Abstract:
A kit for raising and increasing wheel torque of an off road four wheel vehicle comprising four portal boxes, each portal box being associated with an individual one of the vehicle wheels, the portal boxes enclosing identical gear sets and associated bearings, each portal box being adapted to receive the output of an axle constant velocity joint and having an output shaft projecting therefrom, a set of four metal backing plates for joining the portal boxes to the suspension arms of the vehicle, the backing plates being substantially identical, the backing plates each having inwardly extending mounting brackets for attaching to upper and lower suspension arm parts.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a novel portal box construction for use in light off road vehicles. 
     PRIOR ART 
     Off road vehicles in the form of ATV&#39;s (all-terrain vehicles) and UTV&#39;s (utility task vehicles) are produced by numerous manufacturers. Purchasers and users of these vehicles frequently desire to fit them with larger tires to give them greater agility in traversing rough terrain. To fit larger tires on these vehicles, it is common to install a lift kit to raise the vehicle body to make room for the larger tires and to increase ground clearance. Typically, a lift kit will adversely affect constant velocity (CV) joint angles and necessitate replacement of the original equipment axles, including CV joints. Even with these upgrades, steering geometry can be compromised and bump steer, for example, can be introduced. Still further, the final drive ratio measured as available force at the thread surface of the oversize tires is reduced in proportion to the size increase. The foregoing reveals a need for an aftermarket system to mount oversize wheels on off road vehicles that avoids the disadvantage of ordinary lift kits. 
     SUMMARY OF THE INVENTION 
     The invention provides a portal box system for light off road vehicles that is simple, low in cost, and readily adapted for use on vehicles of different manufacturers. The disclosed portal box system comprises a universal backing plate and a narrow profile two-part housing in which is mounted a torque and height increasing gear train. The same backing plate with proper brackets attached can be used at all four wheels of a specific vehicle and with different sets of brackets on several different vehicles. The same left and right housings are used for front and rear wheels of a vehicle to which the system is applied. The same gear train can be used at all of the wheels and only the input gear may be modified to suit a particular brand of vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a light off road vehicle to which the invention is applied; 
         FIG. 2  is a somewhat schematic exploded isometric view of a portal box system employing the invention; 
         FIG. 3  is a somewhat schematic cross-sectional view at one axle of a portal box system constructed in accordance with the invention; 
         FIG. 4  is a fragmentary perspective view of a left front axle and suspension arms of the vehicle of  FIG. 1  on which is assembled a backing plate and associated suspension mounting brackets; and 
         FIG. 5  is a view similar to  FIG. 4  of the left rear axle, associated backing plate and corresponding mounting brackets. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention is useful in lifting the chassis and increasing the wheel torque of light off road four-wheel drive vehicles such as the UTV illustrated in  FIG. 1 . The illustrated vehicle is originally manufactured by John Deere and marketed as a Model RSX 850i. It will be appreciated by those skilled in the art that the invention is applicable to vehicles of other manufacturers. 
     The invention provides a portal box system, available as a kit, that replaces a vehicle&#39;s original wheel hub assemblies. The kit can include four portal boxes  10  and associated backing plates  11 .  FIGS. 2 and 3  illustrate a typical portal box  10  and backing plate  11 . The backing plate  11  at each wheel  12  ( FIG. 1 ) can be identical or essentially identical. Each backing plate  11  is provided with upper and lower mounting brackets  16 ,  17 . Preferably, the backing plate  11  is a steel plate, for example, 1/4  inch thick. The brackets  16 ,  17 , made of 1/2  inch steel plate, for example, are attached to the plate  11  preferably by welding. 
     Referring to  FIG. 4 , the upper bracket  16  can have a hole  18  for attaching an upper ball joint  19  and a hole  20  ( FIG. 2 ) for attaching a steering rod end  21 . Similarly, the lower bracket  17  has a hole  22  for securing a lower ball joint stud  23 . 
     Referring to  FIG. 5 , at a rear axle, an upper bracket  26  has a hole  27  for receiving an upper ball joint stud  28  and a lower bracket  29  has a hole for receiving a lower ball joint stud. A third bracket  31  welded to the backing plate  11  receives the stud of a rod end of a track bar  32 . 
     The backing plate  11  and associated mounting brackets are preferably planar elements cut or stamped from steel plate. It will be seen that the backing plate  11 , which has four major perimeter edges that lie in a common imaginary rectangle, can be reversed side-for-side to serve both sides of the vehicle  15 . The backing plate  11  has the same orientation on each side of the vehicle  15 . Similarly, the mounting brackets  16 ,  17 ,  26 ,  29  and  31  can be reversed when they are attached to a respective backing plate  11  to serve the opposite side of the vehicle  15 . 
     A large clearance hole  36  is cut in the backing plate  11  for the output shaft of the CV joint of the vehicle&#39;s axle or half shaft. A small clearance hole  37  is provided in the backing plate  11  for access to a lubricant fill plug in an inboard face of the portal box  10 . Four spaced portal box mounting bolt holes  38  are provided about the periphery of the plate  11 . 
     The portal box housing comprises a case  41  and a cover  42 . Preferably, both the case  41  and cover  42  are machined metal bodies, preferably of high strength  6061  aluminum. The illustrated case  41  is machined from a solid block of spaced aluminum; alternatively, the case can be cast or forged to a rough configuration, and then finish machined. The case  41  has a rear or inboard main wall  43  and an integral peripheral wall  44 . A face  45  of the peripheral wall  44  lies in a plane parallel to the plane of the main wall  43 . The peripheral wall  44  forms a space for receiving meshed spur gears  46 - 48 . Circular recesses  51 ,  52  are formed in an inside face of the case wall  43  to receive and support bearings  53 ,  54  that rotationally support respective gears  46 - 48 . A recess and bearing for a gear  47  exists in the wall  43  but it is not seen in the plane of  FIG. 3 . An aperture  56  in the case wall  43  receives the CV output shaft  57  of an associated axle. The peripheral wall  44  has a set of through holes  58  alignable with the mounting holes  38  in the backing plate  11 . Internally threaded holes  59  are provided in the peripheral wall  44  at mid-height. All of the holes  58 ,  59  have an integral concentric boss  60  extending outwardly of the peripheral wall face  45 . 
     The cover  42  is a flat plate proportioned to mate with the face  45  of the peripheral case wall  44 . The cover has holes  62  that fit closely over the bosses  60  and thereby register the cover with the case  41 . An inside face of the cover  42  is machined with recesses ( FIG. 3 ) to receive and support bearings  66 ,  67  in alignment with the recesses  51 ,  52  in the case wall  43 . The recess for the bearing of the gear  47  is not seen in the plane of  FIG. 3 . At an upper region, the cover  42  has a clearance hole  68  for receiving the outboard end of the CV shaft  57 . Tapped holes  69  for screws (not shown) hold a cap  70  over the hole  68 . A clearance hole  71  in the cover  42  concentric with the bearing recess  67  allows passage of an output shaft  72 . At its outer face, the cover  42  is provided with an elongated recess  73  for receiving a brake caliper bracket ( FIG. 2 ). The bracket  74  has holes  75  that align with two of the holes  62  in the cover  42  and one of the holes  38  in the backing plate  11 . 
     The upper gear  46  is the input gear to the gear train or set. The gear  46  has an internal spline cut to match the exterior spline on the CV output shaft  57  of the vehicle  5 . The gear  46  has integral hollow stub shafts  77  on both of its sides. The stub shafts  77  are supported in bearings  53 . An idler gear  47  has coaxial stub shafts  78  (only one is seen in  FIG. 2 ) supported in bearings in the case wall  43  and cover  42 . The output gear  48  is internally splined and fits on an external spline of the output shaft  72 . The output shaft is rotationally supported in the bearings  54 , supported in the case wall  43  and cover  42 . It will be seen that the centers of the input gear  46  and output shaft  72  are vertically aligned so that a wheel  12  mounted on the output shaft is dropped vertically from the original vehicle axle represented by the CV output shaft  57 . Moreover, the pitch diameter of the output gear  48  is substantially larger than the input gear  46  so as to multiply the torque available at the output shaft  72 . 
     The cover  42 , case  41 , and backing plate  11  are held together by bolts  81  assembled through respective holes in these components. Commercially available seals (not shown) are provided at the case wall aperture  56  and the cover hole  71  to exclude dirt, dust, and to contain lubricant within the case  41 . A gasket is provided between the cover  42  and case face  45 ; similarly, a gasket is provided between the cap  70  and cover  42 . An internally splined wheel hub  82  is retained on an external spline of the output shaft  72  by a nut  83  threaded on the distal end of the output shaft. 
     The portal boxes  10  on the left front and left rear axles are identical; the front and rear portal boxes  10  on the right side are identical to each other and are mirror images of the portal boxes on the left. Internally, the gears  46 - 48  are identical on the left and right sides of the vehicle  5 . 
     It is expected that the disclosed portal box system can be used with a variety of popular light off road vehicles offered by different manufacturers. The portal boxes  10  are readily adapted to the vehicles by providing suitable brackets as substitutes for he disclosed brackets  16 ,  17 ,  26 ,  29 , and  31  or their equivalents, that can mate with the suspension arms of a particular vehicle. The backing plate  11  is exceptionally versatile since it can accept essentially any suspension, steering and stabilizing bracketry existing on a particular manufacturer&#39;s vehicle. 
     It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular 
     the backing plate  11  and associated mounting brackets are preferably following claims are necessarily so limited.