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CROSS-REFERENCE TO RELATED APPLICATION 
   The present invention is a continuation-in-part application based on prior application Ser. No. 10/613,313 filed on Jul. 7, 2003, now U.S. Pat. No. 7,089,692 and entitled “Slip Hitch for a Snow Plow.” 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to the field of hitches or coupling assemblies that connect a snow plow or other comparable items to drive vehicles, and in particular to one in which the snow plow can momentarily release or slip over a blocking object it encounters as it is moved along the ground during its snow plowing operation, and then return to its original working position after it has passed over the blocking object. It also relates to a slip hitch for a snow plow or other comparable items that enable the snow plow or other comparable items to adjust to the incline and decline of the surface being plowed or scraped. 
   2. Description of the Prior Art 
   The typical prior art hitches or coupling assemblies for snow plows that connect to a drive vehicle have a rigid non-release mechanism. When a blocking object is encountered on the ground, the only way for such prior art connections of a snow plow to a drive vehicle to get over the obstacle is for the operator to manually operate the lifting and lowering mechanism of the coupling assembly to raise the snow plow that way, then drive past the obstacle and then manually operate the lifting and lowering mechanism to lower the snow plow back on to the ground. 
   SUMMARY OF THE INVENTION 
   The hitch or coupling assembly in accordance with the present invention includes an elongated slip hitch operating member that hooks on to the connecting lug of the drive vehicle coupling apparatus, in which the slip hitch operating member has one or more elongated guide slots to receive corresponding guide rods or bolts that are connected to members that are in turn connected to the snow plow. When the snow plow encounters an obstacle on the ground, the lower edge of the snow plow is urged rearwardly which puts rearward pressure on the guide rods in the guide slots of the slip hitch operating member causing them to ride upwardly as the guide rods move upwardly in the guide slots until the snow plow is able to clear the obstacle, after which the guide rods slide back down in the guide slots as the snow plow is lowered by gravity back to its original operating position in contact with the ground. 
   The foregoing applies specifically to the disclosure of the parent application Ser. No. 10/613,313. A second embodiment of the snow plow of the present invention added by way of this continuation-in-part application is quite similar to the one as shown in  FIGS. 1 and 5 , except that the wing plate assembly therein has been modified so as to increase the wing plate assembly length and to include a back support bracket requiring an additional slot on the aft of the wing plate assembly. As a result, this second added embodiment represents an improvement over the embodiment of  FIGS. 1 and 5  since it has the capability of also capturing snow in the reverse direction as well as in the forward direction of travel. Additionally, this second embodiment also reduces the amount of force applied to the aft of the wing plate assembly when the snow plow is fully filled with snow. 
   Further, a third embodiment of the snow plow of the present invention also added by way of this continuation-in-part application is quite similar to the one illustrated in  FIGS. 1-4 , except that the hitch or coupling assembly therein has been modified so as to include a universal adjustable slide mount for the slip hitch. As a result, this third embodiment represents an improvement over the present invention since it accommodates all of the different manufactures&#39; boom spread size. 
   Moreover, a fourth embodiment of the snow plow the present invention also added by way of this continuation-in-part application includes a hinged torsion-spring trip cutting edge so as to allow the moldboard assembly thereof to flex upwardly when an obstacle is encountered by the cutting edge. As a result, the block members that connect the snow plow frame to the moldboard are prevented from being damaged or destroyed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become more fully apparent from the following detailed description when read in conjunction with the accompanying drawings with like reference numerals indicating corresponding parts throughout, wherein: 
       FIG. 1  is an elevation view of the rear of a snow plow having a pair of spaced apart slip hitch connecting members for connection to a drive vehicle; 
       FIG. 2  is an enlarged elevation view of the mid-portion of the rear of the snow plow seen in  FIG. 1  to better illustrate the pair of spaced apart slip hitch connecting members; 
       FIG. 3  is an elevation view of the elongated slip hitch member mounted for limited reciprocal movement relative to the vertical mounting bars between which it is positioned, one of the vertical mounting bars being broken away to better illustrate the slip hitch member, and showing upper and lower guide rods in section in their respective guide slots of the slip hitch member; 
       FIG. 4  is an elevation view of a portion of the side of a snow plow having slip hitch connecting members and also of a portion of the side of a connecting member of a drive vehicle in position to connect to the slip hitch connecting members; 
       FIG. 5  is an elevation view of the front of the snow plow seen in  FIG. 1 ; 
       FIG. 6  is a second embodiment of a snow plow of the present invention, ilustrating the back view of a portion of the wing plate assembly with back support bracket; 
       FIG. 7  is an enlarged, perspective view of the back support bracket of  FIG. 6 ; 
       FIG. 8  is a side view of the wing plate assembly, in accordance with the present invention; 
       FIG. 9  is a third embodiment of a snow plow of the present invention, illustrating the universal adjustable slide mount on the mid-portion of the rear thereof; 
       FIG. 10  is an enlarged perspective view of a portion of the universal adjustable slide mount of  FIG. 9 ; 
       FIG. 11  is a fourth embodiment of a snow plow of the present invention, illustrating a perspective view of the torsion spring trip edge; and 
       FIG. 12  is an enlarged perspective view of a portion of the rear of the snow plow of the present invention of  FIG. 11 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It is to be distinctly understood at the outset that the present invention shown in the drawings and described in detail in conjunction with the preferred embodiments is not intended to serve as a limitation upon the scope or teachings thereof, but is to be considered merely as an exemplification of the principles of the present invention. 
   A slip hitch connecting assembly in accordance with the present invention includes a pair of spaced apart vertical connecting members  2  welded or otherwise secured to the back of a snow plow  4  or other item of equipment that is hitched to a drive vehicle for performing a work function on the surface of the ground as it is moved forward by the drive vehicle. The snow plow  4  shown and described herein has a sectioned moldboard which is the subject of a separate co-pending patent application Ser. No. 10/057,269 filed in the United States Patent and Trademark Office on Jan. 28, 2002 by the same inventor, and has now matured into U.S. Pat. No. 6,823,615 issued on Nov. 30, 2004, but the slip hitch connecting assembly in accordance with this invention can be used with other snow plows and similar equipment as well. 
   Each vertical connecting member  2  is identical so only one need be described in detail. Each includes a first upright bar  6  welded or otherwise secured to the upper horizontal frame bar  8  and lower horizontal frame bar  10  of the snow plow frame  12  which extend across the rear of the snow plow  4 . Each vertical connecting member  2  also includes a second upright bar  14  which is also welded or otherwise secured to the horizontal frame bars  8  and  10  at a location slightly spaced apart horizontally from the first upright bar  6  to provide a through channel  16  between the vertical  6  and  14 . 
   An elongated slip hitch member  18  is received in the through channel  16  for limited reciprocal movement relative to the upright bars  6  and  14  which form the side walls of the channel  16  when the lower edge  20  of the snow plow  4  contacts an item projecting upwardly from the ground causing the upper edge  22  of the snow plow to tip forwardly and upwardly in a limited arcuate path as the lower edge  20  is moved rearwardly and upwardly enough to clear the upwardly projecting item. The upright bars  6  and  14  then slide downwardly relative to the elongated slip hitch member  18  enabling the upper edge  22  and lower edge  20  of the snow plow  4  to move back to their original positions, the lower edge sliding downwardly and forwardly into scraping contact with the ground, the upper edge sliding downwardly and rearwardly in a slight arcuate path. 
   The slip hitch member  18  includes a connecting hook member  24  formed at its upper end  26  facing rearwardly to receive the connecting lug  28  of a drive vehicle coupling assembly  30 . The slip hitch member  18  includes an integrally formed upper flat planar section  32  extending downwardly about eighteen inches from the hook member  24 . The slip hitch member  18  also includes a lower flat planar section  34  which extends another eight inches or so downward to terminate in a hitch member lower edge  36 . A flat planar abutment member  38  is integrally formed to extend forwardly of the slip hitch member  18  and between the upper horizontal frame bar  8  and lower horizontal frame bar  10  of the snow plow  4  when the slip hitch connecting assembly and its slip hitch member  18  are in place on the snow plow  4 . 
   The lower flat planar section  34  has an integrally formed connecting projection  40  extending rearwardly, having a connecting aperture  42  to receive the connecting pin of a drive vehicle coupling assembly  30 . The elongated slip hitch member  18  is able to pivot slightly to the rear on the connecting pin in aperture  42  when the lower edge  20  of the snow plow encounters an obstacle on the ground. That in turn puts rearward pressure on the slip hitch member  18  causing it to pivot slightly to the rear as guide rod members connected to the snow plow slide upwardly and slightly to the rear in guide slots of the slip hitch member as the snow plow is moved rearwardly and upwardly to clear the obstacle. When the obstacle is cleared, the snow plow is free to fall back to its original position by gravity, causing the guide rod members to slide down in their respective guide slots of the slip hitch member to guide the snow plow to its original working position with its lower edge  20  in scraping contact with the ground to resume plowing snow. 
   The slip hitch member  18  includes an upper elongated guide slot  44  to receive an upper reciprocating guide rod or bolt  46  which extends across from the spaced apart upright bars  6  and  14  that are welded to the horizontal frame bars  8  and  10  of the snow plow frame  12  at the level of the upper frame bar  8 . The slip hitch member  18  also includes a lower elongated guide slot  48  to receive a lower reciprocating guide rod or bolt  50  which extends across from the spaced apart upright bars  6  and  14  at the level of the lower horizontal frame bar  10 . When the lower edge  20  of the snow plow  4  contacts an item projecting upwardly from the ground causing the upper edge  22  of the snow plow to tip forwardly and upwardly in a limited arcuate path as the lower edge  20  is moved rearwardly and upwardly enough to clear the upwardly projecting item, the guide bolts  46  and  50  move upwardly in their respective elongated guide slots  44  and  48 . When the lower edge  20  of the snow plow has cleared the upwardly projecting item, the snow plow is then free to move downwardly by gravity to its original operating position whereby the guide bolts  46  and  50  move in a reciprocating manner downward in their respective guide slots  44  and  48 . 
   The elongated slip hitch member  18  is able to pivot slightly to the rear on the connecting pin in aperture  42  when the lower edge  20  of the snow plow encounters an obstacle on the ground that in turn puts rearward pressure on the guide rods  46  and  50  in their respective guide slots  44  and  48  of the slip hitch member  18  causing it to pivot slightly to the rear as the guide rods slide upwardly and slightly to the rear in their guide slots  44  and  48  as the snow plow is moved rearwardly and upwardly to clear the obstacle. 
   In view of the foregoing detailed description, it can thus be seen that the present invention provides a slip hitch for connection to a drive vehicle for a snow plow which includes an elongated flat planar member for hooking onto a connecting lug of the drive vehicle. The flat planar member is mounted on the snow plow frame for reciprocal movement in each of a pair of spaced apart coupling members secured to the snow plow frame for connecting the snow plow to the drive vehicle. 
   The wing plate assembly of the first embodiment suffered from the disadvantage of being only able to capture snow when the snow plow is moved in a forward direction and could not capture snow in the reverse direction. Also, the slip hitch of the first embodiment being secured fixedly to one portion of the snow plow frame could not accommodate wheel loaders of different manufactures having varied boom spread sizes. In addition, the cutting edge of the snow plow of the first embodiment being mounted directly to the moldboard thereof did not offer sufficient flexibility when an obstacle was encountered which resulted in damage to the block members of the snow plow. 
   In order to overcome each and every one of these problems, the wing plate assembly, snow plow frame and cutting edge of the snow plow have been modified. A second embodiment of the snow plow is described and illustrated in  FIGS. 6  though  8  of the drawings. A third embodiment of the snow plow is described and illustrated in  FIGS. 9 and 10  of the drawings. A fourth embodiment of the snow plow is described and illustrated in  FIGS. 11 and 12  of the drawings. 
   Specifically, in  FIGS. 6-8 , there is illustrated a second embodiment directed to a wing plate assembly which includes a back support bracket  652  of the present invention. The back support bracket  652  consists of a top triangular-shaped member  654  and a bottom triangular-shaped member  656 , both of which are identical in shape and size. An L-shaped member  658  is welded in between the top triangular-shaped member  654  and the bottom triangular-shaped member  656 . The L-shaped member  658  includes three vertically aligned apertures  653 ,  655 ,  657 . 
   The back support bracket  652  is welded to the snow plow frame  612 . More specifically, the top triangular-shaped member  654  of the back support bracket  652  is welded to the upper horizontal frame bar  608  of the snow plow frame  612  and the bottom triangular-shaped member  656  of the back support bracket  652  is welded to the lower horizontal frame bar  610  of the snow plow frame  612 . The back support bracket  652  functions to reduce the amount of force applied to the aft of the wing plate assembly when the snow plow is fully filled with snow. 
   Furthermore, the snow plow  604  includes a first wing plate member  666  mounted for limited pivotal movement at one side thereof, and a second wing plate member  667  mounted for limited pivotal movement at the opposite side thereof. Each wing plate member  666 ,  667  includes a first arcuate slot  668 , a second arcuate slot  678  and a circular opening  684 , all of which are located on the aft portion of the wing plate members. Secured to the lower portion of each wing plate member is a skid shoe  672 . The skid shoe  672  includes a flat portion  677 , an upwardly inclined forward portion  674  and an upwardly inclined back portion  676 . Since each wing plate member  666 ,  667  is secured to the snow plow frame  612  and the back support bracket  652  in the same manner, the description of securing only one wing plate member will now be explained in detail. 
   The wing plate member  666  is secured to the snow plow frame  612  by a first bolt and washer combination  680 , the bolt extending through a first retaining plate  670   a , the first arcuate slot  668  and threaded into a threaded tap opening to the outer end of the upper horizontal frame bar  608 , and a second bolt and washer combination  686 , the bolt extending through circular opening  684  in the lower, aft portion of the wing plate member  666  and threaded into a threaded tap opening to the outer end of the lower horizontal frame bar  610 . 
   Furthermore, the wing plate member  666  is also secured to the back support bracket  652 . Placed between the wing member  666  and the back support bracket  652  is a nylon spacer  664 . The nylon spacer  664  includes three vertically aligned apertures which correspond and align with the apertures  653 ,  655 ,  657  located on the L-shaped member of the back support bracket  652 . The nylon spacer  664  is secured to the back support bracket  652  by a first nut and bolt combination  682  and a second nut and bolt combination  688  inserted through the first aperture  653  and the third aperture  657  of the L-shaped member  658 , respectively. Wing plate member  666  is secured to the back support bracket  652  by a bolt  662  and nut  660 , the bolt extending through a second retaining plate  670   b , the second arcuate slot  678 , the middle aperture in the nylon spacer  664 , the second aperture  655  in the L-shaped member  658  of the back support bracket  652  and threaded into nut  660 . 
   In operation, as a vehicle moves the snow plow forward, the first arcuate slot  668  and the second arcuate slot  678  permit the wing member  666 , as the case may be, a limited amount of pivotal movement around the respective bolts  680 ,  662  at the lower, aft portion of the wing member  666  as the skid shoe  672  on the bottom edge of the wing plate member  666  rises and falls with the contour of the surface on which it is sliding. The skid shoe  672  includes an upwardly inclined forward portion  674  to initially contact a rise in the surface on which the snow plow is being used, to thereby pivot the wing plate member upwardly a limited amount and do so automatically to prevent gouging into an upwardly rising ground surface without the need for action or special attention on the part of the operator of the vehicle snow plow. Additionally, the skid shoe  672  also includes an upwardly inclined back portion  676  to facilitate in removing snow when the vehicle is moving in a reverse direction of travel. 
   In  FIGS. 9 and 10 , there is illustrated a third embodiment of a snow plow which includes a universal adjustable slide mount  990  of the present invention. The hitch or coupling assembly of this third embodiment includes a pair of spaced apart vertical connecting members  902 . Each vertical connecting member  902  is identical so only one need be described in detail. All of the elements and interconnections of each of the vertical connecting members  902  in the third embodiment of  FIGS. 9 and 10  are identical to the ones used in each of the vertical connecting members  2  of  FIGS. 1-4 , except that first and second upright bars  906   a  and  906   b  each includes a top and bottom aperture  997 , 998  spaced equal to the distance between the upper horizontal frame bar  908  and the lower horizontal frame bar  910 . To the extent that the rest of the elements and interconnections of each of the vertical connecting members  902  are identical to the ones in each of the vertical connecting members  2  (in  FIGS. 1-4 ), the elements and interconnections of each of the vertical connecting members  902  will not be explained any further as it is fully discussed above. 
   This third embodiment creates an alternative way to secure each of the vertical connecting members  902  to the snow plow frame  912  by way of a universal adjustable slide mount  990 . The universal adjustable slide mount  990  includes first and second upper slotted steel channels  992 , 994  welded or otherwise secured to the upper horizontal frame bar  908  at a location slightly spaced apart horizontally from one another and first and second lower slotted steel channels  993 , 995  welded or otherwise secured to the lower horizontal frame bar  910  at a location slightly spaced apart horizontally from one another, and having the first slotted steel channels  992 , 993  vertically aligned with each other and the second slotted steel channels  994 , 995  vertically aligned with each other. 
   Further, the first upright bar  906   a  of the vertical connecting member  902  is secured to the snow plow frame  912  by using a nut and bolt combination  982   a  through the top aperture  997  of the first upright bar  906  and the first upper slotted steel channel  992 . The first upright bar  906  is also secured to the snow plow frame  912  by using another nut and bolt combination  982   b  through the bottom aperture  998  of the first upright bar  906  and the first lower slotted steel channel  993 . 
   In a similar fashion, the second upright bar  906   b  is secured to the snow plow frame  912  by using a nut and bolt combination  982   c  through the top aperture  997  of the second upright bar  906   b  and the second upper slotted steel channel  994 . The second upright bar  906   b  is also secured to the snow plow frame  912  by using another nut and bolt combination  982   d  through the bottom aperture  998  of the second upright bar  906   b  and the second lower slotted steel channel  995 . 
   In operation, the universal adjustable slide mount  990  allows the user to manually adjust inwardly and outwardly the spread size of the hitch or coupling assembly so as to accommodate all of the different manufacturers&#39; boom spread sizes. This is achieved by loosening bolts  982   a - d  and then sliding each of the vertical connecting members  902  along the respective slotted steel channels  992 - 995  to the desired spread size. Thereafter, retightening of the bolts  982   a - d  is performed so as to secure fixedly the hitch assembly in the new position. 
   In  FIGS. 11 and 12 , there is illustrated the fourth embodiment of a snow plow which includes a hinged torsion-spring trip cutting edge assembly  1199 . The sectioned moldboard  1100  comprises a plurality of independently movable snow plow sections  1125 , arranged in a side-by-side relationship, mounted on a snow plow frame  1112  in such a way that each section  1125  can independently move upwardly and downwardly with the changing contour of the ground surface. Each snow plow section  1125  is secured to the horizontal bars  1108 ,  1110  of the snow plow frame  1112  by flexible polyurethane block members  1103 . 
   Each snow plow section  1125  comprises a curved or arcuate moldboard  1127 , made of steel or other comparably hard and rigid material, having a forwardly facing concave surface (hidden) and a rearwardly facing convex surface  1131 . Two of the flexible polyurethane block members  1103  are secured at their forward ends to the rearwardly facing surface  1131  of each snow plow section  1125  about midway between the upper edge thereof and the lower edge thereof, and are secured at their rearward ends to the upper horizontal bar  1108 . Two additional flexible polyurethane block members  1103  are secured at their forward ends to the rearwardly facing surface  1131  of each snow plow section  1125  near the lower edge thereof, and are secured at their rearward ends to the lower horizontal bar  1110 . 
   The flexible polyurethane block members  1103  are secured to the rearward facing surface  1131  of the moldboard  1100  by upper and lower mounting plates  1107   a ,  1107   b , which are secured to the moldboard, and by upper (hidden) and lower capture plates  1109 , which receive the forward end of the flexible polyurethane block members  1103  between the mounting plates  1107   a ,  1107   b  and capture plates  1109 . The forward end of each flexible polyurethane block members  1103  is thus sandwiched and held in place to the back of the moldboard  1100  by securing a bolt through the mounting plate, the flexible polyurethane block and the capture plate. The rearward end of each polyurethane block members  1103  is similarly secured to the snow plow frame  1112 . 
   The hinged torsion-spring trip cutting edge assembly  1199  consists of left and right tabs  1117   a ,  1117   b . The tabs  1117   a ,  1117   b  are welded directly to the rearwardly facing surface  1131  of the moldboard  1100  and located below each lower mounting plate  1107   b . Located on each side of each tab are apertures  1113 . The bottom portion of tabs  1117   a ,  1117   b  is welded to the top portion of angle iron  1121 , which spans the length of the lower edge of the moldboard  1100 . Bolted to the length of the angle iron  1121  is a steel cutting edge  1123 . 
   A first torsion spring  1105   a  is placed within left tab  1117   a  and a first steel rod  1111   a  is inserted through the apertures  1113  of the left tab  1117   a  and the torsion spring  1105   a , connecting the angle iron  1121  to the moldboard  1100 . Similarly, a second torsion spring  1105   b  is placed within right tab  1117   b  and a second steel rod  1111   b  is inserted through the apertures  1113  of the right tab  1117   b  and the torsion spring  1105   b , connecting the angle iron  1121  to the moldboard  1100 . Additionally, a third torsion spring  1105   c  is secured to the moldboard  1100  and the angle iron  1121 , and is equidistantly located between left tab  1117   a  and right tab  1117   b.    
   In operation, when the moldboard  1100  impacts an obstacle, the hinged torsion spring trip cutting edge folds backwards, exceeding an angle of 45 degrees, so as to cause the cutting edge  1123  to push the moldboard assembly upward and allowing the snow plow to clear the obstacle in the road. Once the obstacle is cleared, the hinged torsion spring trip cutting edge will go back to its original starting position. 
   While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the central scope thereof. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Summary:
A slip hitch connection to a drive vehicle for a snow plow comprises an elongated flat planar member that can be hooked on to a connecting lug of the drive vehicle, the flat planar member being mounted on the snow plow frame for reciprocal movement in each of a pair of spaced apart coupling assemblies secured to the snow plow frame for connecting the snow plow to the drive vehicle. Each of the elongated flat planar members have an upper and lower elongated guide slot in which guide bolts that move up and down as the snow plow itself is moved up and down are received to enable the guide bolts and snow plow to which they are connected make limited reciprocal movement up and down while hooked up to the drive vehicle and being pushed forward during a snow plowing operation. This enable the snow plow to move rearwardly and upwardly enough to clear an object hit by the leading edge of the snow plow on the ground and then to reciprocate forwardly and downwardly to its original position after passing over the obstacle.