segment <NUM> is contacting uneven ground or is winding around a drive sprocket or idler wheel, etc..

Such a track chain assembly <NUM> includes a plurality of track chain segments <NUM> and at least one track chain segment includes two track chain members <NUM> and a track pin <NUM>. The track pin <NUM> may be cylindrical defining a longitudinal axis L108, a first end <NUM> and a second end <NUM> along the axis L108. The pin <NUM> connects the track chain members <NUM> together by being inserted into track pin bores <NUM> of the track chain members <NUM>, allowing the track chain members <NUM> to rotate relative to each other.

The pin retention device <NUM> may include a member <NUM> proximate the first end <NUM> of the track pin <NUM>. The pin retention device <NUM> defines a longitudinal axis L300 that is non-parallel to the longitudinal axis L108 of the track pin <NUM>.

As best seen in <FIG>, at least one track chain member <NUM> may define a track pin bore <NUM> with a shoulder <NUM> disposed proximate the second end <NUM> of the track pin <NUM>. In such an embodiment, the at least one track chain member <NUM> may define an aperture <NUM> that is at least partially defined by the shoulder <NUM>, and wherein the aperture <NUM> is in communication with the track pin bore <NUM>.

As best seen in <FIG>, the longitudinal axis L300 of the pin retention device <NUM> makes an orthogonal angle α with the longitudinal axis L108 of the track pin <NUM>.

Similarly, as best seen in <FIG>, the track chain member defines a direction of travel <NUM> and the longitudinal axis L300 of the pin retention device <NUM> forms an oblique angle β to the direction of travel <NUM>. In such an embodiment, the oblique angle may range from <NUM> to <NUM> degrees, and in some cases, may be approximately <NUM> degrees. This angle may be varied as need or desired.

Referring back to <FIG>, the pin retention device <NUM> includes a spacer <NUM> and the spacer defines a length L304 and at least one track chain member <NUM> defines a pin retention device bore <NUM> that defines a thru-depth D208, and the length L304 of the spacer <NUM> exceeds the thru-depth D208 by a predetermined amount <NUM>. This allows the pin retention device to float within the pin retention device bore along the L300 axis. A washer <NUM> may also be disposed between the track chain member <NUM> and the spacer <NUM>, helping to prevent deformation of the track chain member <NUM> that could lead to a loss of torque on the fastener <NUM>, leading to a loosening and eventual loss of the pin retention device <NUM>. It is contemplated that a washer may be omitted in some circumstances, such as when the washer is incorporated or integral with the head of the fastener or when the head of the fastener is oversized compared to the spacer. That is to say, for example, the diameter of the head is greater than the diameter of the spacer, etc..

As shown in <FIG>, after the track chain segment <NUM> has been fully assembled, when the track pin <NUM> is disposed in the track pin bore <NUM>, and the pin retention device <NUM> is inserted into the pin retention device bore <NUM>, the pin retention device <NUM> is spaced away from the track pin <NUM> a predetermined distance <NUM> when the track pin <NUM> is fully inserted into the bore <NUM> such that the pin <NUM> contacts the shoulder <NUM> at the opposite end of the bore <NUM>. Thus, the pin may move along the L108 axis before contacting the nut <NUM> or other member of the pin retention device <NUM>.

Looking at <FIG> together, bushings <NUM> may be provided to provide lubricity or other ways of reducing friction so that the joint formed between the track chain members <NUM> and the pin <NUM> may rotate more freely. As shown in <FIG>, separate bushing members <NUM>, <NUM>', <NUM>" may be disposed in each of the track pin bores <NUM>, <NUM>', <NUM>" or a single bushing member that extends through all the track pin bores may be provided. In yet other embodiments, the bushings may be omitted. For example, a self-lubricating pin may be provided that eliminates the need for bushings in some embodiments, etc..

Referring now to <FIG>, a track chain member <NUM> according to an embodiment of the present disclosure comprises a shoe member <NUM> and a first rail member <NUM> extending from the shoe member <NUM>, wherein the rail member <NUM> defines a dimension D214 of greatest extent and a track chain traveling direction <NUM> generally parallel to the dimension D214 of greatest extent. The track chain member <NUM> further defines a track pin bore <NUM> defining a longitudinal axis L202 that is perpendicular to the track chain traveling direction <NUM> when the axis L202 and the direction <NUM> are projected onto the same plane (best seen in <FIG>), and a pin retention device bore <NUM> that defines a longitudinal axis L208, wherein the longitudinal axis L208 of the pin retention device bore <NUM> and the longitudinal axis L202 of the track pin bore <NUM> are non-parallel (best seen in <FIG>). As shown in <FIG>, the shoe member and the rail member may be integral with each other. This may not be true for other embodiments of the present disclosure.

As alluded to earlier with reference to <FIG>, the longitudinal axis L208 of the pin retention device bore <NUM> and the longitudinal axis L202 of the track pin bore <NUM> form a perpendicular angle α with each other. As alluded to earlier with reference to <FIG>, the longitudinal axis L208 of the pin retention device bore <NUM> and the track chain traveling direction <NUM> form an oblique angle β with each other.

Focusing now on <FIG>, the track chain member <NUM> may further comprise a second rail member <NUM> extending from the shoe <NUM> in the same direction as the first rail member <NUM>, defining a pocket <NUM> between the first and second rail members <NUM>, <NUM>. Also, the track chain member <NUM> may comprise a third rail member <NUM> extending in a direction that is opposite the direction the first and second rail members extend <NUM>, <NUM>, the third rail member <NUM> being aligned with the pocket <NUM> along the longitudinal axis L202 of the track pin bore <NUM>. In the embodiment shown, the first, second and third rail members <NUM>, <NUM>, <NUM> form a Y-shaped configuration. Other configurations are possible for other embodiments of the present disclosure.

<FIG> disclose an embodiment of a pin retention device <NUM>. The device comprises a fastener <NUM> defining a longitudinal axis L308, a first end <NUM> and a second end <NUM> along the longitudinal axis L308, a head <NUM> at the first end <NUM> and a threaded portion <NUM> at the second end <NUM>, a tubular spacer <NUM> defining a thru-hole <NUM> configured to receive the fastener <NUM>, and a nut <NUM> defining a threaded hole <NUM> configured to mate with the threaded portion <NUM> of the fastener <NUM>. For reasons set forth above, the device <NUM> may further comprise a washer <NUM> that defines a central aperture <NUM> that is configured to receive the fastener <NUM>.

Looking at the fastener <NUM> more closely as best seen in <FIG> and <FIG>, the fastener <NUM> includes a shank portion <NUM> disposed between the head <NUM> and the threaded portion <NUM> and the washer <NUM> is disposed between the head <NUM> and the tubular spacer <NUM> once the device has been fully installed. The nut <NUM> includes a rectangular configuration that allows the surface area of its flat sides <NUM> to be maximized so that it provides enough bearing surface area should the pin <NUM> contact the flat side <NUM> if the pin become loose. Also, the fastener <NUM> takes the form of a bolt <NUM> that includes a hexagonally shaped head <NUM>. A socket <NUM> may be provided to mate with the head <NUM> while a wrench may be used to hold the nut <NUM> still as the bolt <NUM> is tightened. This continues until the washer <NUM> is sandwiched between the head <NUM> of the fastener <NUM> and the spacer <NUM>. The pin retention device <NUM> is free to float in the pin retention device bore <NUM> since the spacer <NUM> is longer than the depth of the bore <NUM> as previously explained.

As depicted by <FIG>, the pin bushings <NUM> may be pressed into the track pin bores <NUM> of a track chain member <NUM> using a hydraulic pressing device <NUM>. A brace <NUM> may be span between two rail members <NUM>', <NUM> to provide support so that the rail members do not bend during the pressing operation. Then, the track pins may be inserted into the bores using a similar hydraulic device.

Other embodiments of the present disclosure may provide structure to help reduce the spalling or fracturing of track chain members. Referring now to <FIG> and <FIG>, a track chain member <NUM> may comprise a shoe member <NUM>, and a first rail member <NUM> extending from the shoe member <NUM>, wherein the first rail member <NUM> defines a track chain traveling direction <NUM> (this direction is perpendicular to <FIG> and <FIG> and is best seen in <FIG> and <FIG>) and a lateral direction L generally perpendicular to track chain traveling direction <NUM>. The first rail member <NUM> may also include a first support surface <NUM> extending generally in both the track chain traveling direction <NUM> and the lateral direction L defining an outer lateral extremity <NUM>, and a first crest shaped member <NUM> disposed laterally adjacent the outer lateral extremity <NUM> of the first support surface <NUM>. The "outer lateral extremity" is so called as it is closest the outside portion of the track chain member, toward the outside of the machine, once the track chain assembly is mounted on the undercarriage of the machine. The shoe member and any rail member may or may not be integral with each other.

In some embodiments such as the one shown in <FIG> and <FIG>, the shoe member <NUM> and the first rail member <NUM> define metallic outer surfaces. Often, the shoe member and the first rail member consist essentially of metallic material such as cast iron, steel, etc..

Focusing now on <FIG>, the first crest shaped member <NUM> defines a width W410 along the lateral direction L, a vertical direction V that is perpendicular to the lateral direction L and the track chain traveling direction <NUM>, and a height H410 in the vertical direction V, wherein the width W410 exceeds the height H410. The track chain member <NUM> may further comprise a second rail member <NUM> extending from the shoe member <NUM>, wherein the second rail member <NUM> defines a track chain traveling direction <NUM> and a lateral direction L generally perpendicular to track chain traveling direction <NUM>. The track chain member <NUM> may further define a second support surface <NUM> extending generally in both the track chain traveling direction <NUM> and the lateral direction L defining an inner lateral extremity <NUM> and a second crest shaped member <NUM> disposed laterally adjacent the inner lateral extremity <NUM> of the second support surface <NUM>. The "inner lateral extremity" is so called as it is closest the inside portion of the track chain member, toward the inside of the machine, once the track chain assembly is mounted on the undercarriage of the machine.

The second crest shaped member <NUM> may define a width W418 along the lateral direction L, a vertical direction V that is perpendicular to the lateral direction L and the track chain traveling direction <NUM>, and a height H418 in the vertical direction V, wherein the width W418 exceeds the height H418.

Width W410 and W418 may range from <NUM> to <NUM>. Likewise, height H410 and H418 may range from <NUM> to <NUM>. Also, the second support surface <NUM> defines a second support surface width W414 along the lateral direction L and the ratio of the height H418 of the second crest shaped member <NUM> to the second support surface width W414 ranges from <NUM>:<NUM> to <NUM>:<NUM>. These dimensions may be varied as needed or desired in other embodiments.

It should be noted that the track chain member <NUM> of the embodiment shown in <FIG> and <FIG>, as well as other figures of the present disclosure, may have features that are substantially symmetrical about a midplane M located halfway between the rail members <NUM>, <NUM>. One difference that features may be rotated about the midplane as will be discussed later herein. The features of the rail members <NUM>, <NUM> including the crest shaped members <NUM>, <NUM> may be symmetrical and/or have similar or the same dimensions, etc..

As mentioned earlier herein, a track chain assembly <NUM> is provided comprising a plurality of track chain segments <NUM>. The plurality of track chain segments include at least one track chain segment that includes two track chain members <NUM> wherein at least one track chain member <NUM> includes a shoe member <NUM> and a first rail member <NUM> extending from the shoe member <NUM>. The first rail member <NUM> defines a track chain traveling direction <NUM> and a lateral direction L perpendicular to track chain traveling direction <NUM>, a first support surface <NUM> extending generally in both the track chain traveling direction <NUM> and the lateral direction L defining an outer lateral extremity <NUM>, and a first crest shaped member <NUM> disposed laterally adjacent the outer lateral extremity <NUM> of the first support surface <NUM>.

The same track chain member <NUM> may also include a second rail member <NUM> extending from the shoe member <NUM>, wherein the second rail member <NUM> defines the same track chain traveling direction <NUM> as the first rail member <NUM> and the same lateral direction L as the first rail member <NUM>, a second support surface <NUM> extending generally in both the track chain traveling direction <NUM> and the lateral direction L defining an inner lateral extremity <NUM>, and a second crest shaped member <NUM> disposed laterally adjacent the inner lateral extremity <NUM> of the second support surface <NUM>. The first rail member <NUM> is spaced away from the second rail member <NUM>, defining a groove <NUM> therebetween. This groove <NUM> is configured to receive the guiding ridge <NUM> of an idler wheel or track roller <NUM> or the like, helping to keep the track on the undercarriage.

As can be seen by looking at <FIG>, the first and second support surfaces <NUM>, <NUM> are coplanar. This may not be the case in other embodiments. As mentioned previously, the track chain member <NUM> defines a midplane M and the first and second crest shaped members <NUM>, <NUM> are symmetrically shaped about the midplane M for this embodiment. This may not be true in other embodiments.

Referring back to <FIG>, the track chain member <NUM> further defines a concave arcuate surface <NUM> such as a radius joining the first support surface <NUM> to the first crest shaped member <NUM>. More specifically, the first crest shaped member <NUM> defines a first angled surface <NUM> forming a first oblique angle ϕ with the lateral direction L and the concave arcuate surface <NUM> joins the first support surface <NUM> with the first angled surface <NUM>. Similarly, the first crest shaped member <NUM> defines a convex arcuate surface <NUM> such as a radius near the zenith of the first crest shaped member <NUM>. The first crest shaped member <NUM> defines a straight surface <NUM> near the zenith. Alternatively, the convex arcuate surface <NUM> may define the zenith without any straight surface. Also, the first crest shaped member <NUM> defines a second angled surface <NUM> on the opposite lateral side of the first crest shaped member <NUM> as compared to the first angled surface <NUM>, wherein the second angled surface <NUM> forms a second oblique angle γ with the lateral direction L. Although not pointed out in the figures, another convex arcuate shape may blend the top straight surface <NUM> to the second angled surface <NUM>.

It is contemplated that the various dimensions of the first crest member <NUM> may be varied as needed or desired. For example, the first oblique angle ϕ may range from <NUM> to <NUM> degrees. Likewise, the second oblique angle y may range from <NUM> to <NUM> degrees. The second oblique angle may be greater than the first oblique angle as shown in <FIG> and <FIG>. This may not be the case in other embodiments. Any of these dimensions may be varied as needed or desired in other embodiments.

<FIG> illustrate an embodiment of a roller path of a track pad that may reduce the likelihood of fracturing or spalling when the track chain or track chain member is subjected to heavy loads during use. As best illustrated by <FIG> and <FIG>, a track chain member <NUM> according to an embodiment of the present disclosure may comprise a shoe member <NUM> defining a track chain traveling direction T and a lateral direction L perpendicular to the track chain traveling direction T, and a track pad member <NUM> extending from the shoe member <NUM> that is configured to support the weight of the machine as it is transferred to the track pad member <NUM> through a track roller <NUM> or the like. The track pad member <NUM> may include a first lug member <NUM> extending from the shoe member <NUM> in a first direction <NUM> parallel to the track chain traveling direction T, a second lug member <NUM> and a third lug member <NUM> both extending from the shoe member <NUM> in a second direction opposite <NUM> of the first direction <NUM>.

As alluded to earlier herein, the first, second and third lug members <NUM>, <NUM>, <NUM> define a Y-shaped configuration and the first lug <NUM> defines a first lug width W508 along the lateral direction L. Focusing on <FIG>, the first track pad member <NUM> defines a roller support surface <NUM> defining a roller support surface width W518 along the lateral direction L and the first lug width W508 ranges from <NUM>-<NUM>% of the roller support surface width W518. Looking at <FIG>, the first, second and third lugs <NUM>, <NUM>, <NUM> define track pin bores <NUM> for receiving a track pin. The various dimensions and ratios may be varied as needed or desired. For example, the first lug width W508 may range from <NUM> to <NUM> while the roller support surface width W518 may range from <NUM> to <NUM>. Referring back to <FIG>, the second lug member <NUM> is spaced away from the third lug member <NUM>, defining at least partially a void <NUM> therebetween and the first lug member <NUM> is laterally aligned with the void <NUM>.

Looking at both <FIG> and <FIG>, this arrangement allows the first lug member <NUM> to be inserted into the void <NUM> when assembling a track chain assembly <NUM> using similarly configured track chain members <NUM> so that the track pin may be inserted through the track pin bore <NUM> of the second or third lug member <NUM>, <NUM> into the track pin bore <NUM> of the first lug member and the track pin bore <NUM> of the other of the second or third lug member <NUM>, <NUM>, forming a rotating j oint. All the track pin bores <NUM> may have substantially the same diameters when clearance and manufacturing tolerances are taken into consideration. This configuration or features may not be present or may be varied in scope in other embodiments.

Referring back to <FIG>, the second lug member <NUM> defines a second lug member width W512 along the lateral direction L, the third lug member <NUM> defines a third lug member width W514 along the lateral direction L, and the first lug member width W508 is different than the second lug member width W512 and the third lug member width W514. This may not be true for other embodiments. Similarly, the first lug member width W508 is greater than the second lug member width W512 but less than the third lug member width W514. This may not be the case in other embodiments.

The track chain member <NUM> may define a center of mass C and a central axis CA passing through the center mass C wherein the central axis is perpendicular to the lateral direction L and the track chain traveling direction T. The geometry of the track chain member <NUM> may be described as including a circular array wherein the first, second and third lug members <NUM>, <NUM>, <NUM> are rotated about the central axis <NUM> degrees, forming fourth, fifth and sixth lug members <NUM>, <NUM>, <NUM> respectively. The track chain member may further define a central groove <NUM> located at the central axis CA wherein the central groove <NUM> extends generally in the track chain traveling direction T. This feature may allow the guide ridge <NUM> of a track roller <NUM> or the like to ride therein, helping to prevent the track chain assembly <NUM> from falling off the undercarriage of a machine. The support surface <NUM> of the track pad may have a width W518 corresponding with that of a portion <NUM> of the roller <NUM> so that the contact surface between the track roller and the track pad is maximized to reduce the stress exerted on the track pad.

With continued reference to <FIG> and <FIG>, a track chain assembly <NUM> according to an embodiment of the present disclosure may be provided. The track chain assembly <NUM> may comprise a plurality of interlocking track chain members <NUM> wherein each track chain member <NUM> defines a track chain traveling direction T and a lateral direction L perpendicular to the track chain traveling direction T. Each of the interlocking track chain members <NUM> may include a shoe member <NUM> defining a shoe width W502 along the lateral direction L, a first track pad member <NUM> defining a first track pad maximum width W504 along the lateral direction L, and a second track pad member <NUM>' defining a second maximum track pad width W504' along the lateral direction L. The ratio of either the first or second track pad maximum widths W504, W504' to the shoe member width W502 may range from <NUM>:<NUM> to <NUM>:<NUM>.

Focusing on <FIG>, the first track pad member <NUM> is spaced away from the second track pad member <NUM>' a predetermined distance D504 along the lateral direction L. As already discussed earlier herein, both the first track pad member <NUM> and the second track pad member <NUM>' include a first lug member <NUM> extending from the shoe member <NUM> in a first direction <NUM> generally parallel to the track chain traveling direction T, and a second lug member <NUM> and a third lug member <NUM> both extending from the shoe member <NUM> in a second direction <NUM> opposite of the first direction <NUM>. The first lug member <NUM> defines a first lug member width W508 along the lateral direction L and the first lug member width W508 ranges from <NUM>-<NUM>% of either the first or second maximum track pad widths W504, W504'. Any of these dimensions may be varied as needed or desired in other embodiments.

Referring now to <FIG>, a track chain member according to another embodiment of the present disclosure is shown and will now be described. The track chain member <NUM> may comprise a shoe member <NUM> defining a track chain traveling direction T and a lateral direction L perpendicular to the track chain traveling direction T while also defining a first lateral end <NUM> and a second lateral end <NUM> of the shoe member <NUM>. The track chain member <NUM> also comprises a first track pad member <NUM> extending from the shoe member <NUM> including a first lug member <NUM> extending from the shoe member <NUM> in a first direction <NUM> parallel to the track chain traveling direction T, a second lug member <NUM> and a third lug member <NUM> both extending from the shoe member <NUM> in a second direction <NUM> opposite of the first direction <NUM>. This arrangement of the first, second and third lug members <NUM>, <NUM>, <NUM> define a Y-shaped configuration.

The track chain member <NUM> further includes a first rib <NUM> disposed nearest the first lug member <NUM> along the track chain traveling direction T extending from the first track pad member <NUM> along the lateral direction L substantially to the first lateral end <NUM> of the shoe member <NUM>. The first rib <NUM> may define a first concave radial portion <NUM>. Also, the track chain member <NUM> may include a second rib <NUM> disposed nearest the second lug member <NUM> along the track chain traveling direction T extending from the track pad member <NUM> along the lateral direction L substantially to the first lateral end <NUM> of the shoe member <NUM>.

In some embodiments, the first concave radial portion <NUM> defines a radius <NUM> ranging from <NUM> to <NUM>. This value may be varied as needed or desired in other embodiments.

As best seen in <FIG>, the shoe member <NUM> may include a ground engaging portion <NUM> disposed proximate the first lateral end <NUM>, and the shoe member <NUM> may define a notch <NUM> bounded by the first lug member <NUM>, the first rib <NUM> and ground engaging portion <NUM> disposed proximate the first lateral end <NUM>. In some embodiments, the track chain member <NUM> may further comprise a transitional surface <NUM> that at least partially defines the notch <NUM>, wherein the transitional surface <NUM> is bounded by the first lug member <NUM>, the ground engaging portion <NUM> and the first rib <NUM>. The transitional surface <NUM> may include a radial portion <NUM>, a slope portion, etc. This surface may provide clearance so that the second lug member of a similar track chain member may fit into the notch when assembly a track chain assembly.

Looking at both <FIG>, the ground engaging portion <NUM> may extend from the first lug member <NUM> and the second lug member <NUM> to the first lateral end <NUM>, the first lug member <NUM> may be spaced away from the first lateral end <NUM> a first lateral distance <NUM>, the second lug member <NUM> is spaced away from the first lateral end <NUM> a second lateral distance <NUM>, and the first rib <NUM> extends from the first lug member <NUM> to the ground engaging portion <NUM> of the shoe member <NUM> a first rib lateral distance <NUM> that is <NUM> to <NUM>% the value of the first lateral distance <NUM>. Similarly, the second rib <NUM> extends from the second lug member <NUM> to the ground engaging portion <NUM> of the shoe member <NUM> a second rib lateral distance <NUM> that is <NUM> to <NUM>% the value of the first lateral distance <NUM>. These distances may be varied as needed or desired. In many embodiments, the overlap of these distances may be substantial, that is to say, the overlap is <NUM>% or greater.

A similar description may be made regarding the heights of the ribs <NUM>, <NUM> to the height of the track pad measured in the vertical direction of the track chain member. As shown in <FIG>, the first rib <NUM> may range from <NUM> to <NUM>% of the height of the track pad <NUM> while the second rib <NUM> may range from <NUM> to <NUM>% of the track pad <NUM>. Again, these dimensions may be varied as needed or desired in other embodiments.

As discussed earlier herein, a track chain assembly <NUM> (see <FIG>) may be assembled by interlocking a plurality of track chain members <NUM> that are similarly or identically configured such as using a series of track chain members <NUM> as shown in <FIG>. Other configured track chain members such as master links and the like may also be attached to the plurality of identically or similarly configured track chain members.

Furthermore, as can be appreciated in view of <FIG>, <FIG> and <FIG> each of the plurality of track chain members <NUM> may define a center of mass C and a central axis CA passing through the center of mass C wherein the central axis CA is perpendicular to the lateral direction L and the track chain traveling direction T and the track chain member <NUM> may include a circular array wherein the first, second and third lug members <NUM>, <NUM>, <NUM> may be rotated about the central axis <NUM> degrees, forming fourth, fifth and sixth lug members <NUM>, <NUM>, <NUM>. Other features such as the first rib <NUM>, second rib <NUM>, notch <NUM>, and ground engaging portion <NUM> may also be rotated as part of the array, etc..

Focusing now on <FIG> and <FIG>, various features of the track chain member that allow a more consistent thickness will be discussed. As shown, the track chain member <NUM> may comprise a shoe member <NUM> defining a track chain traveling direction T and a lateral direction L perpendicular to the track chain traveling direction T. The shoe member <NUM> may further define a first lateral end <NUM>, a second lateral end <NUM>, and a ground engaging surface <NUM> spanning from the first lateral end <NUM> to the second lateral end <NUM>. The shoe member <NUM> may further define a first side void <NUM> proximate the first lateral end <NUM>, and a second side void <NUM> proximate the second lateral end <NUM>, and the first side void <NUM> terminates a first predetermined distance <NUM> from the first lateral end <NUM> and the second side void <NUM> terminates a second predetermined distance <NUM> from the second lateral end <NUM>. More specifically, the ground engaging surface may define the first and second side voids. Thus, the first and second side voids are not encapsulated in the shoe member. This may not be the case in other embodiments.

In addition, the shoe member <NUM> may further define a main central void <NUM> that is centered along the lateral direction L of shoe member with respect to the first and the second lateral ends <NUM>, <NUM>. The track chain member <NUM> wherein the shoe member <NUM> further define a first auxiliary void <NUM> in communication with the main central void <NUM> and the main central void <NUM> defines a first side end <NUM> and the first auxiliary void <NUM> is positioned proximate the first side end <NUM> of the main central void <NUM>. The shoe member <NUM> may further define a second auxiliary void <NUM> in communication with the main central void <NUM> and the second auxiliary void <NUM> is positioned proximate the second side end <NUM> of the main central void <NUM>. Again, the main central void may be defined by the ground engaging surface so that the void is not encapsulated in the shoe member. As pointed out in <FIG>, the side surfaces <NUM>, <NUM> of the main central void may form an oblique angle with respect to the lateral direction L or the track chain traveling direction T. As best seen in <FIG>, the main central void <NUM> may define a main central void depth D764 in a direction CA perpendicular to the ground engaging surface <NUM>, the first auxiliary void <NUM> may define a first auxiliary void depth D766 in a direction CA perpendicular to the ground engaging surface <NUM>, and the second auxiliary void <NUM> defines a second auxiliary void depth D770 in a direction CA perpendicular to the ground engaging surface <NUM>, and the first and second auxiliary void depths D766, D770 are greater than the main central void depth D764. In some embodiments, these depths may be the same.

As discussed earlier herein, a track chain assembly <NUM> (see <FIG>) may be assembled by interlocking a plurality of track chain members <NUM> that are similarly or identically configured such as using a series of track chain members <NUM> as shown in <FIG> and <FIG>. Other configured track chain members such as master links and the like may also be attached to the plurality of identically or similarly configured track chain members.

Focusing again on <FIG>, the track chain assembly may comprise a plurality of interlocking track chain members <NUM> wherein each track chain member <NUM> defines a track chain traveling direction T, a lateral direction L perpendicular to the track chain traveling direction T, and includes a shoe member <NUM> defining a first lateral end <NUM>, a second lateral end <NUM>, and a ground engaging surface <NUM> spanning from the first lateral end <NUM> to the second lateral end <NUM>. As depicted, a first rail member <NUM> may extend from the shoe member <NUM> disposed proximate the first lateral end <NUM>, and a second rail member <NUM> extending from the shoe member <NUM> disposed proximate the second lateral end <NUM> spaced away from the first rail member <NUM>, defining a central groove <NUM> therebetween.

Referring to <FIG> and <FIG>, the track chain member <NUM> may include a first rib <NUM> and a second rib <NUM> extending between the first rail member <NUM> and the first lateral end <NUM> of the shoe member <NUM>. Similarly, there may be a third rib <NUM> and a fourth rib <NUM> extending between the second rail member <NUM> and the second lateral end <NUM> of the shoe member <NUM>.

Looking at <FIG>, the main central void <NUM> defined by the ground engaging surface <NUM> of the shoe member <NUM> disposed beneath the central grove <NUM> along a direction perpendicular to the ground engaging surface <NUM>. The first side void <NUM> proximate the first lateral end <NUM> is bounded by the ground engaging surface <NUM> and is spaced away from the main central void <NUM> and a second side void <NUM> proximate the second lateral end <NUM> bounded by the ground engaging surface <NUM> spaced away from the central void <NUM>. The first side void <NUM> is bounded on either side along the track chain traveling direction T by the first rib <NUM> and the second rib <NUM>. That is to say, the first side void does not extend further along the track chain traveling direction than any portion of the first or second rib. Likewise, the second side void <NUM> is bounded on either side along the track chain traveling direction T by the third rib <NUM> and the fourth rib <NUM>.

For this particular embodiment, the shoe member <NUM> defines a first curved surface <NUM> at the bottom of the first side void <NUM> and a second curved surface <NUM>' at the bottom of the second side void <NUM>. This may not be the case in other embodiments. The central groove <NUM> defines a width W707 along the lateral direction L and the first auxiliary void <NUM> and the second auxiliary void <NUM> are spaced away from each other a distance <NUM> along the lateral direction L that is greater than the width W707 of the central groove <NUM>.

<FIG> illustrates that track chain member <NUM> defines a cross-section taken along the lateral direction L centered on the shoe member <NUM> along the track chain traveling direction T and a thickness T702 measured along a direction CA perpendicular to the ground engaging surface <NUM> that varies along the lateral direction L. For this embodiment, the thickness T702 is greatest in the areas disposed between either the first side void <NUM> and the main central void <NUM> or the second side void <NUM> and the main central void <NUM>.

In practice, a track chain assembly, track chain member and/or pin retention device may be sold, manufactured, bought etc. and attached to the machine in the aftermarket or original equipment scenarios according to any of the embodiments discussed herein. That is to say, the machine may be sold with the track chain assembly, track chain member and/or pin retention device according to embodiments described herein or the machine may be retrofitted, repaired, refurbished to use any of the embodiments discussed herein. The various components including, but not limited to the track chain members, may be used from any suitable material such as cast iron, grey cast iron, steel, etc..

In one particular application, it has been determined that a M36 bolt may be used as the fastener for the pin retention device. In such an application, the bolt may be tighten using <NUM> or more of torque and the resulting connection may experience no loosening during a period of <NUM>,<NUM> hours of track operation. The device may also withstand <NUM> kN of shear force. If the device is spaced away from the track pin as has been described earlier herein, torque from a spinning track pin may not be effectively transferred to the device, lessening the risk that the device may become loose over time. As mentioned earlier, hand tools may be sufficient to install the pin retention device.

In <FIG>, the right half of this figure from the midplane M illustrates what happens when the idler wheel or track roller <NUM> is angled relative to the track chain member <NUM> as represented by line <NUM> which is angled relative to the lateral direction L. This mimics what happens when the track chain member <NUM> with the crest member <NUM> is subjected to an uneven or angled terrain in use. The amount of stress generated by this situation can be seen by the various cross-hatching in concentric rings located near the outer lateral extremity <NUM>. On the other hand, the left half of this figure from the midplane M illustrates what happens when the idler wheel or track roller is angled relative to the track chain member as represented by line <NUM> which is angled relative to the lateral direction L. Again, this mimics what happens when the track chain member without a crest member is subjected to an uneven or angled terrain. The amount of stress is considerably greater without the crest member. Thus, one skilled in the art would expect using the crest member to reduce the likelihood of fracturing or spalling, etc., helping to reduce the need for maintenance.

For the embodiments disclosed in <FIG> and <FIG> shows a FEA stress plot of a previous design of a track lug in the upper left hand corner thereof while it also shows a FEA stress plot of a track lug such as the first track lug <NUM> of <FIG> and <FIG> in the lower right hand corner, showing a reduction in stress. This reduction in stress indicates to one skilled in the art that the likelihood of fracturing or spalling of the new design is less than the previous design.

Likewise, <FIG> shows that the previous design, shown to the extreme left, has higher stress than that of the embodiment shown in <FIG> and <FIG>, seen in the middle labeled as <NUM>, and that of another embodiment not shown in <FIG> and <FIG>, labeled as <NUM> at the extreme right. So, the improved designs will likely experience less fracturing and spalling. For the embodiments disclosed in <FIG>, the stress plot in <FIG> shows that the maximum stress under the simulated operating conditions is approximately <NUM> MPa on the top portion of the track pad. To the contrary previous designs without the rib designs of <FIG>, were determined using a similar FEA modeling scenario to have peak stresses as high as <NUM> MPa. <FIG> illustrate that the first and second ribs experience a maximum stress of approximately <NUM> MPa. Once more, this indicates a lower likelihood of fracturing or spalling.

For the embodiments shown in <FIG>, <FIG> and <FIG>, the stress plots in <FIG> and <FIG> show that using the provision of the side voids <NUM>, <NUM>, and the central void <NUM> as well as using curved ribs in certain embodiments allows the stress to be reduced to about <NUM>-<NUM> MPa in the corners <NUM> of the central void <NUM> (see <FIG>) and for the stress in the area <NUM> near a lateral end <NUM>, <NUM> to be reduced to about <NUM>-<NUM> in the side void <NUM>, <NUM> (see <FIG>). For previous designs using a slot on the bottom of the track shoe that extends all the way across laterally, similar areas experienced a maximum stress ranging from <NUM>-<NUM> MPa. Again, this indicates that the likelihood of fracture or spalling was reduced.

<FIG> shows an embodiment of a tracked machine <NUM> in the form of a hydraulic shovel that includes an embodiment of a track system <NUM> constructed in accordance with principles of the present disclosure. Among other uses, a hydraulic shovel can be used to load overburden and ore into haul trucks during the mining process in various surface mine applications.

While the arrangement is illustrated in connection with a hydraulic mining shovel, the arrangement disclosed herein has universal applicability in various other types of machines commonly employ track systems, as opposed to wheels. The term "machine" may refer to any machine that performs some type of operation associated with an industry such as mining or construction, or any other industry known in the art. For example, the machine may be an excavator, wheel loader, cable shovel, or dragline or the like. Moreover, one or more implements may be connected to the machine. Such implements may be utilized for a variety of tasks, including, for example, lifting and loading.

As shown in <FIG>, the machine <NUM> may include a body <NUM> with a cab <NUM> to house a machine operator. The machine may also include a boom system <NUM> pivotally connected at one end to the body <NUM> and supporting an implement <NUM> at an opposing, distal end. In embodiments, the implement <NUM> can be any suitable implement, such as a bucket, a clamshell, a blade, or any other type of suitable device. A control system can be housed in the cab <NUM> that can be adapted to allow a machine operator to manipulate and articulate the implement <NUM> for digging, excavating, or any other suitable application.

The body <NUM> may be supported on a main frame <NUM> supported on an undercarriage structure <NUM>. The undercarriage structure <NUM> includes a supporting structure <NUM> that supports a track system <NUM> utilized for movement of the machine <NUM>. The track system <NUM> may include first and second track roller frame assemblies <NUM>, which are spaced from and adjacent respective first and second sides of the undercarriage structure <NUM>. It will be appreciated that only one of the track roller frame assemblies <NUM> is visible in <FIG>.

Each of the track roller frame assemblies <NUM> carries an idler wheel <NUM>, a drive sprocket wheel <NUM>, and a plurality of track guiding rollers <NUM>. The drive sprocket wheel <NUM> is powered in forward and reverse directions by the machine <NUM>. An endless track chain assembly <NUM> encircles each drive sprocket wheel <NUM>, the idler wheel <NUM>, and the track guiding rollers <NUM>. The track chain assembly <NUM> includes a plurality of interconnected track pads <NUM>, also referred to as track chain members herein. The track guiding rollers <NUM> guide the track pads <NUM> as the track chain assembly <NUM> is driven by the drive sprocket wheel <NUM>. The track chain assembly <NUM> may have any track chain member, track pin retention device, and/or track chain assembly as previously described herein. It should be noted that the contents of <FIG> indicate that the apparatus disclosed by <CIT> may be modified to use any track chain member, track pin retention device, and/or track chain assembly as described herein.

Claim 1:
A track chain member (<NUM>) for a track chain assembly, the track chain assembly (<NUM>) comprising a plurality of track chain segments (<NUM>), each track chain segment (<NUM>) comprising two track chain members (<NUM>), the track chain members (<NUM>) being attached to each other via a track pin (<NUM>), the track pin (<NUM>) allowing the track chain members (<NUM>) to rotate relative to each other, wherein the track chain member (<NUM>) comprises:
a shoe member (<NUM>);
a first rail member (<NUM>) extending from the shoe member (<NUM>), wherein the first rail member (<NUM>) defines a dimension of greatest extent (D214) and a track chain traveling direction (<NUM>) generally parallel to the dimension of greatest extent;
a track pin bore (<NUM>) for inserting the track pin (<NUM>) therein and defining a longitudinal axis (L202) that is perpendicular to the track chain traveling direction (<NUM>) when the axis and the direction are projected onto the same plane; and
a pin retention device bore (<NUM>) that defines a longitudinal axis (L208), wherein the longitudinal axis (L208) of the pin retention device bore (<NUM>) and the longitudinal axis (L202) of the track pin bore (<NUM>) are non-parallel,
wherein the longitudinal axis (L208) of the pin retention device bore (<NUM>) and the longitudinal axis (L202) of the track pin bore (<NUM>) form a perpendicular angle (α) with each other, characterized in that the longitudinal axis (L208) of the pin retention device bore (<NUM>) and the track chain traveling direction (<NUM>) form an oblique angle (β) with each other.