Abstract:
An implement support unit for cooperating with an implement-mounting device for an implement for mounting the implement on a trailer unit. Preferably, the support unit is a three point hitch type support unit.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation in part of application Ser. No. 10/424,321, filed Apr. 23, 2003 now U.S. Pat. No. 6,796,384 by Todd Potter and entitled Implement Mounting Fixture. 

   BACKGROUND OF THE INVENTION 
   1. Field of the invention 
   The present invention relates to the field of implement-mounting fixtures. 
   2. Background of the Prior Art 
   Implements, of which farm implements are one example, are used to plow, plant crops, haul materials, and perform a variety of other useful tasks. A work machine carries, deploys, and sometimes powers the implement. Trucks, tractors, all-terrain vehicles (ATVs), maintenance vehicles, and the like are examples of work machines available that typically use implements. 
   An implement-mounting device is a structure forming a part of an implement that allows the implement to be mounted for use on a work machine. 
   A work machine is usually supplied with a structure called an implement attachment unit compatible with implement-mounting devices. This allows a variety of implements to be mounted on a work machine in a similar way. An implement attachment unit and a compatible implement-mounting device will be collectively referred to hereafter as a mounting interface. 
   The square tunnel hitch receiver for pulling trailers and other wheeled implements is a type of implement attachment unit that is now relatively standardized. A bracket attaches a square box beam to the rear or front of the work machine with the box beam tunnel approximately parallel to the work machine centerline. A square hitch bar sized to fit closely within the tunnel has a flat, horizontal plate that projects from the end of the square bar. Aligned holes in the box beam and hitch bar allow a pin to strongly hold the bar in the tunnel. Removing the pin allows the hitch bar removal to prevent the hitch bar from damaging other vehicles, and allows replacement by other hitch bars. The standard trailer hitch attaches to a trailer ball bolted through a vertical hole in the plate. 
   The square tunnel hitch receiver is suitable for pulling trailers and other wheeled implements but is usually unsuitable for other types of implements. For example, many types of implements, such as scrapers, mowers, etc. must be lifted from the ground during use and transporting. 
   A problem with many prior art mounting interfaces that can attach non-trailer type implements to work machines is that they often are unique or proprietary. This results in an implement-mounting device compatible with one type of work machine, but incompatible with other work machines. Other mounting interfaces require bolting at multiple points to attach an implement to the work machine, which is inconvenient and time-consuming. 
   The three-point hitch is an existing design for a mounting interface. The implement attachment unit of a three-point hitch comprises a central upper arm carried on to the work machine and two lower outboard arms. The upper arm attaches to an upper hitch point forming a part of the implement-mounting device. The two lower arms attach to two lower outboard points on the implement forming a further part of the implement-mounting device. 
   Typically, the two lower arms are powered to rotate upwards to lift the implement away from the ground. Gravity lowers the implement to ride across the ground when the two lower arms are rotated downward. Where necessary to properly operate an implement such as an aerator or scraper, the lower arms can be powered to force the implement into the ground as well. The upper arm prevents the implement from tilting forward or backward onto the ground when lifted by the lower arms. 
   The three-point hitch has been in use for 60 years for farm tractors, and has become a de facto standard for tractor mounting interfaces. A detached implement is attached to a tractor having a compatible three-point hitch type implement attachment unit by attaching the three bars of the implement attachment unit to the implement-mounting device on the implement. 
   Of course, the implement attachment unit of a three-point hitch must be compatible with the implement-mounting device of an implement, to mount that implement. Further, many different types of three-point hitch implement interfaces exist that are incompatible with each other. Thus, one problem with existing three-point hitches as well as other mounting interfaces, is that of incompatibility among manufacturers&#39; product lines. 
   SUMMARY OF THE INVENTION 
   The present invention provides trailer-mounted fixture for mounting an implement. In its broadest form, the fixture comprises a frame having a leading side and a trailing side. At least two wheels are mounted on the frame, preferably by an axle. A tongue is attached to the frame and projects from the leading side of the frame. The tongue is to be conventionally attached to a trailer hitch on a work machine. A hitch support unit is mounted on the trailing side of the frame. Preferably the hitch support unit is a three-point hitch support unit. 
   Because the hitch support unit projects behind the wheels, an implement mounted on the hitch support unit applies negative (upward) force to the end of the tongue, which may affect the traction of the work machine to which the tongue is attached. The tongue may include a bracket for mounting a weight near the end of the tongue. This weight counterbalances the implement to provide positive tongue weight. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a first embodiment of the invention. 
       FIG. 2  is a perspective view of a second embodiment of the invention. 
       FIG. 3  is a perspective view of a trailer-mounted embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a first embodiment of an implement attachment unit  10  for mounting an implement to a work machine. 
   The implement attachment unit  10  has a frame  12  having an upper portion  14  and a lower portion  16 . The frame  12  has an upright member  22  that connects to an upper crossbar  18  in the upper portion  14  of the frame  12  and a lower crossbar  20  in the lower portion  16  of the frame  12 . The upper crossbar  18  and lower crossbar  20  are generally parallel to each other and perpendicular to the upright member  22 . 
   A pair of upper lift arms  24  extends from the upper portion  14  of the frame  12 . The upper lift arms  24  have a first end  26  pivotally connected to the upper portion  14  of the frame  12 . The upper lift arms  24  are connected to opposing sides of the upper portion  14  of the frame  12 . The upper lift arms  24  extend outwardly from the frame  12 , generally parallel to one another. 
   A transverse beam  28  extends between the upper lift arms  24 . The transverse beam  28  is connected to the upper lift arms  24  at a position outwardly spaced from the first end of the upper lift arms, between the first end  26  and second end  40 . The transverse beam  28  is fixedly connected to each of the upper lift arms  24  such that a force applied to the transverse beam  28  will cause the upper lift arms  24  to pivot about the first end  26 . 
   A pair of lower lift arms  30  extends from a lower portion  16  of the frame  12 . The lower lift arms  30  have a first end  32  pivotally connected to opposing ends of the lower crossbar  20  of the frame  12 . The lower lift arms  30  extend outwardly from the lower portion  16  of the frame  12 , generally parallel to each other. An implement  34  may be positioned between the outwardly extending second ends  36  of each of the lower lift arms  30 . 
   An adjustable lift arm  38  extends from each of the upper lift arms  24  to a corresponding lower lift arm  30 . The adjustable lift arms  38  are pivotally connected to a second, outwardly extending end  40  of the upper lift arms  24 . The adjustable lift arms  38  are adjustably connectable to the lower lift arms  30 . The lower lift arms  30  have a series of apertures  42  along a length of the lower lift arm  30 . The adjustable lift arms  38  have a mating aperture  44  that is selectively alignable with any of the series of apertures  42  on the lower lift arm  30 . The adjustable lift arms  38  are connected to the lower lift arms  30  by extending a pin  46  through the mating aperture  44  and corresponding aperture  42  of the lower lift arms  30 . The body  48  of the adjustable lift arms  38  may include a ball swivel and clevis. 
   A link arm  50  is pivotally connected to the frame  12 , and extends therefrom for linking to an implement. The link arm  50  is able to extend generally outwardly in the direction of the upper lift arms  24  and lower lift arms  30 . The link arm  50  may pivot within a range extending from the lower portion  16  of the frame  12  to an upper portion  14  of the frame  12 . 
   A hitch tube  52  extends from the frame  12 , in a direction opposite that in which the upper lift arms  24  and lower lift arms  30  extend. The hitch tube  52  is connected to the lower portion  16  of the frame  12 . The hitch tube  52  allows the implement mounting fixture  10  to be mounted to a work machine by receiving a hitch (not shown) from the work machine. The hitch tube  52  may have adjustable or additional components to allow the hitch tube  52  to mate with a work machine. The hitch tube  52  allows the implement mounting fixture  10  to mount to the work machine at a single point, allowing the implement mounting fixture  10  to be mounted to a wide variety of work machines, and to be mounted on either the front or rear of the work machines. The hitch tube  52  may be a two inch hitch tube. Adjustable or additional components may include a 1¼ inch hitch bar, and a pair of ⅜″ spacers, but are not limited thereto. 
   A hydraulic cylinder  54  extends from the frame  12  to the transverse beam  28 . The hydraulic cylinder  54  has a first end  56  connected to the lower portion  16  of the frame  12 . The hydraulic cylinder  54  has a second end  58  connected to the transverse beam  28 . A connecting member  60  connects the hydraulic cylinder  54  to the transverse beam  28 . The connecting member  60  may include a bracket, or other such mechanical connection. The hydraulic cylinder  54  is selectively positionable on the frame  12 . It is contemplated that when the implement-mounting fixture  10  is mounted on a work machine the hydraulic cylinder  54  be positioned on a side of the frame  12  opposite an exhaust system of the work machine. 
   A pump assembly  55  controls operation of cylinder  54 . Assembly  55  includes an electric motor that operates a hydraulic pump. An electrical cable  37  has a connecting plug  35  that allows cable  37  to be connected to a lift control and a source of electrical power on the work machine. 
   The use of hydraulics provides a lifting and downward force in operation. The hydraulic cylinder  54  may provide a predetermined force, either generally upwardly or generally downwardly upon the transverse beam  28 , causing the upper lift arms  24  to pivot about the upper portion  14  of the frame. This force results in a corresponding translation of force to the lower lift arms  30  via the adjustable lift arms  38  connected thereto. 
     FIG. 2  illustrates a second embodiment of the present invention of an implement-mounting fixture for mounting an implement to a work machine. 
   The implement-mounting fixture  10  has a frame  12  having an upper portion  15  and a lower portion  16 . A transverse beam  29  extends through the upper portion  15  of the frame  12 . The transverse beam  29  defines an axis  66  about which the transverse beam  29  is able to rotate while being maintained within the upper portion  15  of the frame  12 . 
   A pair of upper lift arms  25  is connected to opposing ends of the transverse beam  29 . The pair of upper lift arms  25  has a first end  27  fixedly connected to the transverse beam  29  such that when the transverse beam  29  is rotated about the axis  66  the pair of upper lift arms  25  will likewise rotate. 
   A connecting member  61  extends from the transverse beam  29 , perpendicular to the axis  66 . The connecting member  61  has an angle point  63  such that it extends outwardly from the transverse beam  29  for a predetermined distance and then angles for a predetermined distance, forming a perpendicular section  65 , and an angled section  67 . 
   A hydraulic cylinder  54  extends from the frame  12  to the transverse beam  29 . The hydraulic cylinder  54  has a first end  56  connected to the lower portion  16  of the frame  12 . The hydraulic cylinder  54  has a second end  58  connected to the transverse beam  29 , via the connecting member  61 . The second end  58  of the hydraulic cylinder  54  is connected to the angled section  67  of the connecting member  61 . 
   The hydraulic cylinder  54  may provide a predetermined force, either generally upwardly or generally downwardly upon the connecting member  61 , causing the corresponding rotation of the transverse beam  29 . The rotation of the transverse beam  29  causes the upper lift arms  25  to rotate with respect to the upper portion  15  of the frame. 
   As discussed with reference to  FIG. 1 , the application of a force upon the upper lift arms  25  results in a corresponding translation of force applied to the lower lift arms  30  via the adjustable lift arms  38  connected thereto. 
   The embodiment of  FIG. 2  has a pair of lower lift arms  30  extending from the lower portion  16  of the frame  12 , and a pair of adjustable lift arms  38  extending between the upper lift arms  25  and lower lift arms  30 . A link arm  50  is pivotally connected to the frame  12 . A hitch tube  52  is connected to the opposite side of the frame  12 . These elements are described in detail in  FIG. 1 . 
     FIG. 3  shows an embodiment of the invention in the form of a trailer unit  11 . Many of the elements of the implement attachment unit  10  shown in  FIG. 3  are similar to those in  FIGS. 1 and 2 , and these have the same reference numbers. 
   Frame  12  is mounted by welding or clamping on an axle  92  that has a conventional trailer wheel  90  mounted for rotation at each end. Frame  12  carries the implement attachment unit  10  at a trailing side of frame  12 . A tongue  94  is attached by fasteners  86  to a bracket  98  forming a part of a leading side of frame  12 . Tongue  94  thus projects from the leading side of frame  12 . Tongue  94  has a conventional connector element  96  for attaching tongue  94  to a work machine. In this way, the entire assembly may be pulled by a work machine. 
   The implement attachment unit  10  preferably is designed to replicate the functionality and dimensions of the implement attachment unit  10  shown in  FIGS. 1 and 2 , but in the form of a trailer to be drawn by a work machine. Since most work machines have a hitch to which connector element  96  can be attached, this allows nearly every work machine to carry and deploy any implement having an implement-mounting device compatible with the implement attachment unit  10 . 
   A potential problem with a trailer-mounted implement attachment unit  10  is the negative tongue force that the weight of an implement may generate (i.e., upwardly-directed force). To address this problem, axle  92  should as much as possible be placed in substantial vertical alignment with the implement attachment unit  10  as shown in  FIG. 3 . This minimizes the lever arm created by an implement carried on attachment unit  10 , reducing negative tongue force. 
   A further solution to the problem of negative tongue force is to mount weights  80  and  82  on tongue  94  to counterbalance the implement weight. Weights  80  and  82  are detachably mounted on the end of tongue  94  near the connector  96  by pins  84  comprising brackets attached to tongue  94  near connector element  96 . Weights  80  and  82  may have any suitable value to provide sufficient positive tongue  92  force weight. 
   Weights  80  and  82  may be in the range of 20 to 40 lbs. each, sufficient to adequately weight the tongue  94 , and at the same time not so heavy that a person of normal strength has difficulty in mounting the weights. Heavier or lighter weights  80  and  82  and the number used may depend on the weight and configuration of the implement carried by attachment unit  10 .