Abstract:
To reduce the complexity, maintenance, and cost, and to increase the reliability of a riding lawnmower employing a short turn radius steering system, the riding lawn mower may be configured with a linkage and steering assembly that eliminates or reduces complicated gearing. A riding lawn mower may comprise a link system, pivot brackets, and spindle assemblies. The geometry of the steering system may be configured to provide a turn radius of seven inches or less. Moreover, the geometry of the steering system may be configured to provide Ackerman steering, such that, the inside wheel turns sharper than the outside wheel in a turn.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to vehicles, and in particular, to vehicles configured for lawn maintenance including cutting grass. 
       BACKGROUND 
       [0002]    Grass is commonly maintained with lawn care machinery such as, for example, walk behind lawn mowers, riding lawn mowers, lawn tractors, and/or the like. Riding lawn mowers often provide the convenience of a riding vehicle and a larger cutting deck than typical walk-behind lawn mowers. 
         [0003]    Typically, a riding lawnmower has a large turn radius making it difficult to operate in tight spaces and forcing an operator to make wide turns. This generally increases cut time (e.g. the time it takes to a cut a lawn) and requires additional equipment to cut an entire lawn. Short turn radius steering systems have been developed; however, these systems often employ complex gearing and linkage system. Many of the existing short turn radius steering systems are susceptible to failure related to wear and stress. Moreover, these existing systems are usually expensive and difficult to maintain because they are complex. As such, there is a need for a riding lawnmower with a short turn radius steering system that is easy and inexpensive to maintain and reliable to operate. 
       SUMMARY 
       [0004]    The present disclosure is directed to a steering system for a riding lawnmower that provides a short turn radius. In one embodiment, the turn radius provided by the steering system is approximately seven inches or less. Moreover, the steering system is not only reliable, but also easy and inexpensive to maintain. 
         [0005]    In one embodiment, a short turn radius steering system comprises a linkage, a pivot bracket, a bracket linkage, and a spindle assembly. The pivot bracket may couple to the linkage. The spindle assembly may couple to the pivot bracket through the bracket linkage. The linkage may be configured to move in a first direction and causing the pivot bracket to translate the motion such that the bracket linkage moves. The steering system may provide a turn radius of approximately five inches or less. The spindle assembly may comprise a spindle arm and a pitman arm, such that the pivot bracket is configured to conduct a force from the linkage to the pitman arm causing the spindle to move. The spindle arm may be coupled to a wheel. The pitman arm may comprise a tab. The tab of the pitman arm may be configured to restrict the wheel from turning more than 90 degrees in one direction. The pivot bracket may be configured to rotatably couple to an axle of a riding vehicle. 
         [0006]    The steering system may also comprise a pivot bolt, which has a rotating surface and an engagement. The rotating surface may be configured to support the pivot bracket and the engagement may couple to the axle. The pivot bolt may have a hollow cavity along its centerline and a cross passage perpendicular to the hollow cavity. The pivot bolt may be configured to receive a lubricant through the hollow cavity and provide the lubricant to the rotating surface through the cross passage. 
         [0007]    In an exemplary embodiment, a riding lawnmower may comprise a steering system with a user input, an axle, and left and right wheels. The steering system may comprise left and right steering linkages, left and right pivot brackets, and left and right spindle assemblies. The left steering linkage may couple to and conduct a force through the left pivot bracket to the left spindle assembly, which causes the left wheel to move. Similarly, the right steering linkage may couple to and conduct a force through the right pivot bracket to the right spindle assembly, which causes the right wheel to move. The left spindle assembly and right spindle assembly may each comprise a spindle arm and a pitman arm. Each of the pitman arms may comprise a tab that is configured to contact the axle to restrict the left or right wheel from turning more than 90 degrees, when the respective wheel is turned toward the centerline of the riding lawnmower. Moreover, in a turn, the geometry of the steering system causes the one wheel (e.g. the inside wheel) to turn sharper than the other wheel (e.g. the outside wheel). 
         [0008]    The axle and the steering system may each comprise a lubricating system that is configured to provide a lubricant to each of the left and right spindle assemblies, and each of the left and right pivot brackets, to reduce wear and/or contamination. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A more complete understanding may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar elements throughout the Figures, and: 
           [0010]      FIG. 1A  illustrates a top perspective view of an exemplary short turn radius steering system mounted to a riding vehicle chassis, in accordance with an exemplary embodiment; 
           [0011]      FIG. 1B  illustrates a bottom perspective view of an exemplary short turn radius steering system mounted to a riding vehicle chassis, in accordance with an exemplary embodiment; 
           [0012]      FIG. 1C  illustrates a bottom view of an exemplary short turn radius steering system mounted to a riding vehicle chassis, in accordance with an exemplary embodiment; 
           [0013]      FIG. 2A  illustrates a perspective view of exemplary short turn radius steering system components mounted to an axle, in accordance with an exemplary embodiment; 
           [0014]      FIG. 2B  illustrates an exploded view of exemplary short turn radius steering system components mounted to an axle, in accordance with an exemplary embodiment; 
           [0015]      FIG. 3A  illustrates a perspective view of an exemplary pivot bracket, in accordance with an exemplary embodiment; 
           [0016]      FIG. 3B  illustrates a perspective view of an exemplary pivot bracket, in accordance with an exemplary embodiment; 
           [0017]      FIG. 4  illustrates a perspective view of an exemplary pivot bolt, in accordance with an exemplary embodiment; 
           [0018]      FIG. 5  illustrates a perspective view of an exemplary axle, in accordance with an exemplary embodiment; and 
           [0019]      FIG. 6  illustrates an exemplary riding lawn mower, in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The following description is of various exemplary embodiments only, and is not intended to limit the scope, applicability or configuration of the present disclosure in any way. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments including the best mode. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments, without departing from the scope of the appended claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Moreover, many of the manufacturing functions or steps may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. As used herein, the terms “coupled,” “coupling,” or any other variation thereof, are intended to cover a physical connection, an electrical connection, a magnetic connection, an optical connection, a communicative connection, a functional connection, and/or any other connection. 
         [0021]    For the sake of brevity, conventional techniques for mechanical system construction, management, operation, measurement, optimization, and/or control, as well as conventional techniques for mechanical power transfer, modulation, control, and/or use, may not be described in detail herein. Furthermore, the connecting lines shown in various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a short turn radius steering system. 
         [0022]    Principles of the present disclosure reduce and/or eliminate problems with prior short turn radius steering systems. For example, the present short turn radius steering system eliminates the need for a geared steering mechanism. The reliability of the short turn radius steering system is improved by reducing the wear to (and number of) steering system components. Similarly, the maintenance of the short turn radius steering system is reduced by reducing the number and/or complexity of steering system components. 
         [0023]    In various exemplary embodiments, with reference to  FIG. 1A ,  FIG. 1B , and  FIG. 1C , a short turn radius steering system  100  (“STRSS  100 ”) may be any mechanical or electro-mechanical system configured steer a vehicle. STRSS  100  may be configured to provide a short turn radius. For example, the steering system may be configured to provide a turn radius of approximately seven inches or less, when coupled to a vehicle. The vehicle may be a riding vehicle such as, for example, a riding lawnmower (as will be discussed herein as an example). STRSS  100  may comprise a steering assembly  110 , an axle  130 , a user input  140 , and a link  150 . STRSS  100  may be configured to couple to frame  160 . STRSS  100  may also be configured to couple to or otherwise interface with a housing and/or power train. 
         [0024]    STRSS  100  may further comprise an input transfer mechanism  170 . Input transfer mechanism  170  may be any mechanical or electro-mechanical device configured to conduct an input from user input  140  to linkage  150 . For example, input transfer mechanism  170  may be a gear including, for example, a sector gear, a rack, a linkage, or any other device suitable mechanism for transferring an input. 
         [0025]    User input  140  may comprise or otherwise couple to a shaft  142  and an engagement  144 . Shaft  142  may be a mechanical or electro-mechanical device configured to translate an input from user input  140  to transfer mechanism  170  and/or steering assembly  110 . Engagement  144  may be any mechanical or electro-mechanical device configured to interface with transfer mechanism  170 . For example, engagement  144  may be a gear including, for example, a spline gear, a pinion, and/or the like. In one embodiment, shaft  142  and engagement  144  may be coupled together as an assembly or may be formed as a single homogenous structure. Shaft  142  may be made of any suitable material that resists wear including, for example, metal, plastic, a composite material, a polymer material, and the like. Similarly, engagement  144  may be made of any suitable material that resists wear including, for example, metal, plastic, a composite material, a polymer material, and the like. 
         [0026]    Steering assembly  110  may couple to or mount on axle  130 . Steering assembly may also be coupled to link  150 . Steering assembly  110  may be controlled or configured to receive inputs from user input  140  through transfer mechanism  170 . For example, steering assembly  110  is coupled to link  150 . Link  150  is coupled to transfer mechanism  170 . User input  140  is configured to operatively engage transfer mechanism  170  through shaft  142  and engagement  144 . Steering assembly  110  may be configured to receive an input from user input  140 . The input may be translated from user input  140  along shaft  142  through engagement  144  to transfer mechanism  170 . Transfer mechanism  170  may actuate link  150  and provide the input to steering assembly  110 . 
         [0027]    In an exemplary embodiment, with reference to  FIG. 2A  and  FIG. 2B , steering assembly  210  may be any mechanical or electro-mechanical system configured to achieve a short turn radius in response to a user input. In particular, steering assembly  210  may be configured to achieve a turn radius of about 90 degrees. Steering assembly  210  may comprise a pivot bracket  212 , a bracket linkage  214 , and a spindle assembly  216 . Pivot bracket  212  may couple to spindle assembly via bracket linkage  214 . 
         [0028]    Steering assembly  210  may be configured to operatively couple to linkage  250 . Steering assembly  210  may also be rotatably coupled to and retained at axle  230  by bolt  226 . In one embodiment, pivot bracket  212  may be configured to rotate about bolt  226  in response to an actuation of linkage  250  (based on an input from user input  140  as shown in  FIG. 1A  and  FIG. 1B ). The rotation of pivot bracket  212  may be transferred through bracket linkage  214  to spindle assembly  216 , causing spindle assembly  216  to rotate in response to the actuation of linkage  250 . In response to linkage  250  moving in a direction parallel to the centerline of frame  160  (and perpendicular to axle  230 ), pivot bracket  212  transfers motion in a direction perpendicular to frame  160  (and parallel to axle  230 ). 
         [0029]    In an exemplary embodiment, spindle assembly  216  may be any structure suitably configured to retain and steer a wheel. Spindle assembly may comprise a spindle arm  217 , a stop  218  and a pitman arm  220 . Spindle arm  217  may comprise a first end and a second end. At the first end, spindle arm  217  may be configured to rotatably couple to a\the wheel. The wheel may be held in place by stop  218  on one side and by a suitable retainer (e.g. a retainer clip, a fastener, or any other suitable retainer) on the other side. Spindle arm  217  may be coupled to pitman arm  220 . Spindle arm  217  and pitman arm  220  may be coupled to one another. For example, spindle arm  217  may be coupled to pitman arm  220 , such that movement of pitman arm  220  causes rotation of spindle arm  217 . 
         [0030]    At the second end, spindle assembly  216  may be configured to rotatably couple to axle  230 . Spindle assembly  216  may be supported and/or retained within axle  230  by any suitable method. For example, spindle arm  217  may be supported and retained by a washer  222  and retained by a clip  224 . Spindle arm  217  may be configured with a retaining slot, such that when spindle arm  217  is coupled to axle  230 , the slot of spindle arm  217  may be engaged by clip  224 . 
         [0031]    Axle  230  may be configured with a grease fitting  232  (e.g. grease zerk  232 ). Grease fitting  232  may be any suitable structure for receiving and conducting a lubricant (e.g. grease, oil, and the like). When spindle arm  217  is coupled to axle  230 , a lubricant may be supplied through grease fitting  232  to supply a lubricant to spindle arm  217 , such that the amount of heat, wear, and debris is reduced between spindle arm  217  and axle  230 . The addition of the lubricant also provides for smoother rotation at the rotatable joint created when spindle arm  217  is couple to axle  230 . 
         [0032]    Spindle arm  217  may be made of any suitable material to carry a load and inhibit wear. For example, spindle arm  217  may be made of a metal (e.g. steel, titanium, an alloy, and the like), a composite, a polymer or any other suitable material, now known or hereinafter devised. Moreover, spindle arm  217  may be processed in any suitable fashion to inhibit wear and reduce failure. For example, spindle arm  217  may be hardened, stress relieved (e.g. by shot peening), coated (e.g. chromed), or subject to any other suitable processing, now known or hereinafter devised. 
         [0033]    In one embodiment and with continued reference to  FIG. 2A  and  FIG. 2B , pitman arm may be any structure suitable configured to transfer a force and resulting movement. As discussed above, pitman arm  220  may be coupled to spindle arm  217 . Pitman arm  220  may also be coupled to pivot bracket  212  through linkage  214 . Thus, where a force applied to linkage  250  causing linkage  250  to move, the movement (and associated force) are transferred to pivot bracket  212 , which rotates about bolt  226 . The motion and resulting force are applied to bracket linkage  214 , which causes movement of pitman arm  220  and, as such, causes movement of spindle arm  217 . As such, the linear motion of linkage  214  in a first direction is translated through pivot bracket  212  and causes linear motion in a second direction (e.g. perpendicular to the first direction) of bracket linkage  214 . As used herein, “linear” may include fully linear, substantially linear, partially linear, about linear, and/or certain non-linear deviations. 
         [0034]    Pitman arm  220  may be configured with a tab. As discussed above the STRSS  100  is configured to provide a turn radius of substantially 90 degrees. However, in order to insure that STRSS  100  does not allow the wheel of a riding vehicle to turn past 90 degrees, STRSS  100  may be configured with a stop. As such, the tab of pitman arm  220  may be configured and dimensioned such that it contacts and/or engages axle  230  to restrict steering assembly  210  from achieving a turn radius that is greater than 90 degrees when the wheel is turned toward the centerline of a riding vehicle. A turn radius that is greater than 90 degrees may make a riding vehicle difficult to control or may overstress steering components. 
         [0035]    Pitman arm  220  may be made of any suitable material to carry a load to, conduct a force, and inhibit wear. For example, pitman arm  220  may be made of a metal (e.g. steel, titanium, an alloy, and the like), a composite, a polymer or any other suitable material, now known or hereinafter devised. Moreover, pitman arm  220  may be processed in any suitable fashion to inhibit wear and reduce failure. For example, pitman arm  220  may be hardened, stress relieved (e.g. by shot peening), coated (e.g. chromed), or subject to any other suitable processing, now known or hereinafter devised. 
         [0036]    In an exemplary embodiment, with reference to  FIG. 3A  and  FIG. 3B , pivot bracket  312  may be any mechanism configured to translate motion. Pivot bracket may be monolithic or may be an assembly. Each of the top plate and the bottom plate may be configured with one of more coupling points (e.g. holes, threaded studs, and/or the like). Each of the top plate and the bottom plate may also be configured with a hole configured to accept a structure to facilitate rotation. For example, pivot bracket  312  may be configured with a top plate, a bottom plate, and a sleeve. The top plate may comprise a contour, such that, when coupled to the bottom plate there is a gap between the top and bottom plates in the region of the hole configured to accept a structure to facilitate rotation (e.g. pivot hole). The sleeve may be installed at the gap between the top plate and the bottom plate, in each of the top pivot hole and bottom pivot hole. As such, the sleeve acts as a support for a rotating structure such as, for example, a bolt, a spindle, and an axle, or the like. The sleeve may be welded or otherwise fixedly attached to the top plate and the bottom plate to add additional structural support in the region of the pivot holes. Alternatively, a bolt, a spindle, an axle or other suitable rotating structure may be installed directly into the pivot holes of the top plate and the bottom plate. 
         [0037]    Pivot bracket  312  may be configured with appropriate geometric proportions, such that Ackerman steering is achieved in a steering system employing pivot bracket  312 . Ackerman steering describes the situation where the inside wheel of a vehicle is turned sharper than the outside wheel to reduce or prevent scrubbing of the tires. Pivot bracket  312  may be configured to couple to a linkage at a first coupling point, a bracket linkage at a second coupling point and rotate about a structure (e.g. a bolt) at a rotation point. In one embodiment, there may be a linear distance between the first coupling point and the second coupling point of approximately 3.000 inches to 3.700 inches. There may also be a linear distance between the first coupling point and the rotation point of approximately 1.600 inches to 2.250 inches. There may also be a linear distance between the second coupling point and the rotation point of approximately 1.600 inches to 2.250 inches. 
         [0038]    Pivot bracket  312  may be made of any suitable material to carry a load, conduct a force, and inhibit wear. For example, pivot bracket  312  may be made of a metal (e.g. steel, titanium, an alloy, and the like), a composite, a polymer or any other suitable material, now known or hereinafter devised. Pivot bracket  312  may be produced using machined, cast, sintered, stamped (as individual components and assembled) parts, or parts made by any other suitable method. Moreover, pivot bracket  312  may be processed in any suitable fashion to inhibit wear and reduce or prevent failure. For example, pivot bracket  312  may be hardened, stress relieved (e.g. by shot peening), coated (e.g. chromed), or subject to any other suitable processing, now known or hereinafter devised. 
         [0039]    In an embodiment and with reference to  FIG. 4 , bolt  426  may be any fastener suitably configured to support a pivot bracket and facilitate rotation. For example, bolt  426  may comprise threads, a rotating structure comprising a surface suitable for rotation, and a head. The threads may be coupled to the rotating structure. The rotating structure may be coupled to the head, such that the head provides a shoulder for a rotating structure (e.g. pivot bracket  312 ). Bolt  426  may be drilled along its centerline to provide a hollow cavity accessible through the head at an opening. The opening may be configured with threads and configured to accept a grease fitting (e.g. a grease zerk). Bolt  426  may also be cross-drilled to provide a passage, which couples the hollow cavity to the rotating surface. The hollow cavity may be used to supply a lubricant to the rotating surface when bolt  426  is installed with a rotating structure such as, for example, a pivot bracket. The lubricant reduces wear, friction, and contamination between the rotating surface and the rotating structure. 
         [0040]    Bolt  426  may be made of any suitable material to carry a load and inhibit wear. For example, bolt  426  may be made of a metal (e.g. steel, titanium, an alloy, and the like), a composite, a polymer or any other suitable material, now known or hereinafter devised. Moreover, bolt  426  may be processed in any suitable fashion to inhibit wear and reduce or prevent failure. For example, bolt  426  may be hardened, stress relieved (e.g. by shot peening), coated (e.g. chromed, Teflon® coated, and the like), or subject to any other suitable processing, now known or hereinafter devised. 
         [0041]    In an exemplary embodiment and with reference to  FIG. 5 , axle  530  may be an structure suitable to carry the load of a riding vehicle and couple to a steering assembly. For example, axle  530  may be configured to carry a load of at least 2000 pounds when installed on a lawn tractor. Axle  530  may be configured with one or more spindle holes. The spindle holes may be configured to receive sleeves, bushing, bearings and/or the like. The spindle hole may also be configured to receive a spindle assembly. Axle  530  may also be configured with one or more steering system mounting holes. The steering system mounting holes may be configured with threads or other suitable coupling mechanisms. Axle  530  may be configured to couple to a steering system assembly with a fastener such as, for example, a bolt. 
         [0042]    Axle  530  may be made of any suitable material to carry a load and inhibit wear. Axle  530  may be monolithic. For example, Axle  530  may be made of a metal (e.g. steel, titanium, an alloy, and the like), a composite, a polymer or any other suitable material, now known or hereinafter devised. Axle  530  may comprise multiple components coupled together. Moreover, axle  530  may be cast, pressed, sintered, die-cut, machined, stamped, bonded, laminated, polished, smoothed, bent, rolled, molded, plated, coated, and/or otherwise shaped and/or formed via any suitable method and/or apparatus. Axle  530  may comprise various geometries for reducing weight. Moreover, axle  530  may comprise various geometries for reducing stress or bearing a load. 
         [0043]    In an exemplary embodiment, and with reference to  FIG. 6 , the STRSS  100  may be provided as a component of a mowing system. STRSS  100  may be coupled to or installed on a riding lawnmower  680 . Riding lawnmower  680  may be any lawnmower, lawn-tractor, or other suitable riding vehicle configured with a short turn radius. Riding lawnmower  680  may be configured to accept and obtain power from a motor. Moreover, the riding lawnmower may comprise user input  640 , frame  660 , a body  682 , wheels  686 , a cutting deck  688 , and various other components including, for example, gauges, lights, a fuel tank, a starting system, and/or the like. 
         [0044]    Riding lawnmower  680  may be configured with any type of cutting deck  686  including, for example, a center rear discharge cutting deck, a side discharge cutting deck, or any other suitable configuration now known or hereinafter devised. Moreover, riding lawnmower  680  may employ any accessory available or otherwise configured to interface with riding lawnmower  680  including, for example, a vacuum system, a bagging system, a blower system, or any other system now known or hereinafter devised. 
         [0045]    While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, elements, materials and components (which are particularly adapted for a specific environment and operating requirements) may be used without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure and may be expressed in the following claims. 
         [0046]    The present disclosure has been described with reference to various embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. When language similar to “at least one of A, B, or C” or “at least one of A, B, and C” is used in the claims or specification, the phrase is intended to mean any of the following: (1) at least one of A; (2) at least one of B; (3) at least one of C; (4) at least one of A and at least one of B; (5) at least one of B and at least one of C; (6) at least one of A and at least one of C; or (7) at least one of A, at least one of B, and at least one of C.