Abstract:
A preferred embodiment of a sulky includes a removable, adjustable foot platform, replaceable axles, and a hitch including stops that limit the extent of pitch, roll, and yaw motions between the sulky and the towing vehicle. A preferred embodiment also includes damping of motion in the yaw direction to reduce jerkiness in the ride.

Description:
This application is a continuation-in-part of, and incorporates by reference U.S. patent application Ser. No. 09/663,236, filed Sep. 15, 2000, which is a continuation-in-part of and incorporates by reference U.S. patent application Ser. No. 09/474,383, filed Dec. 29, 1999, now U.S. Pat. No. 6,145,855. It also claims priority from and incorporates by reference Provisional Application Ser. No. 60/211649, filed Jun. 15, 2000, and Provisional Application Ser. No. 60/218,884, filed Jul. 18, 2000, relating to a sulky. 
    
    
     BACKGROUND OF THE INVENTION 
     One of the problems with known sulkies is that they can give the user a rough ride. They may be used over rough terrain and can bounce the driver around with every bump in the terrain. 
     Another problem with known sulkies is that they wear out. They generally sit very low to the ground, and they hit curbs, rocks, stumps, and uneven ground, which tends to deform the entire sulky and to erode the edges of the sulky. Even contact with grass erodes the edges of the sulky over time. Many of these problems could be alleviated by raising the floor of the sulky, but then it would not function properly. The floor must be low, because the operator must have a low center of gravity for stability and in order to comfortably reach the controls of the vehicle that is pulling the sulky. The wear and tear of a sulky during normal use also may bend the shafts which support the sulky&#39;s wheels. 
     The mechanism for securing the sulky to the tow vehicle is also of importance for the sulky and its rider. Greater degrees of freedom of movement allow the sulky to better follow the terrain and to ride over an obstruction instead of crashing against it and deforming the sulky. The ability to ride over an obstruction, coupled with limits on how far the sulky will move when riding over such an obstruction, provide a more comfortable ride for the operator. Sulkies typically have a mounting plate or some other type of mounting bracket that mounts to the back of the vehicle, and there are linkages between the sulky and the mounting plate which permit the platform to shift relative to the vehicle. The following standard definitions will aid in the description of the types of relative motion between the platform and the vehicle: 
     1. Pitch motion means pivoting about a horizontal left-to-right axis. 
     2. Roll motion means pivoting about a horizontal front-to-back axis. 
     3. Yaw motion means pivoting about a vertical axis. 
     SUMMARY OF THE INVENTION 
     The present invention provides a sulky which has many of the advantages of Applicant&#39;s prior design, and it solves the problem of sulkies which erode and distort with wear and which give the rider a rough ride. 
     The sulky of the present invention includes a sturdy, rigid frame, which is at a relatively high elevation above the ground, and a foot platform which removably connects to the frame by bolts or other known removable connectors and projects down from the rigid frame to a lower elevation. With this design, if the sulky hits a curb, a rock, or a high spot in the ground, damage is confined to the foot plate, which can easily be removed and replaced. A preferred embodiment of the sulky also includes removable, replaceable axles, so that, if an axle is bent or otherwise damaged during use, it can readily be replaced. 
     The sulky of the present invention may be towed via a hitch mechanism which allows limited pitch, roll, and yaw motion of the sulky for the comfort and security of the operator as well as for the durability of the sulky. 
     The sulky of the present invention also may provide damping to take some of the vibrations out of the ride. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a sulky made in accordance with the present invention connected to a mower—the sulky&#39;s wheels being shown in phantom; 
     FIG. 2 is a front perspective view of the sulky of FIG. 1; 
     FIG. 3 is an exploded front perspective view of the sulky of FIG. 2; 
     FIG. 4 is a front view of the sulky of FIG. 1; 
     FIG. 5 is a side view of the sulky of FIG. 2; 
     FIG. 6 is a top view of the sulky of FIG. 2; 
     FIG. 7 is a perspective, broken away view of the sulky of FIG. 1 secured to a tow vehicle via a hitch; 
     FIG. 8 is a perspective, broken away, detail view taken along the line  8 — 8  and showing one of the brackets that mounts the sulky to the tow vehicle to permit rotation about a left-to-right horizontal axis to provide pitch motion; 
     FIG. 9 is a perspective, broken away view along line  9 — 9  of FIG. 7; 
     FIG. 10 is a view of the mower and hitch of FIG. 1 with the sulky removed; 
     FIG. 11 is a view of one of the mounting brackets of FIG. 1, looking toward the mower; 
     FIG. 12 is a view of the sulky and hitch of FIGS. 1-11 with a type of damper added; 
     FIG. 13 is a view taken along the line  13 — 13  of FIG. 12; 
     FIG. 14 is a top view of the sulky and hitch of FIG. 12 in a neutral position; 
     FIG. 15 is a top view of the sulky and hitch of FIG. 12 with the mower pivoted to the right relative to the sulky; 
     FIG. 16 is a top view of the sulky and hitch of FIG. 12 with the mower pivoted to the left relative to the sulky; and 
     FIG. 17 is a perspective view of the sulky and hitch of FIGS. 1-11 with a second type of damper added. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The sulky of FIGS. 1-11 has a frame  10  made of upper and lower hollow structural beams  12 ,  14  (in this embodiment the beams are made of square tubing, but they could also be made of channels, other formed beams, or other strong, structural members) that have been bent into a substantially U-shape. A vertical connector  16 , also made of a hollow structural beam, is welded between the upper and lower beams  12 ,  14  to maintain them a fixed distance apart. Axle supports  18  are mounted on the lower beams  14  and project outwardly, and stub axles  20  are mounted in those axle supports  18  and into the beam  14 . The axle supports  18  are welded to the outside of the beam  14 . As shown best in FIG. 3, the stub axles  20  include an inner flange  21  with outwardly-projecting bolts  23  welded to the flange  21 . Each stub axle  20  is mounted onto the frame  10  by inserting the axle from the inside of the frame member  14 , through an opening in the frame member  14 , and through the axle support  18 . The bolts  23  are extended through holes in the frame member  14 , and nuts on the outside of the frame member  14  are tightened onto the bolts  23  until the flange  21  of the stub axle abuts the inner surface of the frame member  14 , holding the stub axle in a fixed position on the frame member  14 . The wheels are then mounted on those axles  20 . This puts the bottom of the lower beam  14  about four inches off of the ground and the center of the axle  20  about 5 inches to 5.5 inches off the ground. 
     Upper and lower hitch plates  22  are fixed to the upper beam  12 , preferably by welding, putting them 12-14 inches off of the ground. The upper hitch plate  22  has a hole  25  that is aligned with a hole  25  in the lower hitch plate  22  to receive a vertical pin, which will be described later. 
     The foot platform  24  is a flat sheet of metal which has been formed so that the front and sides of the sheet are bent upwardly to connect to the lower frame member  14 . As shown in FIG. 3, the foot platform  24  has a plurality of sets of holes  27 , which are used to bolt the foot platform  24  to the lower frame member  14 . In this preferred embodiment, there is an upper set of holes  27  and a lower set of holes  27 . Two bolts  29  are inserted through the holes  27  and through the lower frame member  14  in the front, two on the left side, and two on the right side, and nuts are tightened onto the bolts  29  to hold the foot platform  24  in place. If the upper set of holes is used, the foot platform will be lower to the ground, and, if the lower set of holes is used, the foot platform will be mounted at a higher elevation relative to the ground. 
     While it is preferable to bolt the foot platform  24  onto the frame as shown here, the foot platform  24  may alternatively be tack welded to the frame or fastened to the frame by other known means. The foot platform  24  preferably projects downwardly approximately 1.5 to 2 inches from the frame, so that, when the bottom of the frame is 4 inches off the ground, the foot platform is 2-2.5″ off the ground. 
     Since the foot platform is made of a sheet material, while the frame is made up of much stronger structural beams, if the foot platform hits a curb or other obstruction, it may erode or deform, but it will not cause the frame to deform or otherwise cause damage to the frame. The foot platform  24  thus becomes an expendable item, which can readily be removed and replaced without having to replace the entire sulky. 
     Similarly, if the axles  20  are bent or otherwise damaged during use of the sulky, they can readily be removed simply by removing the associated wheel, removing the nuts mounted on the bolts  23 , and sliding the stub axle  20  out of the frame  14 . A new stub axle  20  may then be installed quickly and economically. 
     Looking at the front portion of the sulky, it can be seen that the upper and lower hitch plates  22  each have left and right outwardly-projecting arms  30 , which prevent the sulky from pivoting too far to the left or right relative to the mower or other towing vehicle. When the sulky is pivoting about the vertical axis of the pivot pin  32  relative to the towing vehicle, one of the arms  30  will abut the hitch mechanism and serve as a stop to prevent the sulky from pivoting too far about that vertical axis, thus limiting the yaw motion of the sulky. 
     Referring now to FIGS. 7-11, a linkage arrangement  33  includes mounting brackets  34 , a U-shaped mounting yoke or arm  36 , a connecting shaft  38 , and the upper and lower plates  22  fixed to the frame  12  of the sulky  10 . The L-shaped mower mounting brackets  34 , shown best in FIGS. 8 and 11, are secured to the rear of the self-propelled vehicle by bolts  60 , although they could also be connected by welding or other known means. Each mounting bracket  34  includes a pair of upper holes, a pair of central holes, and a pair of lower holes, through which the bolts  60  can pass to provide height adjustment. In this view, the bolts  60  pass through the central set of holes. Each mounting bracket  34  includes one leg  45  that lies flat against the rear surface of the vehicle  40  and another leg  46 , having left and right side walls  46 A,  46 B and at least a top web  47  connecting the left and right side walls  46 A,  46 B, to form an inverted U-shaped cross-section. In this embodiment, there is also a bottom web  47  connecting the left and right side walls so that the bracket can be reversed and used on the other side, and this adds a bottom closure to the U-shaped cross-section, giving the leg  46  a rectangular cross-section. The leg  46  projects rearwardly and defines left-to-right horizontal holes (not visible). The holes of the left and right brackets  34  are aligned and receive bolts  50 , that are used to mount the connecting arm  36  to the mounting bracket  34 . The connecting arm  36 , shown in FIG. 7, is a substantially U-shaped yoke, including two vehicle mounting ends  54  and a central portion  55  that mounts to the coupler shaft  38 . The vehicle mounting ends  54  of the connecting arm  36  define holes which are aligned with the respective holes in the bracket legs  46 A,  46 B, and the bolts  50  extend through the respective holes in the bracket legs  46   a ,  46 B and through the respective holes in the mounting ends  54  of the connecting arm  36  to pivotably mount the connecting arm  36  on the mounting brackets  34 . This permits the connecting arm  36  to pivot up and down (pitch motion) relative to the vehicle  40  about a left-to-right horizontal axis  52 . The upper web  47  of the bracket projection  46  serves as a stop, limiting the amount of pitch. Once the connecting arm  36  rotates upwardly relative to the brackets  34  a certain distance, it will contact the upper wall  47 , thereby limiting the pitch. The lower wall  47  also limits downward pitch of the sulky relative to the mower. 
     It should be noted that a spring  62  is mounted on each of the bolts  50 . The spring  62  wraps around its respective bolt  50  and has two free ends. The first free end  64  wraps under the arm  36 , and the second free end  66  extends into a slot  68  on the bracket  34 . The springs  62  bias the yoke  36  upwardly so that, when the sulky is removed from the yoke  36 , the springs  62  cause the yoke  36  to pivot upwardly relative to the mower, as shown in FIG. 10, leaving the yoke mounted to the mower but in a position in which it does not interfere with using the mower. 
     The front of the frame  12  is mounted to the connecting arm  36  through the coupler shaft or connecting shaft  38 , as shown in FIG.  7 . The coupler shaft  38  has a round cross-section in the forward portion  58  (See FIG.  9 ), which mounts to the connecting arm  36 , and it has a square cross-section in the rear portion  60 , which mounts between the plates  22  that are fixed to the frame  12 . There is a forward-to-rear directed tube  63  fixed on the central portion  55  of the connecting arm  3 , which receives the round cross-section forward portion  58  of the coupler shaft  38 . A vertical hole  61  in the round cross-section portion  58  of the coupler  38  receives a linch-pin  4 B, which retains the coupler shaft  38  on the connecting arm  3 . directed tube  63  fixed on the central portion  55  of the connecting arm  36 , which receives the round cross-section forward portion  58  of the coupler shaft  38 . A vertical hole  61  in the round cross-section portion  58  of the coupler  38  receives a linch-pin  64 B, which retains the coupler shaft  38  on the connecting arm  36 . A forward projection  65  of the tube  63  has two recesses  67  cut into its forward edge. The linch pin  64 B lies in those recesses  67 . As the connecting shaft  38  rotates about the front-to-back horizontal axis, in the roll direction, the linch-pin  64 B will contact the sides of these recesses  67 , thereby limiting the roll of the sulky  10  relative to the mower  40 . The hole  32 A in the rear portion of the coupler shaft  38  receives the pin  32 , which extends through the mounting plates  22 . 
     Thus, the mounting arrangement provides for pitch, roll, and yaw motion of the sulky relative to the towing vehicle, while also providing limits for all three types of motion. 
     Due to irregularities in the surface over which the sulky travels, there is a tendency for the sulky to continuously jerk back and forth about the vertical axis, making the ride uncomfortable for the driver and causing wear to the mechanism. FIGS. 12-16 show the sulky described above with a damping mechanism added to dampen this yaw motion. As shown in FIG. 12, the damping mechanism includes a fluid cylinder  70 , such as a hydraulic or pneumatic shock absorbing cylinder, mounted across the pivot joint that provides pivoting about the vertical pin  32 . The cylinder  70  is mounted from the yoke  36  of the hitch mechanism to the upper beam  12  of the sulky frame. As shown in FIG. 13, the first end of the cylinder  70  is mounted to the yoke  36  by means of a bracket  72 , which receives a pin  74 , and the first end of the cylinder  70  pivots about the axis of that pin  74 . 
     As shown in FIG. 12, a piston rod  76  projects out the other end of the cylinder  70 , and the free end of the piston rod  76  mounts to the sulky frame member  12  by means of a ball joint  78 . As shown in FIGS. 14-16, in order for there to be yaw motion between the sulky and the mower, the piston  76  must move in and out of its cylinder  70 . The cylinder  70  permits its fluid to bypass the piston head through an orifice (not shown but well known in the art). This dampens the jerky motion in the yaw direction, limiting the jerky motions that interfere with the driver&#39;s comfort, while continuing to permit yaw motion as well as the other motions provided by the hitch arrangement. 
     FIG. 17 shows a second type of damping mechanism. This rotary damper  80  also mounts across the vertical pivot joint. In this case, the damper  80  mounts on the upper plate  22  of the sulky and has a rotary arm  82  with a pivot axis aligned with the axis of the pin  32 . The other end of the rotary arm  82  mounts to the yoke  36  of the hitch by means of a ball joint  84 . Again, the damper  80  dampens motion in the yaw direction. While these two types of damping mechanisms are shown, it would be obvious to use other known types of dampers as well. 
     While jerky motion in the yaw direction is generally the most annoying to the driver, it will now be obvious to those skilled in the art that dampers could also be added to dampen the jerky motion or vibrations in other directions if desired. 
     It will be obvious to those skilled in the art that modifications may be made to the embodiments described above without departing from the scope of the present invention.