Abstract:
A tracked suspension for a tractor or other work vehicle is disclosed having an endless belt, a belt tensioner, a drive wheel, and a plurality of idler wheels mounted to a suspension frame or idler carriage, the assembly being arranged such that the belt tension provided by the tensioner is absorbed within the frame and is not transmitted to the axle extending from the tractor that drives the tracked suspension. The tracked suspension can be adjusted by loosening or removing mounting bolts that fix the suspension to beams extending from the vehicle, sliding the suspension toward or away from the vehicle, and tightening the bolts. By absorbing the belt tensioning forces within the tracked suspension itself, rather than transmitting the belt tensioning forces to the axle, the suspension can be more easily adjusted without requiring the removal and replacement of the drive axle.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates generally to tracked vehicles having adjustable suspensions. More particularly, it relates to agricultural tractors with tracked suspensions having lateral adjustability and internal track strain absorption.  
         BACKGROUND OF THE INVENTION  
         [0002]    Tracked vehicles have been provided for use in agricultural operations that provide a fixed track width. One of the reasons the tracked width is fixed is because the drive axle extending from the vehicle and coupled to the drive wheel is neither easily removable or adjustable since it must be strong enough to resist bending forces applied to it by the track spring tension. It is an object of this invention to provide an agricultural tractor that is more easily adjusted for lateral track width. It is an object of this invention to provide such a tractor by absorbing track tension stresses within the tracked suspension itself, and not transmitting them to the drive axle.  
         SUMMARY OF THE PRESENT INVENTION  
         [0003]    In accordance with the first embodiment of the invention, a tracked suspension for a work vehicle is provided including an endless track, a suspension frame configured to be slidably and fixedly mounted to at least one suspension beam extending from a frame of the vehicle, a beam extending parallel to a direction of travel and pivotally coupled to the suspension frame about a first pivotal axis substantially perpendicular to the direction of travel, a first idler wheel coupled to a fore portion of the beam and rotatable with respect thereto, a second idler wheel coupled to a rearward portion of the beam and rotatable with respect thereto, a belt tensioner configured to tension the endless track, a drive wheel support fixed to the suspension frame, a drive wheel rotatably coupled to the drive wheel support and having a drive wheel rotational axis, and a drive wheel axle rotationally coupled to the drive wheel to drive the drive wheel in rotation, wherein the track tensioner is disposed to tension the track about the periphery of the drive wheel and the first and second idler wheels without transferring tension to the drive wheel axle.  
           [0004]    Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a perspective view of an agricultural tractor in accordance with the present invention having left and right front and left and right rear tracked suspensions, each supported on beams extending from the tractor;  
         [0006]    [0006]FIG. 2 is a top view of the tractor of FIG. 1, showing the track arrangement of the tracked suspensions, in an extended and retracted position, together with the differentials and transmission;  
         [0007]    [0007]FIG. 3 is an exploded perspective view of a typical tracked suspension of the tractor of FIGS. 1 and 2;  
         [0008]    [0008]FIG. 4 is a side view of a typical tracked suspension of the tractor of FIGS.  1 - 3  from the tractor side of the suspension;  
         [0009]    [0009]FIG. 5 shows a partial cross-sectional view of a drive wheel and drive wheel support for a typical suspension of the tractor of FIGS.  1 - 4 ; and  
         [0010]    [0010]FIG. 6 is a partial cross-sectional view of an idler beam and associated idler wheels and roller wheels. 
     
    
       [0011]    Before explaining at least one embodiment of the invention in detail it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    Referring to FIGS.  1 - 6 , an agricultural tractor  10  is illustrated supported by four tracked suspensions  12 ,  14 ,  16 ,  18 . Each of these suspensions is slidably mounted on two associated beams  20 , extending laterally outward from the vehicle at each suspension point. The beams are preferably disposed in a fore-and-aft arrangement such as that shown from right front suspension  12  in FIG. 1.  
         [0013]    Suspensions  12 ,  14 ,  16 ,  18  are each driven by drive axles  36 ,  38 ,  40 ,  42 . The left front and right front suspensions are coupled to a front frame  44 , the left rear and right rear suspensions are coupled to a rear frame  46 . The left and right front suspension beams are fixed with respect to and extend from front frame  44 . The left and right rear suspension beams are fixed with respect to and extend from rear frame  46 . A middle frame  48  is provided that is pivotally coupled to both front frame  44  and rear frame  46  via two articulation joints  50 ,  52 . Front articulation joint  50  pivotally couples front frame  44  and middle frame  48  and permits pivotal movement between the two, primarily in a horizontal plane. Rear articulation joint  52  is coupled between middle frame  48  and rear frame  46  and permits pivotal motion between middle frame  48  and rear frame  46 , primarily in a horizontal plane.  
         [0014]    Engine  54  is fixedly mounted to front frame  44  and drives the tractor  10 . It is coupled via a drive shaft  56  to transmission  58  which is driven by engine  54 . Transmission  58 , in turn, drives front drive shaft  60  and rear drive shaft  62 . Front drive shaft  60  is coupled between transmission  58  and front differential  64  and transmits power from transmission  58  to front differential  64  to drive front differential  64 . Rear drive shaft  62  is similarly coupled between transmission  58  and rear differential  66  and transmits power from transmission  58  to rear differential  66 .  
         [0015]    Front differential  64  drives laterally opposed left front suspension  12  and right front suspension  14 . Rear differential  66  drives laterally opposed left rear suspension  16  and right rear suspension  18 . Each of the three drive shafts  56 ,  60 ,  62  includes a flexible coupling  68 ,  70 ,  72  disposed in its length to permit relative motion between the differentials and the transmission and between the transmission and the engine to allow the front, middle and rear frames to pivot with respect to each other about their flexible couplings.  
         [0016]    Each of the four tracked suspensions  12 ,  14 ,  16 , and  18  are preferably the same, a single example of which is illustrated in FIGS.  3 - 6 . The discussion below is directed to single suspension, but applies equally to all four. The tracked suspensions on the left side are mirrored on the right side of the vehicle. Internal details of the front and rear differentials are disclosed in the application entitled “Track Vehicle Track Width Adjustment,” Attorney Docket No. 018483/0513, filed contemporaneously herewith and incorporated herein by reference for all that it teaches.  
         [0017]    Each tracked suspension includes a drive wheel assembly  100  mounted on an idler wheel carriage  102  which supports the idler and roller wheels. The idler wheel carriage is slidably supported on two beams  20  that extend laterally from the front or rear frame of the vehicle. Idler wheel carriage  102  is pivotally coupled to idler wheel assembly  104 .  
         [0018]    There are two beams extending from the left front of the vehicle which support the left front tracked suspension, two beams that extend from the from the right front of the vehicle that support the right front tracked suspension, two beams that extend from the left rear of the vehicle that support the left rear tracked suspension, and two beams that extend from the right rear of the vehicle that support the right rear tracked suspension.  
         [0019]    The drive wheel assembly includes a drive wheel  106  rotationally supported on a drive wheel support  108 . Drive wheel  106  includes a rim  110  that is bolted to drive wheel hub  112  which is supported in rotation by drive wheel support  108 . Drive wheel support  108  is fixedly mounted to idler wheel carriage  102 . Drive wheel  106  is supported on bearings  114 ,  116  and  118  which permit the drive wheel to rotate with respect to drive wheel support  108 . Drive wheel  106  is driven by ring gear  121  disposed between and fixedly mounted to inner and outer portions of drive wheel hub  112 . Drive wheel support  108  is fixedly mounted to idler wheel carriage  102  both on the inboard side and the outboard side of drive wheel  106 . On the inboard side, a downwardly extending flange  120  of drive wheel support  108  is fixedly mounted to inboard carriage support  122 . On the outboard side, a cylindrical portion  124  of drive wheel support  108  is fixedly mounted to a plate  126  extending upward from outboard carriage support  128 . Drive wheel support  108  also supports an outboard end of drive axle  130  in rotation. The outboard end of drive axle  130  is rotationally coupled to flexible coupling  132 , which in turn is coupled to stub axle  134 . A sun gear  136  is fixedly mounted to stub axle  134  and engages a plurality of planetary gears  138  (only one shown for convenience) that are supported in rotation by drive wheel support  108 . Planetary gears  138 , in turn, engage and drive ring gear  121 . In this manner, when drive axle  130  is rotated, it drives sun gear  136  in rotation, which drives planetary gears  138  in rotation, which drive ring gear  121  and therefore drive drive wheel hub  112  in rotation.  
         [0020]    Rim  110  includes to axially extending flanges  140  and  142  that support and drive track  144 . A recess  146  is located between the two flanges and receives lugs  148  extending inwardly from an inner surface of track  144 . A plurality of axially extending rods  150  extend between and are fixed at both ends with respect to axially extending flanges  140  and  142  and across the recess. Each of these rods  150  engage lugs  148  and drive track  144  about the periphery of drive wheel  106 .  
         [0021]    Idler wheel carriage  102  includes two laterally extending members (or brackets)  152 ,  154  that are coupled to beams  20  extending from the vehicle&#39;s frame. Inboard and outboard carriage supports  122  and  128  extend between and are fixedly mounted to laterally extending members  152  and  154 . Carriage support  122  is disposed inboard of drive wheel  106  and carriage support  128  is disposed outboard of drive wheel  106 . Carriage supports  122  and  128  define carriage pivots  156  and  158 , respectively, which pivotally support idler beam  160  of idler wheel assembly  104 . In this manner, idler beam  160  is permitted to rotate about a substantially horizontal pivotal axis  161  that extends laterally with respect to the vehicle and is defined by carriage pivots  156  and  158 . This pivotal axis is preferably disposed below the drive wheel&#39;s rotational axis, and above and between the rotational axes of idler wheels  162  and  164 . The pivotal axis preferably intersects the drive wheel. Each of the carriage pivots includes an inboard and outboard pin supports  166 ,  168  having holes through which pins  170  are inserted. Pins  170  extend laterally with respect to the vehicle, and are substantially coaxial. Pins  170  are supported at their inner and outer ends by their associated inboard and outboard supports. Each of the laterally extending members  152  and  154  have a plurality of holes  172  through which bolts  174  are inserted. Similarly spaced holes  176  are provided on beams  20  to receive these bolts. To adjust the position of the tracked suspension with respect to the vehicle, the bolts are removed and the suspension is slid inward or outward on beams  20  until a new set of holes on the laterally extending members and the beams are aligned. Surfaces  178  and  180  on laterally extending members  152 ,  154  are substantially parallel where intersected by a horizontal plane or planes and mate with similar parallel surfaces  182 ,  184  on beams  20 . At this point, the bolts are been reinserted in the newly aligned holes and tightened. To make this adjustment relatively trouble free, alignment marks are preferably provided on at least one beam and its corresponding tracked suspension for each of the four suspensions of the vehicle.  
         [0022]    Idler wheel assembly  104  includes an elongate horizontally extending idler beam  160  which supports idler wheels  162  and  164  (and roller wheels  186  and  188 ) in rotation. Pivot ears  191  and  193  are fixedly mounted to idler beam  160  and extend upwardly and outwardly to pivotally engage carriage pivots  158  and  156 , respectively. In this manner, idler wheel assembly  104  and its two idler and two roller wheels, pivot with respect to drive wheel  106  about the pivotal axis defined by carriage pivots  156  and  158 .  
         [0023]    Idler wheels  162  and  164  are biased away from each other by coil spring  190  disposed between the idler wheels and above idler beam  160 . Both idler wheels are in the form of two discs spaced apart from each other and sharing a common rotational axis. A pivotal link  192  is pivotally coupled to an end of idler beam  160 . Idler wheel  164  is rotationally coupled to pivotal link  192 , having a disk disposed on either side of pivotal link  192 . An elongate member  194  is pivotally coupled to an upper end of pivotal link  192  and biases pivotal link  192  outward with respect to idler beam  160 . The inner end of elongate member  194  abuts a first end of spring  190  which pushes the elongate member outward with respect to idler beam  160 . A second end of spring  190  abuts piston rod  196  which extends from and is biased toward spring  190  by hydraulic cylinder  198 . By filling hydraulic cylinder  198  with hydraulic fluid, piston rod  196  is forced out of the cylinder and toward the spring, compressing this spring and biasing idler wheel  164  outward. In this manner, track  144 , which extends about the periphery of idler wheel  162 , idler wheel  164 , and drive wheel  106 , can be appropriately tensioned or pre-loaded. Spring  190  is shrouded by spring housing  200  which extends around the outside of spring  190  on an upper surface of idler beam  160  and keeps dirt and other contaminants from filling the coils of spring  190 . Hydraulic cylinder  198  and spring housing  200  are fixedly mounted to an upper surface of idler beam  160 . Idler wheel  162  is supported by the other end of idler beam  160  and rotates with respect thereto. Roller wheels  186  and  188  are also mounted on bearings to idler beam  160  for rotation with respect to idler beam  160 . These wheels are disposed between idler wheels  162  and  164  and are also in the form of two discs, one disposed on either side of idler beam  160 .  
         [0024]    Thus, it should be apparent that there has been provided in accordance with the present invention an improved tracked suspension that fully satisfies the objectives and advantages set forth above. Although the invention has been described in conjunction with specific embodiments thereof, it is evidence that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.