Abstract:
A utility vehicle is provided with a bogey beam on which are mounted the steering axle at the forward end of the bogey beam and the middle axle on the rearward end of the bogey beam. A rear drive axle is supported by the frame of the utility vehicle. The bogey beam is connected to the frame by a pivot assembly defining a transverse pivot axis about which the bogey beam can oscillate. The weight transferred to the bogey beam is proportionately distributed between the front steering axle and middle axle. As a result, the steering characteristics of the steering axle are not impaired by the imposition of a load in the load bed of the utility vehicle, as the middle axle cannot be loaded sufficiently to overpower the front steering axle. The middle axle is rotatably driven by a chain drive transferring rotational power from the rear drive axle. The bogey beam is provided with a plurality of pivot axis locations to vary the proportions of the load applied to the front and middle axles as a result of the longitudinal movement of the bogey beam pivot.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to off-road motor vehicles, such as utility or recreational vehicles, and more particularly, to an adjustable bogey beam support apparatus for the front and middle axles of a utility vehicle to vary the distribution of load between the front and middle axles.  
         BACKGROUND OF THE INVENTION  
         [0002]    Small off-road vehicles such as utility or recreational vehicles are becoming popular for recreational and other general purpose off-road usage. Such utility vehicles can be found in U.S. Pat. No. 4,706,770. These utility vehicles have found usage on golf courses and at sporting events, and are particularly adaptable for utilization on a farm. This type of flexibility in the wide variety of uses necessitates a vehicle that is highly flexible, highly maneuverable and the like. This demands a vehicle that will afford a high degree of maneuverability and ease of steering.  
           [0003]    Steering characteristics of known utility vehicles provide poor turning performance. Known utility vehicles have turning clearance circles having a diameter greater than twenty-one feet. The use of independent front wheel suspension mechanisms on known utility vehicles, coupled with the mounting of the rack and pinion systems on the frame of the vehicle, introduces minor king pin rotations as the steering tires ride over ground undulations. Such construction reduces steering precision and can accelerate the wear of the tires on the steering axle.  
           [0004]    Placing a load on the utility vehicle typically results in a variation in the steering performance of known utility vehicles. For example, one known embodiment having a front steering axle, a rear drive axle, and a middle drive axle carries the load placed on the vehicle on the middle and rear axles, resulting in proportionately less weight on the steering axle and a reduction in maneuverability. Accordingly, known utility vehicle construction results in a significant influence on the steering performance by the load carried on the vehicle. Preferably, loads should not change the steering characteristics for any vehicle.  
           [0005]    Furthermore, conventional utility vehicle construction mounts the middle axle directly to the frame of the vehicle, resulting in a harsh ride characteristic and direct application of any load placed into the load bed onto the middle axle as well as the rear drive axle. It would, therefore, be desirable to enhance the ride characteristics, as well as the steering performance of utility vehicles by distributing the weight of the loads being carried in a different manner.  
           [0006]    Steering characteristics can be varied by changing the load applied to the front and middle axles. Depending on the steering characteristics desired by the operator, it would be advantageous to be able to vary the proportional distribution of the load applied to the front and middle axles.  
           [0007]    It is therefor desirable to provide a utility and recreational vehicle that overcomes the disadvantages of the known prior art utility vehicles.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, an important object of the present invention is to provide a middle axle for a utility vehicle that is not directly mounted to the frame of the vehicle.  
           [0009]    It is another object of this invention to provide a bogey beam apparatus for supporting the front and middle axles on a utility vehicle.  
           [0010]    It is a further object of this invention to provide support for the middle axle of a utility vehicle in such a manner as to prevent the load placed thereon from overcoming the steering operation of the front axle.  
           [0011]    It is a feature of this invention to add a bogey beam extending longitudinally at the center line of the utility vehicle to interconnect the front and middle axles.  
           [0012]    It is another feature of this invention that a portion of the load placed into the load bed of the utility vehicle will be distributed to the bogey beam to be re-distributed to the front and middle axles in a predetermined proportion.  
           [0013]    It is still another object of this invention to provide an adjustable pivot mechanism for the bogey beam to vary the proportional loading between the front and middle axles.  
           [0014]    It is still another feature of this invention that the proportional loading between the front and middle axles can be varied at the discretion of the operator.  
           [0015]    It is an advantage of this invention that maneuverability of the utility vehicle is preserved during load bearing operations.  
           [0016]    It is another advantage of this invention that the steering characteristics of a utility vehicle can be adapted to the desires of the operator by changing the proportional loading between the front and middle axles.  
           [0017]    It is still another advantage of this invention that the ride characteristics of a utility vehicle are improved, particularly under load bearing conditions.  
           [0018]    It is still another feature of this invention that the loads placed on the load bed of the utility vehicle are proportionally distributed between the front steering axle and the middle drive axle of the utility vehicle.  
           [0019]    It is a further object of this invention to provide a bogey beam mechanism for an off-road vehicle that is durable in construction, inexpensive to manufacture, carefree in maintenance, easy to assemble, and simple and effective in use.  
           [0020]    These and other objects, features, and advantages are accomplished according to the present invention by providing a utility vehicle having a bogey beam on which are mounted the steering axle at the forward end of the bogey beam and the middle axle on the rearward end of the bogey beam. A rear drive axle is supported directly on or suspended from the frame of the utility vehicle. The bogey beam can be rigidly or resiliently connected to the frame by a pivot assembly defining a transverse pivot axis about which the bogey beam can oscillate. The weight transferred to the bogey beam is proportionately distributed between the front steering axle and middle axle. As a result, the steering characteristics of the steering axle are not impaired by the imposition of a load in the load bed of the utility vehicle, as the middle axle cannot be loaded sufficiently to overpower the front steering axle. The bogey beam is provided with a plurality of pivot axis locations to vary the proportions of the load applied to the front and middle axles as a result of the longitudinal movement of the bogey beam pivot.  
           [0021]    The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows, in conjunction with the accompanying sheets of drawings. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:  
         [0023]    [0023]FIG. 1 is side perspective view of a utility vehicle incorporating the principles of the present invention;  
         [0024]    [0024]FIG. 2 is a top plan view of the utility vehicle of FIG. 1, the seats and control apparatus being shown in dashed lines, the frame and axles being shown in phantom;  
         [0025]    [0025]FIG. 3 is a top plan view of the frame and drive mechanism with the chassis removed for purposes of clarity;  
         [0026]    [0026]FIG. 4 is an enlarged cross-sectional view of the utility vehicle taken along lines  4 -- 4  of FIG. 3 to show the drive mechanism and the orientation of the bogey beam supporting the front steering axle and the middle drive axle;  
         [0027]    [0027]FIG. 5 is an enlarged cross-sectional view of the utility vehicle taken along lines  5 -- 5  of FIG. 3 to show an elevational view of the middle drive axle;  
         [0028]    [0028]FIG. 6 is an enlarged cross-sectional view similar to that of FIG. 4 but showing flotational movement of the middle axle, the normal position of the middle axle being shown in phantom;  
         [0029]    [0029]FIG. 7 is a top plan view of the frame similar to that of FIG. 3, but showing variable placement of the bogey beam pivot, alternative bogey beam pivot locations being shown in phantom; and  
         [0030]    [0030]FIG. 8 is an enlarged cross sectional view similar to that of FIG. 4, but showing variable placement of the bogey beam pivot, alternative bogey beam pivot locations being shown in phantom.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Referring to FIGS.  1 - 3 , a utility vehicle incorporating the principles of the present invention can best be seen. Any left and right references are used as a matter of convenience and are determined by standing at the rear of the vehicle and facing forwardly into the direction of travel.  
         [0032]    The utility vehicle  10  includes a frame  12  supported above the ground G by a pair of steered wheels  22 ,  23  mounted on a front steering axle  20  and by a pair of driven wheels  25  mounted on a rear drive axle  24 . In the preferred embodiment depicted in FIGS.  1 - 3 , a middle drive axle  27  is also provided with a pair of opposing support wheels  28 . The frame  12  supports an operator compartment  13  including seats  14  for the comfort of the operator and control apparatus, such as a conventional steering wheel  15  and a gear shift lever  16 . A throttle control  17  and a brake control  18 , along with other conventional control devices, are also included within the operator compartment  13  for the control of the vehicle  10 . The frame  12  also supports a load bed  19  rearwardly of the operator compartment  13  over the middle and rear drive axles  27 ,  24  respectively, to carry cargo over the surface of the ground G.  
         [0033]    Referring now to FIG. 3, the frame  12  with the axles  20 ,  24 ,  27  mounted thereon can best be seen. The rear drive axle  24  is rotatably supported on the frame  12  and is powered by a drive mechanism  26  powered by an engine  11  supported by the frame  12 . The middle axle  27  is pivotally supported from the frame  12  by a pair of support links  29  and is connected to the rearward end of a bogey beam  30 , which will be described in greater detail below. The middle axle  27  is preferably formed as a pair of stub shafts  27   a,    27   b  connected to said respective support links  29 . A support beam  32  is pivotally mounted on a rearward end of the bogey beam  30  for oscillatory movement about a longitudinally extending pivot axis  33   a.  The support wheels  28  on the middle axle  27  are driven by respective chain drives  26   a  to provide a four wheel drive capability for the vehicle  10 .  
         [0034]    Front axle  20  and the mounting member  35  are attached to the forward end of the bogey beam  30  and, therefore, also pivot about axis  33   a.  The bogey beam  30  is pivotally connected to the frame  12  by a pivot assembly  37  positioned beneath the operator compartment  13  to provide an oscillation of the bogey beam  30  about the transverse pivot axis  38 . Accordingly, the front steering axle  20  and the middle axle  27  generally oscillate in opposing vertical directions on opposite ends of the bogey beam  30  due to the pivotal mounting thereof by the pivot assembly  37 .  
         [0035]    The pivot assembly  37  can be formed as a simple pin pivotally connecting the bogey beam  30  to the frame  12  of the vehicle  10  to define the transverse pivot axis  38 , as is shown in the drawings. The pivot assembly  37  can also suspend the bogey beam  30  from the frame  12  by providing a link (not shown) that pivotally connects at one end to the bogey beam  30  and is centrally connected to the frame  12  with the opposing end of the link being connected to a spring mechanism (not shown) that provides some resiliency between the bogey beam  30  and the frame  12 . Under such a suspended bogey beam arrangement, the transverse pivot axis  38  would be located at the pivotal connection between the link (not shown) and the bogey beam  30 , but would be vertically movable relative to the frame  12  about the pivotal connection between the link (not shown) and the frame  12 , the spring mechanism (not shown) interconnecting the frame  12  and the link (not shown) to offset forces encountered by the bogey beam  30 . The location of the central pivot on the link (not shown), pivotally connecting the link to the frame  12 , being positioned between the opposing ends of the link to provide the desired resiliency for the selected size of the spring mechanism.  
         [0036]    Any load placed in the load bed  19  will be transferred to the rear axle  24  through the mounting thereof with the frame  12  and to the bogey beam  30  via the pivot assembly  37 . The weight carried by the bogey beam  30  will be shared in a proportionate manner between the front steering axle  20  and the middle axle  27 . The respective proportions will be determined by the location of the pivot assembly  37  along a length of the bogey beam  30 . Accordingly, any load transferred to the bogey beam  30  will always be proportionately divided between the front steering axle  20  and the middle axle  27 . As a result, the steering characteristics will not be impacted by any load placed into the load bed  19 , as the middle axle  27  cannot overpower the front steering axle  20 .  
         [0037]    The front steering axle  20  is operatively associated with a steering mechanism  40  to effect turning movement of the steered wheels  22 ,  23 . The steering mechanism  40  is actuated through manipulation of the steering wheel  15  by the operator through the universal connecting linkage  42 . The steering mechanism  40  includes a rack and pinion assembly  45  which includes a conventional pinion (not shown) rotatably associated with the steering wheel  15  and a conventional rack  47  that is linearly movable in conjunction with the rotation of the pinion  46  in a known manner.  
         [0038]    The rack  47  is pivotally connected to a first bell crank  50  at a first connection point  48 . The first bell crank  50  is pivotally mounted on the mounting member  35  for movement about a pivot  51 . The connection point  48  is positioned forwardly of the pivot  51  to effect pivotal movement of the first bell crank. The right steered wheel  22  includes a spuckle  52  having a steering arm  53  extending rearwardly therefrom. The first bell crank  50  is connected to the right steering arm  53  by a steering link  54  that extends laterally and rearwardly from the first bell crank  50  to the rearward end of the steering arm  53 .  
         [0039]    The steering mechanism  40  also includes a second bell crank  55  pivotally mounted on the mounting member  35  for movement about a pivot  56 . The second bell crank  55  is connected to the first bell crank  50  by a tie rod  60  for coordinated movement therebetween. Accordingly, pivotal movement of the first bell crank  50  is transferred to the second bell crank  55  through connection with the tie rod  60 . The left steered wheel  23  includes a spuckle  57  having a steering arm  58  extending rearwardly therefrom. The second bell crank  55  is connected to the left steering arm  58  by a steering link  59  that extends laterally and rearwardly from the second bell crank  55  to the rearward end of the steering arm  58 . Accordingly, the left and right steered wheels  22 ,  23  are steered in concert with one another in response to a manipulation of the steering wheel  15  by the operator.  
         [0040]    Referring now to FIGS.  3 - 5 , the details of the bogey beam construction and the support of the middle drive axle  27  can best be seen. The support beam  32  at the rear end of the bogey beam  30  has the stub axles  27   a,    27   b  mounted directly to the laterally opposing ends of the support beam  32 . The support beam  32  further has a pair of mounting brackets  34  projecting rearwardly therefrom interiorly of the stub shafts  27   a,    27   b  to pivotally connect with the support links  29 . The support links  29  pivotally interconnect the frame  12  just forwardly of the rear drive axle  24  and the mounting brackets  34  on the support beam  32 . While the drawings depict the support links  29  connected to the frame  12  and the rear drive axle  24  fixed to the frame  12 , an alternative configuration can suspend the rear drive axle  24  from the frame  12  such that the rear drive axle  24  is vertically movable relative to the frame  12 . In such a configuration, the support links  29  would preferably be mounted to the rear drive axle  24  to be vertically movable therewith, but pivotable about an axis that is not coincidental with the axis of the rear drive axle  24 . Furthermore, the pivotal connection between the support links  29  and either the frame  12  or the rear drive axle  24 , or alternatively the length of support links  29 , will be positionally adjustable in a fore and aft direction to provide for adjustment of the tension in the chain drive mechanism  26   a,  as will be described in greater detail below.  
         [0041]    The support beam  32  is also connected to a central support bracket  31  which, in turn, is connected to the rearward end of the bogey beam  30  by a ball joint  33  defining the oscillation axis  33   a  which permits the middle axle  27  to oscillate about a longitudinally extending axis  33   a  to permit the middle axle  27  to follow ground undulations. The central support bracket  31  also defines a pivotal connection between the bogey beam  30  and the support beam  32  such that the support beam  32  which is fixed to the central support bracket  31  is free to pivot about a bolt defining a transversely extending pivot axis  31   a  that is eccentric with respect to the transverse axis of the middle axle  27 . Accordingly, the middle axle  27  is capable of simultaneous pivotal movement about the transverse axis  31   a  and the pivotal connections between the support links  29  and the mounting brackets  34 . Preferably, the pivotal connection between the support links  29  and the mounting brackets  34  are in alignment with the stub shafts  27   a,    27   b  defining the middle axle  27 . The transverse pivot axis  31   a  is located below the line of the middle axle  27 .  
         [0042]    The pivotal connection of the support links  29  to the frame  12  (or alternatively to the rear drive axle  24 ) is preferably formed as an assembly that is longitudinally movable to control the tension in the chain drive mechanism  26   a.  With specific reference to FIG. 4, the position of the support beam  32  on top of the bogey beam depicts the forwardmost adjustable movement of the support links  29 . One skilled in the art will readily recognize that a fore-and-aft movement of the support link  29  will cause pivotal movement of the support beam  32  about the transverse pivot axis  31  a carried by the rearward end of the bogey beam  30 . Accordingly, the normal operative position of the support beam  32  will be at an orientation above the bogey beam  30  to allow for wear adjustment of the chain mechanism  26   a,  similar to the solid line depiction in FIG. 6.  
         [0043]    In operation, as best seen in FIGS.  4 - 6 , the middle axle  27  is free to float with respect to frame  12  of the utility vehicle  10 . The vertical movement of the middle axle  27  is accommodated by the pivotal connections of the support links  29 , the bogey beam  30  and the support beam  32 . The support links  29  impose a controlled positional relationship with respect to the movements of the middle axle  27  relative to the rear drive axle  24 , thus keeping the chain drive mechanism  26   a  in a proper drive transferring condition. The support links  29  do not pivot on a center coincident with the rear drive axle  24 , but are pivoted at a point forwardly of the rear drive axle  24 . Accordingly, the pivotal movement of the middle axle  27 , as represented by the arc  29   a,  will slightly shorten the distance between the middle axle  27  and the rear drive axle  24 , thus allowing a little slack in the chain drive mechanism  26   a  to accommodate a slight twisting of the chain drive mechanism  26   a  when the middle axle oscillates about the pivot axis  33   a.  The floating movement of the middle axle  27  about the rearward end of the support links  29 , whose pivot axis is forward of the rear drive axle  24 , will maintain acceptable tension in the chain drive mechanism  26   a  for proper drive transmission to the middle axle  27 .  
         [0044]    Furthermore, the middle axle  27  is mounted on the rearward end of the bogey beam  30  and any vertical floating movement of the middle axle  27  must also move in conjunction with the limits imposed by the bogey beam structure  30 , as represented by the arc  30   a.  Since the support beam  32  is pivotally connected to the rear end of the bogey beam  30  by the central support bracket  31 , the support beam  32  is capable of pivoting rearwardly about the pivot axis  31   a,  as represented by the arc  32   a.  Accordingly, the middle axle  27  vertically floats through pivot arcs  29   a,    30   a,  and  32   a  that coordinate to provide substantially vertical movement for the middle axle  27 .  
         [0045]    The vertical floating movement of the middle axle  27  is best shown in FIG. 6. The normal position of the middle axle  27  is shown in phantom lines, while the raised position of the middle axle  27  to accommodate a ground undulation is shown in solid lines. The vertical movement of the middle axle  27  raises the rearward end of the bogey beam  30 , pivoting the bogey beam  30  about the front axle  20 , and slightly raises the operator compartment  13  as represented by the vertical movement of the transverse pivot  38 . The pivotal movement of the middle axle  27  with respect to the support links  29  results in a corresponding pivotal movement of the central support bracket  31  about pivot axis  31   a,  causing the support beam  32  to raise above the bogey beam  30 . This flotational capability of the middle axle  27  results in a smoother ride for the operator than is known in the prior art construction with the middle axle  27  fixed to the frame  12 .  
         [0046]    The downward vertical movement of the middle axle  27  results in a similar operation of the pivot arcs  29   a,    30   a,  and  32   a.  The downward displacement of the middle axle  27  moves the rearward end of the bogey beam  30  downwardly along the arc  30   a.  The fixed length of the support links  29  results in a pivotal movement of the support beam  32  about the transverse pivot axis  31   a,  raising the support beam  32  relative to the bogey beam  30 .  
         [0047]    An alternative configuration of the pivot assembly  37  can best be seen in FIGS.  7 - 8 . By changing the location of the pivot axis  38 , the proportions of the load distribution between the front and middle axles  20 ,  27  can be varied due to the difference in moment arms between the front and middle axles  20 ,  27  and the pivot axis  38 . Changing the load distribution provides a difference in steering characteristics which can be selected by the operator simply by relocating the pivot axis  38  into one of the alternative openings  38   a,    38   b  in the bogey beam  30 . Alternatively, the pivot assembly  37  can be equipped with an automatic adjustment mechanism (not shown) that would effect a relocation of the pivot axis  38  by the operator from the operator compartment  13 .  
         [0048]    The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.