Abstract:
A load coupling apparatus for a wheeled vehicle includes load linkage members that pivotally suspend the vehicle and load weight below the axles of the vehicle, allowing limited relative displacement of the axles and the load in the direction of vehicle travel. The load is displaced by moving the axles in the desired direction of travel, whereafter the suspended load follows the axles in a swinging motion as the effects of gravity overcome the load inertia. The effort required to initiate movement of the load is significantly reduced due to the relative displacement of the axles and the load, and the mechanical advantage afforded by the load linkage members. Once in motion, the load continues to track the axles in the direction of travel, providing continued reduction in motive effort even when the load reaches a constant forward speed.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to load suspension in wheeled vehicles, and more particularly to a vehicle load coupling apparatus that reduces the effort required to move the vehicle and its load.  
       BACKGROUND OF THE INVENTION  
       [0002]     The conventional approach to movement of a load by a wheeled vehicle, whether by road or rail, is to place the full weight of the load (including the vehicle frame and engine, if any) directly on the wheel axles. Although suspension system components such as springs and dampers are often used to isolate the load from the axle, the load and the various components of the vehicle are moved in unison in the direction of travel. This means that the motive power source, whether in the form of an internal combustion engine, an electric or hydraulic motor, or even manual labor, must expend sufficient energy to initiate movement of the entire weight of the vehicle and load. Various efforts have been made in the transportation industry to improve energy conversion efficiency and reduce frictional losses such as rolling resistance, but the improvements continue to be incremental in nature, and the overall rates of fuel consumption and combustion emission production remain unacceptably high. Accordingly, what is needed is a way of moving wheeled vehicles and their loads with reduced effort, leading to corresponding reductions in fuel consumption and combustion emission production.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention provides a new and improved load coupling apparatus for coupling loads to the wheels of a wheeled vehicle. Fundamentally, the invention involves the use of load linkage members for pivotally suspending the load weight below the axles or center-points of the wheels, allowing limited relative displacement of the wheels and the load in the direction of vehicle travel. The load is displaced by moving the vehicle wheels in the desired direction of travel, whereafter the suspended load follows the wheels in a swinging motion as the effects of gravity overcome the load inertia. The effort required to initiate movement of the load is significantly reduced due to the relative displacement of the wheels and the load, and the mechanical advantage afforded by the load linkage members. Once in motion, the load continues to track the wheels in the direction of travel, providing continued reduction in motive effort even when the load reaches a constant forward speed. Dampers can be employed to control forward shifting of the load when the wheels are decelerated during braking. The apparatus can be applied to any wheeled vehicle, including manually operated vehicles, self-propelled vehicles, and trailered vehicles. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0005]      FIGS. 1A and 1B  diagrammatically depict the axle of a trailered vehicle equipped with a load coupling apparatus according to a first embodiment of this invention.  FIG. 1A  presents an end or longitudinal view, while  FIG. 1B  presents a side or lateral view illustrating the operation of the load coupling apparatus of  FIG. 1A .  
         [0006]      FIGS. 2A and 2B  diagrammatically depict the axle of a trailered vehicle equipped with a load coupling apparatus according to a second embodiment of this invention.  FIG. 2A  presents an end or longitudinal view, while  FIG. 2B  presents a side or lateral view illustrating the operation of the load coupling apparatus of  FIG. 2A .  
         [0007]      FIGS. 3A and 3B  diagrammatically depict the axle of a trailered vehicle equipped with a load coupling apparatus according to a third embodiment of this invention.  FIG. 3A  presents an end or longitudinal view, while  FIG. 3B  presents a side or lateral view illustrating the operation of the load coupling apparatus of  FIG. 3A .  
         [0008]      FIG. 4  depicts a fifth-wheel coupling for connecting a towing vehicle to the trailered vehicles of  FIGS. 1A-1B ,  2 A- 2 B and  3 A- 3 B.  
         [0009]      FIGS. 6A-6B  diagrammatically depict the chassis and wheel of a vehicle equipped with a load coupling apparatus according to a fourth embodiment of this invention.  FIG. 6A  depicts the load coupling apparatus in a rest position, while  FIG. 6B  depicts the load coupling apparatus with the vehicle wheel displaced relative to the vehicle chassis. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]     The present invention is described herein primarily in the context of roadway vehicles, and particularly semi-tractor-trailers. However, it will be understood that the invention is also directly applicable to other roadway vehicles, as well as to railway vehicles, and off-road vehicles such as agricultural vehicles, bicycles, etc.  
         [0011]     As indicated above, the present invention is fundamentally directed to a load coupling apparatus for pivotally suspending the load weight of a wheeled vehicle below the wheel axles or center-points so as to allow limited relative displacement of the wheels and the load in the direction of vehicle travel. In the case of a towed or trailered vehicle where there is no mechanism for driving the wheels, the wheel axles are displaced by a drawbar coupled to the towing vehicle.  FIGS. 1A-1B ,  2 A- 2 B and  3 A- 3 B depict three different possible mechanizations of a trailered vehicle load coupling apparatus, but it will be appreciated that other mechanizations are also possible. In general,  FIGS. 1A-1B  depict an embodiment of the load coupling apparatus in which the swinging linkage member pivots about the axle  16 , and the drawbar is coupled to the swinging linkage member itself, whereas  FIGS. 2A-2B  and  3 A- 3 B depict embodiments of the load coupling apparatus in which the swinging linkage member is hung from the axle  16 , and the drawbar  22  is coupled to the wheel or axle. The drawbar may be directly coupled to the towing vehicle, or through a fifth-wheel assembly as illustrated in  FIG. 4 .  
         [0012]     In each of the  FIGS. 1A, 2A  and  3 A, the reference numeral  10  generally designates a wheel/axle assembly of a trailered vehicle. The tire sets  12 ,  14  may each comprise one or more individual tires, and are supported on the axle  16  in the usual way. The load coupling apparatus ( 18  in  FIGS. 1A-1B ,  18 ′ in  FIGS. 2A-2B , and  18 ″ in  FIGS. 3A-3B ) is symmetrical about the longitudinal axis of the trailer  10 , and couples the trailer bed  20  to the axle  16 . One or more drawbars  22  are coupled between the towing vehicle (not shown) and the load coupling apparatus or the wheel/axle assembly to impart motion to the trailer  10 .  
         [0013]     Referring particularly to the embodiment of  FIGS. 1A-1B , each load coupling apparatus  18  includes two members: a load support member  24  and a swinging linkage member  26 . A set of bolts or pins  28  rigidly couple the upper end of load support member  24  to the trailer bed  20 , and a pin  30  rotatably couples the lower end of load support member  24  to the lower end of swinging linkage member  26 . The swinging linkage member  26  is rotatably supported on the respective end of axle  16 , and the drawbars  22  are coupled to the upper end of the swinging linkage member  26 . Finally, a cross-bar  32  interconnects the swinging linkage members  26  on the left and right sides of trailer bed  20 .  
         [0014]     The side view of  FIG. 1B  illustrates the operation of the load coupling apparatus  18  when the drawbars  22  are initially pulled forward (i.e., to the right in  FIG. 1B ) by the towing vehicle. The lever action of swinging linkage member  26  amplifies the force applied to pin  30 , but the force is predominantly applied to axle  16  due to the inertia of the trailer bed  20  and its load. The load coupling apparatus  18  allows movement of the axle  16  relative to the trailer bed  20 , and the forward movement of drawbar  22  rotates the swinging linkage member  26  about axle  16  (as indicated by the dashed member  26   a ). The rotation of swinging linkage member  26  produces initial forward displacement of the axle  16  and tire set  12  (as indicated by the dashed members  12   a ,  16   a  and  26   a ), and slightly elevates the trailer bed  20  (as indicated by the pin position  30   a  and the dashed member  20   a ). The load support member  24  concentrates the weight of the trailer bed  20  and its load at the pin  30 , and the weight creates a restoring force for repositioning the pin  30  directly under the axle  16 . A forward component of this restoring force aids the force applied to drawbars  22  by the towing vehicle, and the trailer bed  20  begins to move forward as the forward force component overcomes the combined inertia of the trailer bed  20  and its load. While the initial rotation of the swinging linkage member  26  has been exaggerated in  FIG. 1A  for the sake of illustration, it is estimated that the forward component of the load weight will produce initial forward movement of the trailer bed  20  and its load upon forward rotation of the swinging linkage member  26  by 2-5 degrees. As the towing vehicle continues to pull the drawbars  22  forward, the trailer bed  20  and its load continue to track the axle  16  at a reduced displacement. Of course, an equivalent but opposite relative displacement of the axle and trailer bed  20  occurs when the towing vehicle pushes the drawbars  22  when operating in reverse. Although not depicted in  FIGS. 1A-1B , a damper can be used to prevent or severely attenuate forward motion of the trailer bed  20  when the towing vehicle decelerates or brakes.  
         [0015]     In the embodiment of  FIGS. 2A-2B , the load coupling apparatus is designated by the reference numeral  18 ′, and includes a swinging linkage member  40  that is hung from a pin  42  positioned above the axle  16 . The pin  42  is supported on a stand-off member  44  that is either integral with the axle casting or rigidly secured thereto. Also, the drawbars  22  in this embodiment are coupled either directly to the axle  16  as shown, or to the stand-offs  44 . In other respects, the load coupling apparatus  18 ′ is similar to the load coupling apparatus  18  of  FIGS. 1A-1B , and like reference numerals have been used to identify like elements.  
         [0016]     In the illustration of  FIG. 2A , the load coupling apparatus  18 ′ is repeated not only at each end of axle  16 , but also directly inboard of each tire set  12 ,  14 . It will be noted that the pins  42  of each inboard load coupling apparatus  18 ′ are positioned rearward of the axle  16  to prevent interference between the axle  16  and the respective linkage members  24  and  40  in the rest position. If the pins  42  are positioned such that the inboard load support members  24  abut the axle  16  in the rest position, relative displacement of the axle  16  and trailer bed  20  will not be possible when the towing vehicle operates in reverse, and the trailer bed  20  will not be able to shift forward of the axle  16  during forward motion of the trailer when the towing vehicle decelerates or brakes. If the inboard load coupling apparatuses  18 ′ are omitted, relative displacement of the axle  16  and trailer bed  20  will occur during both forward and reverse operation of the towing vehicle, and a damper may be provided to prevent or severely attenuate over-center shifting of the trailer bed  20  when the towing vehicle decelerates or brakes.  
         [0017]     The side view of  FIG. 2B  illustrates the operation of the load coupling apparatus  18 ′ when the drawbars  22  are initially pulled forward (i.e., to the right in  FIG. 2B ) by the towing vehicle. The force applied to drawbars  22  produces forward motion of axle  16  and rotation of swinging linkage member  26  about pin  30  (as indicated by the dashed members  12   a ,  16   a  and  40   a ), slightly elevating the trailer bed  20  (as indicated by the pin position  30   a  and the dashed element  20   a ). The load support member  24  concentrates the weight of the trailer bed  20  and its load at the pins  30 , and the weight creates a restoring force for repositioning the pins  30  directly under the respective pins  42 . A forward component of this restoring force aids the force applied to drawbars  22  by the towing vehicle, and the trailer bed  20  begins to move forward as the forward force component overcomes the combined inertia of the trailer bed  20  and its load. As the towing vehicle continues to pull the drawbars  20  forward, the trailer bed  20  and its load continue to track the axle  16  at a reduced displacement.  
         [0018]     In the embodiment of  FIGS. 3A-3B , the load coupling apparatus is designated by the reference numeral  18 ″, and includes a swinging linkage member  46  that is hung from the axle  16  or wheel  12 . The drawbars  22  are coupled to the hub  48  of a small sprocket  50  that pivots about a pin joint  52  on trailer bed  20 , and a chain  54  couples the sprocket  50  to a large sprocket  56  rigidly secured to the axle  16 . Alternatively, the sprockets  50 ,  56  and chain  54  may be replaced with similarly sized pulleys and a belt. The small sprocket  50  is positioned near the upper periphery of the large sprocket  56  so that the force exerted on drawbar  22  by the towing vehicle is essentially applied to the top of the sprocket  56 , providing increased mechanical advantage compared to the embodiment of  FIGS. 2A-2B , for example. In other respects, the load coupling apparatus  18 ″ is similar to the load coupling apparatus  18  of  FIGS. 1A-1B , and like reference numerals have been used to identify like elements.  FIG. 3B  depicts the load coupling apparatus  18 ″ following an initial forward movement of the drawbar  22  and axle  16 .  
         [0019]     While the drawbars  22  for the above-described embodiments of the load coupling apparatus may be attached directly to the towing vehicle,  FIG. 4  illustrates a preferred implementation in which the drawbars  22  are connected to the towing vehicle via a modified fifth-wheel coupling. Referring to  FIG. 4 , the reference numeral  58  designates a portion of a fifth-wheel coupling in which a hitch pin  60  is received in a slot  62   a  of a skid plate  62  mounted on the towing-vehicle. The drawbar  22  is coupled to the skid plate  62  by the pin  64  near the open end of the slot  62   a , creating a lost-motion coupling between the hitch pin  60  and the skid plate  62 . The hitch pin  60  is initially in a forward position as shown in  FIG. 4 , and forward movement of the towing vehicle produces a pulling force on the drawbar  22  without applying any forward force to the hitch pin  60 . The hitch pin  60  will move back and forth in the slot  62   a  with the relative displacement of the load coupling apparatus  18 ,  18 ′,  18 ″, and its steady-state position within the slot  62   a  will be a function of road grade, air resistance, and so forth. A damper mechanism  66  such as a shock absorber or the like couples the hitch pin  60  to the chassis of the towing vehicle to prevent or severely attenuate forward shifting of the trailer bed and its load when the towing vehicle decelerates or brakes (in embodiments where such motion is possible).  
         [0020]      FIG. 5  depicts an application of the load coupling apparatus of the present invention to a towing vehicle  68 , such as the tractor of a tractor-trailer vehicle. In such vehicles, an engine or motor  70  provides motive power by rotating one or more drive wheels of the vehicle, and there is no need for a drawbar such as used for trailered vehicles. In the embodiment of  FIG. 5 , the towing vehicle  68  has a front wheel set  71 , and tandem rear axles  72 ,  74 , with rear wheel sets  76 ,  78 . The engine  70  drives the rear axles  72 ,  74  through a conventional drivetrain including a jointed drive shaft  80  and a differential gearset (not shown). The vehicle chassis  82  is coupled to the front wheel set  71  in a conventional manner, and to each of the rear axles  72 ,  74  using load coupling apparatuses  84 ,  86  according to this invention. For example, the load coupling apparatuses  84 ,  86  may be constructed as shown in  FIGS. 2A-2B  or  3 A- 3 B, but without the drawbars  22 . A fifth wheel assembly  88  such as depicted in  FIG. 4  is attached to the chassis  82  for coupling to a trailer hitch pin. Finally, the engine  70  is pivotably suspended from the chassis  82  via the swing arms  89   a ,  89   b , which of course are repeated on the opposite side of engine  70 . In operation, the application of motive power from the engine  70  to the rear axles  72 ,  74  produces a forward movement of the axles  72 ,  74  and engine  70  relative to the chassis  82 , after which the chassis  82  and load follow once the swinging linkage members of the load apparatuses  84 ,  86  develop enough forward force to overcome the inertia of the suspended weight.  
         [0021]     Finally,  FIGS. 6A-6B  depict an embodiment of the load coupling apparatus of the present invention that is well suited to both trailered vehicles (including manually towed vehicles) and manually powered vehicles such as wheelchairs and the like. Ordinarily, of course, the weight of the vehicle chassis  90  and load is mounted on the wheel axles. In the case of a wheelchair, the user grasps the top of the wheel  92  and pushes it forward or rearward to initiate movement. Although the wheel afford a mechanical advantage that multiplies the user&#39;s force, the applied force has to be sufficient to initiate movement of the entire weight of the vehicle and its occupant (load), just as in the case of any conventional vehicle.  
         [0022]     Referring particularly to  FIG. 6A , the wheel  92  is essentially a cylinder having an inner periphery  92   a  on which ride three idler wheels: a follower wheel  94  and a pair of offset wheels  96  and  98 . Alternatively, the idler wheels  94 ,  96 ,  98  may be constructed as pulleys, and the inner wheel periphery  92   a  notched to constrain lateral movement of the pulleys. The load coupling apparatus comprises load support members  100 ,  102 , a swinging linkage member  104 , and an offset wheel arm  106  which may be integral with swinging linkage member  104 . The load support members  100 ,  102  are rigidly fastened to the chassis  90 , and to a support plate  108  welded to the axle hub of follower wheel  94 . The swinging linkage member  104  is pivotably coupled to the plate  108  on pin joint  110 , and the offset wheel arm  106  supports the offset wheels  96 ,  98  on the pins  114 ,  116  at its opposing extremities, allowing the swinging linkage member  104  and offset arm  106  pivot as the wheel  92  is displaced with respect to the chassis  90  as shown in  FIG. 6B . If the vehicle is a trailered vehicle, the swinging linkage member  104  can be extended upward as illustrated in phantom and designated by the reference numeral  112 ; in this case, a drawbar (not shown) pulls the top of swinging linkage member  104  forward, producing the relative displacement illustrated in  FIG. 6B . Alternatively, a belt or chain drive arrangement of the type depicted in  FIGS. 3A-3B  could be utilized. If the vehicle is not a trailered vehicle, the upper extension of swinging linkage member  104  is omitted, and the swinging linkage member  104  pivots as shown in  FIG. 6B  when the wheel  92  is rotated forward. Rotation of the wheel  92  may be achieved either by hand, as in the case of a typical wheelchair, or by machine, in which case an electric (or hydraulic) motor is directly or indirectly coupled to the wheel  92 . In either case, the chassis  90  raises slightly as the follower wheel  94  tracks the inner periphery  92   a  of wheel  92 . The combined weight of the chassis  90  and load are concentrated at the pin joint  110 , producing a force in the desired direction of travel, and when that force overcomes the inertia of the chassis  90  and load, the chassis  90  and load support members  100 ,  102  will move forward in a swinging motion. As with the other vehicles depicted herein, the chassis  90  and load support members  100 ,  102  will tend to lag the center of the wheel  92  so long as the wheel  92  is being pulled or pushed forward, and the return to the rest position depicted in  FIG. 6A . Movement in the opposite direction is initiated in much the same way by pulling the swinging linkage member extension  112 , or pushing the wheel  92 , to the right as viewed in  FIGS. 6A-6B .  
         [0023]     It will be appreciated that the load coupling apparatus of this invention is also applicable to tracked vehicles such as tanks where a rubber or steel track encircles front and rear wheels of a vehicle. In such an application, the load coupling apparatus of  FIGS. 6A-6B  may be applied to both front and rear wheels of the vehicle. In a particularly advantageous configuration, only one of the front and rear wheels is motor-driven, and the swinging linkage members of the front and rear wheels are coupled by a mechanical or hydraulic link (a drawbar, for example) so that the motor effectively drives both front and rear wheels.  
         [0024]     In summary, the present invention provides an improved load coupling apparatus that significantly reduces the effort required to initiate and maintain movement of a wheeled vehicle. As applied to a manually propelled vehicle such as a wheelchair, the user effort level is significantly reduced, making the wheelchair so equipped particularly beneficial to persons with limited upper body strength. As applied to trailered and towing vehicles, the peak motive power requirements are significantly reduced, contributing to substantial improvements in fuel economy and emissions, and lower initial powertrain expense. While the invention has been described in reference to the illustrated embodiments, it should be understood that various modifications in addition to those mentioned above will occur to persons skilled in the art. Accordingly, it will be understood that systems incorporating these and other modifications may fall within the scope of this invention, which is defined by the appended claims.