Abstract:
A coupler for attaching an implement to a tractor is provided. The coupler has three pivot arrangements allowing pivoting about three axes that are generally normal to one another with two axes of pivoting lying in substantially in a first plane and the third axis of pivoting intersecting that plane at a variable angle in a second plane generally perpendicular to the first plane. The three axes of pivoting substantially intersect and the implement may be attached wherein the load from the implement is directed downwardly and over the draft arms of the tractor.

Description:
BACKGROUND OF INVENTION 
     Work machines such as tractors are often used to pull implements such as box blades, compactors, rollers, scrapers, etc. These implements may be supported by wheels or may drag along the ground. Implements are typically not dedicated to a particular work machine and therefore are in the need of a fast, efficient and effective means to couple the implement to the work machine (hereinafter tractor). Tractors typically have a three point hitch arrangement and many implements only use two points of the three point hitch arrangement particularly those implements utilizing one or more wheels for support. Two point hitch arrangements utilize the two draft arms which are selectively moveable between elevated and lowered positions and retainable at one of various positions between a lowered position and an elevated position. A cross bar may be secured to the draft arms to extend therebetween and is typically pivoted to the draft arms for rotation about a generally horizontal axis or an axis generally parallel to the axis of the rear wheel axles of the tractor. 
     Numerous types of couplers have been devised for connecting an implement to a tractor. The couplers may be divided into three categories. The first category is the coupler that attaches to a draw bar with multiple pivots trailing behind the draw bar a substantial distance. Examples of these can be found in U.S. Pat. Nos. 5,706,901, 5,531,283 and 4,838,015. This style of coupler, unless the implement is supported by front and rear wheels can apply a significant amount of downward force to the tractor hitch and can result, in some cases, in lifting the front wheels of the tractor from the ground. To avoid this, implements have been provided with front and rear wheels when such implements or their loads are heavy. 
     A second type of coupler releasably attaches the tongue of the implement to the draw bar as for example with a ball or pin or the like. The tongue rests on the draw bar and pivotal movement is accomplished by rotation about the ball in multi-axes or about a hitch pin through holes within the coupler arrangement. While effective, the freedom of movement about a ball or hitch pin is limited. A pintle hook is another such type of hitch. 
     A third form of coupler arrangement is shown in U.S. Pat. No. 2,091,009. As shown, and described, the coupler is required to be forward of the rear wheels in order to prevent lifting of the front wheels when heavy loads are encountered. To accomplish that goal, a large U-shaped yoke bridges the drive train in front of the rear wheel differential allowing pivoting in a forward and rearward direction by being hinged at pins connected to the drive train. Second and third pivots are provided to provide both steering pivoting and irregular terrain pivoting. However such an arrangement is cumbersome and eliminates, at least for modern tractors, the ability to use the seat on the tractor. Also, because of the large height of the coupler, large moments (torque) will result. Such an arrangement would also be difficult to attach an implement to the tractor and the ability to raise and lower the implement is precluded. 
     One common element to many of these hitches, particularly of the first and third categories just described, is the ability to provide pivoting about three distinct axes using three separate pivot arrangements. Further, the first and third categories tend to be complex mechanisms that do not accommodate the applied forces necessarily very well. Thus, there is a need for an improved coupler and tractor/implement/coupler arrangement. 
     SUMMARY OF INVENTION 
     The present invention involves the provision of a tractor, implement and coupler arrangement that includes a coupler attachable to the draft arms of a tractor and having three pivot devices for allowing the tractor and implement to pivot relative to one another about three axes. The axes of the pivots are such as to substantially intersect with one another to provide a low profile coupler arrangement. The coupler interconnects the tractor hitch arrangement and hence the tractor to an implement having a draw tongue. The tongue is preferably, at least for certain types of implements, a goose neck type tongue to help provide clearance for tight turns without interfering with the rear wheels or other portions of the tractor. The implement may use support wheels or may have support wheels that are selectively engageable with the ground or in certain cases the implements may not utilize wheels for support. The coupler permits the use of a link from the third point of a three point hitch, in a selective manner, to elevate certain implements for transport by using the three point hitch arrangement on the tractor. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a side elevation view of a tractor, implement and coupler connecting the implement to the tractor. 
     FIG. 2 is a plan view of the tractor implement and coupler as shown in FIG. 1 with various pivoted positions of the implement relative to the tractor shown in phantom. 
     FIG. 3 is an enlarged perspective view of one form of coupler device. 
     FIG. 4 is an exploded view of the coupler as seen in FIG.  3 . 
     FIG. 5 is an enlarged perspective view of a second form of coupler device. 
     FIG. 6 is an exploded view of the coupler of FIG.  5 . 
    
    
     Like numbers utilized throughout the various Figures designate like or similar parts. 
     DETAILED DESCRIPTION 
     A work machine (herein “tractor), designated generally  1 , includes a hitch mechanism designated generally  2  that is semi-permanently attached to the tractor. A coupler device designated generally  4  is attached to the hitch  2  and a tongue  6  of an implement  7 , releasably coupling the implement to the tractor  1 . 
     The tractor  1  includes a frame  11  on which are mounted motive members  13  such as tires or tracks. A power plant  15  such as an internal combustion engine is provided and through a drive train  17  selectively drives a tractor  1  forward and/or rearward. The tractor is also steerable for left and right turns as is well known in the art. An operator station  19  is provided as well as a steering device  20  for steering the tractor during movement. 
     The tractor  1  includes the hitch mechanism  2 . Typical hitch mechanisms for wheeled tractors includes a three point hitch arrangement that can be used as a three point or two point hitch. The hitch  2  includes a pair of draft arms  22  pivotally mounted at their forward ends to the tractor and also to a hydraulic drive arrangement  24  via links  25  which will selectively move the draft arms  22  between a lowered position and an elevated position and is operable to selectively fix the draft arms at any position between the low and high positions. Such hitch arrangements are well know in the art. Connectors  26  are secured to the distal ends of the draft arms and preferably are balls  27  in sockets with through bores for the receipt of hitch pins  28  (FIGS. 2,  4 ,  6 ) therethrough. The draft arms  22  are mounted in a manner to permit their side to side pivoting at their mounting to the tractor whereby the distal ends can be varied in the degree of separation to accommodate different type and sizes of couplers and hitch arrangements. A three point hitch arrangement on a tractor includes an upper pivot  30  to which a link (not shown) may be connected, which link would have a free end connectable to an implement. Such three point hitch arrangements are well known in the art and need not be further described herein. 
     The implement  7  can be any suitable implement for example an earth scraper, box blade, compactor, roller, chisel, mower, rototiller or the like. In a preferred embodiment the implement  7  includes one or more support wheels  33  usable for supporting the implement body  34 . The wheel(s)  33  may be selectively adjustable relative to the body  34  for positioning of portions of the implement relative to the ground. Mechanism may be provided to allow the wheel(s)  33  to be in a down position for transport of the implement and in an up position when the implement is to be used, for example, in a grading project. Devices for positioning the wheel(s)  33  are well known in the art. The implement  7  includes the tongue  6  which in the illustrated structure is a, goose neck type tongue having an elevated bight portion  36  and a distal connector portion  38  connected to the bight portion  36  and depending downwardly therefrom forming a clearance gap  39 . The tongue  6  may be raised and lowered by raising or lowering the draft arms  22 . Goose neck tongues are well known in the industry. Examples of the foregoing implements include RB Scrapers, DB Scrapers and TL Rollers available from Hoelscher, Inc. of Bushton, Kans. 
     The two forms of coupler  4  are best seen in FIGS. 3-6. The coupler  4  includes three pivot arrangements designated generally  41 ,  42  and  43 . The coupler  4  includes a trunnion  45  which is in the form of a flat cross bar having opposite ends  46 ,  47 . The pivot arrangement  41  includes a pair of pivot pins  49  each extending outwardly from its respective end  46 ,  47  and adapted for pivoting receipt within the pivot balls  27  of the draft arms  22 . A hitch pin  28  or other suitable keeper  28  is utilized to retain the pins  49  within the balls  27  and connected to the draft arms  22 . The trunnion  45  and pins  49  can pivot about a generally horizontal axis through the pins  49  and the balls  27 . As used herein the terms vertical and horizontal are used in the reference frame of the tractor and implement being on a horizontal surface. However, it is to be understood that in the use of the tractor and implement that many times the tractor and implement will not be on a horizontal plane or a common plane. The pivot axis X of the pins  49  and trunnion  45  is also generally parallel to the axis of the rear axles of the tractor. It is to be understood however that the draft arms may be adjustable relative to one another to induce a side to side (of the tractor) cant in the trunnion  45  changing the plane of the X pivot axis from horizontal to non-horizontal but it is still considered generally horizontal as used herein. The X pivot axis extends through the trunnion  45  and is preferably generally centrally located therein. 
     Two forms of pivots  42  are illustrated in FIGS. 3-6. The first form of pivot  42  is shown in FIGS. 3 and 4 and the second form is shown in FIGS. 5 and 6. In the first form of the invention (FIGS.  3  and  4 ), the pivot  42  includes a pair of pivot pins  52  removably mounted in a through bore  53  through the trunnion  45 . An opening  55  extends between opposite faces of the trunnion  45  with the bore  53  opening into the opening  55  on opposite sides thereof. A coupler  57  such as a bearing block or other suitable pivot member is pivotally mounted on the pins  52  for rotation or pivoting movement about the Y axis within the opening  55 . Mounting the coupler  57  within the opening  55  provides a low profile for the coupler  4 . The opening  55  is sized such that the coupler  57  when in cooperative interengagement with the pivot device  43  can move, as shown by the arrows A, in a plane generally normal to the Y axis plus or minus about 45°. This plane of movement extends generally transverse to the longitudinal axis of the tractor. The plane of movement may be changed relative to the ground by pivoting the trunnion  45  about the X axis. 
     The pivot  43 , in the illustrated embodiment of FIGS. 3,  4  is shown as a pintle type pivot and includes a pin  61  cooperatively interengageable with a sleeve or socket  62  such that the trunnion  45  and tongue  6  can pivot relative to one another to provide pivoting about a Z axis. As shown, the pin  61  is mounted to the coupler  57  and is generally upstanding therefrom and the trunnion  45 . In the illustrated embodiment, the pin  61  extends through a through bore  63  of the coupler  57  and be rotatable relative thereto. The Z axis can be and is shown as generally vertical including its movement about the X and Y axes. In the illustrated structure, the socket  62  is secured to the tongue  7  preferably at the distal end of the tongue portion  38 . The socket  62  is preferably secured to the tongue  7  in a removable manner as by a plate  64  bolted to a corresponding plate  65  permanently secured to the tongue portion  38 . A keeper  67  allows the pin  61  to be removed from the socket  62  for separation of the coupler  4  from the implement  7 . A cylindrical bushing  68  is sleeved onto the lower portion of the pin  61  with the coupler  57  positioned between the bottom of the socket  62  and the top of the bushing  68 . A second keeper  67  also releasably secures the pin  61  to the coupler  57  and socket  62 . The bushing  68  acts as a spacer and a thrust washer. In normal use, the pin  61  may be left attached to the tongue  7  if desired. Suitable lubricating devices such as zerk grease fittings  69  may be provided for the pivots  41 ,  42 ,  43 . 
     In the illustrated embodiments of the coupler  4 , the X and Y axes lie generally in the same plane which is shown as a generally horizontal plane while the Z axis lies in a plane generally normal to the plane of the X and Y axes and is shown as a generally vertical plane when the pivots  41 ,  42 ,  43  and are each in a neutral or normal position, as shown in the Figures. The X, Y and Z axes are generally normal to one another. The X, Y and Z axes substantially intersect with one another and particularly the X and Y axes substantially intersect providing the low profile arrangement. It is preferred that the X, Y and Z axes substantially intersect with one another by passing within approximately 3 inches of each other more preferably within about 2 inches of each other and most preferably within about 1 inch of each other. Preferably the pivot pins  49 ,  52  and  61  are removable for maintenance purposes. The pins  49  may be threaded into the trunnion  45  while the pins  52  may be held within the bore  53  by a screw or bolt  67  or frictional engagement. The pin  61  may, in addition to the mounting described above, be threaded into the coupler  57  and rotatable in the socket  62  or may be permanently attached thereto and replaceable either on its own or in combination with the coupler  57 . A spacer  70  can be used to space the bottom of the socket  62  from the coupling  57  to permit the pivotal movement of the pin  61  about the pivot pins  52 . Such a spacer may be, for example, a thrust washer or bushing sleeved over the pin  61  or could be part of the socket  62 . The Y pivot axis is generally parallel to the longitudinal axis of the tractor  1  while the pivot axis X is generally transverse to the longitudinal axis of the tractor. The Y pivot axis moves in a plane that is generally transverse to the longitudinal axis of the tractor when the pin  61  is in a generally vertical plane. 
     FIGS. 5,  6  illustrate an alternate embodiment of the coupler. It includes a trunnion in the form of a cross bar or tow bar  71  similar to the trunnion  45  but without the need for through opening  55 . The bar  71  has pins  49  secured to and extending from opposite ends thereof. One or two pivot pins  73  can be used to connect a clevis  75  to the bar. The clevis  75  has arms  76 ,  77  forming a gap  79  therebetween which receives the bar  71  therein. As shown, the pin  73  extends through each of the arms  76 ,  77  and pivotally mounts the clevis  75  to the bar  71  and can be removably secured to the clevis  75  and bar  71  with hitch pins  28 . The clevis can pivot about the Y axis as does the coupler  57 . A cross member  81  joins the arms  76 ,  77  together and provides a mounting member for the pin  61 . The pin  61  is secured to the clevis  75  as by threaded engagement or welding or may be integral therewith. The pin  61  rotates relative to the socket  62 . A bearing bushing  85  may be sleeved over the pin  61  to be positioned between the clevis  75  and socket  62 . In function and arrangement of the X, Y and Z axes, the coupler  4  shown in FIGS. 5,  6  is the same as that of the coupler  4  shown in FIGS. 3,  4 . 
     In operation, the implement  7  is towed behind the tractor  1  with the implement being pivotable relative to the tractor about three axes to accommodate for changes and differences in terrain supporting the tractor and implement. The tractor  1  may turn left and right allowing the implement to pivot on the pivot arrangement  43 . The goose neck tongue  6  may be high enough to accommodate sharp turns by providing clearance over the top of the tires and fenders on the rear of the tractor. The implement and tractor may pivot relative to one another about the axis X to accommodate ditches, hills, etc. A left-right slope change between the implement and tractor, as viewed from the operators position can be accommodated by rotation about the Y axis. Because of the low profile, the moment applied to the hitch arrangement from the force needed to pull or resist forward movement of the implement relative to the tractor is reduced. Also, by having the X, Y and Z axes substantially intersect, the magnitude of other moments may be reduced. Also, by having the Z axis over the draft arms and close to the end of the tractor, the downward force on the tractor hitch can be reduced (relative to trailing hitches) thereby reducing the tendency of the front wheels to pick up from the ground. 
     The use of the inventive coupler  4  facilitates attachment of the tractor  1  to the implement  7  and alignment of the draft arms  23  with the pins  49  to effect the attachment. The operator backs the tractor  1  into approximate position relative to the implement, may then exit the tractor  1  to place one pin  49  in a respective ball  23  and attach the pin to the draft arm with a suitable keeper. Because of the pivoting nature of the pivots  41 ,  42 ,  43 , the free or unattached end of the pivot  41  may be simply and without the application of force to lift the implement align the other pin  49  with its ball by up and down or forward and back movement of the pin  23  and insert the pin into the ball  23 . A suitable keeper would then be placed on that pin  49  to releasably attach the coupler to the tractor hitch. 
     Thus, there has been shown and described several embodiments of an implement coupler. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. Many changes, modifications, variations and other uses and applications of the present constructions will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.