Abstract:
A traction weight system comprised of a plurality of generally rectangular cast metal plates sized so as to be arranged in a variety of two dimensional arrays to comport with the dimensions of different vehicle cargo compartments, each plate having means to interlock that plate with those adjacent plates along or across their closely confronting edges. The plates may be interlocked by various means, including integral tongue and groove structures formed in each plate, or a series of aligned notches which may receive coupling pins. Each plate preferably has a height dimension substantially less than its width or length dimensions, so that the plates may be arranged across the floor or bed of the cargo compartment without interfering with the normal uses of that cargo compartment for storing or transporting cargo.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to traction weights for vehicles, and particularly to a system of interlocking plates which may be arranged in various arrays corresponding to the dimensions of different vehicle cargo compartments. 
     The benefits of increased traction and maneuverability in vehicles which are weighted on the drive wheels are well recognized. Both passenger vehicles and pickup trucks are aided in snow or winter conditions and over rough terrain by placing greater weight on the pair of wheels that provide drive power, or in the case of four wheel drive vehicles on all the wheels. 
     Recently, the introduction of front wheel drive in many front engine vehicles has provided this same result. In rear wheel drive cars and trucks, however, it is generally necessary to add additional weight in the rear cargo compartment above the rear axle. 
     People have used a number of different methods to weight their vehicles. One common step is to place bags of sand, salt, or gravel in the trunk or a car or cargo bed of a truck. The salt and sand can also be useful in freeing a vehicle which becomes stuck in the snow or on ice. Unfortunately, the bags may be easily ripped or punctured by many sharp edged items frequently carried in the vehicle cargo compartment, or will become saturated and deteriorate if carried in an open cargo bed. 
     In place of bags of sand, other people have used bricks or concrete blocks. While being more durable and easy to handle, such bricks or blocks are generally less dense than their bagged counterparts, and will generally shift around in the cargo compartment risking damage to the vehicle or other cargo. 
     There have been several attempts to design improved systems for adding traction weights to vehicle cargo compartments, predominantly for pickup or similar trucks having cargo beds. 
     U.S. Pat. No. 3,727,971 discloses a system of utility receptacle units which fit along the sidewalls of a truck&#39;s cargo bed, with a recessed region to accommodate the wheel well. These utility compartments may be filled with gravel to increase traction weight, and present less of a risk of puncture or spilling than do bags of similar substances. 
     U.S. Pat. No. 4,190,281 discloses a system of ballast containers which lock into place along the sidewalls of a truck bed, and may be filled with sand or a similar substance. These ballast containers are designed to fit between the wheel well and the vertical framing and cab wall, and are shaped to lock into place against a sidewall having a particular predetermined configuration. 
     While being improvements over the concept of using bags of sand or gravel, each of these systems has several common drawbacks. First, each utilizes some of the area of the truck bed which might otherwise be used for storing or transporting cargo. Second, each must be designed and sized to fit a particular type of cargo compartment, depending upon the shape of the sidewalls, placement and dimensions of the wheel wells, and the type of flooring used in the cargo bed. Third, once filled, these weights cannot be easily removed or repositioned without emptying the contents because of the great weight involved Finally, these weight systems would be impractical to use in the cargo compartment of a vehicle other than a pickup truck, such as the trunk of a passenger vehicle. 
     U.S. Pat. Nos. 3,944,252 and 4,094,534 disclose weight systems mountable on the exterior of a cargo compartment, particularly for the forward end of a tractor or other agricultural vehicle. The weights generally comprise cast metal plates which are removably mounted in a layered configuration on a bracket assembly. 
     While such a detachable weight system is necessary for the steerable front wheels of tractors and other equipment where a cargo compartment is not available, such systems would be neither practical nor workable in other types of vehicles. First, in most instances it is more important to place additional weight for traction over the drive wheels, and in trucks and passenger vehicles the engine provides sufficient weight over the steerable wheels. Second, it is not desirable to mount such weight systems outside the cargo compartment of either trucks or passenger vehicles. Besides being unattractive, such a mounting configuration greatly hampers the maneuverability of the vehicle by adding additional length or width where it is not within easy view of the driver, and similarly presents a danger to other vehicles. Finally, most trucks and passenger vehicles do not have the exposed frame members necessary to mount such weight systems in the rear of the vehicles where they would be most beneficial. 
     U.S. Pat. No. 4,482,169 discloses a traction rack for a rear wheel driven truck which is placed on the bed of the truck extending between the wheel wells, the rack holding a series of weights in position over the real axle. 
     While such a rack system would permit a slightly greater degree of flexibility in accommodating different sized truck beds and wheel well placements, it has several deficiencies. First, such a weight system is only practical to use with a truck cargo bed, and not in a passenger vehicle. Second, while permitting the weight to be focused above the rear axle, such a rack limits the total amount of weight that can be added to a vehicle to a predetermined total number of smaller weights. Third, the rack and weights together occupy the most valuable cargo storage area in the truck bed, directly between the wheel wells where the width of the truck bed is at a minimum. Fourth, because the rack and weights do not extend the full length of the truck bed, they present a hump extending across the width of the truck bed which interferes with placing larger items such as 4&#39;×8&#39;, panels flat within the truck bed. Finally, the system as disclosed makes the individual weights difficult to remove from the vehicle, either to adjust the weight or provide more cargo space when needed. 
     BRIEF SUMMARY OF THE INVENTION 
     It is therefore one object of this invention to design a system of interlocking weights which may be used with the cargo compartment of either a truck or passenger vehicle to increase traction. 
     It is related object of this invention to design the above weight system such that it may be easily configured so as to be used with cargo compartments of widely disparate dimensions, shapes, and constructions, and to be positioned around irregularly shaped structural features such as frame members or enclosed wheel wells. 
     It is additional object of this invention to design the above weight system such that it may be easily placed within, removed from, or repositioned within the cargo compartment of the vehicle. 
     It is yet another object of this invention to design the above weight system such that the individual weights will not shift within the cargo compartment, and will prevent damage to other cargo or the vehicle itself. 
     It is a distinct object of this invention to design the above weight system such that it will not disrupt the normal uses of the cargo compartment, particularly such that it will not interfere with the central area of the cargo bed or in storing or transporting lengthy objects. 
     Briefly described, the traction weight system of this invention is comprised of a plurality of generally rectangular cast metal plates or molded plastic plates with a hollow interior filled with sand or the like, the plates sized so as to be arranged in a variety of arrays extending in two dimensions to comport with the dimensions of different vehicle cargo compartments, each plate having means to interlock that plate with those adjacent plates along or across their closely confronting edges. The plates may be interlocked by various means, including integral tongue and groove structures formed in each plate, or a series of aligned notches which may receive coupling pins. Each plate preferably has a height substantially less than its width or length dimension, so that the plates may be arranged across the floor or bed of the cargo compartment without interfering with the normal uses of the cargo compartment for storing or transporting cargo. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the interlocking weight system of this invention partially arrayed in the cargo bed of a pickup truck; 
     FIG. 2 is a perspective view of a tongue and groove embodiment of the interlocking weight system of this invention; 
     FIG. 3 is a top plan view of the tongue and groove embodiment of the interlocking weight system of this invention shown in FIG. 2; 
     FIG. 4 is a front elevation view of the tongue and groove embodiment of the interlocking weight system of this invention shown in FIG. 2; 
     FIG. 5 is a side elevation view of the tongue and groove embodiment of the interlocking weight system of this invention shown in FIG. 2; 
     FIG. 6 is a rear perspective view of several interlocked weights of the tongue and groove embodiment shown in FIG. 2; 
     FIG. 7 is a cross sectional view of two of the interlocked weights of the tongue and groove embodiment shown in FIG. 2 taken through line 7--7 of FIG. 6; 
     FIG. 8 is a perspective view of the notch and coupling pin embodiment of the interlocking weight system of this invention; 
     FIG. 9 is a top view of several interlocked weights of the notch and coupling pin embodiment shown in FIG. 8; 
     FIG. 10a is a cross sectional view of two interlocking weights of the notch and coupling pin embodiment shown in FIG. 8 taken through line 10--10 in FIG. 9 with the coupling pin removed from the notches; 
     FIG. 10b is a cross sectional view of two interlocking weights of the notch and coupling pin embodiment shown in FIG. 8 taken through line 10--10 in FIG. 9 with the coupling pin inserted in the notches; and 
     FIG. 11 is a front elevation view of the symmetrical flange embodiment of the interlocking weight system of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The system of interlocking weights of this invention is shown in FIGS. 1-11 and referenced generally therein by the numeral 10. 
     Referring to FIG. 1, it may be seen that the interlocking weights 10 of this invention are designed to be arranged in an array or pattern within the cargo compartment 12 of a vehicle such as a pickup truck 14, although the interlocking weights 10 may be used with any type passenger vehicle as well. 
     The pickup truck 14 as shown in FIG. 1 has a rear cab wall 16, a pair of opposing sidewalls 18, and a truck bed 20 or floor which define the cargo compartment 12. The pickup truck 14 may also include a rear tailgate (not shown) which would be pivotably attached near the rear edge 22 of the truck bed 20. The cargo compartment 12 has a height H, a width W measured between the interior surfaces of the sidewalls 18, and a length L measured between the rear cab wall 16 and the rear edge 22 of the truck bed 20. 
     Referring to FIGS. 2-5, a tongue and groove embodiment of the interlocking weight system 10 is shown. Each weight 24 is constructed from a cast plate of dense metal such as steel or may be a plate comprised of a heavy duty hollow plastic container filled with sand or the like, and has a height h which is substantially less than the width w or length l of the weight 24. 
     Extending along the lengthwise edges 26 of each weight 24 and spaced apart from those edges 26 and generally parallel thereto are a pair of tongue members 28 spaced apart from the side edges 26 be a groove 30. The height of each tongue member 28 is less than the height h of the weight 24, but is generally equal to the depth of the groove measured from the top surface 32 of the weight 24. The width of each tongue member 28 is similarly generally equal to or slightly less than the width of the groove 30, such that the tongue member 28 of one weight 24 can be inserted into and engagingly received within one of the corresponding grooves 30 of another like weight 24, with the top surfaces 32 and bottom surfaces 34 of each weight 24 being substantially coplanar, and with the side edges 26 of each weight 24 being maintained in close and confronting edgewise contact as shown in FIG. 6. A portion of the flange member 28 of each weight 24 is engagingly and removably received within the groove 30 of a like weight 24, and vice versa, such that a portion of each flange member 28 if each weight 24 is disposed between the flange member 28 and the side edge 26 of the like weight 24 to which the weight 24 is connected along its side edges 26. 
     Extending from and centered along the front face 36 of each weight 24, and spaced apart from that front face 36 generally parallel thereto and coplanar with the top surface 32, is a front tongue member 38 which extends over approximately one third the width w of the weight 24. The front tongue member 38 is separated from the front face 36 by a front gap 40 similar to the grooves 30 separating the tongue members 28 from the side edges 26 of the weight 24. The rear face 42 and top surface 32 of each weight 24 define a rear channel 44 having a width substantially equal to or slightly greater than the width of the front tongue member 38 such that the front tongue member 38 can be received within the rear channel 44. The rear channel 44 is comprised of a rear wall member 46 having a height equal to the depth of the front gap 40 measured from the bottom surface 34 of the weight 24 and a thickness equal to or slightly less than the thickness of the front gap 40, and a recessed region 48 having a depth equal to the height of the front tongue member 38 and a thickness equal to or slightly greater than the front tongue member 38. The front tongue member 38 may be inserted into and engagingly received within the corresponding rear channel 44 of another like weight 24 such that the rear wall member 46 is received within the front gap 40, the top surfaces 32 and bottom surfaces 34 of each weight 24 being substantially coplanar, and with the opposing front face 36 and rear face 42 of the weights 24 being maintained in close and confronting edgewise contact, as shown in FIGS. 6 and 7. 
     Referring to FIGS. 8-10, a notch and coupling pin embodiment of the system of interlocking weights 10 is shown. Each weight 50 similarly has a height h which is substantially less than the width w or length l of the weight 50, each weight 50 having a pair of opposing side edges 52 and a pair of opposing end edges 54, a top surface 56, and a bottom surface 58. Centered along each side edge 52 and end edge 54, and defined by said edges 52, 54 and said top surface 56 is a notch 60 recessed a predetermined depth from said top surface 56, each weight 50 further defining four bores 62 each extending generally perpendicular to the top surface 56 and at least partially through said weight 50 corresponding to and communicating with the notches 60, each said bore 62 being positioned in substantially the same and uniform relationship with the corresponding notch 60 as the remaining bores 62 and notches 60. 
     While it is contemplated that for ease of use and construction, each notch 60 can be made to have a rectangular configuration with each bore 62 having a circular cross section and being centered within the rectangular notch 60, the notches 60 and bores 62 may be given any suitable shape or cross section, and may be positioned in any manner relative to one another, which permits the weights 50 to be interlocked as described below. 
     Referring again to FIG. 8-10, it may seem that a U-shaped coupling pin 64 having a central bridge portion 66 and a first and second depending legs 68 extending perpendicularly therefrom may be inserted into and received within a pair of aligned and opposing notches 60 and bores 62 of two closely confronting side edges 52 or end edges 54 of two like weights 50, thereby permitting a plurality of weights 50 to be interlocked in a generally coplanar array. The central bridge portion 66 should have a thickness less than the depth of the recessed portions of the notches 60 so that no portion of the coupling pin 64 will extend above the top surface 56 of the weights 50 when the leg segments 68 are inserted in the adjacent and confronting bores 62. 
     Referring to FIG. 11, a symmetrical flange embodiment of the interlocking weight system 10 of this invention is shown. The symmetrical flange embodiment 70 is similar to the tongue and groove embodiment 20 described above and shown in FIGS. 3-7, however, the symmetrical flange embodiment 70 differs in that each weight 70 is constructed so as to have a depending flange 72 separated from the side edge 74 of the weight 70 by a groove 76. The height of each flange 72 measured from the top face 78 of the weight 70 is equal to the depth of the groove 76 measured from the bottom face 80 of the weight 70, with the thickness of each flange 72 being substantially equal to or slightly less than the width of each groove 76 of like weights 70 so as to be slidably and engagingly received within the groove 76 of a like weight 70 when that like weight 70 is inverted and placed adjacent to and closely confronting the first weight 70. In this manner, several weights 70 may be alternatingly inverted and interconnected to form an array within a cargo compartment 12. In such an embodiment having symmetrical weights 70 which are alternatingly inverted, individual weights 70 are preferably only added to or subtracted from the array along the borders of the array, thereby mitigating against the user having to lift a plurality of weights 70 at one time. 
     It is understood that the interlocking weight system 10 of this invention may be formed in a variety of manners wherein the weights 10 are interconnected along vertical planes of separation, rather than horizontal planes of separation as described above in connection with the tongue and groove embodiment 20 or symmetrical flange embodiment 70. In the case where the planes of separation are completely vertical, as in a jigsaw puzzle, each weight 10 should have a generally uniform shape such that an infinite repeating pattern having two directions of extent corresponding to the length and width dimensions of each plate may be formed. In such an embodiment, each edge 26, 36, 42 of the weight 10 should define a path having both convex and concave portions of generally the same shape as the corresponding and confronting edges 26, 36, 42 of the like weight 10 so that the rear edge 42 of the weight 10 may be slidingly and removably engaged by the front edge 36 of the like weight 10, the front edge 36 of the weight 10 may be slidingly and removably engaged by the rear edge 42 of the like weight 10, and each one of the side edges 26 of the weight 10 may be slidingly and removably engaged by the opposing and confronting side edge 26 of the like weight 10. 
     It should be understood that all the shown forms of my invention can be formed as hollow heavy duty plastic containers filled with sand or the like and that such variations can comprise the shown plates and are within the purview of the invention. 
     In operation, a person may arrange a plurality of weights 10 within a cargo compartment 12 in an array which has two linear directions of extent, with those directions generally corresponding to the length L and width W dimensions of the cargo compartment 12. These linear directions of extent need not be perpendicular, however in most cargo compartments a generally perpendicular array will be preferred, with each weight 10 being interconnected within the array along at least two edges, preferably a side and an end edge, with certain weights 10 along the border of the array being interconnected along three edges, and with weights 10 in the central portions of the array being interconnected along four edges. 
     The weights 10 are individually interconnected, and may be individually disconnected for removal from the cargo compartment 12. To interconnect the weights 10, each weight 10 is placed adjacent to and closely confronting an opposing weight 10. In the case of the tongue and groove embodiment 24, one weight 24 having a tongue member 28, 38 which will be inserted into a corresponding groove 30 or channel 44 is generally raised above the top surface 32 of the adjacent weight 24, with the edges 26 moved into close vertical alignment, with the tongue members 28, 38 being engagingly received within the corresponding groove 30 or channel 44 when the one weight is lowered and the weights 24 are brought into coplanar horizontal alignment. In the case of the notch and coupling pin embodiment 50, each weight 50 is placed in close confronting edgewise contact with one or more similar weights 50 in an array, with the notches 60 along the confronting edges 52, 54 being generally aligned, with the depending legs 68 of a coupling pin 64 being inserted within each of the bores 62 of the adjacent notches 62 so as to interconnect the weights 50. 
     In this manner, the weights 10 may be interconnected into one or more generally coplanar patterns or arrays which may be extended indefinitely in either of two linear lengthwise or widthwise directions within a cargo compartment 12 of a vehicle 14. 
     While the preferred embodiments of the interlocking weights system 10 of this invention have been disclosed above with reference to the attached drawing figures, it is understood that certain modifications and changes may be made in the construction and operation of the system of interlocking weights 10 without departing from the spirit and scope of the appended claims.