Abstract:
An equipment rack incorporating four linked members which mount an equipment rack support to a hitch insert. The linked members are formed by two pairs of pivotally linked arms which in turn are pivotally inked to the hitch insert and to an equipment rack mounting bracket. Each pair of linked arms provides three pivot bearings which have mutually parallel axes. In the collapsed position the linked arms making up each pair are parallel and the equipment rack support and hitch insert are in juxtaposition. In the extended position the arms making up each pair are substantially co-linear. A mechanical link locks the rack support to the hitch insert when the rack is retracted against the rear of the vehicle.

Description:
This application is a continuation of Ser. No. 09/115,979 filed Jul. 15, 1998 now U.S. Pat. No. 6,085,954. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to bicycle racks and other equipment carriers which mount to a trailer hitch at the rear of a vehicle. 
     BACKGROUND OF THE INVENTION 
     The development of equipment racks, particularly bike racks which mount bikes or other recreational equipment to the exterior of an automobile has undergone a number of evolutionary steps. There are in general three general types of racks: roof racks, trunk racks, and hitch racks. Recently hitch racks, that is equipment carriers that mount to a trailer hitch at the rear of a vehicle, have become more popular. This popularity is related to the rise of the sport utility vehicle and the wide use of trucks for urban passenger vehicles. Whereas in the past a trailer hitch was a fairly specialized item normally only purchased by those with a trailer to pull, now a wide variety of vehicles come with trailer hitches as standard equipment or as part of a package of options. 
     A rack which attaches to a trailer hitch has many advantages. A trailer hitch provides a standard interface designed to support substantial loads. Installing and removing a rack from a trailer hitch is normally simpler then mounting a carrier directly to a vehicle. A stronger equipment rack, capable of carrying a larger number of bikes or other equipment, is more easily accommodated by a rack mounted to a hitch which is designed to support substantial hitch loads. The rack is also located at the rear of the vehicle where aerodynamic drag is not affected by the presence of additional equipment by virtue of being positioned in the turbulent wake region behind a vehicle. 
     One problem with a rack or cargo carrier which mounts to a trailer hitch at the rear of a vehicle is that the rack may prevent access to the rear door of the vehicle. Although some racks may be designed to pivot away from the rear door, if the rack is supporting a substantial weight in equipment, the bikes or other cargo must be unloaded before the cargo rack is tilted to gain access to the rear of the vehicle. Several existing devices have employed springs or gas shock to balance the weight of equipment particularly bikes, to allow the loaded rack to be pivoted downwardly away from the rear door. However if the rack is unloaded it now becomes difficult to pivot because the force of the spring or gas shock must be overcome. In some circumstances considerable force must be exerted on the rack at the same time that a latch or release must be actuated. This results in needing a combination of strength and dexterity to move the rack towards or away from its carrying position behind the vehicle. 
     The usefulness of a cargo rack increases as the simplicity and ease of use increases. Potential purchasers of cargo racks for use with trailer hitch mounts behind vehicles are typically concerned not only with simplicity and ease of use but cost and durability. 
     What is needed is a mechanism for mounting an equipment rack to a trailer hitch which provides access to the rear of the vehicle and in which movement of the rack is not significantly affected by whether the rack is supporting equipment or is empty. 
     SUMMARY OF THE INVENTION 
     The equipment rack of this invention incorporates four linked members which mount an equipment rack support to a hitch insert. The linked members are formed by two pairs of pivotally linked arms which in turn are pivotally linked to the hitch insert and to an equipment rack mounting bracket. Each pair of linked arms provides three pivot bearings which have mutually parallel axes, the entire rack mechanism thus incorporates six pivot axes. The individual arms are constructed of torsionally stiff members. In the collapsed position the linked arms making up each pair are parallel and the equipment rack support and hitch insert are in juxtaposition. In the rearwardly extended position the arms making up each pair are substantially co-linear. As the equipment rack rotates to one side of the vehicle the arms assumed a bend but extended configuration. The equipment rack support and hitch insert are separated by a distance approximately equal to twice the length of an individual arm. 
     Each pivot bearing which attaches an arm to the rack support or the hitch insert is formed between structural extensions from the arms which overlie the arms and the rack support or hitch insert. These structural extensions prevent interference between the arms and the hitch insert and rack support when the arms pivot with respect to them. Similarly structural extensions extend from one of each pair of arms and overlie the connected arms to allow the arms to pivot without interference. For greater rigidity between the rack support and the hitch insert a mechanical link which locks the rack support to the hitch insert is provided when the linked members position the rack support and hitch insert in juxtaposition. Maximum rigidity is only required while the vehicle is in actual motion and the rack is retracted against the rear of the vehicle. 
     It is an object of the present invention to provide a mechanism for mounting an equipment rack to a vehicle trailer hitch which allows access to the rear door of the vehicle. 
     It is a further object of the present invention to provide a means for moving a loaded or empty rack away from the rear of a vehicle to gain access to the rear of the vehicle without the necessity of applying significant force. 
     Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of the rack extending mechanism of this invention. 
     FIG. 2 is a top plan view of the rear of a vehicle showing the rack extending mechanism in its collapsed position. 
     FIG. 3 is a top plan view of the rack mechanism of FIG. 2 partly extended to the rear of the vehicle. 
     FIG. 4 is a top plan view of the rear of the vehicle showing the rack extending mechanism of FIG. 3 completely extended and rotated to one side of the vehicle. 
     FIG. 5 is an isometric view of an alternative embodiment of the rack extending mechanism of this invention. 
     FIG. 6 is a cross-sectional view of the rack extending mechanism of FIG. 5 taken along section line  6 — 6 . 
     FIG. 7 is a partly exploded isometric view of an alternative rack extending mechanism of invention. 
     FIG. 8 is a side elevational view of the rack extending mechanism of FIG. 7 showing motion of the mechanism as it moves towards a locked position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to FIGS. 1-8 wherein like numbers refer to similar parts a bike rack extension mechanism  20  is shown in FIG.  5 . The rack extension mechanism  20  is composed of a hitch mounting bracket  22  which has a square cross-section tube  38  and which is received in a trailer hitch  24 , and a rack mounting bracket  26  joined by four linked arms  28 . Two of the arms  28  are pivotally linked to form two linked pairs  30 . The linked pairs of arms  30  are pivotally connected at either end between the hitch mounting bracket  22  and the rack mounting bracket  26 . 
     The rack mounting bracket  26  incorporates a square tube section  32  and a pair of upstanding flanges  34  to which an equipment carrying rack may be connected. A strap  36  connects the upstanding flanges  34  to the square tube section  38  of the hitch mounting bracket  22 . The strap  36  forms a lock  40  which, by means of a bolt  42 , connects the strap  36  to the hitch mounting bracket  22  when the hitch mounting bracket  22  and the rack mounting bracket  26  are in juxtaposition. The lock  40  has two conditions, the first where the lip  43  of the strap  36  engages an interlocking projection  45  on the hitch mounting bracket  22 . The second is when the bolt  42  engages threads in the mounting bracket  22  securely joining strap  36  to the mounting bracket  22 . The arms  28  are formed of structural steel C-channels in order to provide torsional and bending stiffness to support the weight of bikes or other equipment which is mounted to the rack mounting bracket  26 . 
     Bearing mechanisms  44 , best shown in FIG. 6, provide for rotation of the arms  28  with respect to each other and the hitch mounting bracket  22  and the rack mounting bracket  26 . Each bearing mechanism  44  incorporates two bearings  46  formed between upper bearing extension plates  48  and upper surfaces  50  of the C-channel and lower bearing plates  52  and lower surfaces  54  of the C-channel. The vertically arrayed bearings  46  form a bearing axis coincident with the bearing bolt  56  which joins the arms  28  to each other and the hitch mounting bracket  22  and the rack mounting bracket  26 . Bolt sleeves  57  prevent localized crushing or excessive loading of the C-section, thus preventing the upper surfaces  50  from being forced by tightening of the nuts  59  toward the lower surfaces  54 . 
     The spaced apart bearings  46  form stiff mechanical joints which, in combination with the structural section making up the arms  28 , provide the structural strength to support a substantial load of up to several hundred pounds. The stiffness of a structural element in bending is a combination of its sectional modulus and the length of the element and how it is supported. The overall stiffness of the arms  28  and the bearings  46  is accomplished by a combination of using a stiff structural cross-section to form the arms and short extensions formed by bearing plates  48  which are rigidly mounted to one arm  28  and have structural bosses  58  which reinforce the bearings  46 . 
     Another rack extension mechanism  60  of this invention is shown in FIG.  1 . The rack extension mechanism is positioned between a rear bumper  62  of a vehicle  63  and a bicycle rack  64 . The rack extension mechanism  60  is has arms  66  which are constructed from square tube sections  68  to maximize arm stiffness, in particular torsional stiffness. The rack extension mechanism  60  has a hitch mounting bracket  70  and an equipment mounting bracket  72  which are joined by pairs  74  of arms  66 . The six bearings which join the arms  66  to the hitch mounting bracket  70  and the equipment mounting bracket  72  are formed by upper plates  76  and lower plates  78  which extend from the arms  66  to overlap adjacent structural sections. The plates  76 ,  78  form bearings with bearing bolts  80  and the structural section through which the bolts pass. The structural section through which the bearing is mounted is supported by a bearing sleeve  82 . 
     The rack extension mechanism  60 , as shown in FIGS. 1-4, has a first arm  84  which is pinned to the right side of the hitch mounting bracket. When the rack extension  60  is in its retracted position the first arm  84  extends substantially perpendicular to the hitch mounting bracket  70 . A second arm  86  has two sets of plates  76 ,  78 . One set extends perpendicular to the second arm  86  to join the second arm to the first arm  84 . Another set of plates  76 ,  78  extends parallel to the second arm  86  and joins the second arm to the equipment support bracket  72 . The second arm  86  is substantially parallel to the first arm  84  when the extension mechanism  60  is in its retracted position as shown in FIG. 3. A third arm  88  and fourth arm  90  are arranged opposite and in mirror symmetry to the first and second arms  84 ,  86 . 
     The bike rack  64  is attached by bolts or pins (not shown) to support flanges  92  which are bolted or welded to the rack mounting bracket  72 . The bike rack has a long vertically extending section  94  and a shorter horizontal section  96  to which bike support brackets are mounted. 
     A fully loaded rack  64  produces a moment arm which acts to twist the arms  66 . This moment produced by the weight of the equipment supported on the rack is best countered by a structural connection  99  which is anchored to the hitch mounting bracket  70  and which extends to a point  100  on the equipment support bracket  72  which is elevated above a horizontal plane containing the portion  102  of the equipment support bracket  72  which abuts the hitch mounting bracket  70 . The rack extension mechanism  60  not only allows the equipment rack to be extended to the rear of a vehicle but also allows the equipment rack to be rotated about the bearings between the arms and the hitch mounting bracket  70  and the bearings between the arms and the equipment mounting bracket  72 . 
     The balanced nature of the rack extension mechanisms  20 ,  60  of this invention will generally allow the bike rack  64  or other equipment rack to be positioned, even when loaded, without requiring pins or locking mechanisms. 
     The rack extension mechanisms  20 ,  60  will typically provide an extension of the rack mounting bracket  26 ,  72  of about 16 inches or however much is necessary to allow the rear door or doors of a vehicle to be opened. Thus the individual arms  28 ,  66  will be about 8 inches long. 
     The rack extension mechanism  20 ,  60  will typically be installed in a rear trailer hitch in a collapsed and lock condition. Bikes  104  are then mounted to the rack  64 . If access to the rear of the vehicle  63  is desired the structural connection  99  is unlocked releasing the equipment mounting bracket  72  from the hitch mounting bracket  70 . The loaded rack  64  may then be pulled to the rear and/or to the side of the vehicle  63  as shown in FIGS. 3 and 4. The unique construction of the extension mechanism  20 ,  60  with the pairs of linked arms results in a stiff structure which deflects little under the load of the bikes  104 , is compact when collapsed, and allows placement of the bikes anyway within a circle defined by the link arms. 
     A further embodiment rack extension mechanism  120  is shown in FIG.  7 . The extension mechanism  120  includes a hitch attachment bracket  122  and a rack mounting bracket  126 . Four linked arms  128  connect the hitch attachment bracket  122  to the rack mounting bracket  126  in a manner similar to that employed in the rack extension mechanism  20  shown in FIG.  5  and in the rack extension mechanism  60  shown in FIGS.  1 - 4 . 
     The rack mounting bracket  126  incorporates a metal stamping  129  which is welded to a bracket  134  to which an equipment carrying rack  135  is connected. The bracket  129  forms a first and a second spaced apart pivot attachment portions through which bearing pins  156  may be placed to connect arms  128 . The bracket wraps around the tubular base of the carrying rack  135 . Protrusions  137  extend inwardly from the tubular portion at the bottom  139  of the rack  135  within the bracket  134 . A bolt  141  locks the rack  135  to the bracket  134 . 
     A locking hasp  143  is pivotally mounted by a bolt  145  to the bracket  134 . The locking hasp  143  has a catch surface  147  which engages the back side  149  of a second metal stamping  151  which is welded to the square tube section  153  of the hitch attachment bracket  122 . The metal stamping  151  is identical to the metal stamping  129  and likewise forms a first and a second spaced apart pivot attachment portions through which bearing pins  156  may be placed to connect arms  128 . As shown in FIG. 8, collapsing the rack extension mechanism  120  brings the rack mounting bracket  126  into juxtaposition with the hitch attachment bracket  122 , with the result that the hasp  143  slides over the top of the metal stamping  129 . The weight of the hasp  143  latches the rack mounting bracket  126  to the hitch attachment bracket  122 . A secondary latch is formed by a T-bolt  155  which is attached to the tube section  153  by a metal strap  157 . The T-bolt passes through a slot  162  in an upwardly facing flange  159  which connects the sides  161  of the hasp  143 . A handle  163  is threaded onto the T-bolt and engages the flange  159  to draw the flange towards the tubular section  153 . The bolt  145  acts as a fulcrum and the upwardly facing flange  159  acts as a lever arm which applies mechanical advantage to the catch surfaces  147  which draws the metal structures  129 ,  157  together. 
     A load path which extends from a portion of the rack mounting bracket above the plane containing the arms  128  and extending downward to the tube section  153  where the metal strap  157  is mounted, provides a means to counteract the bending load imposed on the rack extension mechanism  120  by the weight of bikes or other equipment which is attached to the equipment carrying rack  135 . 
     The arms  128  are formed of structural steel square section in order to provide torsional and bending stiffness to support the weight of bikes or other equipment which is mounted to the equipment carrying rack  135 . 
     Bearing mechanisms  144 , best shown in FIG. 7, provide for rotation of the arms  128  with respect to each other and the hitch mounting bracket  122  and the rack mounting bracket  126 . Each bearing mechanism  144  incorporates two bearings  146  formed between upper bearing extension plates  148  and upper surfaces  150  of the square arm sections and lower bearing plates  152  and lower surfaces  154  of the square section. The bearing plates  148 ,  152  may be formed as metal stampings and are welded to the arms  128  which do not receive the pins  156 . Washers  160 , which are constructed of low friction material such as TEFLON® plastic or other plastic, or sintered metal are positioned between the extension plates  148 ,  152  and the upper surfaces  150  to reduce bearing friction. One or two washers may be used to form each bearing  146 . 
     The vertically arrayed bearings  146  form a bearing axis coincident with the bearing pins  156  which join the arms  128  to each other and the hitch mounting bracket  122  and the rack mounting bracket  126 . Bolt sleeves are not necessary if the joints between the arms are pinned together as shown in FIG.  7 . 
     It should be understood that the arms  28 ,  66 ,  128  can be constructed of any structural section such as a I-beam, Square section, or C-channel, which has a cross-section with a high moment of inertia relative to the section weight so that on a pound to pound comparison the structural member has a high bending and torsional stiffness. Simple solid structural sections such as bars have insufficient bending stiffness or too high a sectional weight. 
     It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.