Abstract:
A towbar adapter assembly that attaches to a towbar boom and acts as a link between the towbar boom and a vehicle attachment point. The assembly has a base for attachment to the towbar boom and an anchoring strut that attaches to the vehicle. The base is incrementally positionable with respect to the towbar boom and the anchoring strut is incrementally positionable with respect to the base.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to devices that are used for securing a vehicle to a towbar boom. 
     There are a number of devices which facilitate the towing of a vehicle behind another vehicle. The towing vehicle typically employs a towbar with at least one boom for lifting one end of the towed vehicle off the road surface. The towed vehicle is secured to the towbar boom by means of chains or similar devices. The use of chains to secure the towed vehicle to the towbar boom presents problems in finding a sufficient number of anchoring points to secure the towed vehicle to the towbar boom. In addition, the use of chains requires an operator to reach underneath the vehicle to be towed, which is time consuming and awkward in adverse conditions such as snow or rain storms. 
     SUMMARY OF THE INVENTION 
     The towbar adapter assembly includes two subassemblies. A receiver sub-assembly is comprised of a base and a body. The receiver base is adapted to be mounted onto a towbar boom and securely attached thereto, for instance, by bolts. The receiver body is attached to the base and projects upward and at a right angle from the base. The attachment position of the receiver body is offset from the centerline of the boom receiver base and towbar boom. 
     The towbar adapter assembly further comprises an anchoring strut subassembly. The strut is adapted to be slidably received by the receiver body and comprises at least one clevis. The vertical position of the strut with respect to the receiver body may be varied by sliding the strut up or down within the body. Once the desired strut vertical position is achieved, this position may be secured, for instance, with a pin. 
     The clevis comprises a set of parallel ears extending from the strut. Each ear has an aperture, which is axially aligned with an opposing aperture. The clevis has a centerline plane which is offset by a distance from the centerline plane of the strut. The vehicle tie ring is positioned between the parallel ears of the clevis and coupled thereto. 
     In use, the receiver base bolts are loosened and the towbar adapter assembly is removed from a storage mount. The receiver base is positioned onto the towbar boom to obtain the desired offset of the receiver body to the towbar boom. The receiver base is secured to the towbar boom. The strut is positioned with respect to the receiver base so that the desired vertical height and offset of the clevis to the base are achieved. The strut is secured to the receiver body to fix this position. The vehicle tie ring, or another similar fixture, is then positioned between the ears of the clevis and coupled thereto. 
     Preferably a pair of towbar adapter assemblies are used for securing the vehicle to the towbar. In this circumstance, the offset distance of each clevis to its base is independently variable. This allows the use of two towbar adapter assemblies of the same dimensional configuration to incrementally accommodate vehicles with an extended range of tie ring spacings. 
     An object of the invention is to provide a rapid and convenient means of adjustably securing a vehicle to a towbar boom via a vehicle tie ring. 
     A further object of the invention is to provide a high integrity attachment of a heavy-duty vehicle to a towbar boom. 
     Another object of the invention is to provide an efficient device capable of readily securing a wide range of vehicles having differing vehicle tie ring locations to a towbar boom. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will be evident from the following detailed description made with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a heavy-duty vehicle (partially illustrated), attached to a towbar boom, (partially illustrated) by a pair of towbar adapters in accordance with the invention; 
     FIG. 2 is a side elevational view of a towbar adapter assembly showing attachment to a towbar boom (partially illustrated in phantom) and a vehicle tie ring; 
     FIG. 3 is an end elevational view, partially in diagrammatic form, of the towbar adapter assembly of FIG. 2 mounted on a towbar boom (partially illustrated in phantom), further illustrating various geometric relations between the components; 
     FIGS. 4A,  4 B, and  4 C are top, partially in diagrammatic form, views of various mounting configurations for the towbar adapter of FIG. 1, further illustrating various possible offset relationships; and 
     FIGS. 5A and 5B are schematic top views of two towbar booms (partially illustrated in phantom), each mounting a pair of towbar adapter assemblies and further illustrating the range of vehicle securing device spacings possible using a pair of the towbar adapter assemblies. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Briefly stated, in the preferred form, the present invention comprises a towbar adapter assembly for securely anchoring a vehicle tie ring to a towbar boom. The towbar boom may be any of a number of devices known in the art such as that described in U.S. Pat. No. 5,249,911 which is incorporated by reference herein. 
     With reference to the drawings wherein like reference numerals represent identical or corresponding parts throughout the Figures, a towbar adapter in accordance with the present invention is generally designated by the numeral  10 . As shown in FIGS. 1 and 2, the towbar adapter assembly  10  is comprised of two subassemblies, a receiver subassembly  20  and an anchoring strut subassembly  40 . Both receiver subassembly  20  and strut subassembly  40  are preferably manufactured from steel or other high strength materials and have a rugged heavy-duty construction. The receiver subassembly  20  has a receiver base  22  for mounting to a towbar boom  60  and a receiver body  30  which projects orthogonally from the base  22 . The anchoring strut  46  has one end which is adapted to be adjustably received by, and secured to, the body  30 , and an opposing second end which includes a clevis  50 . The vehicle tie ring  72  fits within and is readily coupled to the clevis  50 . 
     In a preferred embodiment shown in FIGS. 1 and 3, the receiver base  22  is comprised of a U-shaped member, with the parallel legs of the U-shaped member projecting downward. The legs form guides generally parallel to the towbar boom longitudinal direction  64  so that the towbar boom  60  fits within and slidably receives the U-shaped member. The invention may best be described with reference to various planes, as shown in FIGS. 3 and 4. The receiver base has a centerline plane P 1  traversing through a centerline axis in the towbar boom longitudinal direction  64 . The towbar boom centerline plane P 5  is substantially the same as the base centerline plane P 1 . The receiver base  22  also has threaded bosses  24  in each of the parallel legs and screw pins  26 . Upon suitable positioning of the base, the pins align with unthreaded apertures  62  in the boom. Each screw pin has a threaded shank which is screwed into the boss and an unthreaded tip which protrudes into the aperture in the boom to secure the base  22  to the towbar boom  60 . 
     Alternatively, the screw pins could be replaced with bolts (not shown). Threading the bolt through the threaded boss  24  in a manner similar to the screw pin would allow the end of the bolt to enter the boom aperture  62 , securing the receiver base  22  to the towbar boom  60 . It can readily be seen that other securement hardware and methods could be used, such as pins engaging aligned apertures in the base and the towbar boom. 
     A receiver body  30  is attached at a lower first end to the receiver base  22  with the second end projecting upwardly from, and generally orthogonal to, the base. In the preferred embodiment, the receiver body  30  is made of steel tubing. The receiver body  30  has at least one pair of axially aligned apertures  32  disposed on opposing sides. The receiver body  30  has a centerline plane P 2  (shown in FIG. 3) in the towbar boom longitudinal direction  64 . In the preferred embodiment, this centerline plane P 2  is offset from the centerline plane of the receiver base P 1  by a distance D 3  as shown in FIG.  3 . In one embodiment, D 3  is 1 inch. 
     The receiver subassembly  20  can embody a number of variations. One variation includes at least one gusset-like reinforcing member  36 . In the embodiment shown in FIG. 2, a plurality of reinforcing members  36  are made of steel or another high strength material. The reinforcing members  36  are securely attached to both the receiver base  22  and receiver body  30 , preferably by welding. 
     In another variation, the receiver body  30  further includes a handle  34  to make it easier to move the towbar adapter assembly. The handle  34  can be vertically (not shown) or horizontally disposed on the receiver body. The handle  34  is preferably rigid formed of steel, and welded to the receiver body. 
     The anchoring strut subassembly  40  has a lower first end which is adapted to be slidably received by the receiver body  30  and an upper second end which comprises at least one clevis  50 . An anchoring strut centerline plane P 3  (shown in FIG. 3) intersects the first and second ends parallel to the towbar boom longitudinal direction  64 . In the preferred embodiment, the strut  46  is made of steel tubing, which can be slidably received within the tubing comprising the receiver body  30 . The strut has a plurality of two sets of opposing axially aligned apertures  42 , shown in FIG. 2, which generally extend from the first end to the second end. 
     In this embodiment, the strut subassembly  40  is vertically positioned within the receiver body  30  and a pin  44  is engaged through the aligned apertures of the receiver body  32  and strut  42  to fix that vertical position. Naturally, the securing of the strut  46  to the receiver body  30  could be accomplished by a variety of other means, for instance, bolts could be inserted through the aligned and unthreaded apertures with a nut locking the bolt in place. Alternatively, the apertures could be threaded and bolts screwed through the apertures. 
     The clevis  50 , shown in FIGS. 2 and 3, is comprised of a set of parallel ears  52 , extending from the support strut  46 . Each ear  52  has an aperture  54  that is axially aligned with an opposing aperture. In a preferred embodiment, the clevis centerline plane P 4  is parallel to the towbar boom longitudinal direction  64  and offset from the strut centerline plane P 3 , by a distance D 2 , as shown in FIG.  3 . 
     In another preferred embodiment, shown in FIGS. 1 and 4, the strut  46  is rotatably and slidably receivable by the receiver body  30 , and the strut upper second end has three devises  50 . Each clevis  50  extends from the strut  46  in a different right angle orientation. Rotation of the strut  46  with respect to the receiver body  30  provides a choice of a given clevis  50 . Each clevis centerline plane P 4  is offset from the strut centerline plane P 3  by a different distance D 2 . Rotation of the strut  46  allows an incremental choice of the offset distance D 2  of the clevis centerline plane P 4  to the strut centerline plane P 3  and of the offset distance D 4  of the clevis centerline plane P 4  to the towbar boom centerline plane P 5 . In one embodiment, D 2  ranges from 1 to 2 inches. The choice of clevis used corresponds to a given dimensional requirement presented by the vehicle  70 . In this embodiment, the strut first end is secured to the receiver body  30  to fix the radial direction and vertical height. This embodiment allows a single towbar adapter design to incrementally implement a wide range of offset distances D 4  of the clevis centerline plane P 4  to the towbar boom centerline plane P 5 , as shown in FIG.  4 . 
     The more common usage will be to use a pair of towbar adapters to secure a vehicle to a towbar. Each towbar adapter is positionable on a towbar boom independently of the other. By varying the offset distance of the body to the towbar boom D 3  and/or the offset distance of the clevis to the body D 2 , for either or both towbar adapters, a wide range of vehicle tie ring spacings to be accommodated. FIGS. 5A and 5B schematically show the closest and most distant clevis positions. Naturally, a number of intermediate clevis positions can also be provided. 
     As shown in FIG. 1, a vehicle tie ring  72  is positioned between the ears of the clevis  50 . A pin is inserted through the aligned apertures in the ears  52  and the vehicle tie ring  72  to secure the vehicle  70  to the clevis  50  and ultimately to the boom. 
     While preferred embodiments of the foregoing invention have been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and scope of the present invention.