Abstract:
A track assembly for a track-type machine includes a link assembly having a plurality of interconnected link sets forming an oval track path, a plurality of track shoes, each being coupled to a respective link set, and an elastic member located between a plurality of successive link sets and a plurality of respective track shoes. The elastic member extends continuously along each individual link set of the plurality of successive link sets. The elastic member may extend along substantially the entire oval track path. The elastic member serves to stiffen the link assembly and thereby reduce the amount and force of impacts between the link assembly and other elements of the undercarriage of the track-type machine, resulting in a reduction in the amount of noise emanating from the machine operation.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to a device for reducing the noises emanating from an undercarriage of a track-type machine during operation.  
         BACKGROUND  
         [0002]    Conventional track-type machines emit operational noises that are often considered objectionable to individuals in the vicinity of the machine. The disturbance associated with such noise is compounded by the fact that track-type machines are often operated in places of high human population, such as near office buildings or apartment complexes.  
           [0003]    A portion of the noise created by track-type machines can be attributed to the metal-to-metal contact of the undercarriage of the machine during operation. For example, noises are caused by metal-to-metal contact between the teeth of the drive sprocket and the bushings interconnecting the links of a link assembly, between the surfaces of the idler roller and the links, and between the rolling surface of the carrier rollers and the links. Many attempts have been proposed to reduce the noises created by the undercarriage of track-type machines. For example, U.S. Pat. No. 4,099,796 to Groff discloses a track assembly including track shoes having a cover plate and viscoelastic material affixed to an inner, link-side surface of the track shoes. The cover plate and viscoelastic material act to reduce the noise of the undercarriage of the track-type machine by dissipating and absorbing vibrations of the track shoe during operation. This attempt at reducing the vibrational noise of the undercarriage of track-type machines, however, suffers the drawbacks that this energy dissipating mechanism is limited in the amount of energy that can be absorbed. Further, the cover plates and viscoelastic material disclosed in Groff are not designed to reduce the force and amount of impacts between the link assembly and other components of the undercarriage. The attaching of individual cover plates and viscoelastic material to each track shoe may also be cost prohibitive.  
           [0004]    The present invention provides an apparatus for reducing the noise of an undercarriage of a track-type machine that avoids some or all of the aforesaid shortcomings in the prior art.  
         SUMMARY OF THE INVENTION  
         [0005]    In accordance with one aspect of the invention, a track assembly for a track-type machine includes a link assembly having a plurality interconnected link sets forming an oval track path, a plurality of track shoes, each being coupled to a respective link set, and at least one elastic member located between a plurality of successive link sets and a plurality of respective track shoes, the at least one elastic member extending continuously along each individual link set of the plurality of successive link sets.  
           [0006]    According to another aspect of the present invention, a track assembly includes a link assembly having a plurality of interconnected link sets forming an oval track path, a plurality of track shoes, each being coupled to a respective link set, and an elastic strip located between the link sets and the track shoes and extending over substantially the entire oval track path.  
           [0007]    Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.  
           [0008]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.  
           [0009]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several exemplary embodiments of the invention and together with the description, serve to explain the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a perspective view of a track-type machine incorporating an exemplary embodiment of the present invention;  
         [0011]    [0011]FIG. 2 is a partial perspective view of the track assembly of FIG. 1;  
         [0012]    [0012]FIG. 3 is an exploded partial view of the track assembly of FIG. 1;  
         [0013]    [0013]FIG. 4 is a perspective view of the attachment of the stiffening strip to the track assembly in accordance with an exemplary embodiment of the present invention; and  
         [0014]    [0014]FIG. 5 is a top view of an exemplary embodiment of a shim according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    Reference will now be made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
         [0016]    [0016]FIG. 1 illustrates a track-type machine  10  incorporating the present invention. Track-type machines as defined herein may include, for example, any machine incorporating a track or crawler-type driving system. Such driving systems are commonly used in earth moving, earth digging, and earth carrying machines. Track-type machine  10  may include a machine body  12 , a blade member  14 , and an undercarriage  16  having a track assembly  18 . Although not shown in FIG. 1, undercarriage  16  of track-type machine  10  may include a second track assembly located on a side of machine body  12  opposite track assembly  18 .  
         [0017]    [0017]FIG. 1 further illustrates the basic components that may be included in an undercarriage  16  of a track-type machine  10  according to the present invention. For example, undercarriage  16  may include a drive sprocket  20 , carrier rollers  22  and an idler roller  24  together forming a generally oval track path for a link assembly  28 . Drive sprocket  20  may be rotated by an engine (not shown) of track-type machine  10  causing the teeth  26  of drive sprocket  20  to engage bushings  30  of link assembly  28  to rotate link assembly  28  about the oval track path. Track shoes  32  may be coupled to outer portions of link assembly  28  to form a ground contacting traction surface of track assembly  18 .  
         [0018]    Referring to FIG. 2, link assembly  28  may be formed by a successive set of interconnected link sets  34 . Link sets  34  may include two (2) opposing links  36  connected to each other by a pair of bushings  30 . Link sets  34  may be coupled to track shoes  32  by a plurality of fasteners  38 . As described in more detail below in connection with FIG. 3, a stiffening strip  40  in the form of an elastic strip member may be located between track shoes  32  and link assembly  28  and extend substantially the entire oval track path of link assembly  28 . Stiffening strip  40  may be supported at each link set  34  by a shim  42  bridging opposing links  36  of each link set  34 .  
         [0019]    [0019]FIG. 3 illustrates an exploded view of the connection of a single link set  34  and a single track shoe  32  in accordance with an exemplary embodiment of the present invention. Four (4) bolts  44  of fasteners  38  may extend through bolt holes  46  of track shoe  32  and bolt holes  48  of link set  34  and be secured by nuts  50 . Prior to coupling track shoe  32  to link set  34 , a rectangular-shaped shim  42  may be affixed to an outer surface  52  of link set  34  to bridge links  36 . Shim  42  may be affixed to links  36  so as not to obstruct bolt holes  46  and  48 . Stiffening strip  40  may be located between the outer surface  52  of link set  34  and an inner surface  54  of track shoe  32  and be urged by shim  42  so as not to extend into the link space  56  formed between links  36  and bushings  30  of link assembly  28 .  
         [0020]    Stiffening strip  40  may be formed of an elastic strip member of any type of material capable of absorbing impact loads and vibrations. The term “elastic” as used herein includes any material capable of sustaining deformation without permanent loss of size or shape. For example, stiffening strip  40  may be formed of a two (2) ply styrene-butadiene rubber (SBR) or a three (3) ply polyurethane. For certain exemplary applications, stiffening strip  40  may have a width (w) in the range of approximately 6.35 cm (2.5 inches) to 8.89 cm (3.5 inches), and a thickness (t) in the range of approximately 0.635 cm (0.25 inches) to 0.762 cm (0.3 inches). Stiffening strip  40 , however, may be formed of any width or thickness dimensions allowing for proper coupling of track shoe  32  to link set  34 .  
         [0021]    Stiffening strip  40  may be formed as a continuous strip having a length sufficient to extend over each link set  34  of link assembly  28 . The appropriate length of stiffening strip  40  may be calculated by applying a uniaxial tension test to stiffening strip  40  to determine its yield strength and its strain energy at yield. The length of stiffening strip  40  and the tension to be applied to stiffening strip  40  during attachment to track assembly  18  may then be selected so that stiffening strip  40  can withstand the kinetic energy of the track assembly  28 . The present invention also contemplates stiffening strip  40  being formed of a plurality of elastic members coupled between all or only a portion of link sets  34 .  
         [0022]    [0022]FIG. 4 illustrates a method by which stiffening strip  40  may be coupled to track assembly  18 . Shim  42  may be attached between links  36  of each link set  34  in any appropriate manner, for example by adhesion. One end of stiffening strip  40  may then be placed over a single link set  34 , and a track shoe  32  bolted in place with fasteners  38 . The fastening of track shoe  32  to link set  34  acts to clamp stiffening strip  40  in place between link set  34  and track shoe  32 . After one end of stiffening strip  40  is clamped in position, stiffening strip  40  may be appropriately tensioned and another track shoe  32  may be fastened to a successive link set  34  to clamp the next successive portion of stiffening strip  40  in position. This process is repeated until the entire stiffening strip  40  is mounted to the link assembly  28 .  
         [0023]    [0023]FIG. 5 illustrates an alternative shim  58  according to the present invention. Shim  58  may be formed in a generally C-shaped configuration with holes  60  extending therethrough to align with bolt holes  46  of track shoe  32  and bolt holes  48  of link set  34 . Shim  42  and shim  58  may be formed of any rigid material and have a thickness sufficient to prohibit stiffening strip  40  from entering link space  56 . For example, shims  42  or  58  may be formed of steel or aluminum and have a thickness up to approximately 0.636 cm (0.24 inches). Shims  42  and  58  may also include rounded edges and corners to reduce scratching or scoring of stiffening strip  40  resulting from contact with shims  42  or  58 .  
       INDUSTRIAL APPLICABILITY  
       [0024]    During operation of track assembly  18  of track-type machine  10 , stiffening strip  40  acts to increase the stiffness of link assembly  28  and thus reduce its play. A reduction in the play of link assembly  28  reduces the number and force of impacts between link assembly  28  and other components of undercarriage  16  during operation. Reducing the force and number of impacts between elements at undercarriage  16  reduces the noise produced by track-type machine  10 . Further, stiffening strip  40  also provides an impact impedance reduction at the interface of the track shoes and link assembly. This impedance reduction also acts to reduce the noise radiated from undercarriage  16 .  
         [0025]    As noted above, stiffening strip  40  may be formed of a continuous elastic strip coupled about substantially the entire oval track path of link assembly  28 , or may be formed of a plurality of elastic members together extending over all or a portion of the oval track path. A track assembly  18  having at least one elastic member coupled to at least two (2) successive link sets  34  and corresponding track shoes  32  will still provide benefits associated with an increased stiffness of link assembly  28 .  
         [0026]    It is contemplated that this cost-effective noise reduction system may have wide application in all types of track-type machines. This system may be installed on new machines during the manufacturing process or may be retrofitted onto existing machines in the field.  
         [0027]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example, many different alternatives for coupling link sets  34  to track shoes  32  are possible in accordance with the present invention. Further, washers may be included about holes  46  or  48  when using shim  42 . The washers may protect stiffening strip  40  from detrimental wear resulting from contact with rough surfaces adjacent holes  46  and  48 . It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.