Abstract:
Provided is a sulky in which an operator platform is attached to a hitch arm through the interconnection of a vertical pivot tube and an essentially C-shaped clevis. The vertical pivot tube is secured to the clevis by a vertical pivot pin and hinge. The clevis counter balances and leverages the forces and loads that are applied to the vertical pivot pin while the sulky is in operation and, thereby, prevents the unnecessary anomalies and structural failures of the vertical pivot pin. Alternate embodiments detailing alternate clevis configurations are also presented.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to sulkies for self-propelled walk behind mowers and, more particularly, to a sulky that provides a clevis on the operator platform for attachment to a vertical pivot point on the hitch arm. The improvement improves control of the distributive forces and loads of the sulky and, thereby, prevents unnecessary structural failures in the vertical pivot point.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    Sulky devices have been used in conjunction with power mowers for many years and are, thus, well known in the prior art. Sulkies were originally used with mowers in a general trailer type fashion without the use of pivots. For example, U.S. Pat. No. 2,218,064 to G. A. Amsbury entitled “Riding Trailer” discloses a riding trailer which can be hitched to the rear of a lawn mower by two side bars. The riding trailer has a seat situated above a supporting wheel and the user is provided with foot controls to guide the movements of the lawn mower. A shortcoming of this invention is that the side bars prohibit rotation of the trailer with respect to the lawn mower and, thereby, do not permit use of the lawn mower to manipulate through narrow turns in a specific area.  
           [0003]    Later, sulkies were designed to incorporate the use of a vertical pivot point at the attachment of the sulky to the mower. For example, U.S. Pat. No. 5,118,123 to Betrock entitled “Standing/Sitting Lawn Mower Trailer” discloses a system in which a trailer hitches to a self-propelled lawn mower. The trailer has an elongated towbar which is adjusted and locked to the lawn mower. Similarly, U.S. Pat. No. 5,388,850 to Simone entitled “Convertible Sulky” discloses an H-shaped support wheelbase frame member with a T-shaped mower attachment frame. The H-shaped support wheelbase is attached to the mower through a ball-hitch fixture on the frame. A shortcoming of these devices is that by placing the vertical pivot point so close to the mower, the turning radius of the sulky with respect to the mower is limited since the sulky swings out from behind the mower during a turn, often at a distance greater than an operator is able to control. Thus, devices having an elongated towbar or frame that pivot at the mower/sulky junction only do not permit rotation of the trailer or sulky with respect to the lawn mower and, therefore, neither the trailer nor the sulky permit the user to maneuver through a narrow or small turning radius.  
           [0004]    A vertical pivot point located at the attachment of the sulky to the lawn mower provides a sulky that is more stable for the operator, but less maneuverable, as exhibited by the patents in the preceding paragraph. Conversely, the reverse is true. A vertical pivot point located along the hitch arm of the sulky and not directly with the lawn mower provides a sulky that is less stable, but more maneuverable.  
           [0005]    To accommodate increased maneuverability, sulkies have been designed with vertical pivot points along the attachment arms to enable the lawn mower to maneuver through a narrow or small turning radius or as desired by the user. For example, U.S. Pat. No. 5,004,251 to Velke et al. entitled “Sulky Apparatus Attachable To A Self-Propelled Power Mower” discloses a sulky apparatus that is attachable to a self-propelled power mower to transport an operator in the standing position. The sulky provides a first arm connected to the lawn mower through a horizontal pivot point and a second arm connected to the operator platform. The first arm and the second arm are connected through a vertical pivot point permits movement of the operator platform about the vertical pivot point. In this fashion, the lawn mower can better navigate tight turns.  
           [0006]    Likewise, U.S. Pat. No. 5,810,371 and U.S. Pat. No. 5,882,020 to Velke entitled “Sulky Device With Triple Pivot Attachment To Mower” disclose the sulky in U.S. Pat. No. 5,004,251 with a third pivot point located at the connection of the second arm to the operator platform and an additional wheel to form a two-wheeled sulky. The third pivot point operates along the horizontal axis and theoretically provides a storage position for the operator platform with respect to the lawn mower.  
           [0007]    Although these sulkies permit operation in small areas, they do not, particularly in single wheel sulkies, leverage the forces and loads on the vertical pivot point as applied by the weight of the operator and torque of the mower. Therefore, the vertical pivot point is susceptible to uncontrollable bending or structural failure of the vertical pivot point. Also, the uncontrollable bending or structural failure requires that the weight of the operator must be limited to reduce the counterbalancing forces on the vertical pivot point. Therefore, these sulkies are not practical for all consumers.  
           [0008]    Another shortcoming of these sulkies is that the vertical pivot point permits 360° rotation about the first arm. The inherent danger with the free rotation is that a user is vulnerable to injury if positioned on the operator platform as the second arm rotates the operator platform to cross under the first arm.  
           [0009]    In the prior art designs, placing the vertical pivot point away from the lawn mower and closer to the operator platform leads to unnecessary torquing which, in turn, causes premature sulky failure. Further, the design of these sulkies is suited best in a two wheel design as the torque forces are exacerbated in a single wheel sulky since the operator must balance himself In spite of this problem, many operators prefer single wheeled sulkies over two wheeled sulkies because they maneuver better.  
           [0010]    Thus, there is a need and there has never been disclosed a sulky that provides counter balance and reduction of the forces and loads as applied to the vertical pivot point to prevent the unnecessary structural anomalies and failures in the vertical pivot point.  
         OBJECTS OF THE INVENTION 1 a  
         [0011]    It is the primary object of the present invention to prevent unnecessary structural anomalies and failures in the vertical pivot point of sulkies. A related object of the present invention is to reduce the forces and loads applied to the vertical pivot point that result from the weight of the operator and the torque supplied by the operation of the lawn mower. This is provided for in an operator platform with a clevis to affix to a vertical pivot point on a hitch arm. The clevis is adapted to receive the vertical pivot point on the hitch arm and to coact with the vertical pivot point to secure a hinge and, thereby, attach the operator platform to the hitch arm.  
           [0012]    Another related object of the present invention is to provide a means to counter balance the forces and loads applied to the vertical pivot point.  
           [0013]    Still another object of the invention is to permit the use of the sulky device by heavier operators.  
           [0014]    Still another object of the invention is to prohibit unlimited rotation of the operator platform about the vertical pivot point to provide increased safety to the operator.  
           [0015]    Still another object of the invention is to provide an increased useful life for the vertical pivot point. A related object of the invention is to reduce the costs associated with repairing a damaged vertical pivot point. A further related object of the invention is to provide the user with a more reliable sulky.  
           [0016]    Other objects of the present invention will become more apparent to persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying drawings.  
         SUMMARY OF THE INVENTION  
         [0017]    The objects of the present invention are provided for in a sulky having an improved attachment interrelationship between an operator platform and a hitch arm that connects the sulky to a self-propelled walk behind lawn mower. The operator platform is attached to the hitch arm through a vertical pivot point and a generally C-shaped clevis.  
           [0018]    The hitch arm is connected at one end to the rear of a mower. The opposite end of the hitch arm is fitted with a vertical pivot point. The vertical pivot point comprises a vertical pivot tube and a corresponding vertical pivot pin. Preferably, the clevis has a top support member, a bottom support member, and an operator platform support member. The top and bottom support members extend essentially horizontally from the front of the operator platform and essentially parallel to one another at a predetermined vertical distance from one another. The vertical pivot point is inserted into the opening of the space created by the vertical distance between the top and bottom support members, the vertical pivot point then being secured to the clevis by a vertical pivot pin that is inserted into holes found in the top support member, vertical pivot tube, and bottom support member.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The Description of the Preferred Embodiment will be better understood with reference to the following figures:  
         [0020]    [0020]FIG. 1 is a side elevational view of the sulky device attached to the rear of a self-propelled walk behind lawn mower.  
         [0021]    [0021]FIG. 2 is a side perspective view of the sulky device depicting the operator platform and the clevis member.  
         [0022]    [0022]FIG. 3 is a side partial cross-sectional view of the sulky device as assembled to a hitch arm and illustrating the attachment of the clevis member.  
         [0023]    [0023]FIG. 4 is a bottom view of the sulky device illustrating the clevis member and rotation of the hitch arm with respect to the operator platform.  
         [0024]    [0024]FIG. 4A is a bottom view of the sulky device illustrating the clevis member in a triangle configuration.  
         [0025]    [0025]FIG. 4B is a bottom view of the sulky device illustrating the clevis member in a crescent configuration.  
         [0026]    [0026]FIG. 5 is a side partial cross-sectional view of the sulky device illustrating the clevis as extending directly from the operator platform.  
         [0027]    [0027]FIG. 6 is a side partial cross-sectional view of the sulky device illustrating an alternate embodiment in which the clevis is a single support member extending from the operator platform into a slot located within the vertical pivot point.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]    Turning first to FIG. 1, there is illustrated a sulky  10  attached to a self-propelled walk behind lawn mower  12 . Lawn mower  12  may be any type of mower with which a sulky  10  may be used. Sulky  10  includes a hitch arm  16  which has a distal end  20  and a proximal end  22 . Hitch arm  16  is affixed to lawn mower  12  by a hitch  14  at proximal end  22 . Distal end  20  includes a vertical pivot point  28  and is connected to operator platform  18  by a clevis  24 .  
         [0029]    In the preferred embodiment, clevis  24  comprises a top support member  25 , a bottom support member  27 , and an operator platform attachment member  29  co-formed into a generally C-shaped member. Top support member  25  and bottom support member each have vertical pin insertion holes  31 ,  31   a  (FIG. 3) through their entire thickness at an essentially vertical angle. In this embodiment, operator platform attachment member  29  of clevis  24  is welded to operator platform  18 . Alternatively, clevis  24  may be attached to operator platform  18  by any other means, such as bolting, that would secure clevis  24  to operator platform  18  for operable use.  
         [0030]    In an alternate embodiment, top support member  25  and bottom support member  27  may be attached directly to operator platform  18  (See FIG. 5). So long as top support member  25  and bottom support member  27  are securely bonded to operator platform  18 , the configuration is not critical to the inventive device.  
         [0031]    Also, when viewed from the top, top support member  25  and bottom support member  27  may be configured in a variety of shapes such as a square or rectangle (See FIG. 4), a triangle (See FIG. 4A), or a crescent shape (See FIG. 4B). The triangle shape may be the most economical because it is easy to produce and contains the least amount of material, yet provides a strong support.  
         [0032]    Vertical pivot point  28  comprises a vertical pivot tube  30  and a vertical pivot pin  32  with vertical pivot tube  30  affixed to distal end  20  of hitch arm  16 . In the typical sulky, vertical pivot tube  30  is welded to hitch arm  16 . Vertical pivot tube  30  is rotatably mounted to clevis  24  and provides the connection of hitch arm  16  to operator platform  18 . The details of the attachment of vertical pivot tube  30  to clevis  24  are discussed more fully below.  
         [0033]    In yet another embodiment, a single support member  37  extends outwardly from the front of operator platform  18 . In this embodiment, single support member  37  may rotatably attach to vertical pivot point  28  of hitch arm  16  which includes a slot  39  found along the length of vertical pivot tube  30  (See FIG. 6). In the single support member embodiment, the slotted vertical pivot tube, as depicted in FIG. 6, provides the greatest strength and least risk of malfunction since the forces and loads on the vertical pivot pin  32  are more evenly distributed along its length than in a top or bottom mount configuration of the prior art designs. Likewise, the forces and loads on the vertical pivot tube  30  are also more evenly distributed.  
         [0034]    Operator platform  18  is generally used by an operator in the standing position. Operator platform  18  has feet platforms  34  and  36  (FIG. 2) that are separated by a wheel  38 . While the preferred embodiment is directed to a single wheel sulky, the principals involved work as well with multiple wheeled sulkies. Accordingly, operator platform  18  may have two wheels  38  with the feet platforms  34  and  36  located between wheels  38 . For operator safety, wheel  38  should be covered by a fender  40 .  
         [0035]    Turning to FIG. 2, sulky  10  is depicted as detached from mower  12 . Operator platform  18  with feet platforms  34  and  36  and wheel  38  are illustrated. Wheel  38  is located in the center of operator platform  18  to support the weight of the operator and stabilize the balance of the operator while sulky  10  is in use.  
         [0036]    In FIG. 3, the attachment of operator platform  18  to hitch arm  16  through the interconnection of vertical pivot point  28  and clevis  24  is illustrated. Hitch arm  16  has an arm height  50 . Clevis  24  has an inner clevis height  54  which is slightly larger than tube height  52 .  
         [0037]    Vertical pivot tube  30  has a cylindrical bore  33  through its center to receive and house vertical pivot pin  32 . Top support member  25  and bottom support member  27  are essentially parallel to one another and at a predetermined vertical distance such that vertical tube  30  can be placed between them and move freely.  
         [0038]    To connect vertical pivot tube  30  to clevis  24 , vertical pivot tube  30  is inserted between top support member  25  and bottom support member  27  until the cylindrical bore  33  of the vertical pivot tube  30  is aligned with hole  31  of top support member  25  and hole  31   a  of bottom support member  27 . Vertical pivot pin  32  is then inserted through hole  31  of top support member  25 , bore  33  of vertical pivot tube  30 , and hole  31   a  of bottom support member  27 . Vertical pivot pin  32  has a pin height  70  which is slightly larger than inner clevis height  54  and hole height  64  combined.  
         [0039]    Vertical pivot pin  32  is reversibly secured by a pin securing means  66 , for example a cotton pin, that is inserted through hole  68  to secure vertical pivot pin  32  in position. Pin securing means  66  secures vertical pivot pin  32  in position and prevents vertical pivot pin  32  from exiting through holes  31 ,  31   a  or bore  33 .  
         [0040]    Vertical pivot point enables operator platform  18  to rotate horizontally with respect to hitch arm  16 . The details of the rotation are discussed below with respect to FIG. 4.  
         [0041]    During operation of mower  12 , vertical pivot point  28  absorbs forces and loads supplied by the torque of mower  12  as mower  12  traverses aberrant terrain and the weight of the operator and operator platform  18  as operator platform  18  also adjusts to the same aberrant terrain. Clevis  24  counterbalances the forces and loads absorbed by vertical pivot point  28 . This counterbalance effectively prevents vertical pivot point  28  from uncontrollable bending or experiencing structural failure from the inherent forces and loads applied during operation of sulky  10 . By controlling the inherent forces and loads, clevis  24  effectively provides a longer useful sulky life and a sulky that is capable of use by heavier operators of 200 pounds or more.  
         [0042]    In FIG. 4, horizontal pivot point  26  of hitch arm  16  is illustrated as attached to hitch  14 . Hitch  14  has a hitch bar  74  that extends perpendicular from hitch  14 . Hitch bar  74  contains a hitch tube  76  to receive a horizontal pivot pin  78 . Horizontal pivot point  26  has parallel members  80  each with member orifices  82  to receive horizontal pivot pin  78 . Horizontal pivot pin  78  is secured by hitch bar  74  and a brace  84  on parallel members  80 . Horizontal pivot point  26  and hitch bar  74  permit hitch arm  16  to rotate vertically about horizontal pivot pin  78  to permit easier use of sulky  10  on aberrant terrain when being pulled by mower  12 . Alternatively, sulky  10  may be designed without horizontal pivot point  26  and instead attached directly to hitch  14 .  
         [0043]    In the preferred embodiment, upon rotation of hitch arm  16  along rotation A about vertical pivot point  28  (FIG. 3) with respect to operator platform  18 , attachment member  29  (FIG. 3) of clevis  24  contacts hitch arm  16  to prevent hitch arm  16  from rotating beyond approximately 190 degrees about operator platform  18 . Preferably, hitch arm  16  and operator platform  18  form contact angle  72  with respect to each other when engaged. In the preferred embodiment, contact angle  72  is approximately a 190 degree angle in complete rotation. Although, depending on the design of hitch arm  16 , vertical pivot point  28  and operator platform  18  have a contact angle  72  that may be greater or less than 190 degrees. The engagement of operator platform  18  and hitch arm  16  effectively prohibits operator platform  18  from rotating under hitch arm  16  and, thereby, prevents injury to the operator on the operator platform  18 .  
         [0044]    Thus, there has been provided a sulky that uses a clevis to attach the vertical pivot point of the hitch arm to the operator platform and, thereby, eliminate the uncontrollable anomalies or structural failures in the vertical pivot point that result from the inherent forces and loads applied by the mower and operator during operation of the sulky. While the invention has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it in intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.