Abstract:
A master link for a track chain assembly is provided. The master link includes a body portion having first and second spaced apart apertures extending therethough. A gap extends radially outward from one of the first and second apertures. At least one fastener operatively engages an aperture that extends through the gap. As the fastener is secured the width of the gap is reduced thereby reducing the diameter of one of the first and second apertures providing a clamping force.

Description:
TECHNICAL FIELD 
     The invention relates generally to a track chain for a work machine and, more particularly, to a master link for a track chain assembly. 
     BACKGROUND 
     Track laying work machines utilize endless track chains to propel the work machines over the terrain during operation. The track chains typically use a master connection or master link to facilitate the breaking of the track chain to permit its assembly and removal for repair and servicing. The master link is typically a two-piece or split master link with two half-links. In sealed and lubricated track assemblies, this is especially important so as not to damage or disturb any of the sealed joints during assembly and any subsequent repair. 
     The two half-links have any of a number of interlocking configurations positioned on mating surfaces of each half-link. The interlocking configurations are disposed either along a vertical or a horizontal plane positioned relative to two adjacent track pins or bushings. The two half-links are coupled together by one or more fasteners that are inserted through one half-link and threaded into the other half-link. Often the fasteners are positioned in apertures entering through a mounting surface that receives one of the track shoes. Such bolts are positioned through the track shoe in the same manner as non-master links and are utilized to fasten the track shoe to the link, as well as to retain the half-links together. 
     Past designs have required two separate manufacturing processes, such as forgings, to create each of the half-links. This forces a manufacturer to have two additional forging operations at much lower production rates than the non-master links. At a minimum, manufacturing the two half-links requires an additional cutting step, such as electrical discharge machining, to separate the half-links and form the mating surfaces. Another problem associated with the use of the prior split master links, is encountered during the attachment of the track shoe to the half-links so as to join the ends of the track chain. This problem results from the necessity to achieve and maintain alignment between the boltholes in the half-links, while placing the track shoe onto the link. 
     U.S. Pat. No. 4,636,014 for a “Master Track Chain Connection for Crawler Tractors”, issued Jan. 13, 1987 to Dennison et al., and assigned to the assignee of the present application, solves part of the problem. In this patent the half-links are secured together by fasteners and then independently securing the track shoe to the split master link. 
     The present invention is directed to overcoming one or more of the problems as set forth above. 
     SUMMARY OF THE INVENTION 
     A master link for a track chain assembly is provided. The master link includes a body portion with a first side, a second side positioned opposite the first side and a shoe surface positioned opposite a rail surface. A first aperture extends through the body portion. Spaced from the first aperture is a second aperture that extends through the body portion. A gap is positioned between the first aperture and the second aperture and extends through the body portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top elevational view of a portion of a track chain assembly; 
     FIG. 2 is a side elevational view of a master link from FIG. 1; 
     FIG. 3 is a longitudinal cross sectional view of a cartridge assembly of the track chain shown in FIG. 1; 
     FIG. 4 is a top elevational view of an alternate embodiment of a portion of the track chain assembly; and 
     FIG. 5 is a side elevational view of a master link from FIG.  4 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, a track chain assembly  10 , only a portion of which is shown, includes a plurality of subassemblies  12 . Each subassembly  12  includes a cartridge assembly  14 , an inner and outer link  16 , 18  and a track shoe  20  connected to the outer and inner links  16 , 18 . A number of subassemblies  12  are mechanically coupled to adjacent subassemblies  12  so that when an appropriate number of these sub assemblies  12  are connected together, the track chain assembly  10  is formed. The track chain assembly  10  has a predetermined length for a given application with opposite ends that are capable of being connected together to form a closed loop. The closed loop is formed by mechanically coupling the opposite ends together with an outer and inner master link  22 , 24 . 
     As shown in FIG. 3, cartridge assembly  14  includes a track pin  30 , a bushing  32 , first and second bearing members  34 , 36 , and first and second collars  38 , 40 . The track pin  30  defines a central longitudinal axis  42  and has a bore  44  concentrically positioned therethrough. A cross bore  46  extends from an outer surface  48  of the track pin  30  inward towards the bore  44  normal to the central longitudinal axis  42 . Bushing  32  has an end face  50 , an outer surface  54  and a passage  56  concentrically positioned in respect to the outer surface  54 . It should be appreciated that the first bearing member  34  and first collar  38  are substantially identical to the second bearing member  36  and second collar  40 , therefore only first bearing member  34  and first collar  38 , respectively will be described in detail herein. 
     First bearing member  34  includes a first end portion  60 , a second end portion  61 , a bore  62  and an outer surface  63 . The first end portion  60  extends radially outward away from the bore  62  and forms an abutting surface. A seal groove  64  is positioned in the second end portion  61  such that seal groove  64  is concentric with central longitudinal axis  42 . The seal groove  64  has an outer wall segment  66  and an inner wall segment  68 . Wall segment  66  is tapered outwardly with respect to the central longitudinal axis  42  at a predetermined angle, preferably the predetermined angle is about 5°. In a similar manner inner wall segment  68  is tapered inwardly with respect to central longitudinal axis  42 . It should also be recognized that the inner wall segment  68  extends axially beyond the outer wall segment  66 , the benefits of which will be described in more detail below. 
     Still referring to FIG. 3, a seal arrangement  70  is shown positioned in the seal grove  64 . Seal arrangement  70  includes an annular load ring  72  and a seal member  74 . Load ring  72  and seal member  74  are positioned in seal groove  64  so that load ring  72  urges seal member  74  in an axial direction outward from the seal groove  64 . Having outer wall segment  66  angled away from the central longitudinal axis  42  in the above described manner facilitates the insertion of load ring  72  and seal member  74  into seal groove  64 . In particular, the predetermined angle of outer wall segment  66  enhances the installation capability of machinery utilized to insert seal arrangement  70  into seal groove  64 . 
     First collar  38  includes a first end portion  80 , a second end portion  81 , a bore  82 , and an outer surface  83 . The first end portion  80  extends outward from the bore  82  and forms an outer radial surface. A seal groove  84  is positioned in the second end portion  81  such that seal groove  84  is concentric with central axis  42 . The seal groove  84  has an outer wall segment  86 . Wall segment  86  is tapered outwardly with respect to central longitudinal axis  42  at a predetermined angle similar to the outer wall segment  66  of the first bearing member  34 . Again preferably, the predetermined angle is about 5°. 
     Still referring to FIG. 3, a seal arrangement  90  and an annular axial preload member  92  are shown positioned in the seal grove  84 . Seal arrangement  90  includes an annular load ring  94  and a seal member  96 . Load ring  94  and seal member  96  are positioned in seal groove  84  so that load ring  94  urges seal member  96  in an axial direction outward from the seal groove  84 . 
     Although the example disclosed herein has a seal groove  64  positioned in the bearing members  34 , 36  and a seal groove  84  positioned in the collars  38 , 40 , it is also contemplated that alternative positions for the seal grooves  64 , 84  could be used. For example, a seal groove may be positioned in each end face  50  of the track bushing  32 , with each of the bearing members  34 , 36  flipped end for end and the collars  38 , 40  would be void of a seal groove  84 . Additionally, the bearing members  34 , 36  may not have seal grooves and instead seal grooves only placed in the collars  38 , 40  and each end face  60  of the track bushing  32  for comparable capability, function and results. 
     A pair of plugs  100  are positioned in the bore  44  of the track pin  30  forming a fluid reservoir  102  in the bore  44  thereof. The pair of plugs  100  sealably prevents a fluid, such as lubricating oil, from leaking from the bore  44 . In use, fluid disposed within fluid reservoir  102  of the cartridge assembly  14 , is in fluid communication with and advanced through cross bore  46  to the outer surface  48  of track pin  30 . Once disposed on outer surface  48 , the fluid facilitates the rotation of first and second bearing members  34 , 36 , and bushing  32  relative to track pin  30 . Retention of the fluid within the cartridge assembly is assisted by seal arrangements  70 , 90 , the first ends  60  of bearing members  34 , 36 , and the end faces  50  of the bushing  32  while keeping debris out (e.g. sand, dirt, etc). 
     Referring now to FIGS. 1 and 2, the inner and outer link  1618  and the inner and outer master links  22 , 24  in this embodiment are shown as being straight links each having a first end portion  111  and a second end portion  113 . The inner master link  22  is an exact duplicate of the outer master link  24  therefore only inner master link  22  will be described in detail and the same elements will be represented by like numbers. It should be recognized that the terms outer and inner, in reference to links  16 , 18  and master links  22 , 24 , in this example are used merely as descriptors for the orientation shown in the figures. Other terms such left, right and first, second could be interchangeably used as well. 
     Inner link  22  includes a body portion  104  with a first side  106  and a second side  108  spaced opposite the first side  106 . A first aperture  110  extends through the first end portion  111 . A second aperture  112  extends through the second end portion  113 . Body portion  104  also includes a rail surface  114  and a shoe surface  116 . An aperture  120  is positioned on both sides of and a predetermined distance from a central vertical axis  122 . It should be appreciated that each aperture  120  is laterally centered with respect to the widest portion of body portion  104 . A fastener  124  is positioned in each of the aperture  120  and utilized to secure track shoe  20  to shoe surface  116  of inner master link  22 . Additionally, a gap  126  is formed between the first aperture  110  and the second aperture  112  extending through the body portion  104  from the first side  106  to the second side  108 . As the fasteners  124  are tightened to secure the track shoe  20  to the inner master link  22  the width of the gap  126  is reduced or pulled together, effectively reducing the diameter of the first and second aperture  110 , 112 . Thus, the first aperture  110  and the second aperture  112  are secured to the collars  38 , 40  of adjacent cartridge assemblies  14 . 
     Referring now to FIGS. 4 and 5, an alternate embodiment of the track chain assembly  10 , only a portion of which is shown, with like elements of the first embodiment being represented by a prime designation. The track chain assembly  10 ′ includes a plurality of subassemblies  12 ′. Each subassembly  12 ′ includes a cartridge assembly  14 ′, an inner and outer link  16 ′, 18 ′ and a track shoe  20 ′ connected to the inner and outer links  16 ′, 18 ′. An inner and outer master link  22 ′, 24 ′ is used to connect opposite ends of the track chain assembly  10 ′ to form a closed loop. 
     The inner and outer links  16 ′, 18 ′ and the inner and outer master links  22 ′, 24 ′, in this embodiment, are offset links each being a mirror image of the other, the inner master link  22 ′ therefore will be described in detail. Inner link  22 ′ includes a body portion  104 ′ having a first side  106 ′, a second side  108 ′, a first aperture  110 ′, a second aperture  112 ′, a rail surface  114 ′, and a shoe surface  116 ′. Body member  104 ′ also has an exit hole  130  interposed between first aperture  110 ′ and second aperture  112 ′. A bolthole  120 ′ is positioned on either side of a vertical axis  122 ′. Apertures  120 ′ are positioned at a predetermined angle with respect to the central vertical axis  122 ′. A fastener  124 ′ is positioned in each of the apertures  120 ′ and utilized to secure track shoe  20 ′ to shoe surface  116 ′ of inner master link  22 ′. Additionally, a gap  126 ′ is positioned between the first aperture  110 ′ and the second aperture  112 ′ and extends through the exit hole  130  from the first side  106 ′ to the second side  108 ′. As the fasteners  124 ′ are tightened to secure the track shoe  20 ′ to the inner and outer master links  22 ′, 24 ′ the diameter of the first and second aperture  110 ′, 112 ′ is effectively reduced. Thus, the first apertures  110 ′ are secured to bearing members  34 ′, 36 ′ of one cartridge assembly  14 ′ and the second apertures  112 ′ are secured to the collars  38 ′, 40 ′ of an adjacent cartridge assembly  14 ′. In this embodiment, however, the inner and outer links  16 ′, 18 ′ and the inner and outer master links  22 ′, 24 ′ are offset links. Therefore, this application would require a pair of inner master links  22 ′ and a pair of outer master links  24 ′. In this manner, the first aperture  110 ′ of an inner and outer master link  22 ′, 24 ′ is secured to the bearing members  34 ′, 36 ′ of one cartridge assembly  14 ′ and the second aperture  112 ′ of an adjacent inner and outer master link  22 ′, 24 ′ is secured to the collars  38 ′, 40 ′ of the same cartridge assembly  14 ′. 
     Industrial Applicability 
     The track chain assembly  10 , 10 ′ is assembled and operates as follows. The track pin  30  is inserted into passageway  56  of bushing  32  such that bushing  32  can rotate relative to track pin  30 . Seal arrangements  70  are inserted into the seal groove  64  of the bearing members  34 , 36 . The bearing members  34 , 36  are positioned relative to track pin  28  and bushing  32  such that a portion of track pin  30  extends through bore  62 . The seal groove  64  of each bearing member  34 , 36  is positioned in an adjacent relationship to each end face  50  of bushing  32 . This positions the seal member  74  to be urged against end face  50  of bushing  32 . It should be appreciated that bearing members  34 , 36  can rotate about the track pin  30  in an oscillatory manner around axis  42  relative to both bushing  32  and track pin  30 . 
     Annular axial preload members  92  are positioned about the outer surface  48  of the track pin  30  adjacent to the first end portion  60  of the bearing members  34 , 36 . Seal arrangements  70  are inserted into the seal groove  84  of the collars  38 , 40 . The collars  38 , 40  are positioned relative to track pin  30  and bearing member  34 , 36  so that a portion of track pin  30  extends into bore  82  with the second end portion  81  of collars  38 , 40  in an adjacent relationship to the first end portion  60  of bearing members  34 , 36 . This positions the seal member  94  to be urged against the first end portion  60  of each bearing member  34 , 36 . The annular axial preload member  92  controls the distance between the collars  38 , 40  and bearing members  34 , 36 . In a similar manner, the inner wall segment  68  controls the distance that the bearing members  34 , 36  can be moved axially inward toward the bushing  32 . 
     The collars  38 , 40  are fixed relative to track pin  30  so that collars  38 , 40  will not rotate or move axially relative to track pin  30 . For example, collars  38 , 40  can be press fit or laser welded onto the track pin  30  or connected in any other suitable manner such as adhesive or chemical bonding. Attaching collars  38 , 40  to track pin  30  in this manner helps control end play of track chain assembly  10 , 10 ′. 
     As previously mentioned, referring to FIG. 1, each subassembly  12  includes a cartridge assembly  14 , an inner link  16 , an outer link  18  and a track shoe  20  fastened to the shoe surface  116  of the inner and outer links  16 , 18 . Specifically, one subassembly is completed by positioning inner link  16  relative to cartridge assembly  14  such that bearing member  34  of cartridge assembly  14  is located within aperture  112  of inner link  16 , bearing member  36  of cartridge assembly  14  is located within aperture  112  of outer link  18  forming a subassembly  12 . The next adjacent subassembly  12  would be an outer subassembly  12 , comprised of identical components that has the inner link  16  positioned relative to cartridge assembly  14  so that collar  38  is located within aperture  110  of inner link  16  and collar  40  is located within aperture  110  of outer link  18 . It should be appreciated that bearing members  34 , 36  and collars  38 , 40  are press fit into apertures  110  and  112  of the inner and outer links  16 , 18 . The outer subassembly  12  is fixed relative to collars  38 , 40  and the track pin  30 , with an inner subassembly  12  fixed relative to bearing members  34 , 36 . This allows the inner subassembly  12  to move relative to the track pin  30  and bushing  32 , while the outer subassembly  12  is fixed relative to the track pin  30  but free to pivot relative to the bearing members  34 , 36  and the track bushing  32 . 
     This alternating connection of inner and outer assemblies is continued until an appropriate number of adjacent sub assemblies  12  are connected together to form a track chain assembly  10  of a given length. Then an inner and outer master link  22 , 24  are slid over the collars  38 , 40  of two adjacent subassemblies and the last track shoe  20  is fastened in place. By tightening fasteners  124  the width of the gap  126  is reduced or pulled together effectively reducing the diameter of the first and second aperture  110 , 112 , securing the first and second apertures  110 , 112  to the collars  38 , 40  of the two adjacent subassemblies  12 . 
     In the alternate embodiment shown in FIGS. 3 and 4, each subassembly  12 ′ includes a cartridge assembly  14 ′, an inner link  16 ′, an outer link  18 ′ and a track shoe  20 ′ fastened to the shoe surface  116 ′ of the inner and outer links  16 ′, 18 ′. Specifically, one subassembly is completed by positioning inner link  16 ′ relative to cartridge assembly  14 ′ such that bearing member  34 ′ of cartridge assembly  14 ′ is located within aperture  110  ′ of inner link  16 ′, bearing member  36 ′ of cartridge assembly  14 ′ is located within aperture  110 ′ of outer link  18 ′ forming a sub assembly  12 ′. Two adjacent subassemblies  12 ′ are secured together by placing collar  38 ′ within aperture  112 ′ of the inner link  16 ′ and collar  40 ′ within aperture  112 ′ of outer link  18 ′. It should be appreciated that bearing members  34 ′, 36 ′ are press fit into apertures  110 ′ and collars  38 ′, 40 ′ are press fit into apertures  112 ′ of the inner and outer links  16 ′, 18 ′. The first end portion  111 ′ of each inner and outer link  16 ′, 18 ′ is fixed relative to bearing members  34 ′, 36 ′ and the second end portion  113 ′ of the inner and outer links  16 ′, 18 ′ fixed relative to collars  38 ′, 40 ′ and the track pin  30 ′ of an adjacent an subassembly  12 ′. This allows the first end portion  111 ′ of inner and outer links  16 ′, 18 ′ to move relative to the track pin  30 ′ and bushing  32 ′, while the second end portion  113 ′ is fixed relative to the track pin  30 ′ but free to pivot relative to the bearing members  34 ′, 36 ′ and the track bushing  32 ′ of an adjacent subassembly  12 ′. 
     The connection of subassemblies  12 ′ is continued until an appropriate number of adjacent subassemblies  12 ′ are connected together to form a track chain assembly  10 ′ of a given length. To connect the ends of the track chain assembly  10 ′ of this embodiment together, two inner and outer master links  22 ′, 24 ′ are required. Apertures  110 ′ of the first end portion  111 ′ of an inner and an outer master link  22 ′, 24 ′ are positioned around the bearing member  34 ′, 36 ′ of a cartridge assembly  14 ′. Apertures  112 ′ of the second end portion  113 ′ of an adjacent set of inner and outer master links  22 ′, 24 ′ are positioned around collars  38 ′, 40 ′ of the same cartridge assembly  14 ′. The last two track shoes  20 ′ are then fastened to the shoe surface  116 ′ of the two adjacent sets of inner and outer master links  22 ′, 24 ′. By tightening fasteners  124 ′ the width of the gap  126 ′ is reduced or pulled together effectively reducing the diameter of the first and second apertures  110 ′, 112 ′, securing the first apertures  110 ′ to the bearing members  34 ′, 36 ′ and the second apertures  112 ′ to the collars  38 ′, 40 ′ of the same cartridge assembly  14 ′. Disconnecting the ends of the track chain assembly  10 ′ of this embodiment requires loosening the fasteners  124 ′ of the adjacent sets of inner and outer master links  22 ′, 24 ′, this allows a single cartridge assembly  14 ′ to be removed and the ends of the track chain assembly  10 ′ to be separated.