Patent Publication Number: US-8528915-B2

Title: Rider platform for self-propelled vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Provisional U.S. Patent Application Ser. No. 60/609,206, entitled “RIDER PLATFORM FOR SELF-PROPELLED VEHICLE,” having a filing date of Sep. 10, 2004, U.S. patent application Ser. No. 11/222,279, entitled “RIDER PLATFORM FOR SELF-PROPELLED VEHICLE” having a filing date of Sep. 8, 2005, issued as U.S. Pat. No. 7,458,588 on Dec. 2, 2008, and U.S. patent application Ser. No. 12/323,138, entitled “RIDER PLATFORM FOR SELF-PROPELLED VEHICLE” having a filing date of Nov. 25, 2008, all of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Skid steer loaders have become common in construction and materials handling because of their relatively small size, which lends great versatility and maneuverability. However, in some instances, even these skid steer loaders are too large. Accordingly, a smaller version of these loaders has been developed, which are generally known as self-propelled utility vehicles as well as walk-behind loaders, compact utility loaders, or mini skid steer loaders. These self-propelled vehicles are narrower, and more nimble, allowing the operator to negotiate tighter spaces. In these vehicles, instead of the operator sitting in the vehicle in a seat, the operator walks behind the loader and guides the loader with hand controls located at a rear of the loader. With the controls, the operator controls movement of the loader as well as operation of any attachments such as a loader, auger, bucket, etc. These walk-behind loaders also permit quick access and exit from control of the loader, since the operator need not sit or stand in an enclosure of the loader to operate the loader. 
     However, since the operator no longer rides on the loader, the operator may be forced to walk through substances, such as mud, dirt, or other materials over which the loader travels. In addition, when moving over uneven terrain or steep terrain, the operator is required to maintain stable footing and exert energy to keep up with the loader. This situation can impair the operator&#39;s ability to maintain their hands and arms at the controls of the loader, thereby diminishing the function of the self-propelled loader. Fatigue caused by this constant walking also can further impair hand control of the loader in a walk-behind position. 
     For these reasons, neither conventional skid-steer loaders nor conventional self-propelled utility vehicles meet all the challenges faced by operators of these vehicles. 
     SUMMARY 
     A self-propelled vehicle comprises a frame and a platform pivotally mountable to a rear portion of the vehicle frame. The platform is pivotally movable between a first position in which the platform extends generally horizontally from the rear portion of the frame to support a rider during operation of the vehicle, and a second position in which the platform is removably secured in a generally upright position adjacent the rear portion of the frame to enable walk-behind operation of the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view schematically illustrating a self-propelled vehicle with a rider platform in an in-use position, according to an embodiment of the present invention. 
         FIG. 2  is a side view schematically illustrating a self-propelled vehicle with a rider platform in a storage position, according to an embodiment of the present invention. 
         FIG. 3  is a side view schematically illustrating a self-propelled mower with a pivoting rider platform, according to an embodiment of the present invention. 
         FIG. 4  is a perspective view of a self-propelled vehicle with a rider platform in a storage position, according to an embodiment of the present invention. 
         FIG. 5  is partial side view of a self-propelled vehicle with the rider platform in an in-use position, according to an embodiment of the present invention. 
         FIG. 6  is partial side view of the embodiment of  FIG. 5  with the rider platform in an intermediate position, according to an embodiment of the present invention. 
         FIG. 7  is partial side view of the embodiment of  FIG. 5  with the rider platform in a storage position, according to an embodiment of the present invention. 
         FIG. 8  is enlarged perspective view of a pivot mechanism and stop mechanism of a platform system, according to an embodiment of the present invention. 
         FIG. 9  is an enlarged perspective view of a pivot mechanism and variably positionable stop mechanism of a platform system, according to another embodiment of the present invention. 
         FIG. 10  is schematic illustration of the variably positionable stop mechanism of the embodiment of  FIG. 9 , according to an embodiment of the present invention. 
         FIG. 11  is a side view of a platform system with an alternative mounting frame, according to an embodiment of the present invention. 
         FIG. 12  is a side view of a rider platform in an in-use position, according to another embodiment of the present invention. 
         FIG. 13  is an enlarged perspective view of a pivot mechanism and a stop mechanism of the embodiment of  FIG. 12 , according to an embodiment of the present invention. 
         FIG. 14  is a side view of the embodiment of  FIG. 12  with the rider platform in an intermediate position, according to an embodiment of the present invention. 
         FIG. 15  is a side view of the rider platform of the embodiment of  FIG. 12  in a storage position, according to an embodiment of the present invention. 
         FIG. 16  is a side view of the rider platform of the embodiment of  FIG. 12  in an in-use position with an alternative mounting frame, according to an embodiment of the present invention. 
         FIG. 17  is a perspective view of a platform system, according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, references made to the accompanying drawings, which form a part hereof, and which is illustrated by way of illustrations specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “front,” “back,” etc., is used with reference to the orientation of the figures(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     Embodiments of the invention enable convertible use of self-propelled vehicles, such as mini skid steer loaders or compact utility loaders, in a walk-behind mode or in a ride-on-platform mode. 
       FIG. 1  is a side view schematically illustrating a self-propelled vehicle  10 , according to an embodiment of the present invention. As shown in  FIG. 1 , self-propelled vehicle  10  comprises vehicle frame  12  including front portion  13 , rear portion  14 , mover  15 , and controls  16 . In one embodiment, a tool  18  is removably attached to front portion  13  of vehicle frame  12 . Mover  15  comprises powered wheels or tracks for moving vehicle  10  across ground G. 
     A platform  20  is mounted to rear portion  14  of vehicle frame  14  via pivot mechanism  22 . Platform  20  defines an elevated operator zone  23  at rear portion  14  of vehicle  10  for operating controls  16 . In the in-use position shown in  FIG. 1 , the operator can ride on the platform  20  above the ground (shown by distance H 1 ) while operating the controls  16  of vehicle  10 . 
       FIG. 2  is a side view of the embodiment of  FIG. 1 , except showing platform  20  in a storage position. In the storage position, platform  20  is pivoted via pivot mechanism  22  into a generally upright position and secured into close proximity to the rear portion  14  of the vehicle  10  to enable walk-behind use of vehicle  10 . In the storage position, platform  20  enables unobstructed pedestrian operation of the self-propelled vehicle  10  in the walk-behind mode. 
     This pivotally mounted platform  20  can be constructed as a permanent feature of the self-propelled vehicle  10  or as retro-fit feature that is attached to a self-propelled vehicle not having a rider platform. 
     Riding on the platform  20  introduces greater feedback between movement of the vehicle/loader relative to the operator, since the platform  20  enables an operator to sense vehicle movement through their legs and feet, as well as through their hands at the controls  16 . In addition, platform  20  places the operator at a greater height relative to the vehicle  10 , enabling better line-of-sight to tool  18  (e.g., a loader bucket, auger, pallet fork, etc) at front portion  13  to enhance operator control of tool  18  and/or vehicle  10 . Providing a ride-on platform  20  also enables the operator greater vision of the terrain to spot obstacles, people, and any objects to be manipulated by the vehicle  10 . The operator also experiences less fatigue when riding on platform  20  than in a walk-behind mode since they are carried by the vehicle  10 . Accordingly, many aspects of operating a self-propelled vehicle  10  are enhanced via the elevated operator zone  23  created by the rider platform  20 . 
     Providing a ride-on platform  20  also enables the weight of the operator standing on the platform  20  to act as an additional counterweight on a self-propelled vehicle  10 , thereby increasing the effective weight-bearing capacity of the vehicle at the front portion  13  of the vehicle frame  12 . The weight of the operator also contributes to the function of the platform  20  as an anti-tipping measure, thereby limiting the extent of rearward rotation of vehicle  10 . In particular, the additional effect of the long moment arm relative to a gravitational center of the vehicle (i.e., a fulcrum about which the front and rear of the vehicle tip relative to one another) that is provided by the operator standing on platform  20  multiplies the effect of the operator-provided counter-weight. Moreover, since the operator is not harnessed to a seat, the operator can quickly hop-on or hop-off the platform  20  to quickly add or subtract the counter weight. For example, the lifting capacity at the front portion  13  of the vehicle  10  can be increased when the self-propelled vehicle  10  is on a level surface (or a declining surface) by the operator hopping on the platform  20  at the rear portion  14  of the vehicle  10  to add a counter weight. In another example, when the vehicle  10  is on an inclining surface, and the front portion  13  of the vehicle is not carrying a load, then the operator can hop off the platform  20  to limit the extent of backward tipping of the vehicle. 
     Providing a ride-on platform  20  also enhances tipping control of the vehicle by providing a structure capable of striking the ground, thereby limiting backward rotation of the vehicle  10  when the vehicle experiences loads or terrain that would otherwise cause the front portion  13  of the vehicle to rise in elevation significantly relative to the rear portion  14  of the vehicle. In one embodiment, rollers are attached to the vehicle frame (via a mounting frame of the platform) adjacent the rear portion  14  of the vehicle  10  to act an additional anti-tipping measure. 
     In one embodiment, pivot mechanism  22  also comprises a latch mechanism. The pivot mechanism  22  supports pivotal movement of the platform  20  relative to the rear portion  14  of the vehicle frame  12  between a generally horizontal in-use position ( FIG. 1 ) and a generally upright storage position ( FIG. 2 ). In one aspect, in the storage position of the platform, the latch mechanism is engaged to releasably secure platform  20  relative to rear portion  14  of the frame  12  to maintain platform  20  in a generally upright position, thereby enabling walk-behind use. In the in-use position, the latch mechanism is disengaged to release platform  20  relative to rear portion  14  of the frame  12 , thereby allowing platform  20  to pivot downward to rest in a generally horizontal in-use position to receive a rider. To return the platform  20  to the storage position ( FIG. 2 ), the platform  20  is pivotally rotated upward via pivot mechanism  22  toward the frame  12  until the latching mechanism is engaged to releasably secure the platform  20  relative to rear portion  14  of the frame  12 . 
     Additional components and/or alternative components also comprise other embodiments of the invention. In one embodiment, the platform  20  is height-adjustable in the in-use position enabling the rider to be positioned at different heights relative to the controls  16  mounted at the rear portion  14  of the self-propelled vehicle  10 . In another embodiment, a shock-absorbing connecting link is interposed between the platform  20  and the vehicle frame  12  to absorb the machine vibration to the operator when the platform  20  is in the riding in-use position, thereby minimizing operator fatigue. In another embodiment, the platform  20  includes a padded portion at its rear end and/or its sides to protect an operator or to protect nearby equipment and surroundings from contact with edges or corners of the platform. The padded portion comprises one or more layers or coatings of plastic, rubber, foam, or other cushioning materials. The padded portion also can comprise a non-slip surface. 
     Embodiments of the present invention also comprise variations on mechanisms for pivotally attaching a rider platform to a self-propelled vehicle. In one embodiment, platform  20  is mounted with two pivot mechanisms, with the pivot mechanisms located on opposite sides of the platform  20 . In another embodiment, the pivot mechanism is located adjacent a central region of the platform between two opposite sides of the platform. In this embodiment, a single link pivotally connects the platform  20  to a rear portion  14  of the frame of the self-propelled vehicle  10  and includes a locking mechanism to enable securing the platform in either a generally horizontal in-use position or a generally upright storage position and to enable pivotal movement of the platform between the in-use and the storage position. 
     In one embodiment, the pivot mechanism and its associated latch mechanism are located adjacent each other at a side portion of the platform. In other embodiments, the pivot mechanism and its associated latch mechanism are located in separate positions from each other. In one aspect, one or more pivot mechanisms are located adjacent a side portion of the platform while one or more latch mechanisms are located adjacent a center portion of the platform. In another aspect, one or more pivot mechanisms are located adjacent a central portion of the platform while one or more latch mechanisms are located adjacent a side portion of the platform. 
     Embodiments of the invention enable a walk-behind use of the vehicle  10  without complete removal of platform  20  from vehicle  10  because of the low-profile of platform  20  in its storage position. Accordingly, in one embodiment, platform  20  supports an operator without any additional wheels or rollers mounted at an outer end of platform or underneath platform  20 . However, in other embodiments, wheels, rollers, or skids are mountable at an outer end or bottom surface of platform  20  while still maintaining a low-profile of platform  20  in its storage position. 
       FIG. 3  is a side view illustrating a self-propelled landscaping vehicle  25 , such as a mower. As shown in  FIG. 3 , vehicle  25  comprises frame  26 , handle  27 , and controls  28 . Vehicle  25  also comprises platform  20  which is movable via pivot mechanism  22  between an in-use position  20 B and a storage position  20 A. Platform  20  and pivot mechanism  22  of  FIG. 3  comprise substantially the same features and attributes as platform  20  and pivot mechanism  22  of  FIGS. 1-2 , except for the replacement of vehicle  10  with vehicle  25 . 
     These embodiments of the invention, and additional embodiments of the invention, are described in greater detail in association with  FIGS. 4-17 . 
       FIG. 4  is a perspective view of a platform system  40  of a self-propelled vehicle  30 , according to an embodiment of the invention, including a rider platform  41  in a storage position.  FIGS. 5-7  are side views of the platform system  40  of  FIG. 4  showing the rider platform in an in-use position, an intermediate position, and a storage position, respectively, according to one embodiment of the invention. Various aspects and functions of platform system  40  are described together in association with  FIGS. 4-7 , which illustrate the same components in different views. 
     As shown in  FIG. 4 , vehicle  30  includes vehicle frame  31 , mover  32 , lower portion  33 , rear portion  34  having rear surface  35  and a front portion substantially similar to front portion  13  in  FIG. 1 . The front portion enables removably securing various attachments such as loader buckets, pallet forks, augers, mowers, etc. Mover  32  comprises a drive mechanism such as power-driven wheels, tracks, etc. Vehicle  30  also includes control module  38  positioned at rear portion  34 . Platform system  40  is removably attachable to vehicle frame  31 , and once attached, enables pivotal movement of platform  41  between an in-use position (shown in  FIG. 5 ) and a storage position (shown later in  FIG. 7 ). In the in-use position, platform system  40  enables ride-on operation of vehicle  30 . In the storage position, platform system  40  enables walk-behind operation of vehicle  30 . 
     Platform system  40  defines platform  41  and is mounted to vehicle frame  31  via mounting bracket  42 . Platform  41  is sized and shaped to support an operator standing upright, with some ability to maneuver their feet on the platform. As shown in  FIG. 4 , platform  41  is a generally rectangular shaped member. Platform  41  comprises inner end  50 , outer end  52 , first side  54 , second side  56 , upper support surface  58  ( FIG. 5 ), and lower surface  59 . Platform system  40  includes, for mounting on each of the opposite sides  54 , 56  of platform  41 , a pivot mechanism  44  and latch mechanism  46 , as well as a mounting frame  42  to connect platform  41  to vehicle frame  31 . The respective pairs of pivot mechanisms  44 , latch mechanisms  46 , and mounting frames  42  are laterally spaced apart at the rear portion  34  of vehicle by a distance generally corresponding to a width of rear portion  34 . In another embodiment, the structure and function of mounting frame  42  is provided by vehicle frame  31  so that pivot mechanism  44  and latching mechanism  46  are directly coupled from platform  41  to vehicle frame  31  without a mounting frame  42 . 
     Self-propelled vehicle  30  including platform system  40  is described and illustrated in greater detail in association with  FIGS. 4-17 . 
     As shown in  FIGS. 4-7 , mounting frame  42  is sized and shaped to enable pivot point  80  of pivot mechanism  44  to be located as close as possible to vehicle frame  31  with enough clearance for inner end  50  of platform  41  to rotate relative to rear surface  35  of vehicle frame  31  and for support surface  58  of platform  41  to be closely adjacent rear surface  35  of vehicle frame  31 , when platform  41  is in its storage position. In one aspect, as shown in  FIGS. 4-5 , mounting frame  42  includes first portion  70  and second portion  71 . First portion  70  of mounting frame  42  is fastened to rear surface  35  of vehicle frame  31  and second portion  71  extends outwardly from first portion  70  at an angle (e.g., 90 degrees) to enable mounting of pivot mechanism  44 , latch mechanism  46 , roller  90  and any other associated components of attachable platform  40  relative to mounting frame  42 . 
       FIG. 4  also reveals aspects of pivot mechanism  44 , including but not limited to, pivot arm  60 , pivot point  80 , and stop mechanism  94 . As shown in  FIG. 4 , pivot arm  60  includes first portion  62  and second portion  64  forming a generally obtuse angle relative to each other at junction  66 . First portion  62  of each pivot arm  60  is mounted to a respective first and second side ( 54 ,  56 ) of platform  41 . Second portion  64  of each pivot arm  60  is pivotally mounted (at pivot point  80 ) to a respective mounting frame  42  on opposite sides of rear surface  26 . Pivot point  80  is a point on mounting frame  42  about which pivot arm  60  of platform  41  pivots to move platform  41  between the in-use position ( FIG. 5 ) and the storage position (FIG.  4 , 7 ). Pivot point  80  comprises a combination of pin(s), hole(s), and fastener(s) adapted to enable second portion  64  of arm  60  to pivot relative to second portion  71  of mounting frame  42 . 
     In one aspect, the length of first portion  62  and second portion  64  of pivot arm  60 , relative to each other, and the angle formed between first portion  62  and second portion  64  are selected so that when platform  41  is pivotally mounted to vehicle frame  31  via pivot arm  60 , pivot arm  60  enables extension of platform  41  in a generally horizontal resting position relative to the vehicle frame  31 , and also permit adequate clearance for pivoting of inner end  50  of platform  41  relative to vehicle frame  31  to move platform  41  to its storage position ( FIGS. 4 and 7 ). A variety of lengths of first portion  62  and second portion  64  and a variety of angles at junction  66  of pivot arm  60  can be used to achieve pivoting function depending upon the size and the geometry of vehicle frame  31 . Accordingly, pivot arm  60  is not strictly limited to the shape and geometry shown in  FIGS. 4-17 . 
     As shown in  FIGS. 4-5 , stop mechanism  94  is secured to mounting frame  42 , via spring-loaded fastener  96 , generally below pivot point  80  to limit pivoting movement of arm  60 . Stop mechanism  94  is further described in association with  FIGS. 5-17 . 
       FIGS. 4-7  also illustrate latch mechanism  46 . Latch mechanism  46  selectively maintains platform  41  in the either storage position or the in-use position. As shown in  FIG. 5 , latch mechanism  46  comprises body  47 , pivot point  82 , first end  85 , beveled surface  86 , second end  87 , recess  88 , and flat surface  89 . Pivot point  82  comprises a point of latch body  47  that is pivotally mounted relative to a portion of platform  41 , or a pivot arm  60  of platform  41  (best seen in  FIG. 4 ). Pivot point  82  comprises a combination of pin(s) and hole(s) enabling pivotal movement of latch body  47  adjacent first end  85  so that second end  87  swings in and out of releasable engagement with pin  84  of mounting frame  42 . As shown in  FIG. 5 , in the in-use position in which platform  41  rests in a generally horizontal position, gravitational forces cause beveled surface  86  of latch body  47  to rest against pin  84  of mounting frame  42 . 
       FIGS. 4-7  also illustrate roller  90 , which is mounted to a lower portion of mounting frame  42  in one embodiment of the invention. In one aspect, roller  90  is positioned to make first contact with the ground in the event that vehicle  30  tips backward during ordinary use, thereby relieving pivot mechanism  44  and platform  41  from wear and tear due to ground contact, and helping to stabilize the rider on platform  41 . Accordingly, roller  90  acts as a balancing mechanism for both the rider (standing in operator zone  23  of  FIG. 1 ) and the vehicle  30  when maneuvering the vehicle  30  over an obstacle, uneven terrain, or steep terrain. As shown in  FIG. 5 , the bottom of roller  90  is positioned at a height H 2  above the ground G at a height lower than the general operating height H 1 , at which a lower surface  59  of platform  41  generally extends above ground G. Accordingly, roller  90  is in position to generally strike the ground before platform  41  during a rearward tipping of vehicle frame  12 . 
     In another embodiment, roller  90  is omitted from platform system  40 . 
     While not shown in each Figure of  FIGS. 4-17 , it is understood that platform  40  of vehicle  30  comprises roller  90  in each embodiment, except where roller  90  is omitted selectively as desired by an operator, retailer, manufacturer, etc. In addition, a roller  90  is generally mounted on both sides of the platform (e.g. opposite sides of platform  41  at a respective mounting frame  42  as shown in  FIGS. 4-5 ). 
       FIG. 6  is a side view of platform  40  in an intermediate position, during pivoting movement (represented by directional arrow A) between the generally horizontal in-use position ( FIG. 5 ) and the generally upright storage position ( FIG. 7 ), according to one embodiment of the invention. For discussion purposes, platform  41  is assumed to be moved upward from the in-use position toward the storage position. As shown in  FIG. 6 , outer end  52  of platform  41  is lifted upward with inner end  50  of platform  41  pivoting relative to pivot point  80 , thereby causing beveled surface  86  of latch body  47  to slide upward against fixed pin  84  on mounting frame  42 . This sliding motion continues as outer end  82  of platform  41  is pivotally raised upward so that flat surface  89  of latch body  47  begins to slide against pin  84 . As shown in  FIG. 6 , when platform  41  becomes generally upright and generally parallel to rear surface  26  of vehicle frame  12 , recess  88  of latch body  47  drops (by force of gravity) onto pin  84 . In this position, the operator releases outer end  52  of platform  41  allowing gravity to exert downward forces against second end  52  of platform  41 , with recess  88  of latch body  47  maintaining pressing engagement with pin  84  of mounting frame to prevent downward pivotal movement of platform  41 . 
       FIG. 7  is a side view illustrating platform  41  in a generally upright storage position, according to one embodiment of the invention. As shown in  FIG. 7 , with recess  88  of latch body  47  resting securely on pin  84  of mounting frame  42 , platform  41  is securely positioned close to rear surface  35  of vehicle frame  31  with support surface  58  spaced a short distance D from rear surface  35 . The distance D can be selected to either larger or smaller than shown, and support surface  58  optionally need not be generally parallel to rear surface  35  of vehicle frame  31 . 
     To restore platform  41  to its in-use position, the operator simply supports outer end  52  of platform  41  while lifting second end  87  of latch body  47  upward to withdraw recess  88  from its locked position on pin  84 . As platform  41  is rotated downward to the in-use position, flat surface  89  and beveled surface  86  of latch body  47  slide against pin  84  (shown in  FIG. 6 ) until platform  41 , including latch mechanism  46 , are returned to their in-use position ( FIG. 5 ). 
     In one embodiment, pivot mechanism  44  and latch mechanism  46  are secured relative to platform  41  independent of each other. In another embodiment, pivot mechanism  44  and latch mechanism  46  can take several forms, in addition to those shown, including components such as fasteners, hooks, pivot members, pins, or holes, that reciprocally engage each other and that can be mounted on either the frame of the vehicle and/or the platform in various combinations to achieve the pivoting and latching functions described in association with  FIGS. 1-17 . 
       FIG. 8  is enlarged perspective view of platform  41  in its in-use position, further illustrating interaction between pivot mechanism  44  and stop mechanism  94 . As shown in  FIG. 8 , second portion  64  of pivot arm  60  extends outwardly from underneath inner end  50  of platform  41  and up to pivot point  80 . Contact surface  65  of second portion  64  rests against contact surface  95  of stop mechanism  94 . Stop mechanism  94  prevents further pivotal movement of arm  60  relative to pivot point  80 , thereby maintaining the position of platform  41  in a generally horizontal in-use position because of the relative angle of second portion  64  and first portion  62  of arm  60 . Fastener  96  includes spring  97  and maintains stop mechanism  94  in position relative to mounting frame  42 . As shown in  FIG. 8 , stop mechanism  94  is a generally disc shaped member. 
     In one embodiment, stop mechanism  94  is made from a hard material, such as a metal. In another embodiment, stop mechanism  94  is made from a generally elastic polymer material to thereby act as a shock-absorbing link between platform  41  and vehicle frame  31 . This shock-absorbing link introduces a dampening effect between platform  41  and vehicle frame  31 , thereby diminishing the amount of shock, dramatic forces, and/or vibrations transmitted from vehicle frame  31  to an operator on platform  41 . 
     Moreover, this shock-absorbing link is not strictly limited to providing stop mechanism  94  as an elastomeric material, but can extend to other types of dampening materials, as well as other dampening and/or spring mechanisms and/or other suspension mechanisms, that are interposed between platform  41  and vehicle frame  31 . The shock-absorbing parameters of this link, including a dampening parameter and spring rate, can be selected to vary the quantity and quality of the shock-absorbing link, including making a spring-based shock-absorbing link, either damped or undamped. 
     This shock-absorbing link can be independent of pivot mechanism  44  and stop mechanism  94 , or can be a component of pivot mechanism  44  and/or stop mechanism  94 . 
     A shock-absorbing link, according to one embodiment of the invention, is later described in association with  FIG. 17 . 
       FIG. 9  is an enlarged perspective view of platform  40  in its in-use position, illustrating another embodiment including a stop mechanism  100  (in place of stop mechanism  94 ) which enable platform  41  to be adjusted to different heights relative to vehicle frame  31  in the in-use position of platform  41 . As shown in  FIGS. 9-10 , stop mechanism  100  includes a generally rectangular-shaped block having mounting hole  101 , and four contact surfaces  102 ,  104 ,  106 , and  108 . As shown in  FIG. 9 , contact surface  102  of block  100  is positioned to receive pressing engagement from contact surface  65  of arm  60 . However, fastener  96  enables selective rotation of block  100  into four different positions so that each of the other contact surfaces  104 ,  106  and  108  of block  100  can be pressingly engage contact surface  65  of pivot arm  60 . 
       FIG. 10  is a schematic drawing, illustrating block  100  with its contact surfaces  102 - 108  and mounting hole  101 . As shown in  FIG. 10 , mounting hole  101  is positioned off-center relative to both a major axis and a minor axis of block  100 . This off-center positioning, in combination with the rectangular shape of block  100 , results in each contact surface  102 - 108  causing contact surface  65  of pivot arm  60  to be supported at a different distance relative to fastener  96  on mounting frame  42 , thereby causing platform  41  to be fixed at a different height relative to the ground for each of the different contact surfaces  102 - 108 . While  FIGS. 9-10  illustrate a generally rectangular-shaped block as stop mechanism  100 , other shaped stop mechanisms (e.g., n-gon, triangular, etc) can be used to achieve desired variable height positioning of platform  41 . 
       FIG. 11  is a side view illustrating a self-propelled vehicle having a platform  41  (including pivot mechanism  44  and latch mechanism  46 ) having substantially the same features and attributes as vehicle  30 , except replacing mounting frame  42  with mounting frame  150  to accommodate a different shape of vehicle frame  160  (similar to vehicle frame  31 ). As shown in  FIG. 11 , pivot mechanism  44  and latch mechanism  46  are mounted to mounting frame  150 . Mounting frame  150  is fixed to a side surface  164  of vehicle frame  160  in contrast to mounting frame  42  which is fixed to rear surface  35  of vehicle frame  31  via portion  70  ( FIGS. 4-7 ). 
     As shown in  FIG. 11 , mounting frame  150  comprises first body portion  154 , holes  152  for mounting to vehicle frame  160 , and second body portion  158 . An imaginary line  156  generally denotes a boundary between first and second body portions  154 ,  158 . First body portion  154  of mounting frame  150  is sized and shaped so that when fixed to a side surface  164  at the rear portion of vehicle frame  160 , boundary  215  generally corresponds to a location of rear surface  162  of vehicle frame  160  (similar to rear surface  35  of vehicle frame  31 ) from which second body portion  158  extends. This arrangement enables mounting and functioning of pivot mechanism  44  and latch mechanism  46  at a pivot point  80  and fasteners  84 ,  96  in a position close to, but spaced from, rear surface  35  of vehicle frame  160  to achieve the functions and features previously described for platform  40  in association with mounting frame  42  ( FIGS. 1-10 ). 
     Except for the different position of side-mounting frame  150  relative to vehicle frame  160  in  FIG. 11  (as compared to the position of mounting frame  42  relative to vehicle frame  31  in  FIGS. 4-7 ), all other features and attributes of platform system  40 , including platform  41 , pivot mechanism  44 , and latch mechanism  46  of platform system  200  as illustrated in  FIG. 11  are substantially the same as previously described in association with  FIGS. 1-10 . 
       FIG. 12  is a side view illustrating a platform system  200 , according to another embodiment of the invention. As shown in  FIG. 12 , platform system  200  comprises platform  202 , pivot mechanism  204 , and mounting frame  206 . Platform  202  includes support plate  211  and comprises inner end  217  and outer end  218 . Support arm  212  comprises outer end  230 , secured to and supporting support plate  211 , and inner end portion  232  which are joined together at junction  235  defining an generally obtuse angle between outer portion  230  and inner end portion  232 . Mounting frame  206  comprises first portion  207 , second portion  208 , and lower portion  210  defining slot  209 . Pivot mechanism  204  comprises components mounted on, or interacting with either platform  202  or mounting frame  206  to enable pivotal movement of platform  202  between in in-use position shown in  FIG. 12  and a storage position shown later in  FIG. 15 . 
     As shown in  FIG. 12 , pivot mechanism  204  comprises pin  242  mounted on lower portion  210  of mounting frame  206  and slot  234  of inner end portion  232  of support arm  212 . In one aspect, pivot mechanism  204  also comprises a securing mechanism comprising pin  214  mounted on support arm  212  and a slot  209  of lower portion  210  of mounting frame  206 . Slot  234  of support arm  212  is generally elongate slot with closed ends, enabling sliding movement of inner end portion  232  of support arm  212  relative to pin  242 . However, pin  214  which protrudes from support arm  212  is adjacent an outer edge  238  of lower portion  210  of mounting frame  206 . In one aspect, pin  214  acts to prevent sliding movement of support arm  212  (and platform plate  211 ) inward toward rear surface  35  of the vehicle frame. Further interaction of the components of pivot mechanism  204  is described in association with  FIGS. 13-16 . 
     As shown in  FIG. 12 , stop mechanism  250  (shown in phantom) is secured to lower portion  210  of mounting frame  206  and limits movement of inner end portion  232  of support arm  212  via contact at surface  240  of support arm  212 . Stop mechanism  250  comprises substantially the same features and attributes as stop mechanism  94 , as previously described in association with  FIGS. 1-11 , and as further illustrated in  FIG. 13 . 
       FIG. 13  is a perspective view of the embodiment of  FIG. 12 , which further illustrates the components of platform system  200  as described and illustrated in  FIG. 12 . As shown in  FIG. 13 , pin  242  protrudes through slot  234  of inner end portion  232  of arm  230  while pin  214  protrudes outwardly in a generally opposite direction to enable engagement with slot  209 . 
       FIG. 14  is a side view of the embodiment of  FIGS. 12 and 13 , according to one embodiment of the invention, illustrating the platform  202  in an intermediate position between an in-use position ( FIG. 12 ) and a storage position ( FIG. 15 ). As shown in  FIG. 14 , platform  202  is rotated upward from its in-use position ( FIG. 12 ) via rotatable motion of slot  234  about pin  242 , with pin  214  sliding along (or adjacent to) outer edge  238  of lower mounting portion  210 , until pin  214  is positioned adjacent a mouth of slot  209 . In this position, platform  202  is in a generally upright position. In one aspect, platform  202  is generally parallel to rear surface  35  of the vehicle frame, while in other aspects, the generally upright position is not exclusively limited to this generally parallel relation to rear surface  35  of the vehicle frame. 
       FIG. 15  is a side view of the embodiment of  FIGS. 12-14 , according to one embodiment of the invention, illustrating the platform  202  in a storage position. As shown in  FIG. 15 , platform  202  is moved inward with pin  214  of arm support  212  sliding into slot  209  of lower mounting portion  210 , and with slot  234  of inner end portion  232  of arm support  212  sliding relative to pin  242 . At the completion of this motion, pin  214  in slot  209  releasably secures platform in position adjacent to rear surface  35  of vehicle frame  31  with slot  234  and pin  242  providing an additional mechanism to maintain the position of platform  202 . Accordingly, two simultaneous pin-in-slot movements of pin  214  and slot  209 , and of pin  242  in slot  234 , occur to secure platform  202  relative to rear surface  35  of the vehicle frame. 
     At any time desired by the operator, the platform is returned to the in-use position by pulling outer end  218  of platform  202  outward to slidably remove pin  214  from slot  209 , with slot  234  of inner end portion  232  sliding relative to pin  242 , until pin  214  exits slot  209 . In this position, platform  202  is free to rotate downward to the in-use position shown in  FIGS. 12-13 , in which stop mechanism  250  supports inner end portion  232  of arm  212  at surface  240 , and pin  214  limits inward/outward motion of platform  202  relative to the rear surface  35  of the vehicle frame. 
     In one aspect, in both the in-use position and the storage position, the securing pin  214  and latching slot  209  are laterally spaced further away from the rear surface  35  of the vehicle frame  31  relative to the pivot pin  242 . In another aspect, in the in-use position, the securing pin  214  is positioned lower than the pivot pin  242 , by virtue of angled inner end portion  232  of support arm  212 , and in the storage position, the securing pin  214  is positioned vertically above the pivot pin  242 . 
     This arrangement enables movement of only a single platform assembly (including platform  202 , arm  212  including slot  234 , and pin  214 ), relative to a mounting frame (including slot  209  and pin  242 ). In use, the first slot  234  remains both slidably and pivotally engaged to the second pin  242  while the first pin  214  is releasably slidable into the second slot  209  upon rotation of the entire platform  202 . According, the platform assembly itself effectively acts as the only moving part to enable pivotal movement of platform  202  between the in-use and the storage position and to enable securing the platform  202  in the storage position. 
     In one aspect, platform system  200  uses the force of gravity to maintain the position of the platform  202 . In the storage position, since the securing pin  214  and receiving slot  209  are above the pivot pin  242 , and slot  209  is angled parallel to rear surface  35 , once pin  214  is aligned within slot  209 , gravity assists a user in pushing pin  214  into slot  209  and in maintaining pin  214  in slot  209 . When released from the storage position by pulling platform  202  outward to remove pin  214  from slot  209 , gravity tends to cause platform  202  rotate downward relative to pivot pin  242 , with stop mechanism  250  preventing any further movement of platform  202 . Accordingly, the arrangement of pins and slots of platform system  200  enables the natural force of gravity to facilitate positioning of platform  202  in its respective storage and in-use positions. 
       FIG. 16  is a side view illustrating a platform system  260  for a self-propelled vehicle (including platform  202  and pivot mechanism  204 ) having substantially the same features and attributes as platform system  200  of  FIGS. 12-15 , except replacing mounting frame  206  with mounting frame  270  to accommodate a different shape of vehicle frame. As shown in  FIG. 15 , pivot mechanism  204  is mounted to mounting frame  270 . Mounting frame  270  is fixed to a side surface of a vehicle frame in contrast to mounting frame  206  which is fixed to rear surface  35  of vehicle frame  31  ( FIGS. 12-15 ). 
     As shown in  FIG. 16 , mounting frame  270  comprises first body portion  274 , holes  272  for mounting to vehicle frame  31 , second body portion  276 , and slot  278  (like slot  209  in  FIGS. 12-15 ). First body portion  274  of mounting frame  270  is sized and shaped so that when fixed to a side surface adjacent rear surface  35  of a vehicle frame, pivot mechanism  204  is in a position close to, but spaced from, rear surface  35  of the vehicle frame to achieve the functions and features previously described for platform  202  in association with mounting frame  206  ( FIGS. 12-15 ). 
       FIG. 17  is a perspective view illustrating a platform system  300 , according to an embodiment of the invention. Platform system  300  comprises substantially the same features and attributes as platform systems (including a pivot mechanism and latch mechanism) described in association with  FIGS. 1-16 , except additionally including a shock-absorbing member  310  as shown in  FIG. 17 . Shock-absorbing member  310  establishes a link between platform  202  and rear surface  35  of vehicle frame  31  to minimize vibration that would otherwise be transmitted to an operator standing on platform. In one aspect, the shock absorbing link is a piston-cylinder arrangement (as shown) which provides a variable length to member  310  to facilitate pivotal movement of platform  202 . In another aspect, the shock absorbing link is an elastomeric member. In other aspects, the shock absorbing link is a spring member or other dampening mechanism. 
     In addition, each end of member  310  is pivotally mounted relative to platform  202  and relative to rear surface  35  to enable pivoting of platform  202  between the previously described and illustrated in-use and storage positions of platform  202 . 
     In another embodiment, platform system  300  omits a pivot mechanism (such as pivot mechanism  44 ) and a latch mechanism (such as latch mechanism  46 ) and relies solely on member  310  to provide a pivoting function for platform  202  and a latching function (via gas pressurization in a cylinder of member  310 ). 
     In one aspect, member  310  is mounted at a side of platform  202  as shown in  FIG. 117  while in other aspects, member  310  is mounted adjacent a central region of platform between opposite sides of platform  202 . 
     Embodiments of the present invention enable convertible use of self-propelled vehicles in either a walk-behind or ride-on-platform mode by simple pivotal movement of a platform between a generally horizontal position for riding operation and a generally upright, selectively engaged storage position for walk-behind operation. In one aspect, a pivot mechanism enables single hand use to simply flip the platform upward for storage and to flip the platform down for use. The platform can be built as part of the vehicle frame or attached later as a retro-fit assembly. 
     Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments illustrated and described without departing from the scope of the present invention. Those with skill in the mechanical, electro-mechanical, electrical, and computer arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.