Abstract:
A torsion hitch receiver is provided having a draw bar that is adapted to be received by a vehicle mounted receiver. The torsion hitch receiver has an upper and lower torsion assembly with arms that are linked to a receiver assembly. The receiver assembly has an array of receivers that are sized to receive an accessory draw bar. Applying a downward force to the receiver assembly causes rotation of the arms.

Description:
BACKGROUND OF THE INVENTION 
     This present disclosure relates to hitch receivers and the attachment between a trailer and a towing vehicle. Commonly, when being towed by a vehicle, the trailer is subject to transient forces as the towing vehicle pulls the trailer over various terrain or when loads are moved or placed on the trailer. Trailers have a tongue weight that is borne by the towing vehicle. Some tongue weight is necessary but it is desirable to limit the amount transmitted to the towing vehicle. The transient forces on the trailer can translate to transient tongue forces transmitted to the towing vehicle, at the very least, can be unsettling to the driver. In an extreme enough situation, the transient tongue forces can create a dangerous loss of control. An improved receiver that can be located between the trailer and the towing vehicle is necessary. 
     SUMMARY OF THE INVENTION 
     The present disclosure describes a torsion hitch receiver that will attach to a towing vehicle and absorb transient tongue loading either caused by the towing vehicle or the trailer. By implementing a torsion device, the hitch receiver allows for limited relative vertical motion between the towing vehicle and the trailer. The hitch receiver has multiple receiver holes that are vertically stacked to give the user several options of where to connect up a ball. The vertical stacking is frequently necessary when the trailer tongue height varies from trailer to trailer, and also the height of the receiver on different towing vehicles is different. An optional indicator measures the displacement between a loaded position and an unloaded position to allow the user to monitor tongue loading. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of this invention has been chosen wherein: 
         FIG. 1  is an isometric view of the receiver; 
         FIG. 2  is a front view of the receiver; 
         FIG. 3  is an isometric view  3 - 3  of the receiver in  FIG. 2 ; 
         FIG. 4  is a partially exploded isometric view of the receiver; and 
         FIG. 5  is a rear isometric view of the receiver. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A torsion hitch receiver  10 , as shown in  FIG. 1 , has a fixed portion  12  and a moveable receiver portion  14 . The two are connected to the fixed portion with a rotatable torsion portion  16 . 
     The fixed portion  12  has an elongate draw bar  18  with a series of transverse holes  20 ,  22  near an end  24 . The draw bar  18  has a central axis  19  and is sized to fit into a receiver in a towing vehicle (not shown). The draw bar  18  is affixed to the receiver on the towing vehicle with a pin that fits through existing holes in the receiver and one of the transverse holes  20 ,  22  in the draw bar  18 . The use of a pin to connect to a receiver is well known in the art and the pin that fits through the receiver is not shown. A torsion housing  26  is affixed to the other end of the draw bar  18 . 
     The torsion housing  26  has a main body portion  28  where it is affixed to the draw bar  18 . The main body portion  28  is an assembly of a series of flat or bent sheet metal that is welded or affixed together to form a single structural component. There is an upper back piece  25 , a lower back piece  27 , side pieces  29 ,  31 , and a front curved piece  33 . In addition to the bent and flat sheet metal are torsion tubes  30 ,  32 . There is an upper torsion tube  30  and a lower torsion tube  32  affixed to the main body portion  28 , as shown in  FIG. 1 . Each torsion tube  30 ,  32  is mostly square and has a central axis  34 ,  36  that is perpendicular to the draw bar  18 . The central axis  34  of the upper tube  30  is parallel to the central axis  36  of the lower tube  32 . 
     Residing inside the upper tube  30  is an upper square torsion bar  38  and inside the lower tube  32  is a lower torsion bar  40 . The torsion bars  38 ,  40  can be seen in the cross section of  FIG. 3 . Surrounding the torsion bars  38 ,  40  are resilient cords  42 . The resilient cord  42  supports the torsion bar  38 ,  40  and centers it about its corresponding axis  34 ,  36 . As shown, the torsion bars  38 ,  40  are angled with respect to their corresponding tube  30 ,  32  with the flats facing corners of the tube. This creates a substantially triangular shaped cavity that receives the resilient cords  42 . They fit in the corners of the tubes  30 ,  32  and overlay the flat surfaces of the torsion bars  38 ,  40 . This setup of a torsion bar inside a torsion tube is commonly known in the suspension and spring art. 
     Attached to ends of the upper torsion bar  38  are upper torsion arms  44 . The upper torsion arms  44  are not affixed to the upper torsion tube  30  and rotate with the upper torsion bar  38 . The upper torsion arms  44  are affixed to the upper torsion bar  38  sufficiently close to the ends of the upper torsion tube  30  to prevent excessive axial movement of the upper torsion bar  38  and upper torsion arms  44  along the upper central axis  34 . At the end of the upper torsion arm  44  is an upper pivot point  46 . Both pivot points  46  align to form an upper pivot axis  48 . The upper pivot axis  48  is parallel to and offset from the upper central axis  34 . 
     Correspondingly, attached to ends of the lower torsion bar  40  are lower torsion arms  50 . The lower torsion arms  50  are not affixed to the lower torsion tube  32  and rotate with the lower torsion bar  40  as shown in  FIG. 1 . The lower torsion arms  50  are affixed to the lower torsion bar  40  sufficiently close to the ends of the lower torsion tube  32  to prevent excessive axial movement of the lower torsion bar  40  and lower torsion arms  50  along the lower central axis  36 . At the end of the lower torsion arm  50  is a lower pivot point  52 . Both lower pivot points  52  align to form a lower pivot axis  54 . The lower pivot axis  54  is parallel to and offset from the lower central axis  36 . 
     The receiver portion  14  has an upper pivot tube  60  and a lower pivot tube  62  that are spaced similarly to the pivot points  46 ,  52 . The receiver portion  14 , as shown in all FIGS. has a series of receivers  64 - 70 . Each receiver  64 - 70  is made from a rectangular tube and is sized to receive a slide-in ball hitch or similar device and has transverse holes  66 ,  72  that are adapted to receive a pin to affix the slide-in ball hitch (not shown). As shown in  FIG. 4 , the uppermost  64  and lowermost  70  receivers have an extra transverse hole  72  that allows the separate towing hook or ball to be affixed to the receiver portion  14  at a second position. The receiver portion  14  has sides  74 ,  76  that reinforce and align the receivers  64 - 70 . The pivot tubes  60 ,  62  extend through the sides  74 ,  76  and the uppermost  64  and lowermost  70  receivers. The pivot tubes  60 ,  62  are long enough to fit between the pivot arms  44 ,  50  without allowing excessive axial movement along the pivot axes  48 ,  54 . 
     Due to the resilient nature of the cords  42 , the torsion bars  38 ,  40  are held in a neutral or resting position (as shown in all FIGS) where all of the cords  42  equally apply pressure to the outside flat surfaces of the torsion bar  38 ,  40 . When a load is applied and the torsion bar  38 ,  40  begins to rotate, the torsion bar  38 ,  40  is urged toward the neutral position by the cords  42 . 
     As weight is added to the receiver portion  14  (by the separate towing hook or ball), the entire receiver portion  14  moves down, causing the pivot arms  44 ,  50  to rotate. The cords  42  become distorted by the flat surfaces of the torsion bars  38 ,  40  as they rotate. The resiliency of the cord  42  resists the distortion. The more the torsion bar  38 ,  40  rotates, the more the cords  42  resist. The spacing of the pivot arms  44 ,  50 , pivot points  46 ,  52  and central axis  34 ,  36  causes the receiver portion  14  to move substantially vertical with minimal to no rotation or angular change with respect to the draw bar  18 . 
     An optional displacement or load indicator  80  can be implemented to show the user the amount of tongue weight or displacement of the receiver portion  14  with respect to the fixed portion  12 . As shown in  FIG. 5 , the indicator  80  has a needle  82  that is fixed to one of the pivot arms  44 . As the weight on the receiver portion  14  increases, the displacement indicator  80  shows the user how much load is present. The upper torsion tube  30  has a reference line or feature  84 . As the pivot arm  44  rotates, the needle  82  moves with respect to the feature  84 , showing the user the amount of load on the hitch receiver  10 . As shown in  FIG. 5 , a fastener  86  holds the needle  82  and allows adjustment of the needle  82  to set a desired number or zero reference. 
     It is understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects. No specific limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Modifications may be made to the disclosed subject matter as set forth in the following claims.