Abstract:
A removable tow device and tow device receiver is provided having lugs upon the removable tow device that engage lug pockets within the tow device receiver for secure engagement. The removable tow device and receiver are simple to use, requiring a minimal of manipulation to install. Installation is reduced to insert, twist, and release. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Description:
BRIEF DESCRIPTION OF THE DRAWINGS 
       [0001]    FIG.  1 —A vehicle having removable tow devices. 
         [0002]    FIG.  2 —A vehicle chassis having removable tow devices. 
         [0003]    FIG.  3 —Removable tow device. 
         [0004]    FIG.  4 —Tow device receiver. 
         [0005]    FIG.  5 —Removable tow device inserted into tow device receiver. 
         [0006]    FIG.  6 —Tow device receiver with hold—forward spring. 
         [0007]    FIG.  7 —A vehicle chassis with integrated tow device receiver and front suspension mounts. 
         [0008]    FIG.  8 —Tow device receiver with sloped block and mating tow device feature, inserted. 
         [0009]    FIG.  9 —Tow device receiver with sloped block and mating tow device feature, engaged. 
         [0010]    FIG.  10 —Integrated tow device receiver and front suspension mount. 
         [0011]    FIG.  11 —Removable tow device with engagement and alignment indicators. 
         [0012]    FIG.  12 —Removable tow device having attached hold-forward spring. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Vehicles for operation on the ground are often provided with tow hooks or rings in order to provide a point to attach chains or other towing devices when pulling the vehicle. Some such tow hooks or rings are permanently affixed, so that they protrude from the front of the vehicle at all times. Others are removable, so as to allow the vehicle to comply with aerodynamic or impact absorption requirements. It is advantageous to provide removable tow devices that are simple to attach, do not require tools to do so, and do not require access to the area behind the vehicle bumper in order to insert a pin, clevis, fastener, or the like. It is also advantageous that the tow devices require a minimum of manipulation, such as repeated turning as a threaded fastener, and that once installed provide a robust attachment point. 
         [0014]      FIG. 1  shows a vehicle  101  having a body  102  and a chassis  103 . The chassis  103  is comprised of a ladder-type vehicle frame  104 . The vehicle  101  is provided with removable tow devices  105  that attach to the ladder-type vehicle frame  104  of the chassis  103  in a manner that is shown in subsequent drawings. 
         [0015]      FIG. 2  shows a chassis  103  of a vehicle  101 , similar to the vehicle  101  shown in  FIG. 1 . The chassis is again comprised of a ladder-type vehicle frame  104 , to which ladder-type vehicle frame  104  are attached tow device receivers  106 . Attachment of the tow device receivers  106  to the ladder-type vehicle frame  104  may be by means of bolt, rivet, or other conventional fastener. Removable tow devices  105  are insertable into the tow device receivers  106 , such that the removable tow devices  105  are inserted and twisted approximately ninety degrees to securely lock them into place. 
         [0016]      FIG. 3  shows a removable tow device  105  having an attachment feature  107 , a shank  108 , and lug lobes  109 . The attachment feature  107  may be a hook as shown, or it may be in the form of a ring. Two lug lobes  109  are shown, but a single lug lobe  109  may be used to the same effect. A hold-forward spring  110  is partially visible, and will be shown to greater clarity in subsequent views. 
         [0017]      FIG. 4  shows a tow device receiver  106 , simplified in the sense that any mounting flanges or features that may be present are not shown. The tow device receiver  106  in  FIG. 4  is also shown with one side open, although it may well be closed on all sides. The tow device receiver  106  is provided with a receiver hole  111  which is shaped to admit the removable tow device  105  (not shown), and which is only partially visible in  FIG. 4 . The interior of the tow device receiver  106  is provided with a receiver cavity  112 , into which the receiver hole  111  opens. As illustrated, the receiver hole  111  may open directly into the receiver cavity  112 , or may pass through additional cavities in the tow device receiver  106 , according to construction, weight, and strength requirements. The receiver hole  111  possesses lobe clearance-ways  113  and, on the inner forward wall of the receiver cavity  112 , lobe pockets  114 . When the removable tow device  105  (not shown) is inserted into the tow device receiver  106 , the lug lobes  109  pass through the lobe clearance-ways  113 . The removable tow device  105  is inserted sufficiently far that the hold-forward spring  110  (not shown) is compressed, then the removable tow device  105  is turned ninety degrees. The lug lobes  109  then engage the lobe pockets  114  and are held in such engagement by the hold-forward spring  110  (not shown). 
         [0018]      FIG. 5  shows a tow device receiver  106  with a removable tow device  105  inserted therein. The removable tow device  105  is again provided with an attachment feature  107 , a shank  108 , and lug lobes  109 . The tow device receiver  106  is again provided with a receiver hole  111 , lobe clearance-ways  113 , and a receiver cavity  112 . A hold-forward spring  110  is attached to the end of the removable tow device  105 , and engages the rearmost wall of the receiver cavity  112 , so that once the removable tow device  105  is inserted through the receiver hole  111  with the lug lobes  109  aligned with the lobe clearance-ways  113 , the removable tow device  105  is rotated ninety degrees and the hold-forward spring  110  forces the lug lobes  109  into engagement with the lobe pockets  114 . Note that the lobe pockets  114  are not visible in  FIG. 5 . 
         [0019]      FIG. 6  shows a tow device receiver  106 , again having a receiver hole  111 , a receiver cavity  112 , lobe clearance-ways  113 , and lobe pockets  114 . Note that the lobe pockets  114  are not visible in  FIG. 6 . A hold-forward spring  110  is attached to the rearmost wall of the receiver cavity  112 , and performs the same function as the hold forward spring  110  attached to the removable tow device  105  in  FIG. 5 . The hold-forward spring  110  may be a coil spring as shown, or may be a leaf spring similar to the hold forward spring  110  shown in  FIG. 12 . 
         [0020]      FIG. 7  shows a chassis  103  of a vehicle  101  comprising a ladder-type vehicle frame  104 . Removable tow devices  105  are shown inserted into the receiver holes  111  of tow device receivers  106 , which tow device receivers  106  are integrated tow device receiver and front suspension mounts  115 . The integrated tow device receiver and front suspension mounts  115  shown in  FIG. 7  are shown as castings. However, they may be welded steel constructs or other similar robust construction. 
         [0021]      FIG. 8  shows a cross-sectional view of an embodiment of a tow device receiver  106 . The tow device receiver  106  again has a receiver hole  111  so shaped as to admit a removable tow device  105  having a shank  108  and lug lobes  109 , and also has a receiver cavity  112  with lobe pockets  114 . In addition, the tow device receiver  106  in  FIG. 8  is provided with a receiver cavity inclined surface  116 . A similarly angled tow device inclined surface  117  is provided upon the end of the removable tow device  105 . The receiver cavity inclined surface  116  terminates at its forward edge to adjoin with a receiver cavity engagement wall  118 , the purpose of which receiver cavity inclined surface  116 , tow device inclined surface  117 , and receiver cavity engagement wall  118  will become apparent in  FIG. 9 . Note that although the receiver cavity inclined surface  116  and tow device inclined surface  117  are shown as planar surfaces, they may be non-planar, as will be elaborated in  FIG. 9 . 
         [0022]      FIG. 9  shows another cross-sectional view of an embodiment of a tow device receiver  106 , similar to the tow device receiver  106  shown in  FIG. 8 . The tow device receiver  106  again has a receiver hole  111  so shaped as to admit a removable tow device  105  having a shank  108  and lug lobes  109 , and also has a receiver cavity  112  with lobe pockets  114 . A similar receiver cavity inclined surface  116  and tow device inclined surface  117  are provided, as well as a receiver cavity engagement wall  118 . The removable tow device  105  is shown rotated ninety degrees, so that the receiver cavity inclined surface  116  and the tow device inclined surface  117  have cooperated to force the lug lobes  109  into the lobe pockets  114  upon rotation of the removable tow device  105 . The lug lobes  109  are held in engagement with the lobe pockets  114  by the receiver cavity engagement wall  118 . Note that the receiver cavity inclined surface  116  and tow device inclined surface  117  are again shown as planar surfaces, though they may be non-planar in order to provide clearance as the removable tow device  105  is rotated and the lug lobes  109  enter into the lobe pockets  114 . In order to accomplish this, the receiver cavity inclined surface  116  and tow device inclined surface  117  may describe a segment of a complex convolute, such as a helix. Also, it may be appreciated that the lobe pockets  114  may also by asymmetric, so as to accommodate the rotating entry of the lug lobes  109 . 
         [0023]      FIG. 10  shows a tow device receiver  106  in the form of an integrated tow device receiver and front suspension mount  115 , similar to the integrated tow device receiver and front suspension mount  115  shown in  FIG. 7 . The integrated tow device receiver and front suspension mount  115  shown in  FIG. 10  is provided with a receiver hole  111  having lobe clearance-ways  113 , as well as features not visible in  FIG. 10 , such as a receiver cavity  112 , and lobe pockets  114 . The integrated tow device receiver and front suspension mount  115  may also be provided with a hold-forward spring  110  or a receiver cavity inclined surface  116  and receiver cavity engagement wall  118 . A removable tow device  105  is shown inserted into the receiver hole  111 , which removable tow device  105  is provided with an attachment feature  107 , a shank  108 , and lug lobes  109  (not visible in  FIG. 10 ). The removable tow device  105  may also be provided with a hold-forward spring  110  or tow device inclined surface  117 , depending upon the configuration of the integrated tow device receiver and front suspension mount  115 . Note that the removable tow device  105  shown in  FIG. 10  is shown in an installed position that is different from the installed position that would result from the configuration of the removable tow devices  105  shown in  FIGS. 3 and 5 . Specifically, the lug lobes  109  shown on the removable tow devices  105  shown in  FIGS. 3 and 5  are shown axially aligned with the plane of the attachment feature  107 . The lug lobes  109  are not visible in  FIG. 10 , but are aligned axially ninety degrees from the plane of the attachment feature  107 . Removable tow devices  105  of this configuration are shown in  FIGS. 11 and 12 . An advantage of so orienting the lug lobes  109  ninety degrees from the plane of the attachment feature  107  is that the weight of the attachment feature  107  tends to rotate the removable tow device  105  towards alignment of the lug lobes  109  with the lobe pockets  114 , which lobe pockets  114  may be provided with stops to prevent over-rotation. 
         [0024]      FIG. 11  shows a removable tow device  105  having an attachment feature  107 , a shank  108 , and lug lobes  109 . Note that the lug lobes  109  are aligned axially ninety degrees from the plane of the attachment feature  107 , as mentioned in the detailed description of  FIG. 10 . The shank  108  of the removable tow device  105  is provided with an engagement indicator  119  and an alignment indicator  120 , which assists in verifying that the removable tow device  105  is securely engaged. 
         [0025]      FIG. 12  shows a removable tow device  105  having an attachment feature  107 , a shank  108 , and lug lobes  109 . The removable tow device  105  is also provided with a hold-forward spring  110 . The hold-forward spring  110  may be a leaf spring as shown or a coil spring similar to the hold-forward spring  110  shown in  FIG. 6 . Alternately, the hold-forward spring  110  attached to the removable tow device  105  may be located in a recess in the end of the removable tow device  105  (not shown), and may be provided with a plunger and a threaded retaining sleeve (not shown). Such embodiment would operate by compressing the captured spring when the plunger came into contact with the rearmost wall of the receiver cavity  112 , thereby forcing the lug lobes  109  of the removable tow device  105  into the lobe pockets  114 . 
         [0026]    While specific embodiments have been described in detail in the foregoing detailed description and illustrated in the accompanying drawings, those with ordinary skill in the art will appreciate that various permutations of the invention are possible without departing from the teachings disclosed herein. Accordingly, the particular arrangements disclosed are meant to be illustrative only and 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. Other advantages to a vehicle equipped with removable tow devices and a removable tow device locking system may also be inherent in the invention, without having been described above.