Abstract:
A tow bar assembly includes first and second telescopic members. A releasable locking arrangement holds the first and second telescopic members in an extended position and includes at least one movable member to maintain the telescopic members in the locked relationship and a pivotally mounted release member mounted on one of the telescopic members to move the movable member to permit slidable movement between the first and second telescopic members. The invention provides coupling of interacting members one slidable in the other. The members define an opening for an extended and circular counterpart. The counterpart penetrates the opening and the members are held in position. The members together exert forces on the counterpart and a release device between the counterpart and the members release the members.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 08/904,705, filed Aug. 1, 1997 (now U.S. Pat. No. 6,352,278), which is a continuation-in-part of U.S. patent application Ser. No. 08/421,405, filed Apr. 13, 1995 now abandoned and entitled “Extensible Connector With Lock Mechanism”, which is a continuation-in-part of U.S. patent application Ser. No. 08/110,241, filed. Aug. 23, 1993 now abandoned and entitled “Pressure Release Systems”, which is a continuation-in-part of U.S. patent application Ser. No. 07/867,984, filed Apr. 13, 1992 now abandoned and entitled “Pressure Release Systems”, now abandoned, all of which patent and patent applications are herein incorporated by reference in their entirety. This application is also related to U.S. Pat. No. 5,713,691, which is also herein incorporated by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to vehicle tow bars and, more particularly, to foldable and collapsible tow bars which are easily attached and removed from the towed and towing vehicles. 
   2. Description of the Currently Available Technology 
   Conventional tow bars are typically either single bars or are of an A-frame type that are rigidly mounted to the towed and towing vehicles. Alternatively, collapsible tow bars are known which are arranged to be folded for storage purposes when not in use. Also, known tow bars include telescopically adjustable members which are secured by locking members adapted for remote actuation. 
   U.S. Pat. Nos. 4,978,134; 5,071,153; and 5,147,095 teach the mounting of collapsible, telescoping tow bar members. 
   U.S. Pat. Nos. 5,011,176; 3,984,121; 4,861,061; 2,484,751; 3,492,022; 2,639,160; and 3,158,387 disclose pressure release and/or extension and retraction locking capabilities for telescoping tow bar members. U.S. Pat. No. 3,984,121 discloses a spring-biased pivotal mechanism for a locking pin which is adaptable for insertion into complementary openings to adjust and secure telescoping tow bar members. U.S. Pat. No. 2,639,160 discloses an eccentric roller/cylinder member, an eccentric lobe portion of which engages complementary notches when rotated to lock telescoping bar members in place. U.S. Pat. No. 3,158,387 discloses cam locking means to secure tow bar telescoping members. 
   U.S. Pat. No. 2,914,343 discloses a tow bar mounting attached to a vehicle frame under the bumper and telescoped such that it can be retracted to conceal the mount. 
   U.S. Pat. No. 3,806,162 discloses a clamp attachment to a bumper for a universal tow bar mounting. 
   U.S. Pat. No. 2,667,366 discloses a remote pin release mechanism to permit actuation for locking and unlocking adjustable telescoping tow bar members. 
   While the tow bars described in the above-referenced patents provide some advantages, they do not permit the overall versatility of the present invention. For example, in the prior art structures, there can be considerable difficulty in releasing the locking mechanism for the tow bar members especially when the towed and towing vehicles are stopped at a position where there is a tension force on the tow bar members. In such a situation, it may be necessary to dismount the towing vehicle to manually force disengagement of the locking mechanism by utilizing a hammer or the like. 
   SUMMARY OF THE INVENTION 
   The invention is directed to an easily attachable and detachable tow bar assembly that avoids at least some of the problems of the prior art. 
   In one embodiment, the invention includes a collapsible and universal mount for the tow bar for ease of storage when not in use. The invention can include one or more adjustable telescoping frame members, e.g., tubular frame members, for attachment and detachment to towed and towing vehicles regardless of their static position relative to each other. 
   Each adjustable telescoping tubular frame member can include a pair of telescopic members and an easily actuated release mechanism for securing the telescopic members to each other so that they can be easily released, either remotely or otherwise, despite the fact that the towed and towing vehicles may cause considerable tension forces on the bars. For example, the vehicles may be parked on a hill when it is desired to unhook the tow bar assembly. In this case, it is clear that any release mechanism will be under considerable tension forces making it difficult to affect release without the use of a force applying implement or the like. 
   One embodiment of the invention includes a pivot pin locking device which includes a high leverage release mechanism, e.g., providing a mechanical advantage having a ratio on the order of 10:1 or greater. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a tow bar assembly of the invention having telescopically adjustable frame members; 
       FIG. 1A  is an alternative embodiment of the tow bar assembly shown in  FIG. 1  having three telescopically adjustable frame members; 
       FIG. 2  is a partial vertical section of a first embodiment of a release pin locking arrangement of the invention; 
       FIG. 3  is a protective cover for the locking arrangement of  FIG. 2 ; 
       FIGS. 4 and 6  are partial vertical sections of another embodiment of a release pin locking arrangement; 
       FIG. 5  is a bottom view of the pin release arrangement of  FIG. 4 ; 
       FIG. 7  is a partial vertical section of a locking arrangement having multiple slots for locking the telescopic members in various lengths; 
       FIG. 8  is a partial sectional view of telescopic members having a remote actuator; 
       FIG. 9  is an exploded plan view of the components of the tow bar assembly of  FIG. 2 ; 
       FIG. 10  is a side view of an alternative latch plate of the invention; 
       FIG. 11  is a side view of a gate latch of the invention; and 
       FIG. 12  is a sectional view of the gate latch of  FIG. 11  showing a locking and release mechanism of the invention. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   As used herein, spatial or directional terms, such as “inner”, “outer”, “above”, “below”, “top”, “bottom”, and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention may assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, and the like, used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical value should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 5.5 to 10. 
   Referring to the drawings in detail,  FIG. 1  discloses a tow bar assembly  15  having at least one, e.g., a pair, of frame members F connected to an apex member  13  which can be operatively connected to a towing vehicle (not shown). The other end of each frame member F has a pivot member  6  attached thereto which can be operatively connected to a towed or trailing vehicle (not shown). The tow bar assembly  15  can include one or more, e.g., two, movable (e.g., telescoping) tubular frame members F. One of the tubular frame members F can be pivotally connected to the apex member  13  for movement in a substantially horizontal plane. The other tubular frame member F can also be fixed to the apex member  13 . 
   The trailing (distal) end of each frame member F can be connected to the bumper  29  of the towed vehicle and, with the elements to be described, form universal connections between the frame members F and the vehicle bumper  29 . Each universal connection can include spaced-apart eye bolt members  4  fastened to the bumper  29  by nuts or the like with the eyes of the eye bolts being disposed on a substantially horizontal axis in FIG.  1 . Interposed between the eye bolts is a connecting member  5  having both horizontally and vertically disposed apertures as depicted in FIG.  1 . The horizontally disposed aperture is interposed between the eye bolts and is journaled therebetween by a journal pin  7 . This permits pivotal movement of the connecting member  5 . The vertically disposed aperture of member  5  can be connected to the pivot member  6  of a frame member in any conventional manner, e.g., by a bolt or similar connecting device. A vertically disposed journal pin  8  can extend through the vertical apertures in members  5  and  6  and can be secured by any suitable means. The above-described connection between the members  5  and  6  permits pivotal movement of the pivot member  6  in a horizontal plane. The above-described connection between members  4 ,  5 , and  6  permits a universal connection between each frame member F and the vehicle bumper  29  so that the tow bar assembly  15  is free to move in both horizontal and vertical planes with respect to the bumper  29 . 
   While only one frame member F has been described as attached to the vehicle bumper  29 , it is readily apparent that the other frame member F of the tow bar assembly  15  can be attached to the bumper  29  in a laterally spaced relationship with like connecting means. 
   The universal connection between each frame member and the vehicle bumper permits multiple types of relative motion between the frame members and bumper thus reducing the strain or stress either to the bumper or the respective frame members especially when towing over uneven or bumpy terrain. 
   The universal connections between the frame members and the bumper also permit easy mounting, dismounting, and collapsible storage for the tow bar assembly  15 . Frame members F can be easily disconnected from eye bolts  4  by removing journal pins  7 . Thereafter, frame members F can be folded together by virtue of their pivotal connection to apex member  13 , and stowed in a convenient location. Alternatively, only one frame member need be disconnected and swung together in adjacent relationship with the other frame member, and both frame members may be swung in parallel relationship with the vehicle bumper by virtue of the vertically disposed pin  8  to a storage position. Additionally, both frame members may be swung on journal pins  7  in a vertical plane to an upright position against the vehicle for storage. 
   Each frame member F can include an outer or first, e.g., tubular, telescopic member  1  and an inner or second, e.g., tubular, telescopic member  2  which permit axial adjustment of the frame members for ease of connection between the towing and towed vehicles. Each frame member F can have a locking device, e.g., a high leverage locking and release mechanism, for locking the telescopic members  1  and  2  in various adjusted positions and for providing easily releasable means for unlocking the telescopic elements under a variety of conditions. 
     FIG. 1A  shows an alternative embodiment of the tow bar assembly  15  shown in FIG.  1 . In the embodiment shown in  FIG. 1A , an additional universal connection is located on the vehicle. A similar universal connection  400  is mounted on the apex member  13  and a third center telescoping frame member  402  is connectable between the vehicle and the universal connection  400 . The connecting member  5  of the universal connection  400  can include a hollow extension member  404 . The embodiment shown in  FIG. 1A  is particularly well suited for towing a farm implement. The center universal connection on the vehicle can be positioned higher than the outer two universal connections to hold the tow bar up in a locked position when all three telescoping frame members F are extended. The extension member  404  of the universal connection  400  can be substantially perpendicular to the associated connecting member  5 , through which an associated pin  8  passes allowing horizontal movement of the telescoping frame member  402 . Vertical movement is permitted via the associated journal pin  7 . 
   Where the middle telescoping member of  FIG. 1A  is mounted to a towed unit with eyebolts completing a universal joint, the third (center) tow bar arm can be above the others resulting in no up and down movement when extended and locked, or it can be the same (horizontal) height as the others so it can move up and down when extended and locked, resulting in at least a 33% heavier rated tow bar. 
   If all three universal joints were on the same level, the inner tube would mount to the tongue at the same level also. Only one of the three telescoping members could fasten solid to the tongue, or all of the three members could swivel at the tongue. There could be any number of telescopic members fastened to the tongue. Either end of the telescopic members could be fastened to the universal connector, and either end of the telescopic members could be fastened to the tongue. 
     FIG. 2  illustrates a first embodiment of a high leverage locking and release mechanism  3  which can be adapted to selectively lock the first or outer telescopic member  1  with respect to a second or inner telescopic member  2 . The tow bar can have a single frame member adapted to extend between the towed and towing vehicles or can have two or more frame members, such as the tow bar assembly shown in FIG.  1 . In  FIG. 2 , the first telescopic member  1  can be adapted to be connected to a towing vehicle. The second telescopic member  2  is telescoped within first telescopic member  1  and can be adapted at its outer end to be connected to a towed vehicle. Telescopic members  1  and  2  can be of any convenient length to permit relative adjustment to facilitate attachment to the towed and towing vehicles regardless of their relative spacing. For example, the first telescopic member  1  can be a square, tubular metal member, e.g., steel, having sides in the range of 1 inch to 2 inches wide, e.g., 1½ inches to 1¼ inches wide. The second telescopic member  2  can also be a square, tubular metal member dimensioned to be slidable within the first telescopic member  1 . 
   With further reference to  FIG. 2  of the drawings, first telescopic member  1  carries a high leverage locking and release mechanism  3  which includes a movable member, such as a latch pin  9 , depending from a latch plate  20 . One end of the latch plate  20  is pivotally mounted to the first telescopic member  1  at a distance from the pin  9  and is biased downwardly toward the first telescopic member  1  by a leaf spring  11 . At least one aperture  21  is located in the upper portion of the first telescopic member  1  through which the depending pin  9  can extend. The second telescopic member  2  is provided with at least one aperture  10  which, when in registry with an aperture  21 , locks the telescopic members  1  and  2  relative to each other by virtue of the depending pin  9  on the latch plate  20  passing through both apertures  21  and  10  under the bias of the spring  11 . 
   The locking and release mechanism  3  includes an actuator for releasing pin  9  from inner aperture  10  to permit telescopic adjustment of telescopic members  1  and  2 . The actuator includes an elongated lever  14  which can be pivotally mounted on first telescopic member  1  relatively near depending pin  9 . Lever  14  may also be pivotally mounted between hinge plates  12  on an extension member  27  carried on first telescopic member  1 . Lever  14  includes an upwardly extending projection  22  which is adapted to engage the underside of latch plate  20  near the free end of the latch plate. As can be readily understood from  FIG. 2 , when the free end of lever  14  is pivoted upwardly away from first telescopic member  1 , the free end of projection  22  engages the underside of the latch plate  20  to raise the depending pin  9 . By virtue of the relative spacing of latch plate  20 , the lever pivot points and projection  22  engaging latch plate  20  near its free end, it is apparent that a high leverage moment causes a mechanical advantage, e.g., with a ratio in the neighborhood of 10:1 or greater. In one embodiment, the locking and release mechanism  3  protrudes less than 2 inches above the outer telescopic member  1  in a tow position, e.g., less than 1 inch, e.g., ⅞ inch or less. The mechanism  3  can protrude less than 2 inches from the sides of the outer telescopic member  1 , e.g., less than or equal to 1⅛ inches. 
   First and second telescopic members  1  and  2  can be of any tubular cross-sectional configuration, such as round, square, or rectangular.  FIG. 3  illustrates a cover C which can be placed over mechanism  3  shown in FIG.  2  and attached to outer telescopic member  1 , for example, by welding, to protect mechanism  3  and to push down on leaf spring  11  to assist biasing pin  9  into aperture  10 . 
   Again referring to  FIG. 2  of the drawings, second telescopic member  2  can be provided with a shoulder  23  that has an upper beveled or chamfered surface  24  near aperture  10 . This enables pin  9  to smoothly ride up surface  24  to engage into aperture  10 . The shoulder  23  also cooperates with an inner shoulder  25  carried on first telescopic member  1  to limit telescopic lengthening when the shoulders engage or abut. 
   In operation, the vehicles are positioned relative to one another and telescopic members  1  and  2  are adjusted to attach to the towed and towing vehicles, respectively. The towing vehicle is then driven forward whereupon first telescopic member  1  moves relative to second telescopic member  2  and pin  9  rides along and over beveled surface  24  into locking engagement with aperture  10 . 
   As will be appreciated by those skilled in the art, it can be difficult to unhook a towing assembly from a vehicle upon conclusion of the tow. This is because the towing assembly frame members may be under considerable tension and/or force depending upon the terrain. Locking and release mechanism  3  alleviates this problem since it is only necessary to actuate lever  14  to provide for high leverage release of the pin  9  from aperture  10 . This allows the frame members to rest in a non-tensioning position permitting the unhooking of the tow bar assembly  15  at either end. 
     FIGS. 4 ,  5 , and  6  illustrate a variation of the pin locking mechanism  3  shown in FIG.  2 .  FIG. 4  shows a latch plate  20  pivotally mounted on the telescopic member  2  with a pin  9  extending upwardly therefrom. A leaf spring bias means  47  is attached at one end to telescopic member  2  and the opposite end engages the latch plate  20  at its underside for maintaining pin  9  in an upward position toward apertures  10 . A lever  48  is pivotally mounted on second telescopic member  2  and has a cam  49  engaging the underside of the bias means  47 . When handle  48  is rotated to the left, shown as dotted lines in  FIG. 4 , the cam  49  provides a high leverage on latch plate  20  forcing pin  9  upwardly into an aperture  10 . When the lever  48  is released, pin  9  drops out of aperture  10  by gravity. A depending U-shaped yoke member  35  is welded to the lower surface of telescopic member  2  and serves as a stop for the movement of latch plate  20 . A horizontal member  36  extends from member  35  below the end of the bias means  47  to keep the spring end in place. 
     FIG. 7  shows an alternative positioning of a locking and release mechanism  3  of the invention. If the release mechanism  3  is on top, pin  9  and plate  20  can have a lift spring, such as a torsion spring  60  or a leaf spring, to push them into aperture  10  when cam  49  is released. The bias means  47  can be more rigid than the lift spring so that when cam  49  is engaged, pin  9  falls into aperture  10 . There is always spring pressure on the locking and release mechanism  3  to move in both directions which allows remote control. In  FIG. 7  a torsion spring  60  lifts plate  20  and pulls pin  9  out of aperture  10  when cam  49  is released. The torsion spring  60  is overcome by the force of bias means  47 . The pry bar or lever  14  can be lifted, raising projection  22  which lifts pin  9  from aperture  10 . The yoke member  35  prevents overextension of the projection  22 . Horizontal members  36  and  37  extend over the ends of the bias means  47  to keep it in place. Cam  49  can also be embodied as a solid stop over bias means  47  and spring  62  can be eliminated to form a simple lever operated high leverage latch mechanism. 
     FIG. 8  illustrates a variation of the pin locking mechanism  3  shown in FIG.  4 . Latch plate  20  is pivotally mounted on inner telescopic member  2  with pin  9  extending upwardly therefrom. A bias means  47 , in the form of a leaf spring, is attached at one end to telescopic member  2  while the opposite end engages latch plate  20  such that pin  9  is biased upwardly toward apertures  10  in outer telescopic member  1 . A lever  48  is pivotally mounted on second telescopic member  2  with cam portion  49  engaging the underside of bias means  47 . A depending yoke  35  is attached to the inner surface of telescopic member  2  and serves as a stop for the downward movement of latch plate  20 . A horizontal member  36  extends from yoke  35  below the end of bias means  47  to keep bias means  47  in place. 
   In the embodiment shown in  FIG. 8 , a projection  160  depends from yoke  35  and a projection  161 , having a perpendicular extension  162 , depends from lever  48 . A spring  163  is attached to projection  160  and extension  162  to help bias pin  9  upwardly into one of apertures  10 . A remote actuator, such as a chain  164 , is attached to projection  161  opposite extension  162 . When chain  164  is pulled from, for example, a cab of a vehicle, it removes the contact between cam  49  and bias means  47  allowing pin  9  to drop out of aperture  10 . The latch embodiment may be placed internally, as shown in  FIG. 8 , or may be placed externally on telescopic member  1 . 
     FIG. 9  is an exploded view of the components of a latch mechanism of the type shown in FIG.  2 .  FIG. 10  is an alternative spring mount for the tow bar of FIG.  2 . Instead of a hole in plate  20 , a reinforcement plate  80  is attached to plate  20 . Instead of spring  11  pointed and in a hole in plate  20 , plate  80  positions spring  11 . This also gives more weld area to mount pin 
   In  FIGS. 11 and 12 , a gate latch having a blocking mechanism similar to that of  FIG. 2  fastens to a gatepost  105  by U iron  100 . Pry rod and lever or handle  48  go through a hole  106  in U iron  100 . Extending projection or pry plate  22  is welded to pry rod  48 . Pry rod  48  also goes through a plate  14 , that is welded to the opposite edge side of U iron  100 , further holding pry rod  48 . Pry rod  48  can also extend through plate  14  and be bent parallel with the part shown and be on the other, opposite side of the handle shown and post  105  so gate  214  can be opened from either side. 
   In  FIG. 12 , when gate  214  closes to gatepost  105 , gate latch taper  206 , mounted on gate  214 , moves pin  9  back against the bias of spring  11 . When gate latch  206  reaches hole  172 , pin  9  penetrates aperture  172 , under the bias of spring  11 , locking the gate  214 . If there is pressure against gate  214  when opening, pry rod  48  is activated which urges plate  22  against pin  9  containing plate  20 , which pulls pin  9  out of aperture  172  with approximately a 10:1 mechanical advantage. U iron  100  could also be a square tube with a cover to prevent rust. The gate latch taper  206  can be long to allow for the gate settling downward. Gate latch handle and pry rod  48  can also be bent upward where cattle are unable to move it, and can be operated from horseback. 
   U iron  100  could also be a square tube. Pin  9  can be extended through plate  20  and through an elongated vertical slot at the side, e.g., right side shown in  FIG. 12 , of U iron  100  and into post  105  to prevent pin  9  from twisting under force. The latch shown in  FIG. 12  can be horizontal to post  105 . The latch in  FIG. 12  can also be on the gate  214 . U iron  100  or square tube  100  can be sized or modified to stop plate  20  from over extension. 
   Notch  172  and taper  206  can adjust in and out with a lock bolt  205  and notch assembly  200  can be on gatepost  105 . Pry plate  22  can be longer for faster action. Mechanical advantage of the latch will and can vary depending on the lengths of the parts. 
   Spring  11  can have a cover, e.g., as shown in  FIG. 3 , or a bolt or plate  103  from the right side of U iron  100  and can hold spring  11 . Plate  20  can be two pieces as in parts  80  and  20  in FIG.  10 . Spring  11  can be two springs and exchanged for a coil spring through pin  9  between plate  20  and the right wall of U iron  100 . 
   While a number of embodiments of the invention are described in detail herein, it will be appreciated by those skilled in the art that various modifications and alternatives to the embodiments could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements are illustrative only and are not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.