Abstract:
A vehicle wheel assembly is provided which includes a vehicle frame having a first axle, a wheel assembly having a housing with an aperture engaging the first axle and enabling the wheel assembly to pivot in a first plane about a first axis formed by the first axle. A cylindrical member is carried by the housing of the wheel assembly, the cylindrical member and housing are arranged perpendicular to the first axle. A first wheel is pivotably connected to a first portion of the cylindrical member and a second wheel is pivotably connected to a second portion of the cylindrical member. The first wheel and second wheel independently pivot in a second plane about a second axis formed by the cylindrical member. The first axis is arranged perpendicular to the second axis and the first plane is arranged perpendicular to the second plane.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/708,062, filed on Feb. 18, 2010, which is a continuation of U.S. patent application Ser. No. 09/847,264, filed on May 2, 2001, now U.S. Pat. No. 7,740,084, which claims priority from U.S. Provisional Patent Application Ser. No. 60/201,085, filed May 2, 2000. The disclosures of the prior applications are hereby incorporated in their entirety by reference. 
    
    
     BACKGROUND 
     This disclosure relates to an improved agriculture implement frame and cart. In particular, an improved foldable and stackable frame for supporting planters, sprayers, or similar devices is disclosed. A novel track design that is well-suited for transporting the foldable-stackable frame is also disclosed. A new and improved design for folding wheels that are used to support the free ends of the frame is also disclosed. 
     Foldable frames that are used to support agricultural tools, such as planters, sprayers, or similar tools are well-known and widely used. Typically, the frames are attached to the rear of a tractor, utility cart or similar transportation vehicle. The frames have long booms, or wings, that can be adjusted into an extended working position that is generally transverse to the direction of travel of the tractor. The extended wings are too wide to permit convenient transportation when moving from field to field, or from storage to the field. Therefore, typically, the wings will adjust into a transport position. In the past, this has generally been accomplished by either folding the wings forward along the sides of the transportation vehicle, or by stacking the wings at the rear of the transportation vehicle. Folding the wings forward along the side of the transportation vehicle still leaves the overall width wider than the transportation vehicle, because the tools are still located outside the wheelbase of the transportation vehicle. Stacking the wings may adversely affect the handling characteristics of the transportation vehicle. The present invention relates to a unique design that permits the wings to be folded forward, and then stacked, so as to make the overall width narrower than if the wings were simply folded forward. Also, the handling characteristics of the transportation vehicle are improved over what they would be if the wings were merely stacked. Furthermore, the arrangement of the wings in the transport position leaves an unusually large space in the center of the transportation vehicle for storage of such things as a fertilizer tank, extra seed, or similar items. 
     The wings may be mounted on a utility cart that can be pulled behind a tractor or other pulling device. These utility carts can take many different forms. Most commonly they have a frame on which the wings can be mounted, and wheels that engage the ground. It is also known to substitute tracks or belts for the wheels. One difficulty with these tracks or belts is that the front and rear of the tracks or belts tend to stay in angular alignment with each other in terms of both pitch and roll, which prevents the tracks from closely following the contours of the ground. The present invention utilizes idler wheels mounted on tandem arms to support the track. The idler wheels pivot independently from each other, and allow the track to twist and bend to match the contours of the ground. 
     The handling characteristics of the utility cart and tractor combination can be improved if the weight distribution between the cart and the tractor is adjustable. The utility cart of the present invention may include adjustable hitch plates that allow the weight distribution to be varied. 
     It is common to provide the booms or wings with support wheels near the outboard end of the wings to provide support for the wings when in use. This disclosure discusses a unique and improved design for folding these wheels into a transport position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a preferred embodiment of foldable wings mounted on a utility cart according to the present invention showing the right side wing folded out in working position, and the left side wing is folded in. 
         FIG. 1A  is a top view of an alternative embodiment of the present invention that uses a two-section wing structure and includes foldable wheels on the outboard end of each wing. 
         FIG. 2  is a partial top view of the rear portion of the embodiment shown in  FIG. 1 , with the implements removed from the wings. 
         FIG. 3  is a partial top view close-up of the embodiment shown in  FIG. 2 . 
         FIG. 4  is a partial rear view of the embodiment shown in  FIG. 2 . 
         FIG. 5  is a rear elevation showing a preferred embodiment of the rear stack assembly in the stacked position. 
         FIG. 6  is a partial top view close-up of the front portion of the embodiment shown in  FIG. 2 , with both wings in the folded position. 
         FIG. 7  is a front elevation of front stacking assembly shown in  FIG. 6 . 
         FIG. 8  is a front elevation showing front stack assembly of  FIG. 7  in the stacked position. 
         FIG. 9  is a top view of the embodiment of  FIG. 1A  in a transport position. 
         FIG. 10  is a side elevation of the frame and cart in the stacked transport position. 
         FIG. 11  is a partial cut-away side elevation of the embodiment of  FIG. 10  adjusted to a lowered position. 
         FIG. 12  is a front view of the preferred embodiment of  FIG. 1  in a stacked transport position. 
         FIG. 13  is a rear view of the preferred embodiment of  FIG. 12  in a stacked transport position. 
         FIG. 14  is a partial top view of the right wing pivot and support assembly of the preferred embodiment of  FIG. 1 . 
         FIG. 15  is a partial rear view of the wing pivot and support assembly of  FIG. 14 . 
         FIG. 16  is a partial rear view of the wing pivot and support assembly of  FIG. 14  in a folded position. 
         FIG. 17  A is a side elevation of a preferred embodiment of the wing wheel assembly in lowered position. 
         FIG. 17B  is a side elevation of the wing wheel assembly of  FIG. 17A  in tucked transport position. 
         FIG. 17C  is a top view of the wing wheel assembly of  FIG. 17A . 
         FIG. 17D  is a side elevation of a preferred embodiment of a wing wheel lift bracket. 
         FIG. 18  is a partial cut-away top view of preferred embodiment of utility cart showing left side track assembly. 
         FIG. 19A  is a partial top view showing left front cart and hitch. 
         FIG. 19B  is a partial top view close-up showing details of  FIG. 19A . 
         FIG. 20  is a front elevation of an embodiment of a utility cart. 
         FIG. 21  is a rear elevation of an embodiment of a utility cart. 
         FIG. 22  is a side elevation of utility cart. 
         FIG. 23  is a top close up view of belt tension tube. 
         FIG. 24  is side view of a preferred embodiment of a lower tandem arm that accommodates both pitch and roll changes. 
     
    
    
     DETAILED DESCRIPTION 
     Shown generally in the figures is an improved utility cart  200  for use in association with an improved folding and stacking agricultural implement frame  300 . The utility cart is suitable for being pulled behind a tractor or other similar pulling vehicle. With respect to the figures, right and left designations refer to viewing the cart  200  and implement frame  300  from the rear looking in the direction of travel. The right and left side of this design are mirrored images of each other; therefore, the description will concentrate primarily on the right side. 
     The implement frame  300  is the type that has wings  25 , 26  that fold outward to extend transversely to the direction of travel of the tractor so that several rows of crops can be worked on with a single pass.  FIG. 1  shows a top view of the cart  200  and implement frame  300  combination with a right wing  25  in working position and the left wing  26  still in folded position. Implement frame  300  can have various implements attached for numerous uses such as fertilizer spraying, pesticide spraying, planting, and other uses. For these illustrations, planter units  202  are shown. The wings  25 ,  26  can be varied in length to accommodate different row spacings and number of rows. 
     As best seen in  FIG. 2 , the wings  25 ,  26  comprise a wing tool bar  204  and a wing support bar  206 . The planter units  202 , or other implements, attach to the wing tool bar  204 . According the embodiment shown in  FIG. 2 , a rear tool bar  78  is attached to the rear of the cart  200  to permit attachment of implements. When in full working position, both wings  25 ,  26  are folded out or back perpendicular to the main lift arms  56 ,  57  and in line or parallel to plane of the rear tool bar  78 . Alternatively, the rear tool bar  78  may be eliminated, and the left and right wings  25 ,  26  can be extended inboard. ( FIG. 1A ). In planting position, wing lock arms  29 ,  30  are unfolded and held in a straight or slightly overcentered position by the wing lock arm hydraulic cylinder  28 . Front wing lock arm  30  is attached to a ball swivel in a plate  33  extending from front wing hold assembly  51 . Ball swivel and plate  33  are almost directly in a direct line with the pin  19  in the wing pivot assembly  90 . This allows the entire wing  25  to go up and down following the terrain without binding. 
     The raised/lowered position is controlled by two hydraulic cylinders  67 ,  68  which extend and raise main lift arms  56 ,  57 . ( FIG. 13 ). The right  67  and left  68  main lift cylinders are attached to main frame rails  60 ,  61  by plates of steel  69 ,  70  on each side of the cylinder with pin  71  placed in holes in plates  69 ,  70  and through round sleeve on butt of cylinder forming a pivot. Ram of cylinders  67 ,  68  attach to a pivot plate  81 ,  FIGS. 10 &amp; 11 , which is optional and could be attached directly to main lift arms  56 ,  57 . But pivot plate  81  acts as a manual extra flex in uneven terrain. Raising and lowering can be accomplished by placing a lift wheel behind rear main support frame  1  and/or rear tool bar  78  in many different configurations. 
     Wheel lift assemblies  400  (shown in  FIG. 1A  and further detailed in  FIG. 17 ) are placed on the outboard end of wings  25 ,  26 . Placing of assembly or type of assembly can vary. The wheel assembly ( FIG. 17 ) preferably raises and lowers simultaneously with main frame. These wheel lift assemblies are described in greater detail below. 
     To get to transport position, wings  25 ,  26  are folded in. The left side is shown in folded position in  FIG. 2 . Hydraulic wing fold cylinder  23  ( FIG. 14 ), is retracted, wing  25  is pivoted on pin  17  of wing pivot assembly  90 . Pin  17  also extends through wing pivot support assembly  22  to form a pivot. Part of wing pivot assembly  90  is wing flex sleeve  21  ( FIGS. 14 and 16 ). Pin  19  extends through sleeve  20  and through wing flex sleeve  21  and through round sleeve  39  in wing  25  ( FIG. 15 ). This allows wing to pivot up and down to follow contours of land or whatever application requires. Before hydraulic wing fold cylinder  23  can retract, the wing lock arm hydraulic cylinder  28  has to retract and begin folding the lock arms  29 ,  30  inboard. A hinge allows lock arm  29 ,  30  to pivot in a horizontal plane with wing  25  ( FIG. 2 ). 
     The wing fold cylinder  23  attaches to a plate extending out from wing pivot assembly  90  ( FIG. 14 ). The cleaves end of the butt of the cylinder attaches to a welded ball swivel  82  in the plate. This allows for the wing to flex up and down. The ram end of the cylinder attaches to a ball swivel in flex arm  24  which pivots on a pin  84  which is between two plates of steel with holes forming hinge. This also allows for wing flex without the cylinder extending or retracting during field operations, which is optional in the design. 
     When cylinder  23  is fully refracted, the wing frame  25  is over and up to notch in front wing hold assembly  51 . This can have many different designs to hold wings to the assembly  51  but had to be able to lift the wing  25  in an arcing vertical movement. ( FIGS. 6 ,  7  and  12 ). 
     When wing  25  is on the front wing hold assembly  51  the wing lock arms  29 ,  30  are fully inverted by the wing lock hydraulic cylinder  28  so they are parallel or close to parallel to the wing  25 . Then the stacking hydraulic cylinders  15 ,  50  can be extended simultaneously using rephasing cylinders or master slave cylinder. The butt end of cylinder has a sleeve or cleaves so it may pivot as cylinder is actuated. It is held by a pin  9 ,  53  which passes through a sleeve or holes in the inboard ends of the rear and front bottom stacking arm  4 ,  75  and also through holes or bushings in the steel plates that form rear and front main support frames  1 ,  2 . The cylinder ram pivot  87 ,  88  is at the end of the ram of the stacking cylinders  15 ,  50 . It can be a sleeve or cleaves which is held by a pin  38 ,  54  which passes through welded sleeves  36 ,  37  and  44 ,  45  which are attached by metal plates welded to the top of the stacking arm  3 ,  74  shown best in  FIGS. 3 ,  4 ,  6  and  7 . 
     The top stack arms  3 ,  74  are attached by pin  10 ,  52  which extends through sleeve or holes in the stack arms  3 ,  74  and through a hole or bushing in the upright plates of steel that form the main support frame  1 ,  2 . 
     The outboard ends of both the top and bottom stack arms, front  74 ,  75  and rear  3 , 4  have round sleeves and  11 ,  13  and  12 ,  14  or holes which pins  34 ,  35 ,  55 , and  89  extend through. In the front, stack arms  74 ,  75  pin  55 ,  89  also extend through holes or bushings in the front wing hold assembly  51   FIGS. 6 &amp; 7 . The rear stack arms  3 ,  4  are similar to the front. Pin  34 ,  35  extends through hole or bushings in the wing support pivot assembly  22 . 
     Both front and rear, top and bottom stack arms  3 ,  4  and  74 ,  75  are similar in length and hole or bushings in main support frames  1 ,  2  and front wing hold assembly  51  and wing pivot support assembly  22  are matched in these illustrations which keep the wing frame  25  perpendicular to the main frame through the entire vertical arc of the stacking movement. By varying the length between the pivot points, frame, top stack and bottom stacking arms, the angle of the wing frame could be pitched up or down through the vertical arc of the stacking arm and would accomplish the same basic principle. 
     When the stack cylinders  15 ,  50  are extending close to the top of the arc, they continue to pass top of center and over center ( FIGS. 5 ,  8  and  9 ). Gravity helps to keep the wings  25 ,  26  in the transport position even though there is still pressure via trapped oil within the stack cylinder which will also hold wings  25 ,  26  in transport position ( FIG. 10 ). 
     Going over center is not totally necessary and in some uses other frames may not be designed this way, which would increase the distance between the wings  25 ,  26  in transport position or to narrow main support frame so that total transport width may be narrower. 
     Unstacking the wings  25 ,  26  is performed by applying pressure to the hydraulic oil on the ram side of the stack cylinder  15 ,  50  so that they retract simultaneously until they are totally retracted and the stack arms  74 ,  75  and  3 ,  4  are horizontal ( FIGS. 4 &amp; 7 ). The bottom stack arms  75 ,  4  rest on the retracted stack cylinder  15 ,  51  and also steel plate  72 ,  73  that extend out from the bottom of the main support frame  1 ,  2  ( FIGS. 12 ,  13 ). Also, the tube that connects both sides of stack arms may be welded in a manner that they rest on the vertical plates that form main support frame  1 ,  2 , but in an area where they do not conflict with the stack cylinders  15 ,  51  in any of their range of arc. 
     The front wing hold assembly  51  must be slightly lower than the height of the wing frame  25  at the point where they connect ( FIG. 7 ). Now pressure can be applied to the hydraulic oil on the ram side of the wing fold cylinder  23  which extends it out and pushes the flex arm  24  against the unfolding stop  27  which is made by welding steel plates to the wing frame  25 . As the wing fold cylinder  23  continues to extend, the wing  25  pivots on pin  17  in the welded sleeves  18  of the wing pivot assembly  90  ( FIG. 15 ). The wing pivot assembly  90  is also connected by pin  17  to the wing pivot support assembly  22 . The wing lock cylinder  28  is also extending at the same time as wing fold cylinder  23 . When the wing  25  is in the working position ( FIG. 2 ) shown perpendicular to main lift arm  56  the wing lock cylinder  28  is fully extended and front lock arm  30  and rear lock arm  29  at center lock arm hinge  32  are straight or slightly past center. The unfolding of the wings  25 ,  26  should be performed with the planting units off the ground so not to create more resistance. 
     The main frame has many parts. The base frame  60 ,  61  rest on the frame rails  65 ,  66  of the utility cart. As an alternative, these frame rails  65 ,  66  may be mounted so that their tops are angled slightly inwardly. The base frame members  60 ,  61  must be correspondingly angled in this instance, as shown in  FIGS. 20 and 21 . Angling the frame rails inward facilitates mounting the base frame  60 ,  61  because it will help align the frame rails with the base frame  60 ,  61  if they are slightly off alignment. The leading edges of the frame rails  65 ,  66  may be similar angled in order to help base frame  60 ,  61  align both side-to-side and front-to-rear. When using a removable cart assembly (these drawings use a tracked cart for the carriage) the base frame  60 ,  61  and frame rails  65 ,  66  could be combined for the purpose of a permanent carriage. 
     The base frame  60 ,  61  is attached to the front main support frame  2  by pins  79 ,  92  which extend through plates of steel welded to the bottom of the main support frame. 
     Pins  79 ,  92  extend through holes in plates of steel and then through a hole or sleeve in the base frame  60 ,  61 . This forms a pivot or hinge. ( FIGS. 11 ,  12 ). 
     The front main support frame  2  is attached to the main lift arms  56 ,  57  near the front of frame. These positions can be varied to meet different lengths of wings or different carriage lengths or many other needs. 
     The rear main support frame  1  is mounted at the rear main lift arms  56 ,  57  ( FIGS. 10 ,  11 ). The main support frames  1 ,  2  must be parallel. Further, their vertical planes must be parallel [though not necessarily perpendicular to main lift arms  56 ,  57  or base frame  60 ,  61 ] so that front  74 ,  75  and rear  3 , 4  stacking arms in their arcing movement remain parallel. 
     The main lift arms  56 ,  57  and base frame  60 ,  61  can be designed in many different ways and the design shown in  FIG. 11  is not the only pertinent design. The main lift arm  56 ,  57  must be strong enough to carry all the weight of the wing frames  25 ,  26  and attachments to the wings. 
     Behind the rear main support frame, this design uses an implement tube  78  for mounting units. 
     The base frame  60  rests on the cart frame  65  and is attached as previously described. Extending down parallel from base frame rail  60  is a plate of steel which extends down to the sleeve  91  ( FIG. 13 ) on the butt end of the main lift cylinder  67 . Welded to this plate is another plate which is perpendicular to the first. Welded to this plate is another plate perpendicular to the last that forms a “U” shape. This assembly forms a support for the main lift cylinder  67 . Pin  71  extends through holes or bushings  69 ,  70  in the steel plates and through the sleeve  91  on the butt end of the main lift cylinder  67 . Pin  71  is at a 90 degree angle to the base frame allowing the main lift cylinder to pivot parallel to the base frame  60 . On the extended plate that is 90 degrees from the base frame rail, a horizontal plate should be welded in a manner that it rest and gain support from the rear main carriage axle  58 . Also sleeve  91  should be slightly oversized to allow for some side to side sway. The above described supporting of the main lift arm cylinders  67 ,  68  can be accomplished by other methods. 
     The wing wheel lift assembly illustrated in  FIGS. 17A-D  is unique and is well suited for this tool bar design but is not the only acceptable method of raising and lowering the wing frame  25 ,  26 . 
     The wing wheel lift assemblies for wings  25 ,  26  are identical, so only one will be described here. The leading wheel  141  and the trailing wheel  142  both caster or swivel 3 60 degrees in either direction. The leading and trailing wheels  141 ,  142  are illustrated using a standard fork type mounting  143 ,  144 . A single offset arm and spindle caster could be used. The leading wheel  141  and fork  143  swivels on a vertical shaft  145  that extends through a round sleeve  147  which is attached to an outboard bracket  151 . The outboard and inboard brackets  151 ,  152  are mirror images and both are somewhat “U” shaped. This allows the leading wheel hydraulic cylinder  154  space for its movement. These brackets  151 ,  152  are connected to upper and lower parallel link arms  149 ,  150  by pins  153 A-D which extend through holes or round sleeves in the ends of the parallel link arms  149 ,  150  and through holes in the outboard and inboard brackets  151 ,  152 . In these illustrations, the butt end of the leading wheel hydraulic cylinder  154  pivots on pin  153 D and the ram end pivots on pin  153 B. The end of the cylinder could be attached and pivot on separate pins and still conform to this design. This type design uses parallel link arms to keep the caster wheel at a constant vertical angle which is not unique. What is unique is that the inboard bracket  152  also pivots or swings in and out perpendicular to the frame on pin  153 D. (This pivot could be placed in a different pin or sleeve but still conform to this design.) ( FIGS. 17  A &amp; B). 
     Pin  153 D extends through holes in plates of steel which are vertical and are outside of upper and lower parallel link arms  149 ,  150  and are spaced far enough apart and in front of wing frame  25 ,  26  that it can pivot or swing inward in an arcing movement perpendicular to the wing frame  25 ,  26 . These plates of steel are part of the wing wheel lift bracket  163  ( FIG. 17D ). 
     The bottom of the inboard bracket  152  is attached by pin  162  to bracket  167  which is attached to the back or inboard side of inboard bracket  152  by pin  162  which extends through a hole in wheel tucking link arm  165  forming a pivot. The other end of the wheel tucking link arm  165  is attached to the wheel tucking lever  164  by pin  160  which extends through holes in both  164 , 165  which also forms a pivot. ( FIG. 17C ). 
     The wheel tucking lever  164  is attached to the wing wheel lift bracket  163  by pin  161  which extends through brackets  168 A&amp;B that are attached to wing wheel lift bracket  163  and through a hole at the bottom of the wheel tucking lever  164  forming a pivot. At the top of the wheel tucking lever  164  is another hole where the butt end of the trailing wheel hydraulic cylinder  156  is attached by pin  159 . The ram end of the trailing wheel hydraulic cylinder  156  is attached to a plate or plates of steel extending vertically from the trailing wheel arm  155  by pin  158  which extends through holes in the plates of steel and through the yoke or sleeve  170  at the end of the ram. ( FIGS. 17A-C ) 
     The inboard bottom end of the trailing wheel arm  155  is attached by and pivots on pin  157  which extends through holes in the outboard ends of the wing wheel lift bracket  163  and in a round sleeve  169  attached to trailing wheel arm  155 . This allows the trailing wheel arm  155  a vertical arc perpendicular to the wing frame  25 ,  26 . 
     At the outboard end of the trailing wheel arm  155  is a round sleeve  148  which is attached in a way that the vertical caster shaft  146  extends through the round sleeve  148  and is for the most part straight up and down when the wing  25 ,  26  is in the up working position. Like the leading caster wheel  141  the trailing wheel  142  can swivel 360 degrees in either direction. 
     The leading and trailing wheel  141 ,  142  run in the same path in a straight route of travel reducing the total width of wheel tracks and also reduces the amount of drag caused by wheels running in loose soil. 
     The hydraulic cylinders leading  154  and trailing  156  receive hydraulic oil from the ram side of the right or left main lift cylinder  67 ,  68 . This hydraulic oil is trapped and flows in and out of the butt ends of the leading  154  and trailing  156  hydraulic cylinders. In these illustrations, the bore and stroke of the hydraulic cylinder  154 ,  156  are different sizes, but the volume of hydraulic oil it takes to move the leading and trailing wheels  141 ,  142  is the same. In the working positions up or down on level ground the rams of neither the leading or trailing hydraulic cylinders  154 ,  156  are fully retracted or extended. This allows for movement of the wheels up and down so to traverse uneven ground keeping the wing frame  25 ,  26  from being jarred or bounced over bumps. When the leading wheel  141  rolls over a rock or bump, hydraulic oil is displaced from the leading hydraulic cylinder  154  to the butt end of the trailing hydraulic cylinder  156  and it moves down the same amount that the leading wheel  141  moves up. It works a similar way when the lead wheel  141  passes through a hole or dip because this puts more pressure on the trailing wheel, it pushes the ram in and displaces oil from the butt of the trailing hydraulic cylinder  156  to the leading wheel hydraulic cylinder  154  because of the reduced pressure in the hydraulic cylinder  154 . All this creates a hydraulic walking tandem type situation. 
     The unique operation of this wing wheel lift assembly is the wheel tucking for transportation in the stacked position ( FIGS. 9 &amp; 17D ). In the working position ( FIGS. 17A  &amp; B) the wheel tucking lever  164  is held against the stop adjustment bolt  166  by the pressure of the trailing wheel arm  155 . This pressure, caused by leverage, holds the inboard bracket  152  of the leading wheel assembly in a vertical position by pressure transfer from the wheel tucking lever  164  to the wheel tucking link arm  165 . 
     When the wing frames  25 ,  26  are being stacked, the pressure is taken off the wheels as the wing frame rises. The trailing wheel arm swings down and in pulling the wheel tucking arm  164  back. At the same time this pulls the inboard bracket  152  back and up. This causes the lead caster wheel  141  to be tucked under the wing frame  25 ,  26  ( FIG. 17D ). This may also create a suction effect by further pulling the leading wheel hydraulic cylinder  154  in because the weight of the trailing wheel will pull the ram of the trailing wheel hydraulic cylinder  156  out, creating a need for additional hydraulic oil in the butt side of the hydraulic cylinder which should suck the oil out of the butt end of the leading wheel hydraulic cylinder  154 . 
     In unstacking, the trailing wheel  142  makes contact with the ground first. As the wing frame  25 ,  26  gets closer to the ground the trailing wheel arm  155  pushes the ram of the trailing wheel hydraulic cylinder  156  in, displacing oil to the leading wheel hydraulic cylinder ( 154  also pushing the wheel tucking lever  164  inward towards the stop bolt  166 . This through the wheel tucking link arm  165  pushes the inboard bracket  152  of the leading wheel assembly down and forward back to the vertical position. 
     This frame design is not limited to a utility cart, more so a tracked or belted cart, though due to the ability of the tracked vehicle to carry large loads, a tracked utility cart was used in all of the drawings. In  FIG. 18  a plain top view of the cart shows the left side (as determined by viewing from the rear looking in the direction of travel) with the belts cut out so that the front  122 A&amp;B, rear  123 A&amp;B and idler  124 A-H wheels can be shown. The right side is a minor image of the left. Also shown are the front hubs  101 A&amp;B, rear hubs  103 A&amp;B and idler hubs  102 A-H. The hubs run on shafts that have spindles machined on both ends to form a short axle.  FIG. 19A  shows a close up view of the front axle spindle  112 , which extends through holes or round sleeve  116 A in the top left tandem arm  120 . This top tandem arm  120  is parallel with the cart frame  66  and pivots on pin  111 , which extends through a round sleeve  110  or holes. The rear of the front top tandem arm  120  extends down to another pivot formed by pin  129  and round sleeve  115 . ( FIG. 19A ). Pin  129 ,  129 A extends through holes in steel plates that extend up from the left front lower tandem arm  118  and then through round sleeve  115  in the bottom of the front top tandem ann. 
     A preferred design for the lower tandem arms  118 ,  119  is shown in  FIG. 24 . Each tandem arm includes an upper portion  208  that pivotally mounts to the top tandem arms  120 ,  121 . Attached below the upper portion  208  is an outer roll tube  210 . An inner roll tube  212  slides into the outer roll tube  210 , and is free to rotate within the outer tube  210 . A first axle attachment member  214  is fixedly attached to one end of the inner roll tube  212 , as by welding. A second axle attachment member  216  is pivotally attached to the opposite end of the inner roll tube  212 , and held in place by end cap  218 , so that the first and second axle attachment members  214 ,  216  can pivot with respect to each other about the axis of the inner roll tube  212 . Idler hub spindle axles  113 A&amp;B are attached to the first and second axle attachment members  214 ,  216 . 
     An alternative design for the tandem arms  118 ,  119 , which does not allow for roll along a longitudinal axis is also possible. According to this simpler design, at each end of the front lower tandem arm  118  are holes or round sleeves ( 117  A&amp;B which the idler hub spindle axles  113 A&amp;B extend through. The rear lower tandem arm  119  is identical to the front lower tandem arm  118  using round sleeves  117 C&amp;D and idler hub spindle axles  113 C&amp;D. 
     The left rear top tandem arm  121  and rear lower tandem arm  119  are connected at pivot formed by pin  129 B and round sleeve  115 B. The left rear top tandem arm  121  also like the front top tandem arm  120  pivots on pin  111  which extends through round sleeve  137 . At the opposite end from round sleeve  115 B in the left rear top tandem arm is round sleeve  116 B which the left rear hub spindle axle  138  extends through. All of the before mentioned pivots follow the arms to move in the same vertical plane ( FIGS. 20 &amp; 21 ) which runs parallel to cart frame  66 . This allows for the inner sides of the pairs of wheels front  122 A &amp; B, rear  123 A &amp; B, idlers  124 A &amp; B,  124 C &amp; D,  124 E &amp; F,  124 G &amp; H to form guides for the guide blocks  139 A-D ( FIGS. 20 &amp; 21 ) which are aligned down the center and all the way around the inside of the belts which is somewhat standard on belts. 
     Because of the multiple pivot in the vertical plane the pairs of wheels can move up and down traversing the ground with more equal weight distribution and still guide the belts. 
     The top tandem arms  120 ,  121  are connected to the main cart pivot axles, front  59  and rear  58  by pins  111  and  132 . Both pins are held in round sleeves, front  109  and rear  131 . A bolt or pin may be placed in a hole drilled through the pin and sleeve or pin  111  and pin  132  may be directly fastened to the main cart pivot axles  58 ,  59 .  FIG. 23  shows top view,  FIGS. 20 and 21  show front and back elevation. 
     The cart frame rails  65 ,  66  can be attached in many different ways such as bolt or welded to main cart pivot axles  58 ,  59  or bolted indirectly so to use load cells for a weigh scale. The method that will be described and illustrated uses additional pivots to allow for smoother load transporting in uneven terrain. Also this design allows the same weight to be transferred to or from the draw bar of the vehicle pulling it by moving the front frame pivot assemblies  127 ,  128  forward or backward on the adjustable hitch load plates  125 ,  126 . 
     The adjustable hitch load plates  125 ,  126  have holes drilled in them so to allow the front frame pivot assembly  127 ,  128  to be bolted in incremental positions but staying perpendicular to main cart frame rail  65 ,  66 . ( FIGS. 19 &amp; 20 ) The front frame pivot assemblies  127 ,  128  are connected to the front load pivot assembly  96  by pin  106 ,  107  forming a pivot in round sleeve in the front frame pivot assemblies  127 ,  128 . These round sleeves are perpendicular to the main cart frame rails  65 ,  66 . The pins  106 ,  107  also extend through round sleeves  104 ,  105  which may be drilled and bolted securing the pins  106 ,  107 . It would possible to substitute a single long rod for pins  106  and  107 . The pins  106 ,  107  may be fastened directly to the front load pivot assembly  96  ( FIGS. 19 &amp; 20 ). The side elevation in  FIG. 22  also shows all of this in a cut away view. 
     The front load pivot assembly  96  can slide forward and backward on the front slide pivot axle  95 . In this design the pull is transferred from the hitch  62  to the front main pivot axle  59  to the front top tandem arm  120  to the front wheels  122 A, B which pull the belts  63 ,  64  and the rest of the cart rides on the belts  63 ,  64 . This helps the belts to track or guide easier. This is not totally necessary and may be designed differently. 
     The front slide pivot axle  95  extends through a hole or round sleeve  94  in the hitch cross member  100  and round sleeve  108  in the front load pivot assembly  96  and into a hole or round sleeve  93  attached to front main cart pivot axle  59 . The front slide pivot axle  95  is centered between and parallel to the main cart frame rails  65 ,  66  ( FIG. 19 ). This design permits the weight distribution to be adjusted between the cart and the pulling vehicle. By adjusting the location of the front frame pivot assemblies  127 ,  128  forward or rearward on the adjustable hitch load plates  125 ,  126 , the distribution of the weight can be shifted forward or rearward. As an alternative, it would be possible to add an additional cross member (not shown) to the hitch  62 , similar to cross member  100 , and mount the front slide pivot axle  95  between the two cross members instead of between cross member  100  and the front main cart pivot axle  59 . 
     The hitch  62  (which can be varied in length) is attached to the front main cart pivot axle  59  and extends forward. Illustrated in  FIGS. 18 &amp; 19  is the adjustable length hitch, where an outside hitch tube  97  is incorporated in the design of the hitch  62  and internal hitch tube  98  can be extended or retracted to different lengths. 
     The rear main cart pivot axle  58  can be attached in many ways to the main cart frame rails  65 ,  66 . If using a design similar to this and using a front pivot, the main frame rails  65 ,  66  should be mounted in a ridged way. Shown in  FIG. 21  a frame cross member  133  helps support the main cart frame rails  65 ,  66 . 
       FIG. 23  illustrates a necessity of design which is a belt tension assembly. This may be designed in a different way and placed in a different position. It serves to keep tension on the belts and to keep them guided between the wheels of the carriage. It should extend between the front and rear main cart pivot axles  58 ,  59 . This illustration and design shows arms (plates of steel) extending from a round tube, and pin  132  extending through holes in the plate or round sleeve  140 A &amp; B. This assembly is the external belt tension tube  134 . In the same manner, the internal belt tension tube  135  is built and pivots in hole or round sleeves on pin  111  which is attached to the front main cart pivot axle  59 . The arms of both the internal and external belt tension tubes  135 ,  134  straddle the front and rear top tandem arms  120 ,  121 . These tension tubes  134 ,  135  do not have to straddle the top tandem arms  120 ,  121  and may be placed on either side and may be pinned directly to the front and rear main cart pivot axles  58 ,  59 . 
     When the belts are tensioned, a clamp  136  or some type of stop must be placed on the section of internal tension tube  135  sticking out of or past the end of the external tension tube  134 . These tubes must be able to rotate inside each other to allow for the uneven movement up and down of the main cart pivot axles  58 ,  59 . 
     This cart design could be built using only one top and bottom tandem arm or two top and one bottom tandem arms with a single axle attached at the bottom of the top tandem arm. This would allow for a shorter cart base. When using only one top and bottom tandem arm, one main cart pivot axle would extend out and attach to a hub and spindle which would attach to both the inboard and outboard (front or back) wheels.