Abstract:
A replaceable track pad for use on a track chain of a crawler-type tracked machine reduces damage to a travel surface while providing traction and support to the tracked machine. The replaceable track pad includes a tread supported by a backing plate. The replaceable track pad may be mounted to a track link on a track chain using a mounting plate, forming a track pad mounting assembly. The mounting plate includes a substantially flat mounting surface. A worn or damaged track pad may be removed from the track chain without removing the mounting plate. The worn track pad can be refurbished by removing the worn tread material from the backing plate and attaching a new tread to the backing plate.

Description:
[0001]    A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
       CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0002]    This application claims benefit of the following patent application(s) which are hereby incorporated by reference: None 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates generally to a track shoe for a crawler-type tracked machine. More particularly, the present invention relates to a replaceable track pad and mounting plate forming a track pad assembly providing a tread for travel over a travel surface and for allowing replacement of a worn or damaged track pad from a track link. Additionally, the present invention relates to a method of refurbishing a worn track pad. 
         [0004]    A conventional track, or grouser, shoe for use on a track chain of a crawler-type tracked machine typically includes a steel track shoe having metal projections extending outward from the track shoe away from the track chain. The metal projections extending from the track shoe generally provide traction required for track chain movement in soft surface materials, such as sand, gravel or dirt. Typically, in tracked machines, one conventional track shoe is bolted to each track link using one or more track bolts. A track bolt extends first through a hole in the track shoe and further through a hole in the track link where the track bolt engages a track nut on the inside surface of the track link. 
         [0005]    Conventional track shoes are not well suited for travel on smooth, hard travel surfaces, like pavement, because the metal projections cause surface damage, including crushing and marking of the travel surface. Conventional track shoes also provide inadequate traction on hard, smooth surfaces as the metal projections tend to slide across the surface, thereby reducing machine efficiency and creating an unstable and dangerous situation, especially in wet conditions or when operating on an inclined surface. 
         [0006]    Others have attempted to overcome the traction problems associated with operating crawler-type machinery on hard travel surfaces by placing pads on traditional metal track shoes. For example, U.S. Pat. No. 5,261,733 teaches an elastic material molded directly onto a conventional metal grouser shoe, creating a one-piece track pad. In a conventional one-piece track pad, the elastic material covers the metal projections and forms a relatively soft ground-engagement surface. The one-piece track pad is connected to a track link using a track bolt inserted through a clearance hole extending through the track pad and engaging a track nut. While conventional one-piece track pads are effective at preventing surface destruction and providing traction, they often become worn or damaged during use, requiring replacement. When a one-piece track pad becomes worn, the entire grouser shoe with integrally molded pad must be removed and replaced. The replacement process typically involves removing the track nut from the track bolt and detaching the one-piece track pad from the track link. However, during use, track nuts and track bolts often experience damaging wear and are exposed to corrosive elements, thereby rendering track nuts difficult to remove from track bolts using a wrench. Also, track bolt clearance and countersink holes positioned in the ground engagement surface of the tread can become filled with debris. As a result, a torch is typically used to cut corroded or damaged track bolts and track nuts from track links. The process of cutting track bolts and track nuts from track links for track pad replacement adds time to the track pad replacement process. The cutting process also creates waste by destroying track bolts and increases costs by requiring new replacement bolts or nuts to be installed with each new track pad. 
         [0007]    Others have attempted to overcome the track pad replacement problems associated with prior art one-piece track shoes by creating two-piece track pads. Conventional two-piece track pads typically include a conventional track, or grouser, shoe that is first mounted to each track link using track bolts. The conventional track shoe is modified to include additional tread bolt clearance holes. A separate track pad component, made of a non-marking elastic material, is then secured to the conventional track shoe using tread bolts. The track pad typically includes a steel frame, or skeleton, with an elastic tread material molded around the frame. The frame is typically completely surrounded by tread material, and the frame extends over only a fraction of the tread footprint. The tread footprint is the surface area of the tread that engages the travel surface. Tread bolts extend through clearance holes on the grouser shoe and engage threaded regions or threaded track pad nuts on the frame, as generally described in U.S. Pat. No. 7,156,473. Alternatively, threaded tread bolt studs may extend outward from the frame to engage track pad nuts on the track shoe for securing the track pad in place, as generally described in U.S. Pat. No. 3,944,296. Using a two-piece prior art configuration, a track pad may be replaced after it becomes worn or damaged without removing the track bolts that hold the track shoe to the track link, allowing the steel track shoe to remain attached to the track chain. The two-piece configuration also reduces costs as the less expensive track pad can be replaced without replacing the track shoe and track bolts. This configuration protects tread bolts from excessive wear and corrosive materials on the travel surface. However, the steel frame typically only extends partially through the track pad, leaving regions of the track pad footprint unsupported by the steel frame. As a result, unsupported regions of the track pad have a tendency to experience accelerated wear as compared to fully supported tread regions. Accelerated wear at the tread edges, known in the art as chunking, significantly reduces track pad life. Additionally, unsupported regions may tear away completely, or separate, from the track pad, requiring track pad replacement and potentially causing damage to the travel surface as the metal regions of the track shoe become exposed. The prior art internal frame design also allows the entire track pad to flex during use, which further accelerates tearing, chunking and tread separation. 
         [0008]    Generally, two types of track chain links are included on track chains, master links and standard links. Master links and standard links may have dissimilar track bolt hole patterns because master links include additional internal components for providing a releasable connection with adjacent standard links. Conventional grouser shoe track bolt clearance holes are generally configured for mounting to either a standard link or a master link. Conventional grouser shoes of the prior art generally do not allow one grouser shoe to be used on both standard and master links of track chains. Instead, one grouser shoe model having unique, master link specific track bolt clearance holes must be used on a master link; and a separate, standard grouser shoe model having standard link specific track bolt clearance holes must be used on a standard link. The prior art configuration requiring separate grouser shoe models for standard and master links increases expense and track chain complexity. The prior art two-piece configuration also requires different size grouser shoes for use on different size chains, further increasing the number of parts required for on-site track shoe replacement and complicating manufacturing, ordering of replacement parts and shipping. 
         [0009]    Conventional two-piece track pads generally use a conventional grouser shoe mounted to a track link of a track chain. The prior art configuration typically includes extended regions shaped to fit between the metal protrusions that extend from the grouser shoe. In such a configuration, the overall thickness of the track pad equals the thickness of the track pad extending beyond the metal protrusions plus the thickness, or height, of the track shoe with metal protrusions. Once the track pad component is worn down to the edge of the metal protrusions, the track pad is no longer effective at preventing surface damage. Thus, the effective thickness of the track pad is the distance from the outer edge of the metal protrusions to the ground-engagement surface of the track pad. Additional track pad material molded between the metal protrusions of the grouser is wasted because the additional inter-projection material is not effective for preventing surface damage. In some crawler-type machines, for example a road surface milling machine, the height of the track from the road surface impacts the depth of cut. A thinner track pad reduces the height of the track from the travel surface and increases depth of cut. In many applications it is generally desirable to maximize depth of cut. However, it is also desirable to maximize track pad life. Track pad life is generally maximized by increasing the effective tread thickness. Thus, a track pad should maximize effective tread thickness and minimize overall track pad thickness to simultaneously optimize both depth of cut and track pad life. The prior art two-piece track pad configuration including metal protrusions extending from the track shoe has a relatively small effective tread thickness, leading to a sub-optimal track pad life. 
         [0010]    Thus, there is a need in the art for a replaceable track pad that prevents damage to a travel surface, provides adequate surface traction, allows convenient replacement of worn or damaged track pads without requiring cutting or replacement of track bolts, and provides optimal track pad life by maximizing effective tread thickness for a desired track elevation. There is also a need in the art for a mounting plate for securing a track pad to a track chain that is configured to be interchangeably attached to a standard track link and a master track link. There is also a need in the art for a method of refurbishing worn replaceable track pads for allowing re-use of the backing plate. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention includes a track pad mounting assembly for mounting onto a track link of a track chain on a tracked crawler-type machine. The track pad mounting assembly includes a replaceable track pad secured to a track link by a mounting plate. In one embodiment, the track pad can be replaced without removing the mounting plate. The track pad includes a tread made of a tread material. The tread material may include an elastic or resinous material, such as a rubber or a urethane. The tread is generally adapted for contacting the travel surface over which the tracked machine moves without causing excessive damage to the travel surface while providing traction. A rigid backing plate is secured to the tread. The backing plate can be attached to the mounting plate using track pad fasteners. In one embodiment, the track pad fasteners include tread bolts inserted through tread bolt clearance holes located in the mounting plate. The tread bolt clearance holes in the mounting plate can be positioned so the replaceable track pad can be mounted onto different size track chains. The backing plate includes a first pattern of track pad fastener connectors defined on the backing plate. In one embodiment, the track pad fastener connectors include threaded bores defined on the backing plate, so that each threaded bore may receive a track pad fastener for securing the backing plate to the mounting plate. In another embodiment, the track pad fastener connectors include threaded studs extending from the backing plate for receiving threaded nut fasteners. The backing plate includes a tread side attached to the tread and a mounting side shaped for attaching to the track pad attachment side of the mounting plate. The mounting side of the backing plate is substantially flat for attachment to a substantially flat mounting plate. The backing plate may include a chamfered region on a longitudinal edge for accommodating the structure of an adjacent track pad mounting assembly mounted on an adjacent track link. 
         [0012]    In another embodiment, the present invention includes a replaceable track pad apparatus for attachment with a plurality of track pad fasteners to a mounting plate that is attached to a track link of a track with a plurality of mounting plate fasteners. The track pad apparatus comprises a backing plate having a substantially flat mounting side and a tread side. The backing plate includes a first pattern of fastener connectors defined on the mounting side for threadedly engaging the plurality of track pad fasteners to attach the backing plate to the mounting plate. In one embodiment, a second pattern of clearance recesses is open to the mounting side for providing clearance for the mounting plate fasteners so that the mounting side of the backing plate can flatly engage the mounting plate. The track pad also comprises a tread having a substantially uninterrupted ground engagement surface, and having a back surface co-extensive with and attached to the tread side of the backing plate. 
         [0013]    In yet another embodiment, the backing plate of the track pad apparatus includes a first pattern of threaded bores open to the mounting side, each threaded bore being defined in the backing plate positioned entirely between the mounting side and the tread side of the backing plate. In another embodiment, the fastener connectors are threaded studs extending from the mounting side of the backing plate. 
         [0014]    In one embodiment, the mounting plate of the present invention includes a track surface and a mounting surface. Both surfaces of the mounting plate are substantially flat. The track surface of the mounting plate is generally mounted to a track link on the track chain using one or more mounting plate fasteners. On a tracked machine, one mounting plate is generally secured to each link in a track chain. The mounting plate may also include one or more extended flanges for restricting mud and other debris from entering the spacing between track pads during machine operation or when a machine is stationary. The extended flange may include one or more notched recesses for allowing the chain to bend inward, or back-bend, during movement. The mounting plate also includes an outer pattern of clearance holes for attaching a track pad to the backing plate. In one embodiment, the mounting plate further comprises an inner pattern of mounting plate fastener clearance holes defined therein, each mounting plate fastener clearance hole extending from the track surface to the mounting surface and shaped for receiving a mounting plate fastener for securing the mounting plate to the track link. In another embodiment, the mounting plate further comprises at least one mounting plate fastener hole defining a countersink region for accommodating a mounting plate fastener so that the mounting plate fastener does not extend beyond the mounting surface of the mounting plate when the mounting plate is attached to the track link. In yet another embodiment, the mounting plate further comprises a plurality of threaded studs extending from the mounting side for attaching the mounting plate to the track link. 
         [0015]    Another embodiment of the invention includes a track pad mounting assembly apparatus for mounting a replaceable track pad using track pad fasteners onto a mounting plate attached using mounting plate fasteners to a track link of a track on a crawler-type machine. The track pad mounting assembly apparatus comprises a mounting plate having a substantially flat track surface and a substantially flat mounting surface and including a substantially uniform mounting plate thickness extending between the track surface and the mounting surface. The mounting plate includes an outer pattern of track pad fastener clearance holes defined therein. The track pad mounting assembly apparatus also includes a replaceable track pad for attachment to the mounting surface of the mounting plate. The replaceable track pad of the track pad mounting assembly apparatus comprises a backing plate having a tread side and a substantially flat mounting side, the mounting side of the backing plate flatly engaging the mounting surface of the mounting plate. The replaceable track pad also includes a tread having a substantially uninterrupted ground engagement surface, and having a back surface co-extensive with and attached to the tread side of the backing plate. 
         [0016]    In yet another embodiment, the present invention includes a method of refurbishing a worn track pad by providing a worn track pad apparatus comprising a backing plate having a mounting side and a tread side. The backing plate includes a first pattern of fastener connectors to attach the backing plate to the mounting plate. The worn track pad apparatus includes a worn tread made of a tread material. The tread has a worn ground engaging surface, and has a back surface at least partially co-extensive with and attached to the tread side of the backing plate. The method further includes the steps of removing the worn tread material from the backing plate and attaching a new tread to the backing plate, the new tread having a substantially uninterrupted ground engagement surface, and the new tread having a back surface co-extensive with and attached to the tread side of the backing plate. 
         [0017]    In yet another embodiment, the present invention also includes a tread apparatus for use on a track pad for mounting to a track chain, the tread apparatus comprising a substantially rectangular block of tread material having a ground engaging surface and an opposing back surface, the surfaces being planar and the planes of the surfaces being substantially parallel to each other. The rectangular block includes a lateral edge oriented substantially perpendicular to the direction of track chain travel and a longitudinal edge oriented substantially parallel to the direction of track chain travel. The rectangular block of tread material also includes a perimeter surface extending between the ground engaging surface and the back surface and having an angle of orientation. The juncture of the perimeter surface and the ground engaging surface can be rounded at a first radius on the lateral edge of the rectangular block, and the juncture of the perimeter surface and the ground engaging surface can be rounded at a second radius on the longitudinal edge of the rectangular block, wherein the second radius is greater than the first radius. 
         [0018]    Numerous objects, features and advantages of the present invention will be readily apparent to those skilled in the art, upon a reading of the following disclosure, when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  illustrates a perspective view of a track pad mounting assembly in accordance with the present invention. 
           [0020]      FIG. 2A  illustrates a perspective view of a replaceable track pad in accordance with the present invention. 
           [0021]      FIG. 2B  illustrates a plan view of a backing plate in accordance with the present invention. 
           [0022]      FIG. 3A  illustrates a semi-exploded view of a track pad mounting assembly in accordance with the present invention. 
           [0023]      FIG. 3B  illustrates a semi-exploded view of the track pad mounting assembly of  FIG. 3A . 
           [0024]      FIG. 4  illustrates a semi-exploded view of the track pad mounting assembly of  FIG. 1 . 
           [0025]      FIG. 5  illustrates an exploded view of a replaceable track pad in accordance with the present invention. 
           [0026]      FIG. 6A  illustrates a perspective view of a plurality of track pad mounting assemblies mounted on a track chain in accordance with the present invention. 
           [0027]      FIG. 6B  illustrates a cross-section view of a track pad mounting assembly in accordance with the present invention. 
           [0028]      FIG. 7A  illustrates a plan view of a mounting plate in accordance with the present invention. 
           [0029]      FIG. 7B  illustrates a detail view of the mounting plate of  FIG. 7A . 
           [0030]      FIG. 7C  illustrates a plan view of a mounting plate in accordance with the present invention. 
           [0031]      FIG. 7D  illustrates a plan view of a mounting plate in accordance with the present invention. 
           [0032]      FIG. 8A  illustrates a side view of a mounting plate in accordance with the present invention. 
           [0033]      FIG. 8B  illustrates an elevation view of a track pad mounting assembly mounted on a track chain in accordance with the present invention. 
           [0034]      FIG. 9A  illustrates a detail perspective view of a backing plate in accordance with the present invention. 
           [0035]      FIG. 9B  illustrates a detail perspective view of a backing plate in accordance with the present invention. 
           [0036]      FIG. 9C  illustrates a perspective view of a backing plate in accordance with the present invention. 
           [0037]      FIG. 9D  illustrates an end view of a replaceable track pad in accordance with the present invention. 
           [0038]      FIG. 9E  illustrates a perspective view of a tread in accordance with the present invention. 
           [0039]      FIG. 9F  illustrates a perspective view of a backing plate in accordance with the present invention. 
           [0040]      FIG. 9G  illustrates a detail cross-section view of a replaceable track pad in accordance with the present invention. 
           [0041]      FIG. 10A  illustrates a top view of a tread in accordance with the present invention. 
           [0042]      FIG. 10B  illustrates a lateral side view of the tread of  FIG. 10A . 
           [0043]      FIG. 10C  illustrates a longitudinal end view of a replaceable track pad in accordance with the present invention. 
           [0044]      FIG. 11A  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0045]      FIG. 11B  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0046]      FIG. 11C  illustrates a perspective view of one embodiment of a backing plate in accordance with the present invention. 
           [0047]      FIG. 11D  illustrates a side view of one embodiment of a replaceable track pad in accordance with the present invention. 
           [0048]      FIG. 11E  illustrates a side view of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0049]      FIG. 12A  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0050]      FIG. 12B  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0051]      FIG. 13A  illustrates a perspective view of one embodiment of a mounting plate in accordance with the present invention. 
           [0052]      FIG. 13B  illustrates a side view of the mounting plate of  FIG. 13A . 
           [0053]      FIG. 13C  illustrates a perspective view of the mounting plate of  FIG. 13A . 
           [0054]      FIG. 13D  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0055]      FIG. 13E  illustrates a cross-section of one embodiment of a track pad mounting assembly in accordance with the present invention. 
           [0056]      FIG. 13F  illustrates a side view of a track pad mounting assembly apparatus in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0057]      FIG. 1  generally illustrates a track pad mounting assembly  10  for use on a tracked machine in accordance with the present invention. The track pad mounting assembly  10  includes a replaceable track pad  14  attached to a mounting plate  84 . The track pad mounting assembly  10  can be mounted to a track link  112  on a track chain of a tracked machine, as best seen in  FIGS. 6A and 8B . The track pad mounting assembly  10  is generally formed by attaching the replaceable track pad  14  to the mounting plate  84  using one or more track pad fasteners  106 , for example a tread bolt  262  shown in  FIG. 4 . The mounting plate  84  is generally secured to a track link  112  of a track chain using mounting plate fasteners  118 , for example by track bolts  254  shown in  FIG. 3A . In different embodiments, the mounting plate  84  may be attached to the track link  112  either before or after the track pad  14  is secured to the mounting plate  84 . Generally, in one embodiment, the mounting plate  84  does not have to be removed from the track link  112  for the track pad  14  to be replaced. 
         [0058]    Referring now to  FIG. 2A , the track pad  14  includes a tread  20  and a backing plate  50 . The tread  20  is generally adapted for supporting the tracked machine on a travel surface over which the tracked machine travels. The tread  20  may include tread material comprising a rubber, a urethane, a polymer, another resinous or elastic material, or mixtures thereof. In one embodiment, the tread comprises a tread material having a Shore-A durometer hardness of between about 60 and about 99. In one embodiment, the tread material has a Shore-A durometer hardness of about 75. The tread  20  includes a ground engagement surface  26  and a back surface  28 , shown in one embodiment in  FIG. 9E . In one embodiment, the back surface  28  is planar and is attached to the tread side  60  of the backing plate  50  using a chemical adhesive. In another embodiment, the back surface  28  is planar and is directly molded to the tread side  60  of the backing plate  50  using a molding process wherein the tread  20  is positioned in contact with the backing plate  50  and heat or pressure, or both, are applied to the tread  20  or backing plate  50 , or both, thereby causing the tread material to bond to and retain the shape of the tread side  60  of the backing plate  50 . In one embodiment, the tread side  60  of the backing plate  50  undergoes surface preparation prior to direct molding of the tread  20  onto the backing plate  50  to ensure a proper molding bond between the tread  20  and the backing plate  50 . 
         [0059]    Referring now to  FIG. 3A , in one embodiment, the ground engagement surface  26  is substantially uninterrupted and is substantially free from any openings. The tread  20  may also include a surface texture or tread pattern on the ground engagement surface  26 , not shown. In one embodiment, the tread  20  includes a first lateral edge  30  and a second lateral edge  32 , as seen in  FIG. 10A . In one embodiment, the first and second lateral edges  30 ,  32  are oriented substantially perpendicular to the direction of local track chain travel. Each lateral edge  30 ,  32  of the tread  20  may be rounded. In one embodiment, each rounded lateral edge  30 ,  32  of the tread  20  defines a lateral edge radius  176 ,  178 , as seen in  FIG. 10C . The first lateral edge radius  176  and the second lateral edge radius  178  may be equal. In one embodiment, each lateral edge radius  176 ,  178  are substantially between 0.25 and 0.5 inches. Each lateral edge radius  176 ,  178  of the tread  20  can be optimized for maximizing the longitudinal footprint of the tread  20 , thereby increasing stability of the tracked machine. The tread  20  also includes a first lateral surface  168  and a second lateral surface  170 , as seen in  FIG. 10A . In one embodiment, the first lateral surface  168  is oriented at a first angle  164  and the second lateral surface  170  is oriented at a second angle  166  relative to a vertical reference axis  36  oriented normal to the back surface  28  of the tread  20 , as seen in  FIG. 10C . In one embodiment, each angle  164 ,  166  extends substantially between five and twenty-five degrees. The ground engagement surface  26  of the tread  20  also includes a first longitudinal edge  44  and a second longitudinal edge  46 . In one embodiment, each longitudinal edge  44 ,  46  may be oriented substantially parallel to the direction of local track chain travel. Each longitudinal edge  44 ,  46  of the tread  20  may be rounded, as seen in  FIG. 10B . In one embodiment, the first longitudinal edge  44  defines a first longitudinal edge radius  172 , and the second longitudinal edge  46  defines a second longitudinal edge radius  174 . In one embodiment, each longitudinal edge radius  172 ,  174  are larger than each of the lateral edge radii  176 ,  178 . In one embodiment, each longitudinal edge radius  172 ,  174  are substantially equal to one inch. In other embodiments, the lateral and longitudinal edges of the tread  20  may be shaped in angled, rectangular, or various other orientations. In one embodiment the tread  20  is a substantially rectangular block including a perimeter surface. The ground engagement surface  26  and the back surface  28  of the tread may be planar, wherein the planes of each surface  26 ,  28  are substantially parallel to each other. In one embodiment, the perimeter surface of the tread  20  includes an angle of orientation, wherein the angle of orientation is substantially 90 degrees relative to the back surface  28 . In another embodiment, the juncture of the perimeter surface and the ground engagement surface  26  is rounded at a first radius on the lateral edge of the rectangular block and is rounded at a second radius on the longitudinal edge, wherein the second radius is greater than the first radius. 
         [0060]    Referring now to  FIG. 4 , the mounting plate  84  generally includes a track surface  86  for mounting onto a track link  112  and a mounting surface  88  for receiving a track pad  14 , as seen in  FIG. 3B . The mounting plate  84  is generally attached to a track link  112  using one or more mounting plate fasteners  118 , seen in  FIGS. 3A and 3B . Mounting plate fasteners  118  may have several different embodiments in accordance with the present invention. Referring to  FIG. 3A , one embodiment of a mounting plate  84  using mounting plate fasteners  118  to secure the mounting plate  84  to a track link  112  is shown. In this embodiment, the mounting plate fasteners  118  are track bolts  254 . In this embodiment, each mounting plate fastener  118  is inserted through a mounting plate fastener clearance hole  90  located in the mounting plate  84 . The mounting plate fastener clearance holes  90  are arranged in an inner pattern  220 , seen in  FIG. 7A . In one embodiment, each mounting plate fastener clearance hole  90  may have a circular or non-circular shape for accommodating a track bolt  254 . 
         [0061]    A track chain generally includes a plurality of standard track links and at least one master track link. The master track link allows the track chain to be separated for installation or removal from the tracked machine. Standard track links and master track links typically include different hole patterns for receiving mounting plate fasteners  118 . Also, standard track bolts and master track bolts may have different bolt diameters. In one embodiment, shown in  FIG. 7A , the inner pattern  220  of mounting plate fastener clearance holes  90  on the mounting plate  84  is adapted for interchangeably securing a mounting plate  84  onto a standard track link or a master track link by interchangeably accepting standard or master track bolts. In one embodiment, shown in  FIG. 7B , a mounting plate fastener clearance hole  90  of a mounting plate  84  includes a standard track bolt clearance hole  92  overlapping with a non-concentric master track bolt clearance hole  94 . In other embodiments, the standard and master track bolt clearance holes  92 ,  94  of the inner pattern  220  form independent, non-overlapping holes, as seen in  FIG. 7C . 
         [0062]    In another embodiment, show in  FIGS. 13A ,  13 B, and  13 C, the mounting plate includes a plurality of threaded studs  104  extending from the track surface  86 . In this embodiment, mounting plate fasteners  118  comprise threaded track nuts  256  that engage the threaded studs  104  to secure the mounting plate  84  to the track link, as seen in  FIGS. 6B ,  13 D and  13 F. Other embodiments in accordance with the present invention include various other types of mounting plate fasteners  118  not shown for securing the mounting plate  84  to the track link  112 . 
         [0063]    Referring again to  FIG. 3A , in one embodiment the mounting plate fasteners  118  are track bolts  254 . In this embodiment, each track bolt  254  includes a track bolt head  252 , as seen in  FIG. 3B . In the one embodiment shown in  FIG. 3B , each track bolt head  252  protrudes above the mounting surface  88  of the mounting plate  84  when the mounting plate  84  is secured to the track link  112 . Additionally, a washer  212  may be positioned between the track bolt head  252  and the mounting surface  88  of the mounting plate  84 . In other embodiments, a mounting plate fastener clearance hole  90  may include an elongated slot, not shown. 
         [0064]    In the embodiment shown in  FIG. 3B , a replaceable track pad  14  can be attached to the mounting surface  88  of the mounting plate  84 . The replaceable track pad  14  includes a backing plate  50  and a tread  20 . The backing plate  50  includes a mounting side  58  for engaging the mounting surface  88  of the mounting plate  84 , seen in  FIG. 4 . The mounting side  58  of the backing plate  50  is substantially flat for flatly engaging the mounting surface  88  of the mounting plate  84 . Referring now to  FIG. 3B  and  FIG. 4  simultaneously, the backing plate  50  may, in one embodiment, include one or more clearance recesses  82 , each clearance recess  82  being shaped for accommodating a track bolt head  252  when the backing plate  50  is attached to the mounting plate  84 . Each clearance recess  82  may extend only partially through the backing plate  50 , or may extend completely through the backing plate  50  as seen in  FIG. 5 . In one embodiment, the clearance recesses  82  form a second pattern  80  on the backing plate  50 , shown in  FIG. 2B . In one embodiment, the second pattern  80  is substantially rectangular. The clearance recesses  82  are generally open to the mounting side  58  of the backing plate  50 . 
         [0065]    In another embodiment, no clearance recesses  82  are present on the backing plate  50 . In one embodiment, shown in  FIGS. 12A and 12B , the backing plate  50  does not include clearance recesses  82  for accommodating track bolt heads  252 . In this embodiment, the mounting side  58  of the backing plate  50  can flatly engage the mounting surface  88  of the mounting plate  84  because each mounting plate fastener clearance hole  90  includes a countersunk region  120 . In this embodiment, each track bolt head  252  fits in the countersunk region  120  so the backing plate  50  flatly engages the mounting plate  84 . In one embodiment, a mounting plate  84  having mounting plate fastener clearance holes  90  with countersunk regions  120  can be used to mount a backing plate  50  having threaded bores  242  as fastener connectors  64 , shown in  FIG. 12B . In another embodiment, a mounting plate  84  having mounting plate fastener clearance holes  90  with countersunk regions  120  can be mounted to a backing plate  50  having track pad mounting studs  76  as fastener connectors  64 , shown in  FIG. 12B . In other embodiments not show, both a countersunk regions  120  and clearance recesses  82  can be used to allow the backing plate  50  to flatly engage a mounting plate  84 . 
         [0066]    Referring again to  FIG. 4 , in one embodiment in accordance with the present invention, the replaceable track pad  14  can be secured to a mounting plate  84  using track pad fasteners  106 . Each track pad fastener  106  generally engages a fastener connector  64  located on the backing plate  50  for securing the track pad  14  to the mounting plate  84 . 
         [0067]    In the embodiment shown in  FIG. 4 , each track pad fastener  106  comprises a tread bolt  262 . Each tread bolt  262  may include a tread bolt head  264 . In one embodiment, each tread bolt  262  is inserted through a track pad fastener clearance hole  108  in the mounting plate  84 . Also shown in  FIG. 4 , one embodiment of a fastener connector  64  includes a threaded bore  242 . Each threaded bore  242  is open to the mounting side  58  of the backing plate for receiving a track pad fastener  106 . Also, each threaded bore  242  is positioned entirely between the mounting side  58  and the tread side  60  of the backing plate  50 , as seen in  FIG. 11A . The threaded bore  242  extends into the backing plate  50  from the mounting side  58 . The threaded bore  242  includes a threaded bore depth  240 . The threaded bore depth  240  may be less than the backing plate thickness so that the threaded bore  242  does not extend completely through the backing plate  50 , but rather forms a blind threaded bore  242  extending into the backing plate  50  from the mounting side  58 , as seen in  FIG. 11A . In another embodiment, shown in  FIG. 5 , a threaded bore  242  extends completely through the backing plate  50  to form a void extending from the mounting side  58  of the backing plate  50  to the tread side  60  of the backing plate  50 . In one embodiment, only part of the threaded bore  242  is threaded. As seen in  FIG. 11A , in one embodiment, the threaded bore  242  is machined into the backing plate  50 . In one embodiment, both blind and through threaded bores  242  are included on the same backing plate  50 , not shown. 
         [0068]    In another embodiment, shown in  FIGS. 11B and 11C , the fastener connector  64  defined on the mounting side  58  of the backing plate  50  comprises one or more track pad mounting studs  76  protruding from the mounting side  58 . As seen in  FIG. 11D , each track pad mounting stud  76  includes a threaded region for engaging a track pad fastener  106 , as seen in  FIG. 11E . In the embodiment shown in  FIG. 11E , each track pad fastener  106  is a threaded nut  244 . In the embodiments shown in  FIGS. 11C ,  11 D and  11 E, each track pad mounting stud  76  can extend through a clearance hole  108  on the mounting plate  84  to secure the replaceable track pad  14  to the mounting plate  84 . 
         [0069]    In one embodiment, shown in  FIG. 2B , the first pattern  186  of fastener connectors  64  is rectangular. The first pattern  186  includes a first pattern longitudinal dimension  190  and a first pattern lateral dimension  192 . In one embodiment, the first pattern longitudinal dimension  190  ranges from about 1.5 to about 4.5 inches on center and the first pattern lateral dimension  192  ranges from about 7 to about 10 inches on center. In another embodiment, the first pattern longitudinal dimension  190  is about 3.0 inches on center and the first pattern lateral dimension  192  is about 8.5 inches on center. Each fastener connector  64  is aligned coaxially with a clearance hole  108  located on the mounting plate  84 , as seen in  FIG. 4 . Generally, in one embodiment each fastener connector  64  may be disengaged from the track pad assembly  10  to allow removal of the track pad  14  from the mounting plate  84  without removing a mounting plate fastener  118 . 
         [0070]    Referring now to  FIG. 9A , a detail view of a section of a backing plate  50  in accordance with the present invention is generally shown. In one embodiment, the backing plate  50  includes a tread-binding recess  142  defined in the tread side  60  of the backing plate  50 . In one embodiment, the tread-binding recess  142  includes a rectangular cross-section, as seen in  FIG. 9A . Other embodiments may include a tread-binding recess  142  having various other cross-sectional shapes. In one embodiment, the tread side  60  of the backing plate  50  includes a dovetail groove  143 , as seen in  FIG. 9B . In one embodiment, multiple dovetail grooves  143  are located on the backing plate  50 , as seen in  FIG. 9C . A tread-binding recess  142 , shown in  FIG. 9A  or a dovetail groove shown in  FIG. 9B  may extend along either the lateral or longitudinal direction of the backing plate  50  or may be angled across the tread side  60  of the backing plate  50 . Referring now to  FIG. 9D , a track pad  14  in accordance with the present invention is shown. The track pad  14  includes a tread  20  secured to a backing plate  50 . The tread  20  extends into and is coextensive with a plurality of dovetail grooves  143 , as seen in  FIG. 9D . In one embodiment, the tread  20  includes one or more extended regions  148 , each extended region  148  shaped to fit in a tread-binding recess  142  or dovetailed groove  143  on the backing plate  50 . In one embodiment, each extended region  148  is molded into a tread-binding recess  142  or dovetail groove  143 , thereby filling the tread-binding recess  142  or dovetail groove  143  with tread material. In one embodiment, each tread-binding recess  142  is cylindrical, as seen in  FIG. 9F . In this embodiment, the tread  20  includes extended regions  148  shaped for engaging the cylindrical tread-binding recesses  142 , as seen in  FIG. 9E . In another embodiment, a cylindrical tread-binding recess  142  may be threaded, as seen in  FIG. 9G . 
         [0071]    Referring to  FIG. 7C , in one embodiment, one replaceable track pad  14  can be used with a variety of similar track chain sizes based on both the outer pattern  100  of track pad clearance holes  102  on the mounting plate  84  and the dimensions of the first pattern  186  of fastener connectors  64  on the backing plate  50 , also seen in  FIG. 2B . In one embodiment, the lateral dimension  192  of the first pattern  186  is defined by the smallest distance that will fit outside the width of the widest track chain to be accommodated. In one embodiment, the longitudinal dimension  190  of the first pattern  186  is defined by the longest distance that will fit between link pins of the smallest track link  112  and allow for centering the backing plate  50  on the track link  112 , as seen in  FIG. 8B . 
         [0072]    In one embodiment, the mounting plate  84  includes one or more extended flanges  98  protruding from a lateral edge  96  of the mounting plate  84 , as seen in  FIG. 7D . The extended flange  98  of the mounting plate  84  may include one or more notched recesses  136 . In one embodiment, each notched recess  136  is shaped for accommodating a track chain link during movement of the track chain around an idler or during back-bending movement of the track chain. In one embodiment, the extended flange  98  of the mounting plate  84  may restrict mud and other debris from entering the regions between adjacent track pads during movement of the tracked machine or while the tracked machine is at rest, as is seen generally in  FIG. 6A . 
         [0073]    Referring now to  FIG. 8A , in one embodiment, the mounting plate  84  is first attached to a track link  112 . Next, the track pad  14 , including the backing plate  50  and the tread  20 , is attached to the mounting plate  84  to form a track pad mounting assembly  10 , seen in  FIG. 8B . The mounting plate  84  may include a first extended flange  98 . A second track pad assembly  210  is attached to an adjacent track link  112 . In one embodiment, a second extended flange  216  extends from the second mounting plate  214 , defining a gap  218  between the first and second mounting plates  84 ,  214 . In one embodiment, the backing plate  50  may include a chamfered region  56  to allow clearance of the second extended flange  216  on the second mounting plate  214  during movement of the track links  112  around a curved region on the track chain drive path or during back bending of the track chain. 
         [0074]    Thus, although there have been described particular embodiments of the present invention of a new and useful replaceable track pad, track pad mounting assembly, tread apparatus, mounting plate, and method for refurbishing a worn track pad, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.