Abstract:
A tow bar with a torsion spring disposed between the tow bar and a steering arm to urge the tow bar towards an operating position, the torsion spring minimizing the force required by an operator to lift the tow bar.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a tow bar assembly and more particularly to a tow bar assembly including a torsion spring disposed between the tow bar and steering arm to urge the tow bar towards an operating position. 
   BACKGROUND OF THE INVENTION 
   It is known generally to draw trailers with a tow bar. In the aviation industry, for example, trailered ground power units and other trailers are frequently coupled to a towing vehicle by a tow bar. It is also known in this and other applications to pivotally couple the tow bar to a steering arm of the trailer to permit positioning the tow bar between raised and lowered positions. The tow bar is generally lowered to a substantially horizontal position for coupling to the towing vehicle, and raised to a generally vertical position to eliminate any obstruction posed thereby and to facilitate stowage thereof when not coupled to the towing vehicle. 
   Prior art tow bars have the disadvantage that, when lowered, the tow bar tends to pivot downwardly until an end thereof strikes the ground. It is undesirable for the tow bar to contact the ground as the tow bar may become damaged, particularly the end portion thereof that hitches to the towing vehicle. In addition, if dropped, the tow bar can cause injury to an operator&#39;s foot. 
   When being connected to the towing vehicle, the tow bar must be raised upwardly from the ground. Raising the tow bar and bearing the weight of the tow bar during alignment with the vehicle hitch is inconvenient, and in some applications may require substantial physical exertion. 
   It would be desirable produce a tow bar assembly where the force required to raise the tow bar is minimized. 
   SUMMARY OF THE INVENTION 
   Consistent and consonant with the present invention, a tow bar assembly where the force required to raise the tow bar is minimized, has surprisingly been discovered. 
   The tow bar assembly comprises a tow bar having a first end, the tow bar adapted to be coupled with a towing vehicle, the first end of the tow bar having at least one aperture formed therein; a pin supported by a steering arm of a towed vehicle, the pin disposed in the at least one aperture of the tow bar to facilitate a pivotal movement of the tow bar about the pin; a spring supported by the pin and having a first linear spring extension and a second linear spring extension, the first spring extension extending outwardly from the spring into contact with the tow bar to urge the tow bar in an upward direction, the second spring extension adapted to contact the steering arm of the towed vehicle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above, as well as other objects, features, and advantages of the present invention will be understood from the detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings, in which: 
       FIG. 1  is an exploded partial perspective view of a tow bar and a steering arm assembly and an insertion assist pin in accordance with the present invention; and 
       FIG. 2  is a partial plan view of the tow bar illustrated in  FIG. 1 , with a hitch pin removed and a portion of the steering arm cut away. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIGS. 1 and 2 , there is shown generally at  10  a tow bar and steering arm assembly in accordance with the present invention. The tow bar and steering arm assembly  10  includes an elongate tow bar or draw bar  12 , a torsion spring  14 , and a steering arm  16 . In the embodiment shown, the tow bar  12  includes a pair of spaced apart longitudinally extending side rails or edge portions  18 . A first end  20  of each of the side rails  18  has a laterally extending aperture  22  formed therein. A web  24  extends between the pair of side rails  18  to form an inverted u-shaped channel. A first end  26  of the web  24  is spaced from the first end  20  of the side rails  18  to expose the apertures  22 . The apertures  22  of the side rails  18  of the tow bar  12  are aligned to receive a hitch pin or bolt  28  therein. The other end of the tow bar  12  is adapted to be connected to a towing vehicle (not shown). 
   The torsion spring  14  is formed by a series of helically wound coils defining an open interior  30 . The hitch pin  28  is received in the interior  30  of the spring  14 . A first end or extension  32  of the spring  14  extends radially outwardly in intimate contact with a bottom portion of the tow bar  12  when assembled. A second end or extension  34  of the spring  14  extends radially outwardly from the other end of the torsion spring  14  in intimate contact with a bottom portion of the steering arm  16  when assembled. When assembled, the spring  14  is disposed between the side rails  18  of the tow bar  12 , allowing use of the original hitch pin  28  and not requiring use of a new, longer pin. Additionally, the first end  32  of the spring  14  and the second end  34  of the spring  14  facilitate the use of the original tow bar  12  and the steering arm  16 , without the use of additional parts or hardware. It is understood that other spring types could be used without departing from the scope and spirit of the invention. 
   The steering arm  16  includes a pair of spaced apart longitudinally extending side rails  36 . A first end  38  of each of the side rails  36  has a laterally extending aperture  40  formed therein. A web  42  extends between the pair of side rails  36  to form an inverted unshaped channel. The apertures  40  of the side rails  36  of the steering arm  16  are aligned to receive the hitch pin  28  therein. The other end of the steering arm  16  is adapted to be connected to a trailer or towed vehicle (not shown). The cross sectional shapes of the tow bar  12  and the steering arm  16  are not critical to the invention and other cross sectional shapes and configurations such as square tubing, for example, may be used for the tow bar  12  and the steering arm  16  without departing from the scope and spirit of the invention. 
   To assemble the tow bar and steering arm assembly  10 , the tow bar  12  and the steering arm  16  are axially aligned in a substantially horizontal position. The apertures  22  of the side rails  18  of the tow bar  12  are aligned with the apertures  40  of the side rails  36  of the steering arm  16 . The hitch pin  28  is inserted through one set of the aligned apertures  22 ,  40  as indicated by the arrow in  FIG. 2 . 
   An insertion assist pin  44  is inserted through the other set of aligned apertures  22 ,  40  as indicated by the arrow in  FIG. 2  to maintain the desired alignment of the tow bar  12  and the steering arm  16 . The tow bar  12  is pivoted about the hitch pin  28  and the assist pin  44  to a substantially vertical position. The interior  30  of the torsion spring  14  is aligned with the apertures  40  of the side rails  36  of the steering arm  16 . The hitch pin  28  is then caused to slide through the interior  30  of the torsion spring  14 , into contact with the assist pin  44 . The assist pin  44  is caused to slide out of the set of apertures  22 ,  40 , and is replaced therein by the hitch pin  28 . The hitch pin  28  is then secured in place with fasteners or safety pins,(not shown), for example, to militate against axial movement of the hitch pin  28 . The tow bar  12  is then lowered to a substantially horizontal position for operation, thereby loading the torsion spring  14 . Thus, the tow bar  12  is urged in an upward direction or towards a vertical position by the torsion spring  14 . It will be appreciated that the spring  14  is effective to maintain the tow bar  12  and the steering arm  16  in a substantially axially aligned horizontal position. Any downward loading of one or the other of the pivotally interconnected members will tend to wind the spring  14  and militate against any relative downward pivotal movement. 
   To disassemble the tow bar and steering arm assembly  10 , the tow bar  12  is raised to the substantially vertical position. The fasteners or the safety pins are removed from the hitch pin  28 . The assist pin  44  is placed into contact with the hitch pin  28  causing the hitch pin  28  to slide out of the one set of apertures  22 ,  40 . The hitch pin  28  is then caused to slide out of the interior  30  of the torsion spring  14 , thus freeing the torsion spring  14 . Further disassembly by removal of the hitch pin  28  or replacement of the torsion spring  14  can be accomplished as desired. 
   In use, once the tow bar and steering arm assembly  10  is assembled, the tow bar  12  is pivotable about the hitch pin  28 . When the trailer or towed vehicle is not being towed, the tow bar  12  can be positioned vertically. When the operator lifts the tow bar  12  to the vertical position, the torsion spring  14  urges the tow bar  12  upward, thus assisting the operator in lifting the tow bar  12 . When it is desired to tow the trailer or towed vehicle, the tow bar  12  is lowered to the substantially horizontal position, and held in this position while being coupled to the towing vehicle. The torsion spring  14  urges the tow bar  12  upward during the coupling operation, thus reducing the lifting forces required and assisting the operator in holding the tow bar  12  in the desired position. 
   From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.