Abstract:
A wheeled vehicle, which may be a bicycle, having independent front and rear wheel steering, and rear wheel propulsion from a pedal assembly. The rear wheel is pivotally mounted to enable steering. The rear sprocket transmits torque to a jointed drive shaft which drives the rear wheel at any degree of steering. Rear steering is actuated by a frame mounted control lever, which draws a flexible cable which extends through the hollow frame. Indicia indicates the degree of rear steering. The control lever has a locking feature to prevent inadvertent steering. The rear wheel is pivotally mounted to the frame to enable clearing obstacles in the road.

Description:
FIELD OF THE INVENTION 
     The present invention relates to bicycles, and more particularly to a bicycle having rear wheel steering which is independent of front wheel steering. 
     BACKGROUND OF THE INVENTION 
     Bicycles have been provided with special riding effects to offer variety to the otherwise usual riding experience. For example, rear wheel steering is known. Another variation to traditional riding characteristics is the so-called “swing bike”. A swing bike is essentially an articulated bicycle which introduces more dynamic responses to steering inputs due to its articulated frame. 
     SUMMARY OF THE INVENTION 
     The present invention contemplates a wheeled vehicle, which may be a bicycle, which has rear wheel steering which is independent from its front wheel steering, in combination with rear wheel propulsion via an endless flexible drive chain or belt. The rear wheel is pivotally mounted to the frame to enable steering to the right and to the left. 
     The rear wheel steered vehicle provides new avenues in special effects vehicles. Illustratively, with the rear wheel turned to a right angle to the frame, pedaling can result in the rear wheel describing circles around the front wheel. The rear wheel may be turned to a lesser degree, and with the front wheel being steered, the entire vehicle may travel at an acute angle to the longitudinal direction of the frame. If the front and rear wheels are steered either simultaneously or one at a time while the vehicle is under propulsion, many additional effects may be enjoyed which would not be available from for example a traditional bicycle or even an articulated bicycle. 
     The novel vehicle accommodates the functions of steering and propulsion in the following way. A drive chain or belt using sprockets or the like may be provided. The chain or belt and its associated sprockets occupy a vertical plane. Changes in the heading of the steerable rear wheel may be accommodated by a jointed shaft which transmits torque from the rear sprocket to the rear wheel. 
     The rear wheel steering system may be actuated by a control lever mounted on the frame in front of the seat. The control lever may be slid longitudinally along the frame. The control lever may pull a flexible cable which extends to the rear wheel. The cable may engage the rear wheel at points near the rubber tire, so that the cable enjoys significant leverage over the resistance of the rear wheel to heading changes, in response to the linear motion of the control lever along the frame of the vehicle. The cable may pass through hollow frame tubing of the vehicle for at least part of its length. The vehicle frame may bear indicia indicating the degree of steering of the rear wheel. The control lever may have a lockup feature which opposes unintended steering changes of the rear wheel. 
     The rear wheel may be pivotally mounted to the vehicle frame, for example to enable rising and falling to clear minor obstacles. 
     It is therefore an object of the invention to provide a pedaled vehicle having both front wheel steering and also independent rear wheel steering, in combination with rear wheel propulsion. 
     It is an object of the invention to enable many unusual driving effects to be made possible in a pedaled vehicle. 
     It is an object of the invention to provide a cable steering system operated by a control lever which is slidably mounted on the frame of the vehicle. 
     A further object of the invention is to provide a lockup feature which opposes unintended rear wheel steering. 
     It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is a side view of a wheeled vehicle according to at least one aspect of the invention, showing a rear wheel in a conventional steering attitude. 
         FIG. 2  is a side view similar to  FIG. 1  but showing the rear wheel in an alternative steering attitude. 
         FIG. 3  is a partial diagrammatic top plan view of a wheeled vehicle at a steering attitude similar to that of  FIG. 1 . 
         FIG. 4  is a partial diagrammatic top plan view similar to  FIG. 3 , but showing the rear wheel at an intermediate steering attitude. 
         FIG. 5  is a partial diagrammatic top plan view similar to  FIG. 3 , but showing the rear wheel at a progressively greater steering attitude. 
         FIG. 6  is a diagrammatic top plan detail view of a wheeled vehicle according to at least one aspect of the invention, illustrating a possible range of steering rotation of the steered rear wheel. 
         FIG. 7  is a diagrammatic exploded perspective detail view of wheel details taken from the center left of  FIG. 2 . 
         FIG. 8  is a diagrammatic exploded perspective detail view of a housing enclosing the subject matter of  FIG. 7 . 
         FIG. 9  is a diagrammatic enlarged side detail view of controls mounted on the frame of the wheeled vehicle, according to an aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a wheeled vehicle in the form of a bicycle  10  according to at least one aspect of the invention. The bicycle  10  may have a frame platform  12  made from tubing forming a triangle, comprising a generally vertical seat post  14  having a proximal end  16  adapted to receive and support a bicycle seat  18 , and a distal end  20  adapted to rotatably support a crank assembly  22 . The crank assembly  22  is part of a drive system disposed to rotate the rear wheel under power, the drive system being further detailed hereinafter. The frame platform  12  may further comprise a generally horizontal frame member  24  having a proximal end  26  connected to the seat post  14  near the proximal end  16  of the seat post  14 , and a distal end  28  located forwardly of the proximal end  26 , terminating in a steering support  30 . The steering support  30  may support a steering fork assembly  32  to which a front wheel  34  is mounted. Handle bars  36  may be connected to the steering fork  32 , which are adapted to steer the front wheel  34  in a conventional manner. The frame platform  12  may further comprise an inclined connector bar  36  spanning and fixed to the distal end  28  of the horizontal frame member  24  via the steering support  30  and the distal end  20  of the seat post  14 . The seat post  14 , the horizontal frame member  24 , and the connector bar  36  may collectively generally form a triangle. 
     At the front of the bicycle  10 , the fork assembly  32 , which is rotatably supported at the steering support  30  for rotation about a generally vertical axis, may be steered in conventional manner by handle bars  38 . The crank assembly  22 , which is rotatably supported at the distal end  20  of the seat post  14 , has pedals  40  and  42  connected thereto. 
     Orientational terms such as up and down refer to the described object as it is depicted in the referenced drawing figure. The front of the wheeled vehicle such as the bicycle  10 , is that end having the handle bars  38  and facing the usual direction of travel. The rear end is that end proximate the seat  18 , or closer to the seat  18  than to the handle bars  38 . A forward direction is from the seat  18  to the handle bars  38 . It will be appreciated that the subject wheeled vehicle is capable of traveling in many directions including maneuvers wherein one wheel such as the front wheel  34  may possibly not progress along the ground but instead may only pivot, while the other wheel or wheels, such as the rear wheel  44 , orbit around the pivoting wheel. Therefore, orientational terms must be understood to provide semantic basis for purposes of description, and do not limit the invention or its component parts in any particular way. 
     It should be noted that while the bicycle  10  has a front wheel  34  and a rear wheel  44  mounted to the frame platform  12 , a different number of wheels may be accommodated by the invention. Thus, a vehicle having three, four or even more wheels (none shown) may enjoy the benefits of the invention. 
     The front steering system comprising the handle bars  38 , the steering support  30 , the front fork  32 , and the front wheel  34 , for turning the front wheel  34  to the right and to the left is conventional. However, this is not the case with a rear steering system for turning the rear wheel  44  to the right and to the left independently of steering the front wheel  34 , especially when taken in combination with a drive system disposed to rotate the rear wheel  44  under power. The rear steering system is capable of directly imposing rotational steering inputs to the rear wheel  44 . That is, the rear steering system directly and actively turns the rear wheel  44  to the right and to the left, as opposed to passively following the front of the bicycle  10  or passively steering responsive to the rider leaning to the right and to the left. This holds true for all vehicles according to at least one aspect of the invention, and not just for the bicycle  10  which has one and precisely one rear wheel  44 , and one and precisely one front wheel  34 . 
     The crank assembly  22  drives a flexible endless drive element, which may comprise a belt (not shown) or a chain  46 , disposed to transmit power to the rear wheel  44 , as will be explained in greater depth hereinafter. 
     Turning now to  FIG. 2 , the rear wheel  44  has been turned to an angle perpendicular to its former orientation seen in  FIG. 1 . This is enabled by an arrangement wherein the rear wheel  44  is mounted to enable pivoting relative to the frame platform  12  about a generally vertical axis  48 . Of course, the rear wheel can rotate about a generally horizontal axis  50  for propulsion. 
     Relationship of fixed components to components which are pivotal for steering purposes is best understood with reference to  FIGS. 3 ,  4 , and  5 . Bearing in mind that FIGS.  3 ,  4 , and  5  are diagrammatic, and serve only to explain rear wheel steering, it is seen that a structural bar  50  which connects the rear wheel  44  to the frame platform  12  (not seen in  FIGS. 3-5 ) may be regarded as a fixed member for the purposes of explaining steering. The structural bar  50  is fixed in the sense that it always is aligned along the length of the bicycle  10 . The chain  46  (see  FIGS. 1 and 2 ) drives a rear sprocket  52 , which although rotatable, is fixed in position relative to a housing  54 . The housing  54  is a mobile stable wheel holding base which is fixed to the structural bar  50 , also referred to as a main bar  50 . 
     The rear wheel  44  is held by a pivotal bearing arrangement, which will be further described hereinafter, to enable the rear wheel  44  to undergo steering turns. Therefore, it will be appreciated that the main bar  50  and the housing  54  remain fixed, or longitudinally aligned with the frame platform  12 , while enabling the rear wheel  44  both to rotate about a generally horizontal axis  56  for propulsion and also to pivot about the generally vertical axis  48  to steer. The axes  48  and  56  are best seen in  FIGS. 1 and 2 . 
       FIG. 3  shows the rear wheel  44  in an orientation appropriate for conventional travel, or directed parallel to the longitudinal axis of the bicycle  10 .  FIG. 4  shows the rear wheel turned to about a forty-five degree angle to the conventional orientation of  FIG. 3 . In  FIG. 4 , it becomes clear that the main bar  50 , the rear sprocket  52 , and the housing  54  remain in constant or fixed orientation relative to the fore and aft direction, which direction coincides with the longitudinal axis of the bicycle  10 . It also becomes clear that a multi-jointed universal drive  58  accommodates steering of the rear wheel  44  while rotating the rear wheel  44  responsive to movement of the chain  46 . 
     The universal drive  58  may comprise a primary driven shaft  60  which is driven by the chain  46  via the rear sprocket  52 ; an intermediate driven shaft  62 , and a final driven shaft  64  which is driven by intermediate shaft  62 . A first universal joint  66  is connected between and transfers drive torque from the primary driven shaft  60  and the intermediate shaft  62 . A second universal joint  68  is connected between and transfers drive torque from the intermediate shaft  62  to the final driven shaft  64 . 
       FIG. 5  shows a further degree of steering of the rear wheel  44 . It should be noted that the rear wheel  44  may be steered to a still further steering orientation. This is shown in  FIG. 6 , wherein the range of steering which is available is indicated by the arrow  65 . To prevent collision of a wheel component, such as an eye  94 , a rubber bumper  67  may be fixed to the main bar  50 . A corresponding rubber bumper (not shown) may be fixed to the main bar  50  at the opposite side. 
       FIG. 6  also shows more of the apparatus of the rear steering feature according to at least one aspect of the invention. The frame platform  12  is shown only in part, including that part which supports the cranks assembly  22 . The crank assembly is seen to comprise a crank arm  70  to which are mounted the pedal  40  and a front sprocket  72 . The chain  46  (see  FIG. 2 ) is connected to the front sprocket  72  and the rear sprocket  52  to drive the latter upon rotation of the front sprocket  72 . 
     One aspect of the invention is clearly shown in  FIG. 6 , namely, that the main bar  50  is pivotally connected at its proximal end to the frame platform  12  at a clevis  74 . The distal end of the main bar  50  is pivotally connected to the rear wheel  44  to support the rear wheel  44  in a manner to be described hereinafter. The main bar  50  and hence the rear wheel  44  may pivot relative to the frame platform  12  about a generally horizontal axis  76 . This feature enables for example the rear wheel  44  to rise to clear a small obstruction (not shown) which may be present in its path, without causing the frame platform  12  to be displaced upwardly. 
     Returning momentarily to  FIG. 1 , pivotal connection of the main bar  50  is supplemented by a telescopic mobile bar  84  connected to the frame platform  12  and to the main bar  50  near the distal end of the latter. 
     The main bar  50  and the telescopic mobile bar  84  collectively connect the rear wheel  40  to the frame platform  12  while enabling the rear wheel  44  to pivot in a vertical plane relative to the frame platform  12 . 
     Returning now to  FIG. 6 , a flexible cable  78  on which the rear wheel steering system is based may be seen. The flexible cable  78 , which is adapted to provide steering rotation inputs to the rear wheel, engages an eye  80  fixed to a steering arm  82  which in turn is fixed to a pivotal portion of the rear wheel  44 . At its other end (not shown, the steering cable  78 , which may pass through hollow frame tubes of the frame platform, such as the hollow horizontal frame member  24 , for at least part of the extent of the cable  78 , engages a manual control to be described hereinafter. Companion steering cable  86  is similarly routed to the manual controller. The steering cables  78  and  86  may comprise two separate cables or alternatively may comprise a single cable. 
     The steering arm  82  also supports a brake caliper  84 . Brake cables, such as the brake cable  88  (see  FIG. 2 ) may also be routed through at least one hollow frame tube, such as the horizontal frame member  24 . 
     The brake disc  98  which may be subjected to braking forces imposed by the brake caliper  85  may be seen in  FIG. 7 , to which attention now turns. Pivotting of the rear wheel  44  as seen in  FIGS. 3-5  is enabled by a mobile stable wheel holding base or pivotally mounted wheel spindle  90 , which is ultimately fixed to the main bar  50  by connection at the housing  54 . The wheel spindle  90  may include the steering arm  82  and a corresponding steering arm  92 . The steering arms  82  and  92  have mobile anchors or eyes  80  and  94 , respectively, for engaging or anchoring the ends of the steering cables such as steering cables  78  and  86  respectively. The brake caliper  85  and a corresponding brake caliper  96  are mounted on the respective steering arms  82  and  92  in proximity to a brake disc  98 . The rear wheel  44 , shown only partially in  FIG. 7 , is mounted to the brake disc  98  by spokes  100 . 
     The spindle  90  has a central opening which is not called out by reference numeral, but is seen to be aligned with the rotational axis  56  of the rear wheel  44 . This central opening enables the final driven shaft  64  of the universal drive  58  to pass through the spindle  90  to drivably engage the brake disc  98 . The brake disc  98  also has a central opening  102 , which is square or otherwise has non-circular characteristics, so that it may be driven by the square drive of the final driven shaft  64  of the universal drive  58  (see  FIG. 4 ). A nut  104  may be provided to secure the brake disc  98  and hence the rear wheel  44  to the spindle  90 . 
     The wheel spindle  90  is fixed to the main bar  50  (see  FIG. 6 ) by a pivotal bearing arrangement adapted to engage the rear wheel  44  and to enable the rear wheel  44  to undergo steering turns, while the main bar  50  remains longitudinally aligned with the frame platform  12 , while still enabling the rear wheel  44  to steer. To this end, the wheel spindle  90  pivots about a generally vertical axis  112 , which is seen to pass through the centers of two trunnion holders  108  and  110 . The trunnion arrangement, which enables the wheel spindle  90  to be supported on the housing  54  in a manner enabling the wheel spindle  90  to pivot about a generally vertical axis  112  while enabling the rear wheel  44  to be rotatably mounted on the wheel spindle  90  in a manner enabling the rear wheel  44  to rotate about the axis  56  to enable propulsion of the bicycle  10 , is further explained hereinafter. 
     The wheel spindle  90  may have fixed thereto a guide arm  114  having a pin  116  bearing an enlarged head  118 . This guide arm  114  guides the spindle  90  to move through an arcuate path when the spindle  90  rotates bout the axis  112 . 
     Turning now to  FIG. 8 , details of the housing  54  and its cooperation with the spindle  90  are explained. The housing  54  may comprise a vertical perimetric wall member  120  which supports a rotatable rear drive element such as the primary driven shaft  60 , which is aligned with the rotational axis  122  of the rear sprocket  52 . Of course, the axis  122  will be coincident with the axis  56  when the rear wheel  44  is in the orientation shown in  FIG. 3 , but may be non-coincident at other steering positions. 
     The wall member  120  may have a window  124  through which the universal drive  58  passes as it extends from the primary driven shaft  60  to the spindle  90 , as shown in  FIG. 7 . A recess  126  enables the guide arm  114  to pass into the housing  54  from the spindle  90 . 
     The wall member  120  is closed by an upper wall  128  and a lower wall  130 . The wall members  120  and  130  are seen to have respective trunnion passages  132  and  134 . The trunnion passages  132  and  134  are symbolic in nature as they are intended to designate respective mounting locations of trunnions  136  and  138  rather than literally signifying mounting details of the trunnions  136  and  138 . The trunnions  136  and  138  may be mounted in any suitable way such that they coincide with the axis  112 , as shown, and may be components separate from the housing  54  or alternatively may be integral therewith. Of course, the housing  54  may be formed from separate pieces such as the wall member  120 , the upper wall  128 , and the lower wall  130 , or alternatively, any of these members may be integral with another, or in a further alternative may be formed in more than the three components shown. 
     The lower wall  130  is seen to have a grooved track  140  fixed thereto. The grooved track  140  bears an arcuate slot or groove  142 . The groove  142  is dimensioned and configured to receive the enlarged head  118  of the guide arm  114  in close interfit. As the spindle  90  rotates about the axis  112 , the enlarged head  118  moves in the arcuate path of the groove  142 . The grooved track thereby assists in guiding the spindle  90  during steering. 
     Referring now to  FIG. 9 , the rear steering feature is controlled by a steering control handle  150  mounted at the front of the seat  18 , such as on the horizontal frame member  24  of the bicycle  10 . The handle  150  is adapted to transmit tensile forces to the flexible cable or cables, such as the cables  78  and  86 , responsive to being moved along the horizontal frame member  24  by a person&#39;s hand such that the flexible cable or cables impart steering inputs to the rear wheel  44  responsive to the operating forces. 
     The rear steering feature further comprises a vertical release member  152  which is adapted to release the steering control handle  150  to move between a locked position in which the rear steering system is constrained against changing steering attitude of the rear wheel  44 , and a released position in which the rear steering system is movable to enable the steering control handle  150  to be moved to provide steering inputs to the rear wheel  150 . The vertical release member  152  may be movable from the position shown in solid line upwardly as depicted to the position shown in broken line. When released, the control handle  150  may be slid along the horizontal frame member  24  in the fore and aft direction, as indicated by the arrows  154  and  156 . 
     The horizontal frame member  24  may have wheel turn indicia  158 A,  158 B,  158 C,  158 D,  158 E disposed to indicate the degree to which movement of the steering control handle  150  steers the rear wheel  44 . 
     The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts. For example, although the invention has been described with respect to bicycles, it may apply equally to other vehicles. The invention is not to be limited by the examples presented above, but is to encompass any structures falling within the scope of the appended claims.