Patent Publication Number: US-2023150593-A1

Title: Idler for undercarriage system having sacrificial wear rings and wear ring for same

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to an idler for an undercarriage system in a track-type machine, and more particularly to an idler having sacrificial wear rings seated in ring channels in an outer rim surface of the idler. 
     BACKGROUND 
     Track-type machines are used throughout the world in a great many different off-highway applications. In a typical configuration each of two ground-engaging tracks in a machine includes an endless loop of track links in two parallel track chains extending about rotating elements including one or more idlers and a drive sprocket. Track shoes, commonly equipped with grousers, are attached to the track chains and contact a substrate to propel and steer the machine. In rough, uneven, rocky, steep, and/or slippery field service environments track-type machines are indispensable for many activities. 
     Due to the nature of substrate materials and service conditions, wear between and among components in an undercarriage system of a track-type machine can be relatively severe. In view of the wear phenomena, and the necessity for generally robust and sophisticated track and undercarriage construction, inspection, servicing, and replacement of undercarriage parts is routine. As noted above, one or more idlers are typically provided which rotate passively in contact with the track as the track advances during service. The idler is commonly arranged to rotate in contact with track rails formed by the parallel chains of track links. Over the course of time material of the contacting components tends to be worn away, eventually requiring replacement of the idler. 
     Various proposals are known for reuse, repair, and otherwise extending idler service life. In commonly owned U.S. Pat. No. 8,770,672 to Yelistratov, an undercarriage system includes an idler having a compound annular rim capping a hub and formed of a relatively higher hardness metallic material. The use of relatively higher hardness metallic material apparently is intended to extend idler service life, and the disclosed techniques can enable replacement of worn-away material in a used idler, for example. While Yelistratov may have various applications and advantages, there is always room for improvement and development of alternative strategies. 
     SUMMARY 
     In one aspect, an idler for an undercarriage system in a track-type machine includes an idler rim having an outer rim surface extending circumferentially around an idler axis of rotation and forming a centrally located guide flange, and an inner rim surface. The outer rim surface forms a first ring channel upon a first axial side of the centrally located guide flange and a second ring channel upon a second axial side of the centrally located guide flange. Each of the first ring channel and the second ring channel extends circumferentially and continuously around the idler axis of rotation. The idler further includes a first sacrificial wear ring seated in the first ring channel, and a second sacrificial wear ring seated in the second ring channel. 
     In another aspect, an idler for an undercarriage system in a track-type machine includes an idler rim having an outer rim surface extending circumferentially around an idler axis of rotation and forming a centrally located guide flange, an inner rim surface, a first axial end face, and a second axial end face. The outer rim surface further forms a first ring channel and a second ring channel structured to receive, respectively, a first sacrificial wear ring and a second sacrificial wear ring. The first ring channel extends circumferentially and continuously around the idler axis of rotation and includes an inboard channel wall spaced axially outward of the centrally located guide flange, and an outboard channel wall spaced axially inward of the first axial end face. The second ring channel extends circumferentially and continuously around the idler axis of rotation and includes an inboard channel wall spaced axially outward of the centrally located guide flange, and an outboard channel wall spaced axially inward of the second axial end face. 
     In still another aspect, a sacrificial wear ring for an idler in an undercarriage system includes a one-piece metallic ring body including an outer link-contact surface and an inner idler-contact surface each extending circumferentially around a ring center axis between a first ring body end and a second ring body end. The one-piece metallic ring body further includes a first ring axial side surface and a second ring axial side surface oriented normal to the ring center axis and extending from the outer link-contact surface to the inner idler-contact surface. The one-piece metallic ring body is elastically deformable between an installation configuration where a split gap extends in a circumferential direction between the first ring body end and the second ring body end, and a service configuration where the first ring body end and the second ring body end are in abutment and the split gap is closed. A ring width dimension (RW) is defined between the first ring axial side surface and the second ring axial side surface, and a ring thickness dimension (RT) is defined between the outer link-contact surface and the inner idler-contact surface. A ratio of RW to RT is from 2.5 to 5.0. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side diagrammatic view of a portion of an undercarriage system in a track-type machine; 
         FIG.  2    is a diagrammatic view of an idler, according to one embodiment; 
         FIG.  3    is a diagrammatic view of an idler equipped with sacrificial wear rings, according to one embodiment; 
         FIG.  4    is a sectioned diagrammatic view of a portion of an idler equipped with sacrificial wear rings, according to one embodiment; and 
         FIG.  5    is a diagrammatic view of a sacrificial wear ring for an idler, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , there is shown a track-type machine  10  including an undercarriage system  12 , according to one embodiment. Undercarriage system  12  includes a track roller frame  14 , a track  16 , a drive sprocket  18 , an idler  20 , and a plurality of track rollers  22  coupled to a track roller frame  14 . Ground-engaging track  16  includes a plurality of track links  26  coupled together end-to-end to form an endless loop extending about the various track-contacting components. Track links  26  may be attached to track shoes  28  equipped with grousers, with track links together forming a track rail  27 . Track rail  27  is one of two track rails formed by two parallel track chains of track links  26  in the illustrated embodiment. A second ground-engaging track, idler, drive sprocket, et cetera, may be conventionally positioned upon an opposite side of track-type machine from that shown. Idler  20  and track rollers  22  ride upon track rail  27  during advancing track  16  to propel and/or steer track-type machine  10 . In the illustrated embodiment idler  20  is a back idler, and a similar or substantially identical front idler may be positioned at an opposite end of track roller frame  14 . Idler  26  is supported for rotation within idler blocks  24 , one of which is visible in the illustration of  FIG.  1   . Track  16  is arranged in a so-called high drive configuration. In other embodiments, track  16  could have an oval configuration, or still another. Undercarriage system  12  can be used in a track-type tractor, a track-type loader, or any of a variety of other types of off-highway machines. In a practical implementation machine  10  is a track-type tractor as might be used for construction, mining, forestry, or a variety of other applications. As will be further apparent in view of the following description idler  20  is configured with replaceable sacrificial wear parts for extended service life in undercarriage system  12 . 
     Referring also now to  FIGS.  2 - 4   , idler  20  includes an idler rim  30  having an outer rim surface  32  extending circumferentially around an idler axis of rotation  34  and forming a centrally located guide flange  36 . Idler rim  30  also includes an inner rim surface  38  which may form a shaft bore extending between a first axial side and a second axial side of idler  20 . Idler rim  30  may be a one-piece forging of a suitable iron, steel, or other alloy metallic material. During service, guide flange  40  may be received between parallel chains of track links  26  and assists in maintaining idler  20  and track  16  in a desired arrangement. An idler shaft  71  extends through idler rim  30  and rotatably journals idler rim  30 . Components including journal bearings, thrust bearings, and seals, for example, may be within idler rim  30  and supported on or around idler shaft  71 . A clamping ring or plate  73  may be attached to idler rim  30  by a plurality of bolts, with another counterpart ring or plate hidden from view in the illustrations. In other embodiments, idler rim  30  and idler shaft  71  could be fixed to rotate together, with idler shaft  71  being a live shaft supported for rotation in idler blocks  24 , or in another suitable arrangement. 
     As used herein, the terms “radially inward” and “radially outward” are used according to their common definitions relative to idler axis of rotation  34 . The terms “axially inward” and “axially outward” are understood to mean directions along or parallel to idler axis of rotation  34  toward and away from, respectively, a geometric center point of idler  20  intersected by idler axis of rotation  34 . Idler  20  may be axially symmetric about a central plane oriented normal to idler axis of rotation  34 , thus description and discussion herein of parts, structure, or functionality upon one side of idler  20  should be understood by way of analogy to refer to another axial side of idler  20 . 
     Idler rim  30  further includes a first axial end face  48  and a second axial end face  50  each extending radially inward from outer rim surface  32 . Outer rim surface  32  further forms a first ring channel  40  upon a first axial side of centrally located guide flange  36  and a second ring channel  42  upon a second axial side of centrally located guide flange  36 . First ring channel  40  and second ring channel  42  are structured to receive, respectively, a first sacrificial wear ring  44  seated in first ring channel  40  and a second sacrificial wear ring  46  seated in second ring channel  42 . Each of first ring channel  40  and second ring channel  42  extends circumferentially and continuously uninterrupted around idler axis of rotation  34 . 
     First ring channel  40  includes an inboard channel wall  52  spaced axially outward of centrally located guide flange  36 , and an outboard channel wall  54  spaced axially inward of first axial end face  48 . Second ring channel  42  is likewise understood to include an inboard channel wall (not numbered) spaced axially outward of centrally located guide flange  36 , and an outboard channel wall (not numbered) spaced axially inward of second axial end face  50 . Each inboard channel wall  52  and outboard channel wall  54  may be oriented normal to idler axis of rotation  34  and extends radially inward to a cylindrical channel floor  60  of the respective first ring channel  40  or second ring channel  42 . With focus on  FIG.  4   , idler rim  30  may include a hollow rim body  56  with welded attached end plates  58  to form enclosed axial sides of idler  20 . In other embodiments, a solid central web or the like could extend between an outer rim region and an inner hub region in a one-piece forging or the like. 
     As noted above, idler  20  includes a first sacrificial wear ring  44  seated in first ring channel  40 , and a second sacrificial wear ring  46  seated in second ring channel  42 . The term “sacrificial” is used in reference to expected and intended wearing away of material of first sacrificial wear ring  44  and second sacrificial wear ring  46  during service, as further discussed herein. First sacrificial wear ring  44  and second sacrificial wear ring  46  may each be formed from an elongate single piece of a suitable metallic material produced, for example, by forging. The material forming first sacrificial wear ring  44  and second sacrificial wear ring  46  might be the same as the material forming idler rim  30 , including iron, for example, or a different material. First sacrificial wear ring  44  and second sacrificial wear ring  46  could be heat treated or hardened by another process in some embodiments. In a practical implementation, each of first sacrificial wear ring  44  and second sacrificial wear ring  46  has a uniform material composition including iron, and a uniform quadrilateral cross-sectional shape between ends of the wear rings, as further discussed herein. 
     Referring also now to  FIG.  5   , there are shown and identified features of first sacrificial wear ring  44  in further detail. It will be understood that description and discussion of first sacrificial wear ring  44  is understood to refer by way of analogy to any other sacrificial wear ring according to the present disclosure. Sacrificial wear ring  44  includes a one-piece metallic ring body  72 , referred to at times herein interchangeably with first sacrificial wear ring  44 , including an outer link-contact surface  74  and an inner idler-contact surface  76 . Each of outer link-contact surface  74  and inner idler-contact surface  76  extends circumferentially around a ring center axis  78  between a first ring body end  80  and a second ring body end  82 . Ring center axis  78  may be coaxially arranged with idler axis of rotation  78  when sacrificial wear ring  44  is installed for service on idler rim  30 . One-piece metallic ring body  72  further includes a first ring axial side surface  84  and a second ring axial side surface  86  each oriented normal to ring center axis  78  and extending from outer link-contact surface  74  to inner idler-contact surface  76 . Outer link-contact surface  74  may be cylindrical. Inner idler-contact surface  76  may also be cylindrical. A ring width dimension (RW)  90  is defined between first ring axial side surface  84  and second ring axial side surface  86 . A ring thickness dimension (RT)  92  is defined between outer link-contact surface  74  and inner idler-contact surface  76 . In an implementation, a ratio of RW to RT is from 2.5 to 5.0. In a refinement, the ratio of RW to RT is from 2.8 to 4.6. 
     One-piece metallic ring body  72  may be elastically deformable between an installation configuration where a split gap extends in a circumferential direction between first ring body end  80  and second ring body end  82 , and a service configuration where first ring body end  80  and second ring body end  82  are in abutment and split gap  88  is closed. Either of the installation configuration or the service configuration could be a rest configuration, with one-piece metallic ring body  72  deformed in opposition to an internal spring bias from one of the installation configuration or the service configuration to the other of the installation configuration or the service configuration. 
     From the foregoing description it will be appreciated that one-piece metallic ring body  72  may be springy and can be slipped onto outer idler surface  34  and seated in first ring channel  40 . Second sacrificial wear ring  46  can be analogously installed. Once installed in the respective first and second ring channels  40  and  42  assembly of idler  20  can be completed by welding ring body ends  80  and  82 . It will be recalled split gap  88  extends between first ring body end  80  and second ring body end  82 . When installed on idler rim  32  one-piece metallic ring body  72  can be closed, or making use of an internal spring bias permitted to close, and first ring body end  80  and second ring body end  82  placed in abutment for welding. As depicted in  FIG.  3    first sacrificial wear ring  44  includes a welded joint  47  attaching the respective ring body ends  80  and  82 . Second sacrificial wear ring  46  analogously includes a welded joint  49 . Also in a practical implementation first sacrificial wear ring  44  and second sacrificial wear ring  46  are not directly or fixedly attached to idler rim  30 . Thus, each of first sacrificial wear ring  44  and second sacrificial wear ring  46  may be non-welded attached to idler rim  30 . 
     When installed for service each inboard axial side surface or first ring axial side surface  84  may be spaced axially outward of centrally located guide flange  36 . Each outboard axial side surface or second ring axial side surface  86  may be spaced axially inward of the respective first axial end face  48  or second axial end face  50 . As can be seen from the drawings, in particular  FIG.  4   , first sacrificial wear ring  44  and second sacrificial wear ring  46  may stand proud of outer rim surface  32 . 
     Returning to dimensional and proportional attributes of first sacrificial wear ring  44 , inner idler-contact surface  76  may define an inner diameter dimension (ID)  94  when one-piece metallic ring body  72  is in the service configuration. Outer link-contact surface  74  may define an outer diameter dimension (OD)  96  in the service configuration. A ratio of ID to OD may be from 0.93 to 0.95. In some applications, ID is greater than 600 millimeters. Also in certain applications, RT is greater than 20 millimeters. 
     As also depicted in  FIG.  4   , an outboard width dimension (OW)  64  is defined between centrally located guide flange  36  and each respective first axial end face  48  and second axial end face  50 . Centrally located guide flange  36  defines an axial width dimension (AW)  66  that is greater than OW. Each of first ring channel  40  and second ring channel  42  defines a channel width dimension (CW)  68  and a channel depth dimension (CD)  70 . CW may be greater than 75% of OW and greater than 400% of CD in some embodiments. Proportional and dimensional attributes of wear rings  44  and  46  described herein can be expected to scale across a range of idler sizes, such as a range of idler sizes used in different size track-type tractors. 
     INDUSTRIAL APPLICABILITY 
     Referring to the drawings generally, during service idler  20  will rotate with the advancement of track  16  in forward directions or reverse directions about the various track-contacting rotatable elements in undercarriage system  12 . Sacrificial wear rings  44  and  46  will rotate in contact with track rail  27  and the track rail hidden from view in the illustration of  FIG.  1   . Contact between the materials of wear rings  44  and  46 , as well as substrate particles and the like, will tend to cause material of wear rings  44  and  46  to wear away. It is contemplated that idler  20  may be maintained in service at least up until such time that material of wear rings  44  and  46  that is radially outward of outer rim surface  32  has worn away and material of idler rim  30  is expected to begin to wear. 
     When undercarriage system  12  has reached a desired or prescribed state of wear, undercarriage system  12  can be disassembled, and idler  20  removed. Wear rings  44  and  46  can be cut and dismantled from idler rim  30 , and replacement sacrificial wear rings swapped into place and seated in first ring channel  40  and second ring channel  42 . 
     The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.