Patent Publication Number: US-2009223095-A1

Title: Hitching system for road construction tractor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to provisional U.S Patent Application Ser. No. 61/035174 filed Mar. 10, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to a hitching system and, in particular, to a hitching and support system for a tractor scraper. More specifically, but without restriction to the particular use which is shown and described, this invention relates to a hitching and support system providing a single joint or interface between the tractor and the trailer that allows rotation of the hitch through pivot, oscillation, and pitch. Preferably, the joint consists of a ball that freely rotates or a hitch receiver including a plurality of pins, wherein each pin allows one of pivot, oscillation, and pitch of the system. 
     2. Related Art 
     Tractor scrapers are used in many construction applications, such as road building, wherein the scraper is used to transport heavy loads of material such as dirt, rock, and gravel over rough terrain from one location to another for leveling or filling the terrain. The scraper comprises a tractor and an earthmoving trailer which are coupled via a hitch extending from the trailer and a hitch receiver coupled to the tractor. Typically, the hitch receiver is coupled to a back end of the tractor. Accordingly, a majority of the weight from the trailer is transferred to the back wheels of the tractor, often causing the front wheels of the tractor to be lifted from the ground. Specifically, in at least one known tractor scraper, approximately 23% of the scraper&#39;s weight is carried by a tongue of the hitch and 77% of the weight is carried by the rear wheels of the tractor. 
     Other trailers are coupled to the tractor via a gooseneck that more evenly distributes the weight of the trailer. However, according to the teaching of a prior invention, the gooseneck should be coupled to the tractor with a kingpin. The kingpin is used in a complicated system to adjust the relative pitch and oscillation angles between the scraper pan and the tractor, and substantially limits freedom of movement between the scraper and the tractor. Specifically, oscillation and pivoting of the scraper relative to the tractor is severely limited. Accordingly, such tractor scrapers often have a complicated hitch connection that includes several components to provide oscillation and pivot to the scraper. These complicated connections often result in an increased amount of maintenance and costs associated with operating and maintaining the tractor scraper. Moreover, the complicated design prohibits easily and quickly connecting and disconnecting the trailer from the tractor. 
     It is, therefore, an object of this invention to improve hitching systems for tractor scrapers by providing a single hitch connection that allows free rotation of the hitch while also substantially evenly distributing the weight of the trailer among the wheels of the tractor. Another object of this invention is to improve the amount of time and ease with which the trailer can be connected to and disconnected from the tractor. 
     SUMMARY OF THE INVENTION 
     The present invention is a hitching system for a tractor scraper that includes a tractor and a scraper attached thereto. The tractor includes a frame and a front and rear axle that are each attached to the frame. The scraper includes a frame and a gooseneck arm extending from the frame. A hitch-receiver pair is provided to fixedly attach the trailer to the scraper. The hitch-receiver pair includes a receiver and a hitch fixedly attach to the receiver. One of the hitch and the receiver is attached to the gooseneck arm, and the other of the hitch and the receiver is attached to the tractor frame above and ahead of the rear axle. 
     The hitch is configured to freely rotate with respect to the receiver. Specifically, the hitch freely pivots, pitches, and oscillates with respect to the receiver. In one embodiment, the hitch is a spherical interface and the receiver is a socket configured to receive the spherical interface. In another embodiment, the hitch is multi-joint hitch that includes a pivot component, a pitch component, and an oscillation component. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIGS. 1(   a ) and  1 ( b ) are schematic illustrations of a tractor scraper. 
         FIG. 2  is a schematic illustration of one embodiment of the hitch receiver pair shown in  FIG. 1 . 
         FIG. 3  is a schematic illustration of another embodiment of the hitch-receiver pair shown in  FIG. 2 . 
         FIG. 4  is schematic illustration of the pivot range of the hitch-receiver pair shown in  FIG. 1 . 
         FIG. 5  is a schematic illustration of the oscillation range of the hitch-receiver pair shown in  FIG. 1 . 
         FIGS. 6(   a ) and  6 ( b ) are schematic illustrations of the pitch range of the hitch-receiver pair shown in  FIG. 1 . 
         FIGS. 7(   a ) and  7 ( b ) are schematic illustrations of the location of the hitch-receiver pair shown in  FIG. 1 . 
         FIG. 8  is a view of the tractor shown in  FIG. 1  having a water wagon attached thereto. 
         FIG. 9(   a ) is a top view of the locking mechanism shown in  FIG. 2  in a closed position. 
         FIG. 9(   b ) is a top view of the locking mechanism shown in  FIG. 9(   a ) in an open position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring now to  FIGS. 1-8  there is shown a hitching system  10  for a tractor scraper  12 . Although the hitching system disclosed herein maybe used with various vehicles, for convenience of illustration the preferred embodiment is illustrated with reference to its use with a six-wheel, three-axle tractor scraper. 
     Generally, a tractor scraper  12 , as illustrated in  FIG. 1  includes a tractor  14  and a trailer  16  that has a bin  18  supported at its rear end  80  by a pair of wheels  20  and at its front end  82  by a frame  22 . The bin  18  has vertical sidewalls  26  that extend between the front end  82  and the rear end  80 . Frame  22  has a pair of arms  24  pivotally connected to the vertical sidewalls  26  of the bin  18  by a pivot axis  28 . Frame  22  also includes a gooseneck arm  30  coupled to anus  24  via a pivot axis  32  and extending forward from front end  82 . 
     A hydraulic jack  34  couples bin  18  to gooseneck arm  30  so that bin  18  can be raised and lowered relative to the ground. Specifically, the bin  18  includes a blade  36  that spans across the front end  82  and excavates earth as the tractor scraper  12  passes along the ground. An amount of material removed as the scraper  12  passes is controlled by raising or lowering the blade  36  of the bin  18 . The blade  36  is positioned by operating the hydraulic jack  34  to rotate the blade  36  upward and downward. More specifically, hydraulic jack  34  is expanded or contracted to determine the depth of the blade  36  with respect to the ground. Bin  18  is positioned directly behind the blade  36  to receive dirt severed from the terrain by the blade  36 . 
     A rotating apron or gate is provided near the front end  82  of bin  18 . The gate forms an operable front wall for the bin  18  that extends laterally between the bin sidewalls  26 . The gate rotates about a pivot axis to open so that dirt severed from the terrain is forced backward into the bin  18 . When the bin  18  is filled with dirt, the apron is lowered to its closed position so that the load can be carried to its ultimate place of disposal. 
     The tractor  14  is supported by a front pair of wheels  38  on a front axle  46  and a rear pair of wheels  40  on a rear axle  48  coupled to a frame  44 . Tractor  14  includes an operator cab  42  having an instrument and control panel for controlling the tractor scraper  12  as well as to monitor or adjust various accessory or auxiliary equipment of the tractor scraper  12 . Fluid conduits and/or hoses extend from tractor  14  and are turned across the gooseneck arm  30  to supply fluid hydraulic jack  34  to permit an operator in the cab  42  to control functions of the depth of blade  36 . 
     The trailer  16  is joined to the tractor  14  by means of a hitch-receiver pair  90  that includes a hitch  50  and a receiver  52 , as illustrated in  FIG. 2 . In the illustrated embodiment, hitch  50  is coupled to gooseneck arm  30  and receiver  52  is coupled to tractor  14 ; however, in an alternative embodiment, hitch  50  may be coupled to tractor  14  and receiver  52  may be coupled to gooseneck arm  30 . Hitch-receiver pair  90  provides a single joint or interface  54  to couple the gooseneck arm  30  of trailer  16  to tractor  14  without a king pin. The single interface  54  enables a quick and easy connection and disconnection between the trailer  16  and the tractor  14 . 
     Preferably, hitch-receiver pair  90  is fixedly attached to tractor  14  approximate to rear axle  48  between rear axle  48  and front axle  46 . More specifically, hitch-receiver pair  90  is fixedly attached above and ahead of rear axle  48 . In the exemplary embodiment illustrated in  FIGS. 7(   a ) and  7 ( b ), hitch-receiver pair  90  is fixedly attached  16  inches ahead of rear axle  48  and 26.13 inches above rear axle  48 . Also, as illustrated in  FIG. 1(   b ), hitch-receiver pair  90  is fixedly attached to tractor  14  at a vector angle of 20 degrees and 53 minutes. Accordingly, a small moment arm is provided to reduce the possibility of wheels  40  leaving the ground while operating tractor scraper  12 . Hitch-receiver pair  90  is also preferably centered between a first side  56  of tractor  14  and a second side  58  of tractor  14 . 
     The position of hitch-receiver pair  90  facilitates supporting trailer  16  by distributing the weight of trailer  16  between wheels  40  of tractor  14  and gooseneck  30 . Specifically, the position of hitch-receiver pair  90  distributes approximately 33-40% of the weight of trailer  16  on gooseneck  30  and approximately 60-67% of the weight on rear wheels  40  of tractor  14 . Accordingly, the position of hitch-receiver pair  90  hitch-receiver pair  90  also facilitates keeping the wheels  38  and  40  of tractor  14  in contact with the ground so that proper traction can be maintained. In the exemplary embodiment, a base plate  60  is coupled to tractor frame  44  at interface  54 . Receiver  52  is fixedly attached to base plate  60  in the illustrated embodiment; however, as described above, hitch  50  can be fixedly attached to base plate  60 . 
     Hitch-receiver pair  90  enables free rotation of trailer  16  with respect to tractor  14 . Specifically, hitch-receiver pair  90  enables pivotal rotation (turning), pitch rotation, and oscillation or roll of trailer  16  with respect to tractor  14 . Preferably, hitch-receiver pair  90  enables trailer  16  to pivot/turn within a range of ±95 degrees, as illustrated in  FIG. 4 , oscillate within a range of ±20 degrees, as illustrated in  FIG. 5 , and pitch within a range of ±20 degrees, as illustrated in  FIGS. 6(   a ) and  6 ( b ), with respect to tractor  14 . As will be appreciated by one of skill in the art, hitching system  10  could be designed to pivot, pitch, and oscillate trailer  16  within a wide variety of ranges with respect to tractor  14 . 
     In one embodiment, illustrated in  FIG. 2 , the hitch-receiver pair  90  has a spherical interface  54   a  with a ball hitch  50   a  and a corresponding ball socket  52   a  that is configured to receive the ball hitch  50   a.  The spherical interface  54   a  permits the hitch-receiver pair  90  to freely rotate without any kingpin constraining the movement. Accordingly, the ball hitch  50   a  freely pivots, oscillates, and pitches with respect to the ball socket  52   a.  Accordingly, trailer  16  is enabled to freely rotate by pivoting, oscillating, and pitching with respect to the tractor  14 . 
     A locking ring  94 , as illustrated in  FIGS. 9(   a ) and  9 ( b ), is positioned around the ball hitch  50   a  and secured to the ball socket  52   a.  Locking ring  94  includes a first hemi-spherical half  96  and a second hemi-spherical half  98  that are positioned together to secure the ball hitch  50   a  to the ball socket  52   a.  Each half  96  and  98  includes a split end  100  and a notched end  102  having a hinge  110  that enables the locking ring  94  to be opened and closed around the ball hitch  50   a  by pivoting the halves  96  and  98  about hinge  110 . Specifically,  FIG. 9(   a ) shows locking ring  94  in a closed position  104 , and  FIG. 9(   b ) illustrates locking ring  94  in an open position  106 . Locking ring  94  further includes a plurality of apertures  108  through which a fastening mechanism, such as a screw or pin, is inserted to secure the locking ring  94  to the ball socket  52   a.  Accordingly, locking ring  94  operates to secure the ball hitch  50   a  to the ball socket  52   a  when the hitch-pair receiver  90  is in use. 
     In another embodiment, illustrated in  FIG. 3 , the hitch-receiver pair  90  has a multi-joint interface  54   b  with a multi-pin hitch  50   b  that is configured to attach to the fixed receiver  52   b.  The multi-joint hitch  54   b  includes a pivot pin  66 , a pitch pin  70 , an oscillation pin  74 , a first link  76 , and a second link  78 . First link  76  and second link  78  are coupled at their first ends  62  and  64  via oscillation pin  74 , pivot pin  66  is attached to a second end  68  of first link  76 , and pitch pin  70  is attached to a second end  72  of second link  78 . First link  76  attaches to one of gooseneck  30  and base plate  60  via pivot pin  66 , and second link  78  attaches to the other of gooseneck  30  and base plate  60  via pitch pin  70 . The multi-joint hitch  50   b  is configured to pivot about pivot pin  66 , pitch about pitch pin  70  and oscillate about oscillation pin  74  such that trailer  16  pivots, pitches, and oscillates with respect to tractor  14 . 
     Accordingly, hitching system  10  enables trailer  16  to rotate freely with respect to tractor  14 . In particular, the trailer  16  will pivot, pitch, and oscillate freely with respect to the tractor  14 . This enables the tractor scraper  12  to operate on rough terrain with an unlevel grade without having the trailer  16  become detached from the trailer or otherwise inoperable. 
       FIG. 8  is an illustration of tractor  14  having a water wagon  92  attached thereto using hitching system  10 . As will be appreciated by one of ordinary skill in the art, hitching system  10  can be used to attach a water wagon and a dump trailer to tractor  14 . 
     As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.