Abstract:
A trailer hitch is disclosed having a spacer in the form of a fastener or stopper that limits the travel of a spring clip so as to allow complete removal of the safety pin from the associated weight distribution rod, but does not allow the clip to extend to a position where the pin&#39;s end passes the entrance of the hitch&#39;s outer surface. The fastener/stopper thus prevents the user or vibration/wear from allowing the clip to overextend to the point where the pin may become separated from the hitch.

Description:
BACKGROUND 
     The present invention is directed to weight distribution trailer hitches, and more particularly to a weight distribution trailer hitch with a novel safety clip that prevents dislodgement of the safety pin. 
     Weight distribution trailer hitches are well known in the art. The purpose of a weight distribution hitch is to prevent the weight of the trailer from causing the juncture of the tow vehicle and the trailer to drop, which can lead to the front of the tow vehicle raising up. This is an unsafe condition that can place undue stress on various elements of the trailer and the tow vehicle. The weight distribution hitch removes excess weight from the tow vehicle&#39;s rear axle and distributes the excess weight to the front wheels of the tow vehicle and the trailer wheels. 
     Reference to weight distribution trailer hitches can be found, for example, in U.S. Pat. No. 6,722,682 to Valliere et al., U.S. Pat. No. 5,868,414 to McCoy et al., and U.S. Pat. No. 5,984,341 to Kass et al., the contents of each of which are fully incorporated herein by reference. 
     Weight distribution hitches normally utilize a shank formed of a tubular shaft that is secured to the tow vehicle with a hitch pin. A shank bar is a rectangular member with spaced holes that mounts vertically to the shank and is used to set the height of the hitch. The hitch includes a U-shaped section that receives the shank bar, and includes bolt holes that align with holes on the shank bar so that the hitch may be bolted to the shank with an adjustable height to accommodate different size trailers and tow vehicles. The hitch includes a pair of weight distribution rods that have upturned proximal ends. The distal ends of the weight distribution rods are configured to secure a lift chain that connects the weight distribution rods to the trailer. The upturned proximal ends of the distribution rods are releasably received from below in two tubular cavities in the hitch. To prevent the distribution rods from falling out of the hitch&#39;s tubular cavities, a pin is used that passes through the wall of the tubular cavity and into an aperture in the distribution rods. The lift chains serve to establish a maximum distance that the weight distribution rods extend below the trailer, which in turn prevents the hitch from dropping much below its unhitched elevation. This system causes much more balanced towing and helps to prevent tipping or loss of control of the trailer. 
     It has been discovered that the pin used to maintain the weight distribution rods in the tubular cavities of the hitch can become inadvertently dislodged when subject to the routine vibrations of towing conditions, particularly on uneven roads and at higher speeds. Loss of the pin can result in separation of the trailer from the towing vehicle, loss of control of the trailer, or damage to the hitch. Therefore, it is also known in the art to provide a spring clip between the head of the pin and the outer surface of the tubular cavity on the hitch. The spring clip is riveted or otherwise mounted at a lower surface to the outer surface of the hitch&#39;s tubular cavity, and the spring clip includes a vertical slot that receives the shank of the pin. The spring clip&#39;s upper portion is biased to bear against (or generally against) the outer surface of the cylindrical cavity, while the bottom portion is mounted directly to the same surface. When it is desired to remove the weight distribution rods, the clip can be pulled back manually against its bias away from the surface of the hitch&#39;s tubular cylinder, allowing the pin to be removed from the proximal upturned end of the weight distribution rods. With the pin removed, the rods can be easily removed from the hitch and the hitch can then be disassembled, adjusted, or removed from the tow vehicle/trailer. When it is desired to reassemble the system, the clip is pulled away from the surface of the hitch so that the pin is extracted from the cavity. With the pin displaced, the weight distribution rods can be inserted into the cavity and the spring clip released to position the pin back in its designated position to once again retain the weight distribution rods in the hitch. 
     The present inventor has discovered that the above described system still has a shortcoming, namely the propensity for the pin to become separated or lost. The pin may become lost due to the clip&#39;s loss of resiliency after many repeated openings, to the point where the clip no longer bears against the surface of the hitch and gradually becomes more and more separated from this surface, until eventually the vibration of the towing operation can cause the pin to become dislodged. The pin can also become dislodged while the weight distribution rods are being inserted or removed from the hitch. That is, if the user does not open the spring clip far enough, the pin will not clear the cavity and the rods cannot be removed/inserted. However, if the clip is opened too far, the pin may become dislodged and fall into the dirt, roll away, or become lost. With repeated use, the spring clip can begin to lose its capacity to snap back into position and lose its spring action, leading to overextension of the clip. When trying to insert or remove the weight distribution rods, the loss of the pin can be particularly disconcerting and can present a dangerous situation. The present invention addresses these shortcoming and provides an economic solution to prevent dislodgement of the pin from the hitch. 
     SUMMARY OF THE INVENTION 
     The present invention is a spacer in the form of a fastener or stopper that limits the travel of the spring clip on a trailer hitch so as to allow complete removal of the safety pin from the associated weight distribution rod, but does not allow the clip to extend to a position where the pin&#39;s end passes the entrance of the hitch&#39;s outer surface. The fastener/stopper thus allows the system described above to be used exactly as before, but prevents the user or vibration/wear from allowing the clip to overextend to the point where the pin may become separated from the hitch. 
     These, and other advantages of the present invention, will become apparent from the figures and the detailed description of the invention set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevated, perspective view of a weight distribution hitch; 
         FIG. 2  is an enlarged, sectional view of the connection of the weight distribution rods to the hitch; 
         FIG. 3  is a side view in cross section of the weight distribution rods in the hitch with the pin located in the rod; and 
         FIG. 4  is the view of  FIG. 3  with the clip extended to the stopper to permit removal of the pin from the rod without removal of the pin from the hitch. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  illustrates a trailer hitch illustrating one embodiment of the present invention. It is to be understood that while a particular embodiment is illustrated and described, the scope of the invention is not limited to the particular embodiment(s) shown in the drawings or described herein. Rather, the descriptions and depictions are intended to teach the concepts of the present invention without imposing any limitation as to shape, size, dimension, method, or any other specific feature shown or described. Further, the mechanics of hitching the trailer to the tow vehicle using a weight distribution hitch is well known in the art, and the full description of the techniques, methods, and structure are omitted herein for brevity except to help define the environment of the present invention. Further details of the hitching process can be found in the Valliere, McCoy, and Kass patents previously referenced and incorporated herein by reference. 
     Returning to  FIG. 1 , hitch  10  is shown coupling a tow vehicle  12  to a trailer  14  as is known in the art. The hitch uses a pair of horizontal weight distribution rods  16  that connect at a distal end to lift chains  18  via a half ring mount  20 , where the lift chains  18  are hooked onto the trailer  14  at hook  22 . Hitch  10  includes a ball mount  24  that is captured by the trailer&#39;s ball mount shroud  26  to position the trailer on the hitch  10 . The tow vehicle  12  has a hitch socket  28  sized to receive a hitch shank  30 , which locks into the hitch socket  28  by virtue of the lock pin  32 . 
     With reference to  FIG. 2 , the hitch shank  30  includes an integral, downwardly projecting shank bar  34  with vertically spaced holes (not shown) that receive mounting bolts  36 . The shank bar  34  is slidingly received within a U-shaped mounting unit  38  that is formed as part of the hitch  10 . The mounting unit has bolt holes that align with the bolt holes of the shank bar  34  so that bolts  36  can pass through the mounting unit  38  and form a solid connection for the hitch  10  to mount to the tow vehicle  12 . The mounting unit  38  can take outer forms, such as clamps, cylindrical enclosures, etc., and the particular mounting type for the hitch plays no particular role in the present invention. 
     The mounting unit  38  is connected to a face plate  40  that supports the ball mount  24  thereon, and includes first and second hollow cylindrical pipes  42  that are sized to receive the weight distribution rods therein. The weight distribution rods  16  have an upturned proximal end that are received in the open end of the hollow cylindrical pipe  42 . To maintain the upturned end  44  of the weight distribution rod  16  inside the cavity  46  defined by the hollow cylindrical pipe, the weight distribution rod  16  includes a hole  50  that receives a safety pin  52  passing through an aperture  84  in the hollow cylindrical pipe  42 . With the safety pin  52  engaged with the hole  50  of the weight distribution rod  16  (see  FIG. 3 ), the weight distribution rod  16  is captured inside the cylindrical pipe  42  and the system is secured. 
     The safety pin  52  is carried by a spring clip  54  that is affixed at a first end  56  by a fastener  58  such as a rivet, and the second end is formed into a U-shaped configuration to form a pull tab  60  that can be grasped or actuated by a finger to pull the spring clip  54  away from the hollow cylindrical pipe  42 . As is known in the art, the spring clip  54  is biased with the help of the fastener  58  to bear against the outer surface  62  of the hollow cylindrical member  42 . The safety pin  52  has an annular groove  64  that engages inner edges  66  of a vertical slot  68  extending longitudinally down the middle of the spring clip  54 , so that when the spring clip  54  is pulled away from the hollow cylindrical pipe  42 , the safety pin  52  is pulled out of the hole  50  of the weight distribution rod  16  and the rod can then be removed from the hitch  10  (see  FIG. 4 ). When the pull tab  60  is released, the spring clip  54  returns to its biased state as shown in  FIG. 3 . Thus, a position of the safety pin  52  can be controlled by pulling the spring clip  54  at the pull tab  60  and then releasing the pull tab  60  to position the safety pin  52  back in the weight distribution rod  16 . 
     To prevent the spring clip  54  from being over-extended, thereby releasing the safety pin  52  from the hollow cylindrical pipe  42 , a stopper  70  is placed between the fastener  58  and the safety pin  52 . The stopper  70  is threaded or otherwise fixed in the hollow cylindrical pipe  42  and includes a shaft  72  and a head  74 . The head  74  has a width that is greater than a width of the slot  68 , as shown in  FIG. 2 , so that the spring clip  54  cannot extend past the head  74  of the stopper  70 . With the first end of the shaft  72  of the stopper  70  mounted in the cylindrical pipe  42 , a length of the shaft  72  defines a range of motion of the spring clip  54  toward and away from the hollow cylindrical pipe  42 . The opposite ends of the range of motion of the spring clip  54  is shown in  FIGS. 3 and 4 , respectively. In  FIG. 3 , the spring clip  54  bears against the outer surface  62  of the cylindrical pipe  42 , and in  FIG. 4  the spring clip  54  bears against the head  74  of the stopper  70 . The motion of the spring clip  54  must fall between these two positions at all times. 
     From  FIG. 4 , it can be seen that the safety pin  52  can be removed from the weight distribution rod  16  by pulling the pull tab  60  of the spring clip  54  to its maximum position away from the hollow cylindrical pipe  42 , but the safety pin&#39;s tip never exits the aperture  84  of the hollow cylindrical pipe  42 . Therefore, the presence of the stopper  70  and more particularly the position of the stopper head  74  establishes a range of motion that prevents the safety pin  52  from ever becoming dislodged either by manual over-extension of the pull tab  60  or via excessive vibration or deformation of the spring clip  54  due to wear. The length of the shaft  72  of the stopper  70  is therefore selected to permit the spring clip  54  to distend from the hollow cylindrical pipe  42  far enough to allow the safety pin  52  to be removed from the weight distribution rod  16 , but not far enough to allow the safety pin  52  to withdraw beyond the outer surface of the hollow cylindrical pipe  42 . 
     The present invention addresses the problem of safety pin dislodgement without impeding or hindering the function and operation of the spring clip/safety pin assembly. Although specific embodiments have been described, the scope of the present invention is properly defined by the appended claims without limitation to any specific embodiment or drawing used to illustrate the invention.