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You are an expert at summarizing long articles. Proceed to summarize the following text: 
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to utility vehicles such as tractors. Particularly, the invention relates to a tractor that is provided with a detachable rear-mounted implement, such as a backhoe. 
     BACKGROUND OF THE INVENTION 
     Utility vehicles, such as compact tractors, are configured to accept a plurality of rear-mounted implements. Such implements include mower decks, tillers, cultivators, trenchers and backhoes. For attaching a rear-mounted implement, a mounting system is required. A mounting system must allow for attachment and detachment of the rear-mounted implement to the utility vehicle such that other rear-mounted implements can be used alternatively. A rigid and secure rear-mounted implement mounting system is required. 
     Most backhoe mounting systems in use today require the operator to be on the ground, out of the vehicle cab or operator station, to attach the backhoe attachment, thus exposing the operator to certain inconveniences and hazards inherent in manipulating such a large and heavy attachment. These mounting systems are cumbersome and complex. 
     The present inventors have recognized the desirability of providing a rear-mounted implement mounting system that is rigid and secure but which also is easily attached and detached. The present inventors have recognized the desirability of providing a rear-mounted implement mounting system that can be engaged to a utility vehicle by the operator without leaving the vehicle cab or operator station. 
     SUMMARY OF THE INVENTION 
     The invention provides a rear-mounted implement mounting system for a utility vehicle, including a rear-mounted implement, that comprises a first connection arranged between the utility vehicle and the rear-mounted implement, the first connection being engageable in a first direction and restrained along a second direction, the second direction substantially perpendicular to the first direction, and a second connection between the utility vehicle and the rear-mounted implement, the second connection being engaged in a tangential direction rotationally about the first connection, and thereafter restrained along the tangential direction. 
     Advantageously, the first direction is a substantially vertical direction and the second direction is a substantially horizontal direction, although the invention encompasses other directions angled to the vertical and horizontal directions. The invention allows for a setting of the first connection and a pivoting of the rear-mounted implement to set the second connection, engaged in the tangential direction, and once set, restrained in the tangential direction. 
     The present invention provides a rear-mounted implement mounting system for a utility vehicle that includes a set of lower hooks or seats and a set of upper receivers, located on a chassis of the utility vehicle. The rear-mounted implement includes round bar features that are configured to be inserted into the lower hooks, and boss features that are configured to be engaged to the upper receivers. Locking devices can be engaged to the bosses and receivers to lock the rear-mounted implement to the utility vehicle. 
     According to one aspect of the invention, in order to mount the rear-mounted implement, the utility vehicle is backed up to a detached rear-mounted implement, and the operator connects the hydraulic supply lines of the rear-mounted implement to the utility vehicle. Using hydraulic power, the round bar features on the rear-mounted implement are set above the lower hooks on the utility vehicle. The rear-mounted implement is then lowered to position the bar features into the hooks using lateral stabilizers of the rear-mounted implement. The boom cylinder of the rear-mounted implement is then extended which rotates the entire rear-mounted implement base into a mounting position. The boss features on the rear-mounted implement contact specially machined receivers, which force the rear-mounted implement into its final attached position. The operator can then easily insert and lock-in mounting pins by hand. All of these tasks can be accomplished from the operator&#39;s seat. 
     The present invention allows the operator to attach and detach a rear-mounted implement without the need to exit the utility vehicle cab. This enhances productivity and safety of the operator. Secondly, the mounting system is robust, and securely mounts the rear-mounted implement to the utility vehicle. Thirdly, the number of parts required to assemble the mounting system is low. This further reduces complexity of the mounting system, and increases the robustness of the mounting system. The mounting system allows mounting of the rear-mounted implement to the utility vehicle even if the rear-mounted implement is stored on unlevel ground or dirt. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary elevational view of a tractor and a backhoe attachment with a foreground rear wheel removed for viewing portions behind the wheel; 
     FIG. 2 is an enlarged fragmentary elevational view of an interface between the tractor and the backhoe attachment; 
     FIG. 2A is a fragmentary sectional view taken generally along line  2 A— 2 A of FIG. 2; 
     FIG. 3 is an enlarged fragmentary perspective view of the mounting arrangement of the backhoe attachment to the tractor; 
     FIGS. 4A through 4D are fragmentary elevational views of the tractor and the backhoe attachment in progressive stages of attachment; and 
     FIG. 5 is a schematic diagram of the backhoe attachment and mounting system of the tractor of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     FIG. 1 illustrates a utility vehicle  20  and a rear-mounted implement, such as a backhoe attachment  24 . The utility vehicle  20  includes a cab or operator&#39;s station  28  including a seat  32 , a steering wheel  34 , and controls  36 . The cab is supported on a chassis  42  that is supported on front wheels  44  and larger rear wheels  46 . The foreground rear wheel is removed in FIG. 1 to view portions behind the wheel. The utility vehicle  20  can be equipped with a front mounted loader assembly  48 . 
     The backhoe attachment  24  includes a bucket  54 , a distal arm or dipperstick  58 , an intermediate arm or boom arm  62 , a swivel arm or swivel tower  66  and a base assembly or mainframe  67 . The distal arm  58  can be pivoted about a pivot point  58   a  with respect to the intermediate arm  62  by a hydraulic cylinder  70 . The intermediate arm  62  can be pivoted with respect to the swivel arm  66  by a hydraulic cylinder or boom cylinder  74 . The swivel arm  66  can be rotated about a vertical axis with respect to the base assembly  67 . The bucket  54  can be curled with respect to the distal arm  58  by a hydraulic cylinder  76 . The operation of the hydraulic cylinders is by rear-mounted controls  82 . 
     The chassis  42  includes a rear-mounted implement mounting structure  42   a  located on a rear end of the chassis  42 , facing the backhoe attachment  24 . The backhoe attachment base assembly  67  includes features that engage the rear-mounted implement mounting structure  42   a . The rear-mounted implement mounting structure  42   a  and the base assembly  67  are both substantially mirror-image symmetrical about a vertical, longitudinal plane. 
     As illustrated in FIGS. 2,  2 A and  3 , the backhoe attachment base assembly  67  includes horizontal upper and lower plates  83 ,  84  and side plates  85 ,  86 . The side plate  85  is shown in phantom in FIG. 3 to allow viewing of the receiver  112 . Laterally directed, round bars  92 ,  94  extend on opposite sides of the base assembly  67  on a bottom thereof (FIG.  2 A). As illustrated in FIG. 3, the base assembly  67  includes cylindrical bosses  102 ,  104  located substantially above the round bars  92 ,  94  and extending laterally on opposite sides of the base. 
     The mounting structure  42   a  includes hooks or seats  106 ,  108 , open upwardly and located on opposite lateral sides of the rear portion of the chassis  42  of the utility vehicle. The seats  106 ,  108  are sized to receive the round bars  92 ,  94  therein. The mounting structure  42   a  further includes semi-cylindrical receivers  112 ,  114  that are sized and shaped to receive the bosses  102 ,  104  therein and guide the bosses into a mounting position. The receivers  112 ,  114  are open horizontally toward the backhoe attachment. 
     FIG. 2 illustrates in an enlarged view, the partial engagement of the base assembly  67  of the backhoe attachment  24  to the mounting structure  42   a . The round rods  92 ,  94  are already fit into the seats  106 ,  108 . The bosses  102 ,  104  are being rotated upwardly about the rods  92 ,  94  to engage the receivers  112 ,  114  in a tangential direction. The receivers  112 ,  114  include semi-circular rim portions  112   a ,  114   a  and pin receiving cylinder portions  112   b ,  114   b . The bosses  102 ,  104  include central bores  102   a ,  104   a . When a boss  102 ,  104  is fit into the receiver rim portions  112   a ,  114   a  the bores  102   a ,  104   a  aligns with the bores  112   c ,  114   c  as the bosses  102 ,  104  fit coaxially against the cylinder portions  112   b ,  114   b.    
     As shown in FIG. 3, cylindrical connection pins  115  fit through the central bores  102   a ,  104   a  of the bosses  102 ,  104 , respectively, and through the adjacent bores  112   c ,  114   c  of the cylinder portions  112   b ,  114   b  of the receivers  112 ,  114 . 
     The cylindrical portions  112   b ,  114   b  include a radial through-hole  130  penetrating completely through the cylinder portions  112   b ,  114   b  in order to receive a retainer pin  117 . Once the respective connector pin  115  is pushed through both the bosses  102 ,  104  and the respective cylinder portions  112   b ,  114   b , a retainer pin  117  is inserted through both the cylinder portions  112   b ,  114   b  and through a through-hole  115   a  of the respective connector pin  115  to retain the connector pins  115  in place. This locks the backhoe attachment to the utility vehicle. 
     FIG. 4A illustrates the first step of attachment of the backhoe attachment  24  to the utility vehicle  20 . The round bars  92 ,  94  are positioned above the hooks  106 ,  108 . In order to elevate and position the round bars  92 ,  94  above the seats  106 ,  108 , the stabilizers  122  (one shown in FIG. 4A) that are located on opposite lateral sides of the backhoe attachment  24 , are lowered as necessary. The stabilizers can then be raised such that the round bars are lowered to fit snuggly within the seats. 
     FIG. 4B illustrates the next step in the attachment of the backhoe attachment  24  to the utility vehicle  20  wherein the hydraulic cylinder  74  is extended to pivot the base assembly  67  with respect to the utility vehicle  20  to mate the bosses  102 ,  104  to the receivers  112 ,  114 . The base assembly  67  is rotated in the direction R. The rotation also drives the round bars  92 ,  94  into the seats  106 ,  108 . 
     FIG. 4C shows the complete attachment of the backhoe attachment  24 . The round bars  92 ,  94  are completely set into the seats  106 ,  108 . The bosses  102 ,  104  are set into the receivers  112 ,  114 . Connection pins (shown in FIG. 3) have been inserted through the bosses  102 ,  104  and the receivers  112 ,  114  are locked in place. 
     FIG. 4D shows the stabilizers  122  raised and the hydraulic cylinder  74  retracted to make the utility vehicle ready for ground travel. 
     FIG. 5 illustrates the geometric proportions that allow for the easy attachment of the backhoe attachment to the utility vehicle chassis  42 . The bars  92 ,  94  are located at a distance d 1  from the cylindrical bosses  102 ,  104 . The seats  106 ,  108  are located at substantially the same distance to the receivers  112 ,  114 . 
     The pivot point  62   a  of the intermediate arm  62  to the swivel arm  66  is located at a distance d 2  to the bars  92 ,  94 . The pivot point  58   a  between the intermediate arm  62  and the distal arm  58  of the backhoe attachment is located at a distance d 3  to the pivot point  62   a . The pivot point  58   a  is located at a distance d 4  to a bottom  54   b  of the distal arm  58  with the bucket in a fully curled orientation as shown in FIG.  1 A. 
     During the rotary movement of the backhoe attachment, the distal arm  58  remains substantially vertical. The intermediate arm  62  pivots clockwise about the pivot point  58   a . The swivel arm  66  and the base assembly  67  pivot counterclockwise about the bars  92 ,  94  and the bosses rotate counterclockwise in the direction R about the bars  92 ,  94  to engage into the receivers  112 ,  114 . An angle B between the swivel arm  66  and the intermediate arm  62  opens up. 
     According to one exemplary embodiment, the distances set forth in FIG. 5 are: d 1 =500 mm; d 2 =1125 mm; d 3 =2171 mm; and d 4 =1825 mm. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

Summary:
A rear-mounted implement mounting system includes semi-cylindrical seats open upwardly and mounted on a lower back portion of a utility vehicle chassis that receive bar members located on a facing lower part of the rear-mounted implement. The utility vehicle chassis further includes semi-cylindrical receivers open in a rearward direction and adjacent cylinder portions open laterally. The receivers guide cylindrical bosses, located on an upper portion of the rear-mounted implement, into alignment with the cylinder portions, when the rear-mounted implement is pivoted upwardly by extending the boom cylinder of the rear-mounted implement. Connecting pins can be slipped through the cylindrical bosses and cylinder portions to lock the rear-mounted implement to the utility vehicle chassis. An operator remaining in the vehicle cab or operator station can easily operate the mounting system.