Abstract:
In the operation of work machines of the type requiring traversal over rough terrain, it is oftentimes beneficial to provide a work machine with parts requiring little or no maintenance. The present invention provides a work machine having a chassis and at least one mounting member attached to the chassis. At least one elongate member has a first end which is rotatably coupled to the mounting member. A self-lubricating member is situated between the first end and the mounting member.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to a suspension system arrangement and, more specifically, to a suspension system mounting arrangement thereof which utilizes maintenance free members between moving parts.  
         BACKGROUND  
         [0002]    Work machines of the type used to remove downed timber from timber harvest areas oftentimes must navigate across rough terrain consisting of uneven ground slopes and obstacles such as stumps, downed timber and rocks. To navigate over such terrain, it has been found beneficial to employ the use of pendulum arm-type suspensions which allow for greater movement of the work machine&#39;s tires relative to the work machine&#39;s chassis. To provide relative movement between the chassis of the work machine and each pendulum arm, slew bearings, needle bearings or other roller-bearing type devices are typically used to mount the pendulum arms to the chassis all of which oftentimes requires periodic maintenance.  
           [0003]    The prior are is replete with examples of mounting pendulum arm-type suspension systems to the chassis of a vehicle. Example of such mounting arrangement can be found in U.S. Pat. No. 5,263,736 which issued on Nov. 23, 1993 to Stevens; U.S. Pat. No. 4,600,069 which issued on Jul. 15, 1986 to Oswald et al.; U.S. Pat. No. 4,230,341 which issued Oct. 28, 1980 to Hart et al.; U.S. Pat. No. 3,601,424 which issued on Aug. 24, 1971 to Badland; and U.S. Pat. No. 2,988,374 which issued on Jun. 13, 1961 to Boyles. Although each of these arrangements may be adequate for their respective intended purposes, neither teaches to use of a self-lubricating bearings for use in mounting the pendulum arms to the chassis.  
           [0004]    The subject invention is directed at overcoming one or more of the problems as set forth above.  
         SUMMARY OF THE INVENTION  
         [0005]    In one aspect of the present invention, a work machine is provided. The work machine includes a chassis, and at least one mounting member attached to the chassis. Also provided is at least one elongate member having a first end rotatably coupled to the mounting member. A self-lubricating member is situated between the first end and the mounting member.  
           [0006]    In another aspect of the present invention a method of providing a self-lubricating suspension system for a work machine having a chassis is provided. The method includes the steps of coupling at least one mounting member to the chassis, providing at least one elongate member having a first end and a second end, attaching a self-lubricating member to a surface of an opening provided in the first end, and attaching the first end to the mounting member in such manner that the self-lubricating member is between the first surface and the mounting member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a side elevation view of a work machine of the present invention embodying the principles of the present invention;  
         [0008]    [0008]FIG. 2 is a diagrammatical side elevation view of an elongated member for use with the work machine of FIG. 1;  
         [0009]    [0009]FIG. 3 is a diagrammatical cross-sectional view taken through lines  3 - 3  of FIG. 3; and  
         [0010]    [0010]FIG. 4 is a diagrammatical perspective view of a self-lubricating member for use with the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0011]    With reference now to the Figures, shown in FIG. 1 is a work machine  100  embodying the principles of the present invention. The work machine  100  includes a cab portion  101  and a first trailer portion  102  hingedly coupled to the cab portion  101  at articulation joint  105 . As should be apparent, the articulation joint  105  allows the cab portion  101  and first trailer portion  102  to be articulable relative to each other about a vertical axis  106  with articulation preferably being provided in a conventional manner such as by the use of hydraulic cylinders  109 . A second trailer portion  110  is preferably hingedly coupled to the first trailer portion  102  at articulation joint  113 , thereby allowing for relative articulation of the first and second trailer portions  102 , 110  about a vertical axis  114 . As should be appreciated by those skilled in such art, such an arrangement allows for tighter turning radii than otherwise would be possible for a single trailer having the same effective length as the combined first and second trailers portions  102 , 110 .  
         [0012]    The cab portion  101  along with the first and second trailer portions  102 , 110  collectively define a chassis of the work machine  100  which is shown generally at  117 . A bunk assembly  118  is pivotally attached to the chassis  117  and is defined by central beam  121  and a plurality of posts  122  attached thereto on each side of the chassis  117  and extending upwardly therefrom. The bunk assembly  118  therefore defines an open bunk area  123  for retaining a load, for example logs, therein. A conventional gate  125  may also be attached to the central beam  121 . A work implement, preferably comprising a crane  126 , is pivotally attached to the chassis  117  and is used for placing the logs within the bunk area  123 .  
         [0013]    A plurality of ground engaging members, preferably comprising six tires  129  (three shown), are coupled with the chassis  117  by use of corresponding elongated members or arms  130 ,  130 ′,  130 ″ (three shown).  
         [0014]    Although the details of coupling each of the arms  130 , 130 ′, 130 ″ to the chassis  117  will be described in greater detail as this disclosure progresses, suffice to say for now each arm  130 , 130 ′, 130 ″ is rotatably coupled to the chassis  117  and each is controlled by a respective hydraulic cylinder  133 , 133 ′, 133 ″. It is to be understood that although only three arms  130 , 130 ′, 130 ″ and respective hydraulic cylinders  133 , 133 ′, 133 ″ are shown, the work machine  100  described herein also includes three corresponding hydraulic cylinder/arm arrangements on the other side of the work machine  100 .  
         [0015]    In FIG. 2 is shown arm  130  with the tire  129  removed. For purposes of brevity, the following discussion will make reference to arm  130  only but it is to be understood that the teachings herein apply equally to the remaining arms  130 ′ and  130 ″. Arm  130  includes a first end  201  which is pivotally coupled to the chassis  117 , and a second end  202  which forms a housing for receiving a motive device  203  for imparting motion to a respective tire  129 . For the work machine  100  described herein, it is preferred that the motive device  203  comprise a hydraulic motor, however other motive devices  203  may be employed without deviating from the present invention such as, for example, an electric motor, a chain drive system, or other like arrangements. As is further shown, the second end  202  includes a flange  206  for coupling the arm  130  to the hydraulic cylinder  133 . The arm  130  further includes a planar portion  209  extending between the first and second ends  201 , 202 .  
         [0016]    Shown in cross-section in FIG. 3 are the details of the first end  201  of arm  130  as attached to the chassis  117 . The first end  201  includes a sleeve portion  301 , having a surface  302 , sized to receive a mounting member, preferably comprising an axle  303 , which is coupled to the chassis  117 . As shown, the axle  303  is preferably substantially hollow and may include a shim  305  attached adjacent to the axle end  306 . Substantially abutting the shim  305  is a retainer cap  309  which is attached to the sleeve portion  301 . A seal  310 , preferably comprising a Teflon seal, may be placed between the retainer cap  309  and sleeve end portion  311 . A plate  312  extends substantially between the retainer cap  309  and the planar portion  209 . As shown, the plate  312  preferably is oriented at an angle relative to the sleeve portion  301  so as to provide the first end  201  with a substantially truncated cone geometry.  
         [0017]    Situated between the axle  303  and the sleeve portion  301  are preferably a pair of self-lubricating members  313  which are used to facilitate relative movement between the axle  303  and sleeve portion  301 . As should be appreciated, and as the name implies, the self-lubricating members  313  are preferably dry sliding bearings of the type commercially available under the trademark GLYCODUR® and which do not require outside lubrication to maintain their bearing-like qualities. As should also be appreciated by those of ordinary skill in such art, the self-lubricating members  313  of the type described herein are relatively thin, typically up to and including 2 mm, which allows for smaller sized axles  303  and arms  130 , 130 ′, 130 ″, thereby reducing the overall weight of the work machine  100 . The user may, at the users option, supply an outside source of lubrication to each of the self-lubricating members  313 . To facilitate any such external lubrication, the first end  201  is provided with a passageway  314  which substantially overlaps a corresponding opening  317  provided in the sleeve portion  301 . The provided lubrication fills the opening  318  interleaved between the sleeve portion  301  and the axle  303  and migrates to each self-lubricating member  313 .  
         [0018]    Shown in FIG. 4 is an exemplary self-lubricating member  313  of the type described herein. As shown, each self-lubricating member  313  is substantially cylindrical in shape and comprises a copper-clad sheet steel backing  401  with a 0.2 mm to 0.35 mm thick sintered layer  402  of tine bronze attached to the backing  401 . A surface layer  405 , comprised substantially of acetal resin (polyoxymethylene), is firmly anchored in the sintered layer of tin bronze. The surface layer  405  may include a plurality of lubrication retaining pockets  406  which help to capture and retain any external lubrication that may be used.  
       INDUSTRIAL APPLICABILITY  
       [0019]    With reference to the drawings and in operation, the self-lubricating member  313  allows for relative movement between each respective arm  130 , 130 ′, 130 ″ and its respective axle  303  without the need for periodic maintenance of the self-lubricating member  313 . Also, as should be appreciated, the provision of such a self-lubricating member  313  having a thickness of 2 mm or less allows for the first ends  201  of the arms  130 , 130 ′, 130 ″ and axles  303  to have a smaller diameter relative to what otherwise would be the case if conventional bearings were used. This, in turn, allows for a reduced weight of the work machine  100  resulting in less damage to the ground surface along with an increased clearance.  
         [0020]    Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.