Abstract:
A track driven device having a suspension system, positive hydraulic braking system, positive drive belt system and belt tensioning system for an improved ride, reducing belt wear and belt failure.

Description:
This application claims the benefit of U.S. Provisional application No. 60/392,155 filed on Jun. 27, 2002. 

   TECHNICAL FIELD OF THE INVENTION 
   The present invention relates generally to a wheel and belt or track driven device, and more particularly to a suspension system, positive hydraulical four wheel disc braking system, positive drive belt system, and belt tensioning device for wheel and belt devices. 
   DESCRIPTION OF THE RELATED ART 
   The popularity and nearly universal acceptance of wheel propulsion systems rather than track systems in agricultural use has stemmed primarily from the past track system&#39;s “rough ride,” relatively higher noise levels, higher initial cost, lower maximum travel speed and inability to transport itself on improved road surfaces without inflicting damage thereto. 
   Present day track systems have overcome the majority of these objections by utilizing a propulsion system in which a continuous rubber belt encompasses a pair of wheels. Problems encountered in actually reducing such belt systems to practice include how to drive such belt with the entrained wheels, how to maintain structural integrity of the belt and wheels, how to encompass the belt in lateral alignment with the wheels when the wheels are subjected to large lateral loads, how to provide long life for the belt and wheels, how to accommodate debris ingested between the wheels and belt while maintaining the driving relationship therebetween without damaging either, how to preclude the belt from coming off the wheels, how to brake the belt and wheel systems, how to preclude the belt from coming off of the wheels during braking, and how to maintain proper belt tension during braking and turning. 
   Elastomeric belt systems have been used but they operate such that the elastomeric belt needs to be highly tensioned about a pair of wheels to provide frictional engagement with the wheels. Interposed between the wheels is a roller support system for distributing a portion of the weight and load imposed on the machine frame to the belt. The roller support system includes a mounting structure, which is pivotally connected to the machine frame and, therefore, free to rotate relative to the machine frame to accommodate undulations in the terrain surface while maintaining uniform ground pressure. 
   The frictional elastomeric drive belt system requires a higher belt tension than is required for a positive drive belt system. This higher belt tension causes premature failure of the belt. Further, the elastomeric suspension system only provides for a limited amount of suspension travel. This allows for an exorbitant amount of force being transferred to the frame and operator cabin when crossing rough terrain. Friction drive technology has many disadvantages. For example, track failure is common in wet and rocky conditions, and the track tends to fall off during braking and turning. 
   Current positive drive belt systems usually have only one wheel positively engaged with the belt causing premature wear when braking occurs. Further, known positive drive belt systems provide insufficient recoil to allow foreign material to escape from the belt system. 
   In addition, track driven systems are “hard” riding. Specifically, track driven systems lack suspension systems entirely or have primitive suspension systems resulting in a rough ride. 
   The present invention is directed to overcome one or more of the problems as set forth above. 
   SUMMARY OF THE INVENTION 
   The present invention includes a novel independent suspension for use in conjunction with a positive drive belt system, belt tensioner adapted for use with a positive drive belt system, drive wheel for use in conjunction with a positive drive belt system, and positive braking system for use with a positive drive belt system. 
   There present invention also includes a plurality of middle rollers for use with a positive drive belt system, wherein the group of middle rollers aid in the support of the wheel and belt device and provides a low ground pressure distribution. 
   The present invention further includes an independent suspension system, a positive drive system, and a belt tensioner system for use on a track system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein: 
       FIG. 1  is a side view of a lower section of a track driven device having a suspension system, belt tensioner system, positive braking system and positive drive system thereon according to the present invention; 
       FIG. 2  is a side view according to  FIG. 1  but with phantom lines illustrating hidden components of the track driven device; 
       FIG. 3  is a front view of a wheel for the track driven device shown in  FIGS. 1 and 2 ; 
       FIG. 4  is a side view of the wheel shown in  FIG. 3  for the track driven device; 
       FIG. 5  is an exploded, side view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 1 ; 
       FIG. 6  is an exploded, top view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 1 ; 
       FIG. 7  is a front view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 1 ; 
       FIG. 8  is a front view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 5  but with phantom lines illustrating hidden components of the track driven device; 
       FIG. 9  is a top view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 1 ; 
       FIG. 10  is a top view of one side of the track driven device having the suspension system, belt tensioner system, positive braking system and positive drive system thereon according to  FIG. 9  but with phantom lines illustrating hidden components of the track driven device; 
       FIG. 11  is a side view of the lower section of the track driven device with cutouts showing a hydraulically operated four-wheel disc braking system thereon; 
       FIG. 12  is a side view according to  FIG. 11  but with phantom lines illustrating hidden components of the track driven device; 
       FIG. 13  is a top view of one side of the braking system according to  FIG. 9  with cross-sections through the wheels; 
       FIG. 14  is a top view according to  FIG. 13  but with phantom lines illustrating hidden components of the track driven device; and 
       FIG. 15  is a top view according to  FIG. 12  isolating one of the disc brakes. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. Additionally, the present invention contemplates that one or more of the various features of the present invention may be utilized alone or in combination with one or more of the other features of the present invention. 
   Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIGS. 1 &amp; 2  show a lower section  11  of a track driven device  10 . The track driven device  10  has two belts  13  each encompassing an idler wheel  14  and a drive wheel  15 . The drive wheels  15  drive the belts  13 . The drive wheels  15  are powered by an engine, a transmission system, and other components substantially similar to a Caterpillar® brand Challenger system. 
   Referring now to  FIGS. 3 &amp; 4 , the idler wheels  14  and the drive wheels  15  are shown. In the preferred embodiment, the idler wheels  14  are 26 inches in width by 41.05 inches in diameter, and the drive wheels  15  are 29 inches in width by 41.05 inches in diameter, although such dimensions are not a limtation of the present invention. The idler wheels  14  and the drive wheels  15  have front windows or openings  16  in the circumference. In an alternative embodiment, side windows (not shown) are provided in the side of the wheels  14 ,  15 . The windows  16  allow snow, ice, soil, rocks and other foreign matter to pass freely during operation. In addition, the front windows  16  are used to receive lugs  18  on belts  13 , best shown in  FIGS. 1 &amp; 2 . The lugs  18  enter the front windows  16  in much the same way that meshing gears interact with one another. As the drive wheels  15  rotate, the lugs  18  mate with the front windows  16 , and the belts  13  are positively driven by the drive wheels  15 . In an alternative embodiment, there are no windows  16  in the wheels  14 ,  15 ; rather, the wheels  14 ,  15  and the lugs  18  mate in much the same way as two gears mesh. 
   A suspension system  12  is operatively mounted to each side of the lower sections  11  of the track driven device  10 . The suspension systems  12  provide independent suspension for the belts  13 . The suspension systems  12  absorb load stresses and allows the idler wheel  14  to move vertically when an object is encountered providing a more comfortable, controlled and safe ride while prolonging the life of the track driven device  10 . 
   Although it is understood that the track driven device  10  has two belts  13  and two suspension systems  12 , the description that follows describes one side of the track driven device  10 . Referring in combination to  FIGS. 1 &amp; 2 , the suspension system  12  has a lower suspension bracket  19 . The lower suspension bracket  19  has front ends  23  that are operatively connected to a frame  20  of the track driven device  10  via a suspension cylinder  21  and upper suspension bracket  22 . The suspension cylinder  21  has a first end  50  operatively attached to the lower suspension bracket  19  and a second end  51  operatively attached to the upper suspension bracket  22 . The upper suspension bracket  22  is operatively attached to the frame  20 . 
     FIGS. 5 and 6  show the idler wheel  14  rotatably mounted between a first side  28  and a second side  29  of the lower suspension bracket  19  via an axle  30 . The lower suspension bracket  19  has distal ends  24  operatively attached to a main frame  25 . The main frame  25  is pivotally mounted to a track frame pivot  26 . The track frame pivot  26  is operatively attached to the main frame  25 . The track frame pivot  26  extends from one side of the main frame  25  to the other side for each suspension system  12 . The track frame pivot  26  is operatively connected to the main frame  25  via a bearing cup  38  and a bearing cap  39 . Ends of the track frame pivot  26  ride in the bearing cup  38  and the bearing cap  39 . To hold the track frame pivot  26  in place, the bearing cap  39  is bolted over the track frame pivot  26  to the bearing cup  38 . In the preferred embodiment, the bearing cap  39  and the bearing cup  38  are lined with neoprene rubber. The track frame pivot  26  is preferably a steel bar but other materials could be substituted. 
   The suspension cylinder  21  is generally readily available and one such cylinder is made by Caterpillar Industrial Products, Inc. in Peoria, Ill. under Part No. 151-1179. The suspension cylinder  21  is hydraulically connected to an accumulator  27  via a suspension pressure line  49  to provide suspension travel and load support. Preferably, the accumulator  27  is a high capacity nitrogen accumulator. The accumulator  27  is available over-the-counter and one such accumulator is made by Caterpillar Industrial Products, Inc. in Peoria, Ill. under Part No. 7U5050. It is obvious to those with ordinary skill in the art that other cylinders and accumulators could be substituted for these specific cylinders and accumulators. 
   When the idler wheel  14  encounters an object, the idler wheel  14  moves upwardly and the suspension cylinder  21  absorbs the initial shock of the object. During this upward movement, the suspension system  12  pivots about the track frame pivot  26 . On the downward movement, the suspension cylinder  21  precludes a rapid descent for a smooth ride.  FIGS. 9 and 10  show a roller bearing or side thrust bearing  52  operatively attached between the lower suspension bracket  19  and an inside support  53  to prevent side bearing thrust movement. The side thrust bearing  52  allows the lower suspension bracket  19  to move up and down pivoting about the track frame pivot  26 . The side thrust bearing  52  moves up and down and keeps the track frame from moving. 
   Referring now to  FIGS. 1 ,  2 ,  9  and  10 , a track belt tensioner  31  is used to maintain tension on the belt  13  between the idler wheel  14  and the drive wheel  15 . The amount of tension in the belt  13  is determined by the horizontal distance between the idler wheel  14  and the drive wheel  15 . The drive wheel  15  is rotatably mounted about a powered axle  54 , and the idler wheel  14  is rotatably mounted to a yoke  80  via the axle  30 . 
   Referring now to  FIGS. 5 &amp; 6 , the yoke  80  includes a first axle bracket  81  and a second axle bracket  82  for supporting the rotating axle  30 . A yoke housing  83  is operatively attached to the first and second axle brackets  81 ,  82 . The yoke  80  has guide member  84  moveably mounted to a top surface of the main frame  25 , and the yoke  80  moves horizontally along the main frame  25  when urged by a track tension cylinder  32 . The yoke  80  has a first track guide  85  and a second track guide  86  that surrounds the main frame  25 . The first and second track guides  85 ,  86  are attached to the first and second axle brackets  81 ,  82  and the yoke housing  83 , and the first and second track guides  85 ,  86  keep the yoke  80  on the main frame  25  during the back and forth horizontal movement. The idler wheel  14  and the yoke  80  move along a horizontal axis via the track tension cylinder  32 . 
   A piston rod  90  from the track tension cylinder  32  extends moving the idler wheel  14  and the yoke  80  backward and forward, thereby adding tension on the belt  13 . When the piston rod  90  is retracted, the idler wheel  14  and the yoke  80  are moved closer to the drive wheel  15 , thereby reducing the tension on the belt  13 . The idler wheel  14  is encapsulated in the lower suspension bracket  19 , and the lower suspension bracket  19  keeps the belt  13  from falling off of the wheels  15 ,  15 . During the extension and retraction of the piston rod  90  from the track tension cylinder  32 , the yoke  80  slides on the track frame  20 . Once again, the position of the yoke  80  along with the idler wheel  14  is adjusted horizontally via the track tension cylinder  32  to adjust the belt  13  tension. In addition to adjusting the horizontal position of the yoke  80  to adjust the belt  13  tension, the lower suspension bracket  19  pivots in the vertical direction as previously described. The lower suspension bracket  19  pivots about the track frame pivot  26  but does not move horizontally with the yoke  80 . 
   The combination of the suspension cylinder  21  and the track tension cylinder  32  absorbs the shock placed on the idler wheel  14 . This shock absorption prevents the belt  13  from tearing and falling off the idler wheel  14  and the drive wheel  15  and also provides a smooth ride. 
   The track belt tensioner  31  has the track tension cylinder  32 . The track belt tensioner  31  is operatively mounted to the frame  20  via a cylinder bracket  33 . The cylinder bracket  33  is welded to the lower suspension bracket  19 . A first end of the track tension cylinder  32  is pinned to the cylinder bracket  33 . A second end of the track tension cylinder  32  has the piston rod  90  for adjusting the yoke  80  and the idler wheel  14  in the horizontal direction. The piston rod  90  is operatively mounted to a piston cylinder bracket  34 . In the preferred embodiment, the piston cylinder bracket  34  is triangular as viewed from the side and welded to the frame  20 . The track tension cylinder  32  is hydraulically connected to a tension accumulator  35  to provide belt  13  tensioning and a smooth ride. The tension accumulator  35  is preferably mounted above the track tension cylinder  32 . It is important to note that in the preferred embodiment, there is one tension accumulator  35  and one track tension cylinder  32  per belt  13 ; however, the track tension cylinders  32  could be connected to one accumulator. In yet another embodiment, the track tension cylinders  32  and the suspension cylinder  21  are connected to one accumulator. 
   The tension accumulator  35  is hydraulically connected to the track tension cylinder  32  via a hose  36 . The track tension cylinder  32  is, preferably, a tow large-bore, long-stroke cylinder to provide excellent cushioning and dampening. J. R. Schneider Company, is located at 849 Jackson Street, Benicia, Calif., 94510 and provides a suitable cylinder under the name BAILEY330™ Part No. 216-141. Preferably, the tension accumulator  35  is a high capacity nitrogen accumulator. The tension accumulator  35  can be purchased from DYNA TECH, A Neff Company, located at 1275 Brume Elk Grove Village, Ill., 60007, and provides a suitable accumulator under Part No. A2-30E-OSG-BTY-MIO. It is obvious to those with ordinary skill in the art that other cylinders and accumulators could be substituted for these specific cylinders and accumulators. 
   The tension on the belt  13  needs to be set after the belt  13  is assembled on the idler wheel  14  and the drive wheel  15 . To set the tension, hydraulic fluid is added to the track belt tensioner  31  until the gauge on the track tension cylinder  32  reads 10,000 pound per square inch. The tension accumulator  35  is pre-charged at 600 pounds per square inch with nitrogen. 
   The combination of the suspension system  12  and the track belt tensioner  31  provides independent track suspension. When an object is encountered by the idler wheel  14 , the idler wheel  14  is allowed to move vertically and horizontally because of the suspension system  12  and the track bolt tensioner  31 , respectively. 
   Referring now to  FIGS. 1 ,  2  and  5 , middle rollers  40  are shown. The middle rollers  40  are rotatably mounted to the frame  20  and fixed; the middle rollers  40  are not capable of moving up and down or back and forth. In the preferred embodiment, there are eight middle rollers  40  per belt  13 . There are four middle rollers  40  along the outside of the belt  13 , and there are four middle rollers  40  along the inside of the belt  13 . The eight middle rollers  40  are weight bearing and, thus, provide a low ground pressure design and are load bearing rollers. The middle rollers  40 , preferably, are 21 inches in diameter by 2-5 inches in width fork truck wheels press on wheels. Suitable middle rollers  40  are available through Caterpillar Industrial Products, Inc. under Part No. 120-5746. In arctic use, the ground contacting surfaces of the middle rollers  40  are coated with rubber. Normally, the middle rollers  40  are made with solid rubber. The middle rollers  40  are beveled on one side to match the bevel of the cog of the rubber track. 
   Referring now to  FIGS. 11-15 , a braking system  41  for positive braking is shown. The braking system  41  has calipers  42 , preferably four. The calipers  42  are used on each of the four wheels  14 ,  15 . 
   There are two calipers  42  for each belt  13  system (i.e., one caliper  42  for the idler wheel  14  and one caliper  42  for the drive wheel  15 ). The two calipers  42  operatively controlling the two idler wheels  14  are operatively mounted to the yoke  80 . The two calipers  42  operatively controlling the two drive wheels  15  are mounted to the main frame  25 . Large diameter discs  43  are operatively mounted to the idler wheels  14  and the drive wheels  15 . The calipers  42  act on or contact the discs  43  causing the track driven device  10  to slow or stop. Dust covers  44  enclose the calipers  42 . The braking system  41  results in positive braking due to the combination of lugs  18  on the belts  13  mating with the idler wheels  14  and the drive wheels  15 . The lugs  18  enter the front windows  16  of the idler wheels  14  and the drive wheels  15  in much the same way that meshing gears interact with one another. As the calipers  42  work on the discs  43 , the idler wheels  14  and the drive wheels  15  are slowed as a result of the front windows  16  acting on the lugs  18  thereby positively slowing or stopping the belts  13  from rotating about the idler wheels  14  and the drive wheels  15 . 
   In the braking system  41 , hydraulic pumps  47  supply hydraulic fluid to a master cylinder  46  via brake lines  45 . The hydraulic pump  47  is a mechanically driven hydraulic pump. Supply lines  48  provide pressurized hydraulic fluid from the master cylinder  46  to the calipers  42 . The operation of the braking system  41  is readily apparent by the elements previously described. 
   Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not limited except by the following claims.