Abstract:
A high clearance converter is used for converting a road vehicle, e.g. a pickup truck, to a high clearance vehicle, for example for agricultural use. The converter has front and rear frame components, each with two upright and ground wheels mounted on each of the legs. The front wheel hubs are mounted on the front frame component and the rear axle is mounted on the rear frame component. The front and rear frame components are coupled for relative rolling movement with respect to one another, allowing the frame to flex when travelling over uneven ground.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation in part of application ser. No. 08/904,648, filed Aug. 1, 1997, now U.S. Pat. No. 6,021,861. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a high clearance converter for converting a road vehicle, e.g. a pickup truck, to a high clearance vehicle, for example for agricultural use. 
     BACKGROUND 
     High clearance sprayers are becoming increasing popular for agricultural spraying. These units are quite expensive and have a limited utility so that for much of the year a large investment remains idle. 
     To address this problem, it has been proposed to use a high lift vehicle frame for raising road vehicles to a height suitable for use as a high clearance sprayer. One such proposal is disclosed in Meiners U.S. Pat. No. 5,072,805, issued Dec. 17, 1991. 
     The frame disclosed in the Meiners patent is a rigid frame on which a pickup truck rests with its road tires. The front tires fit into rotatable sockets linked to wheel carrying front legs on the frame for steering purposes. The rear tires rest on rollers, which are connected to rear drive wheels carried on rear legs of the frame. In the preferred embodiment, the truck frame is fastened to the frame by a single hold-down anchor. A second embodiment uses a more positive drive with gear boxes and drive shafts to drive the rear frame wheels from the rear vehicle wheels. With this system, the rigid frame will not allow the ground wheels of the converter to follow uneven ground contours, making both driving and steering problematic on an uneven surface. 
     The present invention relates to certain improvements in converters of this type. 
     SUMMARY 
     According to the present invention there is provided In combination a high clearance converter and a vehicle having a body, two front wheel assemblies, two rear wheel assemblies and a resilient suspension supporting the body on the wheel assemblies, the converter comprising: 
     a front frame component with two upright front legs; 
     two ground wheels mounted on the respective front legs; 
     front vehicle mounts mounting the front wheel assemblies of the vehicle on the front frame component; 
     a rear frame component with two upright rear legs; 
     two ground wheels mounted on the respective rear legs; 
     rear vehicle mounts mounting the rear wheel assemblies of the vehicle on the rear frame component; and 
     flexible couplings coupling the front and rear frame components for relative rolling movement with respect to one another. 
     The term “wheel assemblies” is intended as a general term to mean the components of the vehicle that are not supported directly or indirectly on the suspension springs, including wheel hubs and axles. 
     The use of two frame components coupled to roll with respect to one another, and mounting of the two frame components on the unsprung wheel assemblies allows the vehicle&#39;s suspension to accommodate the uneven ground conditions that may be expected on an agricultural field. 
     The front and rear frame components preferably include front and rear transverse beams and respective laterally spaced longitudinal side rails. The side rail of the front component is coupled to the rear component by a flexible coupling, which may be a ball joint or a rubber joint at the rear, while the side rail of the rear component is coupled to the front component by a flexible coupling at the front. 
     With a rigid axle, for example a solid rear drive axle, the axle may be mounted directly on the frame transverse beam with axle mounting brackets. This leaves the wheel hubs free for connection to drive connections to the frame drive wheels. These drive connections are, in the preferred embodiment, chain drives inside the frame legs, with the legs serving as chain cases. 
     For independent suspension systems, the mounts are designed to accommodate realignment of the vehicle wheels as they travel on the suspension from the neutral position. This may be achieved with resilient mounts for the mounting brackets. 
     Non-driving wheel hubs are preferably mounted on the frame transverse members by brackets that connect to the hubs using the conventional wheel lugs. 
     Steering wheels at the front of the frame may be connected by a tie rod and coupled to the Pitman arm of the vehicle steering box by a drag link. Thus, the front steering wheels of the vehicle are locked up and the vehicle steering system operates directly on the frame wheels. 
     The frame can be modified for four wheel drive using drive from the steering hubs by including constant velocity (CV) joints in the drive linking the vehicle wheel hubs and the front steering wheels of the converter frame. The frame to wheel assembly mounts will then connect the frame component to non-rotating parts of the wheel assemblies. 
     The frame may be made to suit vehicles with a range of wheel bases and tracks. A single adjustable length frame with laterally adjustable hub mounts and axle mounts may be used to achieve this objective. 
     The frame may be equipped with running board brackets and running boards that may be removed and used as ramps at the back end of the frame for loading or unloading the vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, which illustrate exemplary embodiments of the present invention: 
     FIG. 1 is a side elevation of a converter according to the present invention carrying a truck; 
     FIG. 2 is a plan view of the converter of FIG. 1; 
     FIG. 3 is a partial front elevation, partly broken away; 
     FIG. 4 is an isometric of a front hub bracket; 
     FIG. 5 is a partial side elevation of a rear leg; 
     FIG. 6 is a transverse cross section of a rear leg; 
     FIG. 7 is a rear view of a rear hub drive coupling; 
     FIG. 8 is an isometric view of a rear axle bracket; and 
     FIG. 9 is a plan view of an alternative embodiment of the converter. 
    
    
     DETAILED DESCRIPTION 
     Referring to the accompanying drawings, there is illustrated a vehicle converter  10  including a frame  12  for supporting a vehicle above the ground. The frame includes two upright front legs  14  and two upright rear legs  16  with a ground wheel  18  mounted at the bottom end of each leg. 
     As shown in FIG. 1, the frame is supporting a pickup truck  20  with a truck body  22  including a cab  24  and a truck box  26  carrying a field sprayer  28 . The truck is conventional, with front wheel assemblies  21  and rear wheel assemblies  23  (FIG. 7) and a resilient suspension including front springs  25  and rear springs  27  for supporting the truck body on the wheel assemblies. Further elements of the truck will be discussed in the following in connection with their interaction with the converter. 
     The frame includes a front frame component  30  including a transverse front beam  32  and a longitudinal side rail  34  projecting to the rear from adjacent one end of the transverse beam. An angle brace  36  joins the beam  32  and the side rail  34  to provide a rigid sub-frame that will resist the anticipated loadings. Mounted on each end of the transverse beam  32  is a kingpin sleeve  38 , inclined inwardly to the top as illustrated most particularly in FIG.  4 . The sleeve carries kingpin bushings  39  and a kingpin  40  that is held in place in the sleeve using clamps  42  at the top and bottom of the sleeve. The clamps are mounted on an inclined upper end of a respective one of front legs  14  so that the leg will pivot about the inclined kingpin axis. 
     Each of the front legs has a forwardly projecting steering arm  44 . A tie rod  46  extends between the two steering arms  44  and is connected to them by tie rod ends  48  so that the two front legs will pivot together for steering purposes. A drag link  50  is connected to one of the steering arms  44  for transmitting steering movements to the two front legs and the front frame wheels. 
     The front transverse beam  32  carries two front vehicle mounts, in the form of wheel hub mounting brackets  52 . Each bracket includes a vertical flange  54  with a circle of bolt holes  56  surrounding a hub aperture  58 . The flange is mounted on a base flange  60  which has a pair of longitudinal mounting slots  61 . The base flange is adjustably mounted on a rubber mounts  62  by studs  64  through the respective slots  61 , and nuts  66 . The rubber mount has the two studs  64  projecting from a top plate  68  bonded to one side of a rubber block  69 . A plate  70  bonded to the opposite side of the rubber block has bolt holes receiving the ends of a U-bolt  74 , which clamps the plate  70  on the transverse beam  32 . 
     The frame also includes a rear frame component  80  including a transverse rear beam  82  and a longitudinal side rail  84  coupled by an angle brace  86 . As illustrated most particularly in FIG. 2, the longitudinal side rail of each frame component is coupled to the transverse beam of the other side component using a coupling  88 . Each coupling includes a bracket  90  secured to the transverse beam. A second bracket  92  projects from the end of the longitudinal side rail. It is mounted on the rail by bolts  94 . The bracket  92  has multiple bolt holes, allowing adjustment of the length of the side rails to accommodate vehicles with different wheel bases. The end of the bracket  92  is connected to a ball joint  96  mounted on the bracket  90 . 
     The rear beam  82  carries two rear vehicle mounts, in the form of axle brackets  98 . Each of these includes a support plate  100  with a notch  102  at the top to support the axle tube of the truck&#39;s rear axle. A flange  104  projects from one side of the support plate and is bored to receive the ends of a U-bolt  106  over the axle tube. Nuts (not illustrated) hold the U-bolt on the axle, and hold the axle firmly in place on the support plate  100 . The support plate is mounted on a base plate  110  with two pairs of longitudinal slots  112  on opposite sides of the support plate. These slots receive the ends of U-bolts  114  for clamping the bracket to the beam  82  at the desired location. The slots  112  provide for longitudinal adjustment of the axle support  98  on the rear frame component. To fix the adjusted position of the axle, four nuts  118  are fixed to the base plate  110  in alignment with the U-bolts  114 . Adjustment bolts  120  threaded into the nuts engage the U-bolts and fix their positions along the slots  112 . 
     The rear legs  16  are mounted on opposite ends of the rear beam  82 . Each carries, near its bottom end and inside the leg, a chain sprocket  124  connected to a wheel hub  125  for one of the rear drive wheels  18  of the converter. A second sprocket  126  is located inside the leg adjacent the top. It is mounted on a transverse shaft  128  mounted in two bearings  130 . The bearings are carried by mounting plates  132  with vertical slots  133  to receive studs  134  on the rear leg. The bearings are fixed in place using nuts  136  on the studs. 
     To provide for vertical adjustment of the bearings, an angle  138  is fixed to the leg below each bearing. Nuts  140  are fixed to the mounting plate  132  and vertical adjustment bolts  142  are threaded into the nuts to engage the angle  138 . The bolts adjust the vertical position of the shaft  128 . 
     A chain  146  extends around the sprockets  124  and  126  so that the rear wheels of the converter frame can be driven by the shafts  128 . 
     The inner end of shaft  128  is secured to a sprocket  148 . A second sprocket  150  of the same configuration is arranged face-to-face with the sprocket  148 . The second sprocket  150  is mounted on the end of a shaft  152 . The sprockets are joined face to face by a circumferential double chain  154 . On the inner end of the shaft  152  is a further sprocket  156  coupled to a sprocket  158  by a second double chain coupling  160 . The sprocket  158  carries a sleeve  162  that extends over the projecting wheel hub of the truck. A flange  164  around the inner end of the sleeve has a circle of bolt holes  166  to be coupled to the drive wheel hub by the wheel lugs. 
     The two longitudinal side rails  34  and  84  carry running board brackets  168  that project laterally from the rails. Running boards  170  are mounted on these brackets to provide for more convenient access to the cab and box of the truck. The running boards are removable from the brackets  168  and can be coupled to the rear beam  82  to provide a ramp for driving the truck on to or off of the frame. 
     The mounting of the truck on the frame is a relatively simple job that can be accomplished in only a few minutes. The truck is first driven onto the top of the assembled converter using ramps or planks and its wheels removed. The frame is then coupled to the rear axle using the axle brackets and to the front wheel hubs  202  of the vehicle directly using the front hub brackets  52  and the existing wheel lugs  204  of the vehicle as shown in FIG.  1 . The slotted front of mounting brackets  52  and the adjustable axle brackets  98  allow the alignment of the truck rear axle with the shaft  128 . The rear drive adapters, including the sleeves  162  and flanges  164  are then installed using the rear wheel hub lugs. The shaft  152  is coupled between the hub adapter and the shaft  128  using the double chain couplings. The steering is then connected by disengaging the drag link of the truck&#39;s steering from the Pitman arm  172  of the truck steering box  174  and connecting the converter drag link  50  to the Pitman arm to provide direct steering from the truck steering box to the front steering wheels of the converter. 
     An alternative embodiment of the invention is illustrated in FIG.  9 . In that embodiment, the front beam  32  is connected to a front longitudinal member  180  extending to the rear from the centre of the front beam. Angle braces  182  extend between the front longitudinal member and the front beam. At the rear end of the front longitudinal member is a rotary coupling  184  connecting the front longitudinal member to the front end of a rear longitudinal member  186 . The rear longitudinal member extends to the centre of the transverse rear beam  82  where it is fixed in place. The rear longitudinal member  186  is telescopic, with an outer front component  188  fixed to the rotary coupling and an inner rear component  190  that slides along the inside of the front component. The two are fastened in an adjusted position by bolts  192 . Angle braces  194  extend between the inner rear component  190  and the transverse rear beam  82 . 
     In the second embodiment, the rotary coupling serves to provide the relative rolling movement of the transverse front and rear beams  32  and  82  respectively, allowing the converter to follow ground irregularities. 
     The converter provides a robust support for the vehicle to be carried. Because of the flexibility of the support, it allows the suspension of the truck to flex when travelling over rough terrain to accommodate unevenness in the terrain. 
     While one embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention and are intended to be included herein.