Abstract:
A camper tie-down. The tie down is provided for mounting a load such as a camper to pre-existing mounting structure on a motor vehicle frame, such as a hitch or frame portion. The tie-down includes a retractable base portion, an adjustable tension member, and a shock absorbing cushioning member. The tie-down minimizes or eliminates drilling, cutting, welding or other custom mounting structure for installation on most vehicles. One embodiment includes bullet shaped extension plates for extending the attachment point of arms forward or rearward, as appropriate depending on whether the attachment is to be made at the front or at the rear of the vehicle.

Description:
PRIORITY  
       [0001]    This application claims the benefit under 35 U.S.C. Section 120 of prior U.S. Non-Provisional Patent Application No. 09/422,837 filed Oct. 21, 1999, now U.S. Pat. No. 6,260,910, the disclosure of which is incorporated herein by this reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The invention(s) presented herein relate to tie downs for attachment of objects to vehicle frames. More particularly, this disclosure is directed to improved tie downs to secure camper bodies to pick-up trucks.  
         BACKGROUND  
         [0003]    Tie-downs for mounting objects on motor vehicle frames are well known. Such tie downs are often provided for fixed installation to the frame, or to the underside of a vehicle (such as a pick-up truck), for securing a load (such as a camper) to the vehicle frame. Generally, four such tie downs are installed on a vehicle for securing the camper to the pick-up truck&#39;s bed at or near all four corners. The tie downs used by others, in so far as they are known to me generally include a cantilevered telescoping arm projecting horizontally from a secure position on the vehicle frame. Such prior art tie downs include a rigid support member projecting perpendicularly from an outer sleeve of a cantilevered telescoping arm to fixedly attach to a point on the underside of the vehicle to brace the tie down when the load is secured. Also, such tie downs include a chain having one end attached to the end of the telescoping arm opposite the frame mount and the other end free for fixedly attaching to the load, such as a camper, to secure it to the vehicle. The load is secured to the vehicle by tensioning the chain using, for example, a turnbuckle. Thus tensioned, the chain is a rigid member unable to relieve sudden loads, such as those caused by shifting of the camper relative to the truck bed. Such sudden load, when not relieved, may exceed the stress-bearing capabilities of the joints mounting the tie downs to the vehicle and may loosen the joints and/or damage either or both of the vehicle and the tie downs. While a spring-loaded turnbuckle is known, it is a separate assembly from the tie down and forms no part of the tie down.  
           [0004]    It is a drawback that the tie downs used by others must be professionally installed by qualified mechanics, primarily since they are normally provided from the factory in a single embodiment or configuration which requires drilling of additional mounting holes in the vehicle frame. The drilling of such holes in or adjacent to highly loaded or specially hardened steel frame members requires equipment and a skill level ordinarily available only to the professional installer. Furthermore, the warranties provided by many vehicle manufacturers might be violated or voided by the addition of such holes in the vehicle frame members. Therefore, such considerations severely limit the practical application of the known tie downs. Moreover, such restrictions have effectively prevented mail order or Internet distribution of such tie-down designs.  
           [0005]    Undesirably, many tie downs also interfere with use of the vehicle even when the load is removed from the vehicle. This is because rigid support members, not easily or quickly removable, if at all, project from the sleeve of cantilevered telescoping arms, and thus places the tie down components in a position beneath the vehicle in a manner that may interfere with steps, bars and other platforms attached to many vehicles for ease of entry and exit. Many tie downs also interfere with use of the vehicle off-road, because they are positioned below the vehicle, near the ground, and might encounter brush, stumps, rocks and other low lying obstacles.  
         SUMMARY  
         [0006]    The present invention overcomes many limitations of prior art tie-downs by providing a tie down for mounting to hitches, frames, or other pre-existing mounting structure on a vehicle. The present invention thus overcomes the need (found in many prior art devices) to drill, cut, weld or otherwise provide custom mounting structure for a tie downs, and thus tie downs can be provided for each major brand of vehicle, without the need to customize every tie down installation.  
           [0007]    According to one aspect of the invention, the present invention provides first and second spaced apart, mutually perpendicular frame brackets, each frame bracket adapted for mating with pre-existing mounting holes or other structure on a vehicle frame. Generally, the first frame bracket is mounted to a vertical portion of the frame while the second frame bracket is mounted to a horizontal portion of the vehicle frame, i.e., the bottom of the vehicle. The retractable nature of the tie down is provided by a telescoping arm pivotally mounted to a first frame bracket, whereby the telescoping arm is able to rotate relative to the first frame bracket. The telescoping arm includes an outer sleeve, one end of which is rotatably suspended by a pivot mechanism from a face of the first mounting bracket, an inner arm nested in the outer sleeve and able to move axially relative to the outer sleeve, and a releasable clamp which secures the inner arm in fixed axial relationship with the outer sleeve.  
           [0008]    According to another aspect of the invention, a support strut extending between the telescoping arm and the second frame bracket secures the telescoping arm in a fixed orientation with each of the first and second frame brackets.  
           [0009]    According to another aspect of the invention, the telescoping arm includes a movable slide having a clamp for securing the slide in variable positions along the body of the telescoping arm&#39;s outer sleeve. The movable slide includes a second pivot mechanism projecting, to which one end of the support strut extending between the telescoping arm and the second frame bracket is pivotally mounted. The second or horizontally mounted frame bracket includes yet another pivot mechanism to which the other end of the support strut is mounted. Thus, one end of the support strut rotates about the pivot mechanism on the second frame bracket and the other end rotates about the pivot mechanism on the movable slide, while the slide moves along the longitudinal axis of the telescoping arm in order to allow the telescoping arm to rotate up and down relative to the first frame bracket, and thus into different angular orientations with respect to the vehicle frame.  
           [0010]    According to still another aspect of the invention, the support strut is configured as a second telescoping arm and includes its own mechanism for locking its inner arm relative to its outer sleeve.  
           [0011]    In yet still another aspect of the invention, the support strut is configured in a partially collapsed bent tubular configuration, so that a tubular insert is provided that is able to slide inside of a welded steel tube, without the need to remove weldment where the larger tube has been fabricated.  
           [0012]    In yet still another aspect of the invention, a clamp is provided for attaching arms to a trailer hitch, which clamp eliminates the need to drill holes in a hitch or in a vehicle frame, in order to securely attach the arm to the hitch or frame.  
           [0013]    In yet still another aspect of the invention, a bullet shaped (in cross-section) plate is provided to extend, either forward or aft, as the case may be, the attach point at the end of attachment arms, so that increased leverage is available to secure the load against shifting.  
           [0014]    In yet another aspect of the invention, an easily adjustable clamp is provided for adjustment of arm positions relative to frame mounts.  
           [0015]    In a still further aspect of the invention, a fixed size arm is provided with certain frame mounts, as such mounts easily serve a multitude of vehicles of the same make and/or model.  
           [0016]    Various embodiments of the invention are disclosed in which the mechanical features described above are achieved in disparate physical configurations.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0017]    [0017]FIG. 1 illustrates a pictorial isometric view of an unmodified vehicle, for example a pick-up truck, having four retractable frame mounted tie downs of the invention installed thereon.  
         [0018]    [0018]FIG. 2 shows a side view of the vehicle of FIG. 1 with a camper installed in the pick-up bed and the retractable frame mounted tie downs of the invention extended to secure the camper;  
         [0019]    [0019]FIG. 3 is an exploded view of one exemplary embodiment of the retractable frame mounted tie downs of the invention.  
         [0020]    [0020]FIG. 4 illustrates the spaced apart, mutually perpendicular relationship of first and second frame brackets of the retractable frame mounted tie downs of the invention as installed on a vehicle frame using fasteners threaded through pre-existing mounting holes on the vehicle frame provided by the original manufacturer such that no drilling of the vehicle frame is needed for installation.  
         [0021]    [0021]FIG. 5 shows an exploded view of an exemplary embodiment of the shock absorber portion of the present invention, utilizing a universal mounting mechanism on the retractable frame mounted tie downs.  
         [0022]    [0022]FIG. 6 illustrates one embodiment of a frame bracket portion of the retractable frame mounted tie downs, as adapted to mate with pre-existing mounting holes in the frame of one configuration of vehicle available from one manufacturer, other embodiments of the frame bracket portions of the invention (not shown) are similarly adapted to mate with pre-existing mounts available on the frame and undercarriage of other vehicles available from other manufacturers.  
         [0023]    [0023]FIG. 7 illustrates one exemplary embodiment of the forward frame bracket, with extensible mount, utilizing an adjustable mounting mechanism on tie down arm to locate it as it extends outward from the frame bracket.  
         [0024]    [0024]FIG. 8 illustrates, in use on a vehicle, the mounting bracket, tie-down load bearing arm, and shock absorber mount just illustrated in FIG. 5 above.  
         [0025]    [0025]FIG. 9 shows the use of trailer hitch transverse rear tube to accept an appropriately crimped first end of a load bearing arm, and showing the stud for use in securing a mounting clamp.  
         [0026]    [0026]FIG. 10 is a view similar to the view just illustrated in FIG. 9 above, now adding a clamp to be affixed by the fastener system of the stud first shown in FIG. 9 and a selected nut to be further illustrated in FIG. 11 below.  
         [0027]    [0027]FIG. 11 is a view similar to the view just illustrated in FIGS. 9 and 10 above, now adding an acorn nut be affixed to finalize the fastener system and thus securely affix the load bearing arm to the hitch.  
         [0028]    [0028]FIG. 12 shows a load bearing arm similar to that just illustrated in FIGS. 9, 10, and  11  above, but now removed from the transverse rear tube of the hitch, and more clearly showing the first, interior end which is crimped and shaped to slidingly and snugly interfit into the transverse rear tube, as well as the U-shaped clamp, stud, and acorn nut.  
         [0029]    [0029]FIG. 13 shows the load bearing arm just illustrated in FIG. 12 above, but now additionally showing the use of a tubular load bearing end piece having a first, interior end adapted to insert and snugly fit in close fitting relationship to the interior tubular wall of the second, exterior end of the load bearing arm, with the load bearing arm and tubular load bearing end piece secured together with a conventional pin and transverse cotter pin, and also showing at the second, exterior end of the tubular load bearing end piece, a bullet shaped (as if the bullet were cross-sectioned) mounting plate, affixed to the mounting foot of the tubular load bearing end piece.  
         [0030]    [0030]FIG. 14 illustrates the bullet shaped mounting plate, before attachment to the mounting foot of the tubular load bearing end piece.  
         [0031]    [0031]FIG. 15 illustrates the mounting of the bullet shaped mounting plate being affixed to the mounting foot of the tubular load bearing end piece.  
         [0032]    [0032]FIG. 16 shows the bullet shaped mounting plate affixed to the mounting foot of the tubular load bearing end piece.  
         [0033]    [0033]FIG. 17 illustrates the correct mounting orientation of the bullet shaped end piece, with the pointed end directed forward, in order to decrease the angle of the tie down chains with respect to the horizontal (; i.e., stretch the lower end of the forward chains more forward on the vehicle).  
         [0034]    [0034]FIG. 18 illustrates the correct mounting orientation of the bullet shaped end piece, with the pointed end directed rearward, in order to decrease the angle of the tie down chains with respect to the horizontal (; i.e., stretch the lower end of the rear chains more rearward on the vehicle).  
         [0035]    [0035]FIG. 19 illustrates the use of a transverse rear hitch tube to accept an appropriately crimped end of a load bearing arm.  
         [0036]    [0036]FIG. 20 further illustrates the use of a transverse rear hitch tube to accept an approriately crimped first end of the load bearing arm.  
         [0037]    [0037]FIG. 21 shows the first end of an appropriately crimped load bearing arm, sized and shaped for use on a typical Dodge pickup truck trailer hitch.  
         [0038]    [0038]FIG. 22 illustrates a load bearing arm, much like that shown in FIG. 21, but this one is sized and shaped to fit a typical Ford pickup truck trailer hitch.  
         [0039]    [0039]FIG. 23 illustrates yet another embodiment of a load bearing arm, sized and shaped to fit the interior of a typical Chevrolet pickup truck trailer hitch, and especially showing the use of a pair of “crimped” receiver inserts, each of which has a centrally located edge indented portion with respect to the line formed below the line connecting two selected corners; the inserts are sized and shaped to fit the interior of a trailer transverse rear tube, and avoid the weldment at the seam used to join the hitch tube.  
         [0040]    [0040]FIG. 24 is a side perspective view of the load bearing arm just illustrated in FIG. 23 above.  
         [0041]    [0041]FIG. 25 is a perspective view of the load bearing arm just illustrated in FIGS. 23 and 24 above, but now showing the arm mounted in the rear transverse tube of a typical trailer hitch, and with the U-shaped clamp installed to secure the load bearing arm.  
         [0042]    [0042]FIG. 26 is yet another perspective of the load bearing arm just illustrated in FIG. 25 above, showing additional perspective of the rear transverse hitch tube and the hitch receiver.  23  and  24  above, but now showing the arm mounted in the rear transverse tube of a typical trailer hitch, and with the U-shaped clamp installed to secure the load bearing arm.  
         [0043]    [0043]FIG. 27 is an exploded perspective schematic showing the various components of one exemplary embodiment of a front tie down assembly having adjustable strut locations.  
         [0044]    [0044]FIG. 28 illustrates the first step in installing the front tie-down assembly just shown in FIG. 27, wherein fasteners are prepared to receive the passenger side front adjustable mounting bracket.  
         [0045]    [0045]FIG. 29 illustrates the second step in installing the front tie-down assembly just shown in FIG. 27, wherein the passenger side front upper adjustable transverse mounting bracket is secured in place by fasteners.  
         [0046]    [0046]FIG. 30 shows the third step of the installation of the passenger side front mounting bracket, wherein the first axial mounting bracket is affixed to the frame.  
         [0047]    [0047]FIG. 31 shows the next step in the installation of the passenger side front mounting bracket, wherein the first load bearing arm is secured to the first axial mounting bracket, and wherein the passenger side front lower adjustable transverse mounting bracket is secured in place , with the strut running between the adjustable upper and adjustable lower transverse brackets.  
         [0048]    [0048]FIG. 32 illustrates yet another embodiment of a second axial mounting bracket, affixed on the drivers side, and which has been configured for a fixed length, non-adjustable strut, and a fixed upper transverse mounting point, and a fixed lower transverse mounting point.  
         [0049]    [0049]FIG. 33 provides additional detail of an exemplary cross-section of a “crimped” tubular member as taught herein, showing a portion of an outer tubular member, such as a transverse rear hitch tube having a weld joint at the bottom thereof, and an insert, “crimped” second tubular end portion inserted therein, and where a clearance D is provided outward of the central portion of one or more of the tubular sides, with respect to the line formed between adjacent corners of the crimped member.  
         [0050]    In the various figures, like numerals indicate like elements, and may be used without additional discussion thereof. In addition, the foregoing figures, being exemplary, contain various elements that may be present or omitted from actual implementations depending upon the circumstances. An attempt has been made to draw the figures in a way that illustrates at least those elements that are significant for an understanding of the various embodiments and aspects of the invention. However, various other elements of the camper tie-down system are also shown and briefly described to enable the reader to understand how various optional features may be utilized in order to provide an easy to install, reliable camper tie-down system.  
     
    
     DETAILED DESCRIPTION  
       [0051]    [0051]FIG. 1 is a pictorial isometric view of an unmodified vehicle  2 , for example a pickup truck, having four retractable frame mounted tie downs  10  of the type taught herein installed thereon. In FIG. 1, four retractable frame mounted tie downs are shown in the retracted configuration. The four retractable frame mounted tie downs  10  are shown in phantom lines indicating that, in the retracted configuration, the tie downs  10  lie entirely beneath the vehicle such that they do not interfere with use of the vehicle when a load to be tied down is not present. In the retracted configuration, the retractable frame mounted tie downs  10  do not interfere with steps, bars and other platforms attached to many vehicles  2  for ease of entry and exit. In the retracted configuration, the retractable frame mounted tie downs  10  also do not interfere with use of the vehicle off-road because the tie downs  10  are positioned on a vehicle  2  frame portion and are retracted, preferably within the vehicle  2  wheelbase tread dimension such that brush, stumps, rocks and other low lying obstacles are not encountered by the tie downs  10 .  
         [0052]    [0052]FIG. 2 shows a side view of the vehicle  2  with a load, for example a camper  11 , installed in the pick-up bed B. In FIG. 2, the retractable frame mounted tie downs  10  are extended to secure the load, i.e. the camper  11 . A shock absorber  52  and adjustable tension member  58  (both described in detail below) are used secure a load such as camper  11  to the tie downs  10 .  
         [0053]    [0053]FIG. 3 is an exploded view of one exemplary embodiment of my novel retractable frame mounted tie downs  10 . The various details of tie down  10  are preferably formed of a sturdy machinable metal or other material of suitable strength, such as steel, aluminum or another appropriate material. As shown in this exemplary embodiment, a first mounting bracket  12  is configured as an essentially flat metal plate  13  having one or more mounting apertures  14  defined by edgewall portions  15  and positioned to mate with pre-existing mounting apertures  17  on a frame portion F of a pre-selected vehicle  2 , as provided by a original equipment manufacturer. Mounts  14  (preferably mounting apertures defined by edge wall portion  15 ) have dimensions sized complementary to pre-existing matching holes on a pre-selected vehicle. The size and location of mounts  14  vary for particular makes and models of vehicles  2 , so that in any application the location of mounts  14  match the size and location of particular pre-existing matching holes  17  located on the frame F of pre-selected vehicle. Mounts  14 , when configured as holes, accept bolts  16  previously passed through the pre-existing matching holes 17  in the frame F of a vehicle  2 . Nuts  18  are threadingly engage bolts  16  and are tightened to secure first mounting bracket  12  in place against frame of the vehicle  2 , as shown in FIG. 4, and as described in further detail below. If the pre-selected vehicle includes pre-existing threaded mounting studs protruding from frame F (as an alternative to pre-existing matching holes formed in the frame), then the mounting studs are provided in place of the illustrated bolts  16 , and the mounts  14  in mounting bracket  12  are fitted over such pre-existing studs. Then, nuts  18  are used to secure bracket  12  to the vehicle frame. Mounts  14  may alternatively be provided as threaded studs affixed to one surface of bracket  12 , and sized and positioned to mate with the pre-existing matching holes  17  in frame F of the desired vehicle; nuts  18  secure bracket  12  to the vehicle frame. Mounts  14  therefore mate with pre-existing matching holes or other mounting mechanism in the vehicle frame provided by the manufacturer such that installation of bracket  12  requires no modification to the vehicle frame.  
         [0054]    A second frame bracket  20  is spaced apart from and oriented perpendicular to first frame bracket  12 . While first frame bracket  12  is configured to mount to a vertical portion of the vehicle frame, second frame bracket  20  is configured to mount to a horizontal portion of the vehicle frame, i.e., the bottom of the vehicle, as shown in FIG. 4 and described below. Second frame bracket  20  includes one or more mounts  22  similar in description to mounts  14  of first frame bracket  12 . In a preferred configuration, mounts  22  are mounting holes formed in second frame bracket  20  sized and positioned to mate with matching pre-existing mounting holes in the vehicle frame such that second frame bracket  20  is mounted and secured without modification to the vehicle frame. Mounts  22 , when configured as holes, accept bolts  16  previously threaded through the pre-existing matching holes on the desired vehicle and nuts  18  (shown in FIG. 4) secure second mounting bracket  20  in place on the vehicle, as shown in FIG. 4 and described in detail below.  
         [0055]    A telescoping load bearing arm  24  is rotatably suspended at one end from first frame bracket  12 , preferably by a first pivot mechanism  26  fixed to one surface of first frame bracket  12 . First pivot mechanism  26  preferably constrains telescoping arm  24  to rotate in a plane essentially perpendicular to the generally planar surface of first frame bracket  12 . Telescoping arm  24  includes an outer sleeve  28  that is pinned to first frame bracket  12  at one end by first pivot mechanism  26 . Telescoping arm  24  also includes an inner arm portion  30  configured to fit inside outer sleeve  28  with sufficient clearance to move or slide axially relative to outer sleeve  28  as indicated by double-pointed arrow  32 . Each of outer sleeve  28  and inner arm  30  are, preferably, configured as commonly available standard square (shown), rectangular or tubular extruded sections. A releasable mechanical arm fastener  34  fixes inner arm  30  in an adjustable axial relationship with outer sleeve  28 . Releasable arm fastener  34  is, for example, an “L” pin secured with a security pin  36 . However, those of ordinary skill in the art will recognize that many variations of pins and security pins, including clevis pins with cotter pins and even bolts with nuts, may alternatively replace the “L” pin and security pin shown. Also, telescoping arms having a twisting mechanism for fixing the inner arm and outer sleeve in axial relationship to one another are known and contemplated by an alternative embodiment of the present invention. Thus, the invention does not contemplate being limited to the exemplary embodiment shown in the figures and described herein.  
         [0056]    Inner arm  30  of telescoping arm  24  includes a mechanism for rotatably mounting a tensioning device, shown in FIG. 4 and described in detail below. For example, according to one embodiment of the invention shown in FIG. 3, inner arm  30  includes a foot  38  mounted at the end projecting from outer sleeve  28 . Foot  38  includes a  40 , preferably configured as a through hole (shown). Alternatively, foot  38  is a “U” shaped structure and mounting mechanism  40  is a pin or rod extending between the two parallel legs of the “U” shaped structure. Again, those of ordinary skill in the art will recognize that many variations of foot  38  and mounting mechanism  40  are known and contemplated by alternative embodiments of the present invention. Thus, the invention does not contemplate being limited to the exemplary embodiment shown in the figures and described herein.  
         [0057]    A slide  42  is movably mounted on outer sleeve  28  of telescoping arm  24 . Slide  42  is configured for axial motion along the outer dimension of outer sleeve  28 . A clamp  44  fixes slide  42  at variable positions along the longitudinal dimension of outer sleeve  28 . According to one embodiment of the invention, slide  42  is an extruded “H” shaped section closed on the bottom by a member extending between the two parallel sides of the “H” section such that the bottom portion of slide  42  is a closed configuration sized to fit around outer sleeve  28  with sufficient clearance to move or slide axially relative to outer sleeve  28  as indicated by double-pointed arrow  32 , similar to inner arm  30 . Clamp  44  is, for example, a threaded member, commonly referred to as a set bolt or set screw, turned into a mating threaded hole in the closed bottom portion of slide  42  and clamping slide  42  in a variable fixed position along the longitudinal dimension of outer sleeve  28  by a frictional force exerted by the end of threaded clamp  44  against the surface of outer sleeve  28 . Slide  42  further includes a second pivot mechanism  46  at the open end of the “H” section extending away from the body of telescoping arm  24  and securing a telescoping support strut  48 , described in detail below.  
         [0058]    According to another embodiment of the invention, slide  42  is a bent or extruded “U” shaped member secured to outer sleeve  28  of telescoping arm  24  by threaded clamp  44 . According to this embodiment, threaded clamp  44  is, for example, a threaded bolt screwed into a threaded hole in the bottom portion of “U” shaped slide  42  extending between the two parallel leg portions. The position of slide  42  is adjusted along the longitudinal dimension of outer sleeve  28  by aligning the threaded hole in the bottom portion of “U” shaped slide  42  with a corresponding hole or depression in outer sleeve  28  and turning threaded clamp  44  into the threaded hole in the bottom portion of “U” shaped slide  42  and simultaneously into the corresponding hole or depression in outer sleeve  28 . The parallel legs of “U” shaped slide  42  are longer than the thickness of outer sleeve  28  and extend beyond that side of outer sleeve  28  opposite clamp  44 . A second pivot mechanism  46  is included at the open end of the “U” section extending away from the body of telescoping arm  24  where support strut  48  is secured in axial relationship with telescoping arm  24 .  
         [0059]    Support strut  48  extends between slide  42  and a third pivot mechanism  50  fixed to one surface of second frame bracket  20 . Third pivot mechanism  50  projects away from the vehicle frame. Third pivot mechanism  50  is, according to one embodiment of the invention, formed integrally with second frame bracket  20 . Third pivot mechanism  50  suspends, or anchors, one end of strut  48  for rotational motion relative to second frame bracket  20  and, consequently, to the frame of the vehicle. The end of strut  48  opposite second frame bracket  20  is suspended, or anchored, by second pivot mechanism  46  on slide  42 . Thus, strut  48  provides columnar support to restrict telescoping arm from rotating upwardly toward the underside of the vehicle when a load is secured to the vehicle by a tension member coupled to tie down  10  at mounting mechanism  40  on foot  38 . The suspension provided by both second pivot mechanism  46  and third pivot mechanism  50  allows strut  48  to rotate relative to each pivot mechanism  46 ,  50  when the position of slide  42  is adjusted relative to telescoping arm  24 . According to one embodiment of the invention, strut  48  is a configured as a telescoping strut having an outer sleeve and an inner arm adjustable in axial relationship to one another. Telescoping strut  48  is configured generally consistently with telescoping arm  24  described above, including a mechanism for fixing the inner arm in a desired relative axial position with the outer sleeve.  
         [0060]    [0060]FIG. 4 illustrates the spaced apart, mutually perpendicular relationship of first and second frame brackets  12  and  20  as installed on the vertical and horizontal portions of the vehicle frame, respectively. As described above, first and second frame brackets  12  and  20  are secured to the vertical and horizontal portions of the vehicle frame, respectively, using fasteners threaded through pre-existing mounting holes on the vehicle frame provided by the original manufacturer such that no drilling of the vehicle frame is needed for installation. FIG. 4 also illustrates in phantom retractable frame mounted tie down  10  in a retracted configuration, whereby tie down  10  is retracted entirely beneath the vehicle body such that it does not interfere with use of the vehicle when the load is not present. Telescoping strut  48  in a collapsed configuration (not shown) draws tie down  10  into a yet more compact form in a closer relationship with the vehicle undercarriage.  
         [0061]    [0061]FIG. 4 illustrates, in solid lines, tie down  10  in an extended configuration securing a load, for example a camper, on the vehicle. According to one preferred embodiment, a shock absorber  52  is rotatably suspended from universal mounting mechanism  40  of foot  38  of inner arm  30  (best shown in FIG. 5). An adjustable tension member  54  is pliantly suspended from a universal connector portion  56  of shock absorber  52 . Adjustable tension member  54  typically includes a suitable tensile device  58  and a tensioning device  60  used in adjusting tension member  54 . Tensile device  58  is, for example, a chain (shown), cable, rod, braided wire or other suitable tensile device and tensioning device  60  is, for example, a turn-buckle or other suitable device for tightening tension member  54  to a desired degree. Shock absorber  52  relieves the stress on tie downs  10 , bolts  16 , and the vehicle frame when, for example, travel across uneven terrain tends to induce shock and/or vibration loads on tie downs  10  due to rocking of the load or other relative movement between the load and the vehicle. Thus, shock absorber  52  protects tie downs  10  and the vehicle frame from shock and vibration induced damage in contrast to the more rigid prior art devices.  
         [0062]    [0062]FIG. 5 shows an exploded view of one exemplary embodiment of shock absorber  52  and its rotatable suspension from universal mounting mechanism  40  of foot  38  of inner arm  30 . According to the embodiment illustrated in FIG. 5, shock absorber  52  includes a tubular sleeve  62  rotatably mounted to inner arm  30  at foot  38  by a pivot mechanism, for example, a bolt  66  and nut  68  (shown), a clevis pin, or another suitable mechanism whereby shock absorber  52  is rotatably secured to inner arm  30 . Sleeve  62  includes a cap  64  (shown in phantom) formed at one end opposite the pivotal connection to inner arm  30 . A hanger  70  extends through end cap  64  and includes a universal connector end  72  for rotatably suspending tension member  54  (shown in FIG. 4) securing a load to the vehicle. The end of hanger  70  opposite universal connector  72  extends into sleeve  62  and is configured to compress a cushion  74 , for example a spring (shown) or other suitable cushion device between end cap  64  and a fastener  76  secured to the end of hanger  70 . Cushion  74  performs the shock and vibration absorbing function of shock absorber  52  by maintaining a predetermined tensile force on tension member  54  while providing sufficient clearance between end cap  64  of sleeve  62  and fastener  76  when subjected to momentary severe tensile loads.  
         [0063]    Those of ordinary skill in the art will readily recognize that the embodiment of shock absorber  52  illustrated in the various figures of the drawing and described herein is not intended to limit the scope of the invention and that other configures of the various components are within the skill of one of ordinary skill to design. For example, in FIG. 5, hanger  70  is shown as an eyebolt, but the invention contemplates other hanger configurations adapted to rotatably suspend tension member  54  at one end and adapted to accept a fastener at the other end. For example, universal connector end  72  of hanger  70  is alternatively configured as an open hook while the threads on the opposing end are alternatively replaced by a smooth shaft pierced by a number of holes for inserting pins at various positions along the shaft&#39;s longitudinal dimension whereby cushion  74  is pre-compressed to a greater or lesser degree. In another example, the passage in end cap  64  through which the shaft of hanger  70  passes is alternatively threaded whereby fastener  76 , for example a lock nut, is fixed relative to the end of hanger  70  and cushion  74  is pre-compressed to a greater or lesser degree by turning the threaded shaft of eyebolt hanger  70  which increases or decreases the dimension between end cap  64  and lock nut fastener  76 . In yet another example, tubular sleeve  62  is alternatively shaped with a square or rectangular cross-section. According to another alternative embodiment, tubular sleeve is replaced by a “U” shaped member wherein the structure of end cap  64  is provided by the portion extending between the two parallel legs of the “U” shaped structure and shock absorber  52  is rotatably mounted to inner arm  30  at foot  38  by a pivot mechanism extending through the ends of the two parallel legs opposite end cap  64 .  
         [0064]    According to the exemplary embodiment illustrated in FIG. 5, first and second frame brackets  12  and  20  are configured to adapt to the frame of an embodiment of a 1999 model pick-up truck manufactured by the Ford Motor Company and to mate with pre-existing mounting holes formed in the vehicle vertical and horizontal frame portions, respectively.  
         [0065]    [0065]FIG. 6 illustrates one embodiment of a first frame bracket  12 ′ adapted to mate with pre-existing holes in the frame of one configuration of a 1999 Dodge pick-up truck. Other embodiments of first and second frame brackets  12  and  20  of the invention are similarly adapted to mate with pre-existing mounts available on the frame and undercarriage of other vehicles available from other manufacturers.  
         [0066]    Thus, in the various embodiments of the invention, each embodiment as manufactured for a particular make and/or model is configured to mate with pre-existing mounting holes of a different vehicle frame without need for drilling holes or otherwise modifying the vehicle frame. Because no frame modifications are required for installation, the drill-less retractable frame mounted tie downs of the present invention require neither special tools nor expertise for installation. Nor does the installation of the drill-less retractable frame mounted tie downs of the present invention violate or void the warranties provided by many vehicle manufacturers by the addition of such holes in the vehicle frame.  
         [0067]    Attention is now directed to FIG. 8, which illustrates, in use on a vehicle  78 , an interior load bearing arm  80  having a insertable outer arm  82 , and having a shock absorber  52  mount.  
         [0068]    Turning then to FIGS.  9 ,  10 ,and  11 , a trailer hitch  90  is provided having a transverse rear tubular portion  92 . A first end  94  of transverse rear tubular portion is open. A second end (not shown) is likewise available on the other side of vehicle  96 . An exemplary load bearing interior arm  98  is provided, having a first end  99  crimped (not visible, see FIG. 12) adapted for snug interfitting engagment within interior wall  100  of transverse rear tubular portion  92 . The arm  98  fits into the tubular portion  92  for a distance L T  (see FIG. 12) that is basically defined by the distance between the end  102  of arm  98  and the weldment  103  surrounding fastener stud  104 .  
         [0069]    Turning now to FIG. 10, this is similar to FIG. 9, but now shows the use of a U-shaped clamp  110  being affixed by the fastener system inclusing the stud  104  first shown in FIG. 9, and a selected nut such as acorn type nut  112  shown in FIG. 11. Also, note particularly the crimped region  120  in arm  98 .  
         [0070]    In FIG. 12, an exemplary load bearing arm  98  is shown, but now removed from the transverse rear tube  92  of hitch  90 , and more clearly showing the first, interior end which is crimped and shaped to slidingly and snugly interfit into the transverse rear tube  92 . In FIG. 13, the load bearing arm  98  just illustrated in FIG. 12 is again shown, but now additionally shows the use of a tubular load bearing exterior or end piece  130  having a first, interior end  132  (not seen) adapted to insert and snugly fit in close fitting relationship to the interior tubular wall  134  of the second, exterior end  136  of the load bearing interior arm  98 . The load bearing arm  98  and the tubular load bearing end piece  130  are secured together with a conventional pin  140  and transverse cotter pin  142 . At the second, exterior end  144  of the tubular load bearing end piece  130 , a bullet (shaped as if the bullet were cross-sectioned) mounting plate  150 , is affixed to the mounting foot  152  of the tubular load bearing end piece  130 . As illustrated, a mounting foot  154  is utilized. Suitable fasteners  160  may be utilized to accomplish this task. Preferably, bullet plate  150  has a pair of mounting apertures defined by edge walls  162  (preferably square) for use in connection of bullet plate  150  to the foot  154 . Also, bullet plate has a receiving aperture defined by edge wall  164  for attachment of a suitable chain  58 . In FIG. 14, the bullet plate  150  is illustrated before attachment to the mounting foot  154  of the tubular exterior load bearing arm  98 . FIG. 15 illustrates the mounting of the bullet plate  150  to the mounting foot  154 . FIG. 16 shows the bullet plate  150  affixed to the mounting foot  154  of the tubular exterior load bearing arm  98 .  
         [0071]    Turning now to FIG. 17 this figure illustrates the correct mounting orientation of the bullet plate  150  with the pointed end  170  directed forward, in order to decrease the angle of the tie down chains with respect to the horizontal (; i.e., stretch the lower end of the forward chains  58  more forward on the vehicle). Likewise, FIG. 18 illustrates the correct mounting orientation of the bullet plate  150 , with the pointed end  170  directed rearward, in order to decrease the angle of the tie down chains  58  with respect to the horizontal (; i.e., stretch the lower end of the rear chains  58  more rearward on the vehicle).  
         [0072]    [0072]FIG. 19 illustrates the use of a transverse rear hitch tube  200  of hitch  190  to accept an appropriately crimped end  202  of an interior load bearing arm  204 . In FIG. 20, further illustration of the use of a transverse rear hitch tube  220  to accept an approriately crimped first end  222  (not seen) of the interior load bearing arm  224 . Nut  226  is seen, although the acorn style nut earlier discussed is preferred.  
         [0073]    Turning now to FIG. 21, this illustrates in great detail the dimensions of a crimped tubular member such interior load bearing arms  98 , wherein the first or interior end is crimped  230  intermediate of the corners  240 . This shape is one embodiment that is appropriately crimped, sized and shaped for use on a typical Dodge pickup truck trailer hitch.  
         [0074]    Similarly, FIG. 22 illustrates a load bearing arm  250 , much like that shown in FIG. 21, but this one is sized and shaped to fit a typical Ford pickup truck trailer hitch. Similar crimps  230  and corners  240  are noted.  
         [0075]    [0075]FIG. 23 illustrates yet another embodiment of a load bearing arm  250 , sized and shaped to fit the interior of a typical Chevrolet pickup truck trailer hitch, and especially showing the use of a set (normally but not necessarily a pair) of “crimped” receiver insert plates  260 , each of which has a centrally located edge indented portion  230  with respect to the line formed below the line connecting two selected corners  240 . The inserts  260  are sized and shaped to fit the interior sidewall  262  of a trailer transverse rear tube  264 , and avoid the weldment at the seam S used to join the hitch tube, as seen in FIG. 33.  
         [0076]    Turning now to FIG. 27, an exploded perspective schematic showing the various components of one exemplary embodiment of a front tie down assembly having adjustable strut locations is illustrated. These elements are better seen in subsequent figures, wherein FIG. 28 illustrates the first step in installing the front tie-down assembly just shown in FIG. 27, wherein fasteners  300  are prepared to receive the passenger side front adjustable mounting bracket.  302 . Adjustable mounting bracket has a plurality of holes  304  therein for adjustable strut  306  utilization. FIG. 29 illustrates the second step in installing the front tie-down assembly just shown in FIG. 27, wherein the passenger side front upper adjustable transverse mounting bracket  302 is secured in place by fasteners  300 . FIG. 30 shows the third step of the installation of the passenger side front mounting bracket, wherein the first axial mounting bracket  310  is affixed to the frame  312 . FIG. 31 shows the next step in the installation of the passenger side front mounting bracket, wherein the first load bearing arm  320  is secured to the first axial mounting bracket  310 , and wherein the passenger side front lower adjustable transverse mounting bracket  330  is secured in place , with the adjustable strut  306  running between the adjustable upper  302  and adjustable lower  330  transverse brackets.  
         [0077]    Turning to FIG. 32 yet another embodiment of a second axial mounting bracket  350 , affixed on the drivers side, is illustrated. This configuration has been adopted for a fixed length, non-adjustable strut  352 , and a fixed interior load bearing arm  354 , as well as a fixed upper transverse mounting point  356 , and a fixed lower transverse mounting point  358 .  
         [0078]    Finally, FIG. 33 provides additional detail of an exemplary cross-section of a “crimped” tubular member as taught herein, showing a portion of an outer tubular member, such as a transverse rear hitch tube having a weld joint at the bottom thereof, and an insert, “crimped” second tubular end portion inserted therein, and where a clearance D is provided outward of the central portion of one or more of the tubular sides, with respect to the line formed between adjacent corners of the crimped member.  
         [0079]    It is to be appreciated that the various aspects and embodiments of the pneumatic gun designs described herein are an important improvement in the state of the art, especially for camper tie-down applications. Although only a few exemplary embodiments have been described in detail, various details are sufficiently set forth in the drawings and in the specification provided herein to enable one of ordinary skill in the art to make and use the invention(s), which need not be further described by additional writing in this detailed description. Importantly, the aspects and embodiments described and claimed herein may be modified from those shown without materially departing from the novel teachings and advantages provided, and may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the embodiments presented herein are to be considered in all respects as illustrative and not restrictive. As such, this disclosure is intended to cover the structures described herein and not only structural equivalents thereof, but also equivalent structures. Numerous modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein. Thus, the scope of the invention(s), as set forth in the appended claims, and as indicated by the drawing and by the foregoing description, is intended to include variations from the embodiments provided which are nevertheless described by the broad interpretation and range properly afforded to the plain meaning of the claims set forth below.