Patent Application
20050005479
This invention relates to the field of hitches or coupling assemblies that connect a snow plow or other comparable item to a drive vehicle, 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 item that enables the snow plow or other comparable item to adjust to the incline and decline of the surface being plowed or scraped.
The typical prior art hitches or coupling assemblies for snow plows that connect them 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.
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 in the guide slots. The lower edge of the snow plow is thus able to move rearwardly and 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.
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 Jan. 28, 2002 by the same inventor, 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 bars 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 slightly 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.
