Abstract:
A linkage arrangement is disclosed to provide an articulated machine with an arrangement that allows two frame structures to both articulate and oscillate relative to one another. The linkage arrangement includes a three point pivot arrangement with an angled link. Two of the pivots provide for articulation while two of the pivots provide for oscillation. The two pivots involved for oscillation are of lower overall height than the overall height for the two pivots providing the articulation, thereby reducing overall machine height while maintaining structural integrity.

Description:
PRIORITY STATEMENT 
       [0001]    This application is the National Stage, filed under 35 U.S.C. § 371, of International Application PCT/GB2007/004856 having an International Filing Date of Dec. 18, 2007 and published Jul. 3, 2008, as International Publication No. WO 2008/078072 A1. Applicant claims benefit of priority under 35 U.S.C. § 119(a) and § 365(b) of European Patent Application No. 06127059.1 filed Dec. 22, 2006. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to linkage arrangements for frame structures and in particular to linkage arrangements including universal bearing arrangements for articulated machines such as wheeled loaders. 
       BACKGROUND 
       [0003]    Articulated machines such as, for example, wheeled loaders and site dumpers are machines that use articulation of the body to steer the machine in particular directions. The machine is commonly divided into a front portion and a rear portion that at a neutral machine position are aligned with one another both vertically and horizontally. Such machines may be provided with pivot joints that allow a first front portion of the machine to be connected with a rear portion of the machine in such a manner that the front and rear portions can articulate and oscillate relative to one another. Articulation may thereby be described as that movement wherein the front and rear sections move relative to one another in a sideways manner. Oscillation may be described as that movement wherein the front and rear sections move relative to one another in an up-wards or downwards direction. Of course the two forms of movement may interact simultaneously. 
         [0004]    Current designs, however, do tend to have taller structures due to several reasons; A larger size machine places large demands on the pivot and bearing arrangement as all forces between the two frame structures are guided through the pivot joints. To create a pivot moment large enough to handle all the forces placed on the joints, it is desirable to allow sufficient distance between the various joints. This, however, does tend to increase the size and especially the height of the machine as the lowest portion of the cab has to be placed above some of the bearing arrangement. Hence, one disadvantage associated with the prior art is that it fails to provide an arrangement allowing low overall machine heights while maintaining structural integrity. 
         [0005]    The current disclosure is directed to overcoming one or more of the problems as set forth above. 
       SUMMARY 
       [0006]    In a first aspect of the disclosure there is provided a linkage arrangement for an articulated machine including, a first frame structure having a first longitudinal axis, a second frame structure having a second longitudinal axis, a link member configured to connect the first and second frame structures, a first universal bearing arrangement for pivotably connecting the first frame structure to the link member, the first bearing arrangement having a first pivot center and a second universal bearing arrangement for pivotably connecting the second frame structure to the link member, the second bearing arrangement having a second pivot center. The first and second universal bearing arrangements are configured such that when the first and second longitudinal axes are substantially parallel and substantially horizontal the first and second pivot centers lie in different horizontal planes. 
         [0007]    In a second aspect of the disclosure there is provided a linkage arrangement for an articulated machine including a first frame structure having a first longitudinal axis, a second frame structure having a second longitudinal axis, a link member configured to connect the first and second frame structures, a first universal bearing arrangement for pivotably connecting the first frame structure to the link member, the first bearing arrangement having a first pivot center lying in a first substantially horizontal plane, a second universal bearing arrangement for pivotably connecting the second frame structure to the link member, the second bearing arrangement having a second pivot center lying in a second substantially horizontal plane and a third universal bearing arrangement for pivotably connecting the first frame structure to the second frame structure, the third bearing arrangement having a third pivot center lying in a third substantially horizontal plane. The first, second and third universal bearing arrangements are configured such that when the first and second longitudinal axes are substantially parallel and substantially horizontal the distance between the first and third substantially horizontal planes is greater than the distance between the second and third substantially horizontal planes. 
         [0008]    In a third aspect of the disclosure there is provided an articulated machine including a first frame structure having a first longitudinal axis, a second frame structure articulatedly connected to the first frame structure and having a second longitudinal axis, and a linkage arrangement connecting the first and second frame structures. 
         [0009]    Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a partial schematic view of an embodiment of an articulated machine in accordance with the current disclosures. 
           [0011]      FIG. 2  is a more detailed cross-sectional view of the articulated joint of the machine of  FIG. 1 . 
           [0012]      FIG. 3  is the same as  FIG. 2  showing a multitude of defined planes, axes and reference points. 
           [0013]      FIGS. 4 and 4   a  are schematic representations of the machine of  FIG. 1  in a neutral position,  FIG. 4  representing a plan view and  FIG. 4   a  representing a side view. 
           [0014]      FIGS. 5 and 5   a  are schematic representations of the machine of  FIG. 1  in an articulated position,  FIG. 5  representing a plan view and  FIG. 5   a  representing a side view. 
           [0015]      FIGS. 6 and 6   a  are schematic representations of the machine of  FIG. 1  in an oscillated position,  FIG. 6  representing a plan view and  FIG. 6   a  representing a side view. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Now referring to  FIG. 1 , a portion of an exemplary machine  10  is shown. The machine  10  may be any suitable machine and in this embodiment may be described as an articulated wheel loader. The machine  10  may have a first frame structure  12  and a second frame structure  14 . The first frame structure  12  may be regarded as a front portion of the machine  10  and may for example be provided with a work arm (not shown). The second frame portion  14  may be regarded as a rear portion of the machine  10  and may for example carry an operator platform  16 , for example a cab. The first and second frame structures  12  and  14  have first and second longitudinal axes  13  and  15  respectively which are discussed in more detail below. The first and second frame structures  12  and  14  may be connected together via a linkage arrangement generally designated with numeral  18 . The linkage arrangement  18  is shown in more detail in  FIGS. 2 and 3 . 
         [0017]    The linkage arrangement  18  as shown in more detail in  FIGS. 2 and 3  may include various bearing portions such as the first, second and third universal bearing arrangements generally designated with numerals  20 ,  22  and  24  respectively. Each of the universal bearing arrangements  20 ,  22  and  24  may include bearings  26 - 30  which may have first, second and third housing portions  32 ,  34  and  36  with first, second and third curved portions  38 ,  40  and  42  in the housing portions  32 - 36  such that the curved portions  38 - 42  and their corresponding housing portions  32 - 36  are rotatably fixed with each other. The curved portions  38 - 42  and the housing portions  32 - 36  may be able to rotate relative to one another in more than one plane thereby providing multiple degrees of freedom for pivoting movement between the housing portions  32 - 36  and the curved portions  38 - 42  and any components attached thereto while also providing self-aligning properties. The bearings  26 - 30  may for example be bearings that are commonly referred to as spherical bearings. 
         [0018]    The curved portions  38 - 42  may have first, second and third central bores  44 ,  46  and  48  extending at least partially therethrough. In one embodiment the central bores  44 - 48  extend completely through the curved portions  38 - 42 . 
         [0019]    The universal bearing arrangements  20 - 24  may have first, second and third pivot centers  55 ,  56  and  57 , respectively, which may be defined as the centers around which the pivot action of each of the universal bearing arrangements  20 - 24  takes place. The pivot centers  55 - 57  may lie in planes  70 ,  72  and  74 , respectively, which is described below. 
         [0020]    The universal bearing arrangements  20 - 24  may have first, second and third link pins  50 ,  52  and  54  that extend at least partially through the central bores  44 - 48  and extend at least partially into or through at least one of the frame structures  12  and  14 . Each of the first, second and third link  50 - 54  pins may define a first, second and third longitudinal pin axis  76 ,  78  and  80  respectively. 
         [0021]    The linkage arrangement  18  may further include a link member  60 . In one embodiment the link member  60  may be an angled link having first and second opposing end portions  62  and  64 . The end portions  62  and  64  may both be generally U-shaped and may be configured such that they can receive at least a portion of the spherical bearings  26  and  28 . The end portions  62  and  64  may further have bores  66  and  68  extending at least partially therethrough to receive the link pins  50 - 52  respectively. 
         [0022]    In one embodiment the universal bearing arrangements  20  and  22  are configured such that the housing portions  32  and  34 , but not the link pins  50  and  52 , are mechanically fixed in the frame structures  12  and  14  respectively. This allows the link pins  50  and  52  to change position relative to both the frame structures  12  and  14 . 
         [0023]    In one embodiment the universal bearing arrangement  24  is configured such that the link pin  54  is mechanically fixed in the frame structure  12  by a fastening arrangement  59  and the link pin  54  is therefore positionally fixed to the frame structure  12 . 
       INDUSTRIAL APPLICABILITY 
       [0024]      FIGS. 5-6   b  are schematic diagrams convenient for explaining the operation of an embodiment of the current linkage arrangement. It is to be understood that the diagrams in  FIGS. 5-6   b  are exemplary only and any depicted movement may be exaggerated for clarity purposes. It is to be understood that when referring to  FIGS. 4-6   b  it is to be clear that the positional and axial references are based on a substantially flat and horizontal base line such as base line  11  as shown in  FIG. 1 . For clarity purposes not all components of the machine  10  are shown in  FIG. 1 , but the base line  11  could for example be regarded as the surface upon which the machine  10  is supported. In each of the side views as depicted in  FIGS. 4   a,    5   a,    6   a  and  6   b,  the base line  11  is represented for convenience. 
         [0025]      FIGS. 4 and 4   a  represent the orientation of the first and second frame structures  12  and  14  relative to one another as depicted in  FIGS. 1 and 2 . The machine  10  has substantially no articulation or oscillation such that the first and second longitudinal axes  13  and  15  are substantially parallel and substantially horizontal. 
         [0026]      FIGS. 5 and 5   a  represent the orientation of the first and second frame structures  12  and  14  relative to one another when the machine  10  is articulated, for example for steering purposes. The steering system may be of any suitable type and is not depicted in any of  FIGS. 1-6   b.  It can be seen from  FIG. 5  that in a plan view the longitudinal axes  13  and  15  no longer align and no longer lie in the same plane. However, from a side view as shown in  FIG. 5   a  the longitudinal axes  13  and  15  still appear aligned, as they are still lying in the same plane. The longitudinal axes  13  and  15  are therefore still substantially horizontal. 
         [0027]      FIGS. 6 ,  6   a  and  6   b  represent the orientation of the first and second frame structures  12  and  14  relative to one another when the machine  10  is oscillated. This may for example happen when one of the front wheels (not shown) of the machine  10  is lifted from the base line  11  by for example an obstacle. This may result in one corner of the frame structure  12  being lifted upwards and side-wards.  FIG. 6   b  depicts how the frame structure  12  may move and rotate relative to the frame structure  14 . Oscillation may have multiple components of relative movement between the frame structures  12  and  14  and it is to be understood that part of the movements may be counteracted by the operator, by for example introducing an articulation to counter a natural articulation that may occur during oscillation. It can be seen from  FIGS. 6 ,  6   a  and  6   b  that the longitudinal axes  13  and  15  are no longer aligned and no longer lie in the same plane. At least the longitudinal axis  13  is no longer substantially horizontal. 
         [0028]    It can be seen that when the first and second longitudinal axes  13  and  15  are substantially parallel and substantially horizontal as represented in  FIGS. 1-4   a , the first, second and third pivot centers  55 ,  56  and  57  lie in different planes  70 ,  72  and  74  respectively. Each of the planes  70 ,  72  and  74  is substantially horizontal when the first and second longitudinal axes  13  and  15  are substantially parallel and substantially horizontal. It can also be seen that the first pivot center  55  in horizontal plane  72  lies below the second pivot center  56  in horizontal plane  70 . The third pivot center  57  in horizontal plane  74  lies beneath both the horizontal planes  70  and  72 . 
         [0029]    For convenience, the relationships within the linkage arrangement when the first and second longitudinal axes  13  and  15  are substantially parallel, and substantially horizontal may also be described as follows; A distance D 1  relates to the distance between the two planes  70  and  74  which are the planes associated with the pivot centers involved in providing articulation, i.e. the pivot centers  55  and  57 . A distance D 2  relates to the distance between the two planes,  72  and  74 , which are the planes associated with the pivot centers involved in providing oscillation, i.e. the pivot centers  56  and  57 . It can be seen that D 1  is greater than D 2 . 
         [0030]    When the first and second longitudinal axes  13  and  15  are substantially parallel and substantially horizontal as represented in  FIGS. 1-4   a,  the longitudinal pin axes  76 - 80  are substantially parallel whereby the first and third longitudinal axes  70  and  78  are not only parallel, but are also substantially coaxial. 
         [0031]    The invention allows the second universal bearing arrangement  22  to be lower compared to the prior art. The operator platform  16 , which is mounted on the second frame portion  14  can thus be lower, thereby reducing the overall machine height while maintaining structural integrity. 
         [0032]    Other aspects can be obtained from a study of the drawings, the specification, and the appended claims.