Abstract:
An apparatus for mounting to a truck suspension system which provides reinforcement to standard leaf spring suspensions in a manner that is adjustable and flexible. It provides improved weight distribution while allowing for additional vertical travel of the suspension system during periods of extreme shock loading. The apparatus mounts to the vehicle frame at a location behind the rear axle between the rear axle and rear attachment point of the leaf spring. The apparatus is both vertically and horizontally adjustable and provides an adjustable amount of reinforcement, thus allowing the operator the match the amount of reinforcement to the load. The apparatus can be fully disengaged after installation and selectively used thereafter without requiring removal and subsequent reinstallation. In the disengaged position, the apparatus has no effect on the suspension system of the host vehicle.

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates to the field of vehicle suspension systems and to the augmentation of vehicle suspension systems to enable heavy loading. Specifically, this invention relates to a new and useful attachment which provides for adjustable fortification of standard leaf spring suspension systems for heavy loading applications. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT STATEMENT 
     This invention was not developed in conjunction with any Federally sponsored contract. 
     MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The use of work vehicles continues to increase as best evidenced by continuing growth of pickup truck sales each year. Despite the continuing urbanization of America, the use of work vehicles commonly associated with rural populations continues to increase. Annual sales of half, three quarter, and one ton pickup trucks has never been higher. Pickup trucks are now commonly used in roles once reserved for passenger vehicles, ie., taking kids to school, going to the grocery store, driving to and from work, etc. However, these same “urbanized” work vehicles will often be used for the occasional work task and will be subjected to periodic heavy loading, often exceeding the design limits of the vehicle. 
     Since 1988 and the advent of “sport utility vehicles” (SUV), many car and truck manufacturers have used the same frame and suspension systems for their SUV&#39;s as used in their light and heavy duty pickup trucks. In many cases, the main difference between an SUV and a corresponding pickup truck is the body and interior trim. SUV&#39;s have become popular family vehicles, serving as a means to transport family members to work and school during the week, and serving as a hauling vehicle during the weekends for home projects. Additionally, some “mini-vans” are based upon a truck frame and suspension system, as well. 
     For the remainder of this disclosure, the term “pickup truck” or “truck” will be used to collectively refer to all vehicles based upon a pickup truck chassis. 
     As thoroughly described in the references included herein, an overloaded pickup truck whether carrying the load in the bed or on a trailer, will tend to drop in the rear and rise in the front. This indicates a drastically uneven weight distribution wherein the rear wheels carry most of the load, thus potentially compromising the driving characteristics, handling, and even safety of the vehicle. 
     U.S. Pat. No. 4,671,535 to Hanson, et al. shows an overload mechanism that includes and abutment structure rigidly mounted to the vehicle frame that, when engaged, contacts the leaf spring in a fixed location. This not only limits the travel of the leaf spring, but also acts to redistribute more of the load to the front wheels. 
     U.S. Pat. No. 5,172,930 to Boye et al. shows an overload mechanism basically very similar to that disclosed in the Hanson patent except the Boye apparatus is remotely engageable. This mechanism also limits the travel of the rear leaf springs and further acts to redistribute more of the load to the front wheels. 
     There are known devices which mount to a vehicle frame and engage the rear leaf springs in a fixed position. Each of the above referenced patents disclose abutment mechanisms that are relatively simple, mount between the rear axle and rear bumper, and provide improved weight distribution during overload conditions by effectively lengthening the vehicle wheelbase. The known devices also share the common shortfall that each is effectively non-adjustable. Once it is mounted to the frame, it will always contact the leaf spring in the same location, thereby providing a fixed limit to leaf spring travel. These mechanisms effectively provide a fixed amount of reinforcement. 
     The magnitude to which a vehicle is overloaded will likely vary greatly from load to load-such that one level of reinforcement is not adequate under many real loading conditions. For example, a vehicle used to pull a trailer one weekend might well be used to haul bags of cement the following weekend, then bales of hay the next. In another example, the inventor&#39;s recently issued U.S. Pat. No. 6,148,928 discloses a three point hitch system for mounting to and use with a pick up truck. Loadings applied during the use of this device will vary from application to application, thus the amount of suspension reinforcement needed will vary accordingly. 
     Therefor, there exits a need for a device which provides an adjustable amount of reinforcement for the rear suspension of Pickup trucks, SUV&#39;s and minivans. Additionally, there exists a need in the art for this system to be reliable, easily adjustable, and cost effective for mass production. 
     SUMMARY OF THE INVENTION 
     The system and method of the invention provide an apparatus that, when mounted to a vehicle frame and properly engaged, provides reinforcement to standard leaf spring suspension in a manner that is easily adjustable, and flexible, not rigid, thus providing both improved weight distribution while allowing for additional vertical travel of the suspension system during periods of extreme shock loading such as when an overloaded vehicle might pass over a large pot hole. 
     The apparatus mounts to the vehicle frame at a location behind the rear axle between the rear axle and rear attachment point of the leaf spring. The apparatus is both vertically and horizontally adjustable and provides an adjustable amount of reinforcement, thus allowing the operator the match the amount of reinforcement to the load. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The figures presented herein when taken in conjunction with the disclosure form a complete description of the invention. 
     FIG. 1 shows a side view of the preferred embodiment of the leaf spring overload support apparatus disclosed herein. 
     FIG. 2 shows a rear view of the preferred embodiment. 
     FIG. 3 shows a top view of the preferred embodiment. 
     FIG. 4 shows side views of the preferred embodiment in four different installed configurations. 
     FIG. 5 shows a side view of an alternative embodiment of the leaf spring overload support apparatus. 
     FIG. 6 shows a rear view of the alternative embodiment. 
     FIG. 7 shows a top view of the alternative embodiment. 
     FIG. 8 shows a front view including an alternative embodiment. 
     FIG. 9 shows a side view of a second alternative embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For purposes of description herein, the terms “front,” “side,” “top,” “rear,” “horizontal,” “vertical,” “fore,” “aft” and derivatives thereof shall relate to the invention as oriented in FIG. 4, thus the directive terms included above describe the views with respect to the host vehicle. Also, the terms frame and chassis are used interchangeably with respect to the host vehicle. 
     The overload support apparatus described herein is designed for use with a work vehicle, typically a pickup truck, and attaches to the frame aft of the rear axle. It is further designed to engage the upper surface of a leaf spring assembly wherein the point of engagement is adjustable. 
     Referring first to FIG. 1, the apparatus ( 100 ) is basically composed of mounting frame ( 18 ), fixed column member ( 5 ), adjustable column member ( 6 ), hitch pin ( 11 ), adjustable leaf ( 7 ), U-bolt ( 10 ), nuts ( 20 ) ( 21  not shown), upper plate ( 19 ), lower plate ( 9 ), and abutment pad ( 8 ). Mounting frame ( 18 ) is to be rigidly attached to the frame of a host vehicle by bolts placed through mounting holes ( 12 - 17 ). Mounting frame ( 18 ) includes six holes in order provide a likely match with at least three pre-existing holes per chassis member of the host vehicle. It is recommended that the apparatus ( 100 ) be firmly bolted to the chassis member by at least three bolts. Alternatively, mounting-frame ( 18 ) can be attached by continuous or spot welding or by rivets. If mounting by bolts, and holes in the chassis member do not exist, drilling will be necessary. 
     Spacers may be required for placement between mounting frame ( 18 ) and the frame of host vehicle to insure the overall apparatus is located directly over the leaf spring of host vehicle. Adjustable leaf ( 7 ) is held in a fixed position by U-bolt ( 10 ) which is further placed through concentrically located holes in upper plate ( 19 ) and lower plate ( 9 ). 
     As nuts ( 20 ,  21 ) on U-bolt ( 10 ) are tightened, upper and lower plates-( 19 ) and ( 9 ) respectively are compressed about adjustable leaf ( 7 ) thereby clamping and holding adjustable leaf ( 7 ) in a substantially fixed position. After loosening nuts ( 20 ,  21 ), adjustable leaf ( 7 ) can slide to the left or right thus effectively increasing or decreasing the available length. 
     Adjustable leaf ( 7 ), which is effectively a short leaf spring member, provides for limited vertical travel under heavy loading further providing a non-rigid contact between the overall support apparatus ( 100 ) and the leaf spring of host vehicle. 
     Upon extreme loading conditions such as a acute shock loads, the end of adjustable leaf ( 7 ) will yield and be deflected upward thereby dampening vertical displacement. As the effective length of adjustable leaf ( 7 ) is shortened, -ie., it is moved to the left in FIG. 1, the potential for vertical displacement of the end attached to abutment pad ( 8 ) is reduced thereby reducing the potential for dampening vertical displacement. 
     In a preferred embodiment, abutment pad ( 8 ) is made of a resilient material such as vulcanized rubber, Teflon(TM), or a variety of polymer-based compounds, and is attached to adjustable leaf ( 7 ) by a protruding finger portion ( 26 ) of abutment pad ( 8 ) inserted through a rectangular hole ( 25 , not shown) in adjustable leaf ( 7 ). 
     Referring to FIG. 3 , it is shown that fixed column member ( 5 ) has a substantially square vertical channel there through and adjustable column member ( 6 ), having a substantially square horizontal cross section, is slidably disposed therein. This drawing illustrates a preferred embodiment. However, the vertical opening in fixed column member ( 5 ) and the cross section of adjustable column member ( 6 ) need not be substantially square, but it is advisable that they both be substantially the same to insure a reasonably secure fit. 
     FIG. 3 illustrates hitch pin ( 11 ) placed through both fixed column-member ( 5 ) and adjustable column member ( 6 ) each having concentric holes sized to allow easy insertion and removal of hitch pin ( 11 ). Once inserted, hitch pin ( 11 ) may be held in place by a fastening means such as a cotter pin. 
     FIG. 3 further shows nuts ( 20 ,  21 ) fixed about U-bolt ( 10 ) above upper plate ( 19 ). 
     Referring now to FIG. 2 which shows a rear view of subject apparatus, it can be seen that adjustable column ( 6 ) has a plurality of horizontal holes ( 22 - 25 ) drilled there through (corresponding holes  22 ′- 25 ′ not shown). 
     Fixed column member ( 5 ) has a set of holes ( 27 / 27 ′) which align concentrically with said holes ( 22 - 25 ) and ( 22 ′- 25 ′) as adjustable column member ( 6 ) is moved up or down within fixed column member ( 5 ). The alignment of holes ( 27 / 27 ′) with either sets of holes ( 22 / 22 ,  23 / 23 ′,  24 / 24 ′, or  25 / 25 ′) allow the insertion of hitch pin ( 11 ) thereby fixing the vertical position of adjustable column member ( 6 ). These holes allow the vertical position of adjustable column ( 6 ) to be fixed in one of several available different positions. Four optional positions are provided in the preferred embodiment. As stated above, hitch pin ( 11 ) can be held in position by a cotter pin or other comparable attachment means. 
     Also according to the preferred embodiment and illustrated in FIG. 2, the mounting frame ( 18 ) is attached to fixed column member ( 5 ). The attachment means can be any that provides a rigid attachment of sufficient strength such a continuous weld around the perimeter of the interface. Likewise, upper plate ( 19 ) is substantially perpendicular with and rigidly attached to the lower end of adjustable column ( 6 ). The attachment means can be any that provides a rigid attachment of sufficient strength such as a continuous weld. 
     FIGS. 4 a ,  4   b ,  4   c , and  4   d  show four typical installation configurations. In each installed configuration, the overall assembly ( 100 ) is located between the axle assembly ( 30 ) and rear mounting point of leaf spring assembly ( 29 ), and mounting frame ( 18 ) is attached to chassis member ( 28 ) aft of axle housing assembly ( 30 ). 
     FIG. 4 a  shows an installed but disengaged configuration wherein mounting frame ( 18 ) is attached to vehicle chassis member ( 28 ), adjustable column member ( 6 ) is raised to the top position with hitch pin ( 11 ) inserted through holes ( 22 / 22 ′) in adjustable column member ( 6 ) and holes ( 27 / 27 ′) in fixed column member ( 5 ). Adjustable leaf ( 7 ) is in a fully extended position, but abutment pad ( 8 ) does not engage the leaf spring assembly ( 29 ) of host vehicle. 
     FIG. 4 b  shows an installed configuration wherein mounting frame ( 18 ) is attached to vehicle chassis member ( 28 ), hitch pin ( 11 ) is placed through holes ( 23 / 23 ′) in adjustable column member ( 6 ) and holes ( 27 / 27 ′) in fixed column member ( 5 ), adjustable leaf ( 7 ) is in a fully extended position, and abutment pad ( 8 ) is in firm contact with leaf spring assembly ( 29 ). This configuration will provide limited augmentation of the suspension system, maximum dampening of shock loads, and is recommended when only limited augmentation is required, ie., light loading. 
     FIG. 4 c  shows an installed configuration wherein mounting frame ( 18 ) is attached to chassis member ( 28 ) of host vehicle, hitch pin ( 11 ) is placed through holes ( 24 / 24 ′) in adjustable column member ( 6 ) and holes ( 27 / 27 ′) in fixed column member ( 5 ), adjustable leaf ( 7 ) is fixed in a position substantially halfway between fully extended and fully withdrawn, and abutment pad ( 8 ) is in fining contact with the leaf spring assembly ( 29 ) of host vehicle. This configuration will provide more suspension augmentation than FIG. 4 b  but will provide less dampening of shock loads as only approximately half of adjustable leaf ( 7 ) is allowed to flex. 
     FIG. 4 d  shows an installed configuration wherein mounting frame ( 18 ) is attached to chassis member ( 28 ) of host vehicle, hitch pin ( 11 ) is placed. through holes ( 25 / 25 ′) in adjustable column member ( 6 ) and holes ( 27 / 27 ′) in fixed column member ( 5 ), adjustable leaf ( 7 ) is fully withdrawn, and abutment pad ( 8 ) is in firm contact with leaf spring assembly ( 29 ). This configuration will provide maximum suspension augmentation with minimal dampening of shock loads. Regardless of the specific adjustment settings, ie., vertical position of adjustable column member ( 6 ) and horizontal position of adjustable leaf ( 7 ), the overall adjustments should be made and the apparatus positioned prior to any supplemental load being placed on the host vehicle. It may be advisable in certain situations to raise the rear of the host vehicle via bumperjack or other means thereby removing all loading prior to adjusting the apparatus to allow easier access to and adjustment of subject apparatus. 
     FIG. 5 shows a side view of an alternative embodiment of subject apparatus. Tightening nut ( 31 ) is located concentric to a hole placed through fixed column member ( 5 ) and rigidly attached by a continuous perimeter weld thereon. Alternative attachment means may be used. Tightening bolt ( 32 ) is shown adjustably disposed through tightening nut ( 31 ) so that the end of tightening bolt ( 32 ) extends into the interior of fixed column member ( 5 ) upon clockwise rotation. 
     FIG. 5 further shows an alternative abutment pad ( 34 ) embodiment wherein a molded pad fixed about adjustable leaf ( 7 ) is used. This embodiment prevents any holes placed through adjustable leaf ( 7 ), thus potentially compromising the structural strength thereof. 
     FIG. 5 also shows an alternative embodiment of the horizontal adjustment means of adjustable leaf ( 7 ) that includes alternative flat lower plate ( 35 ) held in place by bolts ( 36 ) and ( 37  not shown) and corresponding nuts ( 38 ) and ( 39  not shown). 
     FIG. 6 is a rear view of the alternative embodiment illustrated in FIG.  5 . FIG. 6 shows knurled area ( 33 ) on the rear surface of adjustable column member ( 6 ). The purpose of knurled area ( 33 ) is to insure a secure grip/connection between fixed column member ( 5 ) and adjustable column member ( 6 ) upon tightening of tightening bolt ( 32  not shown), thus eliminating the possibility of vertical slippage there through. 
     FIG. 6 provides an illustration of bolts ( 36 , 37 ) placed through flat lower plate ( 35 ) and upper plate ( 19 ) and held in place by nuts ( 38 , 39 ) respectively. 
     FIG. 6 also illustrates that in the alternative embodiment adjustable column member ( 6 ) contains no holes, nor does the rear surface of fixed column member ( 5 ). 
     FIG. 7 is a top view of the alternative embodiment described above showing tightening nut ( 31 ) attached to the front surface of fixed column member ( 5 ) and tightening bolt ( 32 ) disposed there through. FIG. 7 further shows abutment pad ( 34 ) molded over the top of adjustable leaf ( 7 ). 
     Continuing an illustration of the alternative embodiment, FIG. 8 shows a front view thereof. Most notably, FIG. 8 further illustrates that, in the alternative embodiment, adjustable column member ( 6 ) contains no lateral holes and the front surface of fixed column member ( 5 ) contains only one hole that disposed concentric to the axis of tightening bolt ( 32 ). 
     It should be further stated that features of the preferred and alternative embodiments are largely interchangeable. For example, as illustrated by FIG. 9, adjustable leaf spring ( 7 ) fitted with alternative abutment pad ( 34 ) could well be held in place by lower plate ( 9 ), U-bolt ( 10 ) and associated nuts ( 20 , 21 ). This configuration might further include alternative tightening bolt ( 31 ) and associated tightening nut ( 32 ) in lieu of the hitch pin configuration illustrated in FIGS. 1-4. 
     While the invention has been set forth in this disclosure with respect to the preferred embodiment, and in some cases optional embodiments have been set forth, it will be appreciated by those skilled in the art that there are many ways to implement the structural design of subject implement frame system without departing from the spirit and scope of the invention and disclosure herein. A specific example being the installation of two overload support apparatus on each side of a host vehicle (four in all), one in front of the axle housing and one behind. 
     The embodiments shown and described above are exemplary. Many details are found in the art, therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present invention have been shown in the drawings and accompanying text, the description is illustrative only, and changes may be made in the detail, especially in matters of size, shape and arrangement of parts within the principles of the invention to the full extent indicated by the broadest possible meaning of the terms of the attached claims. Further, not all details and features of the invention as disclosed must be adopted to realize the invention. The limits of the inventions and bounds of the patent protection are measured by and defined in the following claims.