Abstract:
An improved counterweight apparatus for vehicles includes a counterweight support structure, a set of separately installable and removable counterweights and a retaining plate. Each counterweight is shaped to be received by the counterweight support structure and each counterweight has at least one retaining plate surface. The retaining plate is retained adjacent to the counterweight support structure and can be moved between a retracted position and an advanced position. The retaining plate has a first surface located to register with the retaining plate surface of each counterweight. When a counterweight is placed in the counterweight support structure and the retaining plate is moved to the advanced position, the first surface of the retaining plate engages the retaining plate surface of the counterweight to secure the counterweight support structure. A counterweight can be removed from the counterweight support structure if the retaining plate is moved to the retracted position.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/493,772 filed on Jun. 6, 2011 which is incorporated herein by reference. 
    
    
     FIELD 
     This invention relates to a vehicle counterweight apparatus. 
     BACKGROUND 
     Counterweights are used to balance vehicles such as riding lawnmowers. Counterweights are used when a riding lawnmower or tractor carries an attachment that causes the vehicle to become unbalanced. A counterweight apparatus works best for an operator if it is versatile and easy to use. A counterweight apparatus is versatile if it is possible to mount one, some or all of a set of generally identical counterweights. It is preferable that the individual counterweights be generally identical, heavy enough to provide a significant counterweight for the vehicle and relatively easy to install and remove. 
     SUMMARY 
     A counterweight apparatus for a vehicle addresses the above described needs relating to versatility and ease of use. The present counterweight apparatus includes a counterweight support structure, a set of separately installable and removable counterweights and a retaining plate. The counterweight support structure is fixed to the vehicle. The set of counterweights includes a plurality of counterweights. Each counterweight is shaped to be received by the counterweight support structure and each counterweight has at least one retaining plate surface. The retaining plate is retained adjacent to the counterweight support structure and can be moved between a retracted position and an advanced position. The retaining plate has a first surface located to register with the retaining plate surface of each counterweight. When at least one counterweight is placed in the counterweight support structure and the retaining plate is moved to the advanced position, the first surface of the retaining plate engages the retaining plate surface of the counterweight so that the counterweight is secured to the counterweight support structure. A counterweight can be removed from the counterweight support structure if the retaining plate is moved to the retracted position. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a first perspective view of the apparatus for mounting counterweights. 
         FIG. 1A  is a perspective view showing how the apparatus for mounting counterweights is mounted to a lawnmower frame. 
         FIG. 2  is a second perspective view of the apparatus for mounting counterweights. 
         FIG. 3A  is a first perspective view of a counterweight. 
         FIG. 3B  is a second perspective view of a counterweight. 
         FIG. 3C  is a rear view of a counterweight. 
         FIG. 3D  is a side view of a counterweight. 
         FIG. 4  is a top view of a counterweight mounted in a counterweight support structure. 
         FIG. 5  is a top view of a retaining plate. 
         FIG. 6  is a cross-section view of a counterweight shown raised above a cross-section view of the counterweight support structure. 
         FIG. 7  is a cross-section view of a counterweight and the counterweight support structure taken from plane A-A indicated in  FIG. 4 . 
         FIG. 8  is a second rear view of a counterweight showing additional dimension indicators. 
         FIG. 9  is a top view of a counterweight installed in the counterweight support structure. 
         FIG. 9A  is a cross-section view of a counterweight installed in the counterweight support structure taken from plane A-A of  FIG. 9 . 
         FIG. 9B  is a cross-section view of a counterweight installed in the counterweight support structure taken from plane B-B of  FIG. 9 . 
         FIG. 10  is a top view of a counterweight installed in the counterweight support structure with the retaining plate in a refracted position. 
         FIG. 10A  is a cross-section view of a counterweight installed in the counterweight support structure with the retaining plate in the retracted position taken from plane A-A of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings,  FIG. 1  shows an example embodiment of the counterweight apparatus  10  shown exploded away from riding lawnmower frame  5 . Riding lawnmower frame  5  is shown without wheels and other equipment for clarity and will be easily identifiable by those skilled in the art as the frame of a riding lawnmower. Lawnmower frame  5  is shown in  FIG. 1  to include at least forward wheel support members  6 A and  6 B as well as a transverse frame member  7 . Counterweight apparatus  10  includes a counterweight support structure  20 , counterweights  50  and a retaining plate  80 . Direction arrows  2  in  FIG. 1  provide the orientation of mower frame  5  as well as counterweight support structure  20 , counterweights  50  and retaining plate  80 . 
     As can be seen in  FIG. 1 , in this example, counterweight support structure  20  includes a bay portion  22  which is defined by a forward wall  22 A 1 , two side walls  22 B 1  and  22 B 2 , a floor  22 C, and a back wall  22 D. A divider  22 E divides bay portion  22  into two preferably identical bay recesses  23 A and  23 B. In this example, eight evenly spaced rubber pads  23 C are located at the bottom of each bay recess  23 A and  23 B. Accordingly, two rubber pads  23 C provide a cushion for the bottom surface of each counterweights  50  as can be best seen in  FIGS. 7 and 9A . 
     In this example, each bay recess  23 A and  23 B is shaped and sized to receive and support two counterweights  50 . Accordingly, in this example, counterweight support structure  20  is adapted to support four generally identical counterweights  50 . An example counterweight  50  will be described in greater detail below. Counterweight support structure  20  also includes an elongated generally horizontal ledge flange  24  generally extending back from the upper edge of back wall  22 D of bay portion  22 . Ledge flange  24  also extends to the right and to the left in the area behind bay portion  22 . Evenly spaced generally identical anchor openings  26  are defined in ledge flange  24  adjacent to back wall  22 D. Each anchor opening  26  exposes an edge portion  26 A of back wall  22 . As will be explained in greater detail below, anchor openings  26  are arranged to receive anchor portions that project from counterweights  50 . 
     In this example, counterweight support structure  20  also includes side support members  32  and  34  extending from either side of bay portion  22  as well as a back flange  36  extending diagonally down and away from ledge flange  24 . These structural elements are arranged to be fastened or bolted to structural elements at the forward end of mower frame  5 . Generally, counterweights  50  are mounted to the forward end of a mower frame  5  to counterbalance equipment mounted to the back end of a riding mower, such as, for example, a grass catcher assembly. In this example, in order to secure counterweight support structure  20  to frame  5 , fastener holes  32 A and  32 B and  34 A and  34 B may be defined in side support members  32  and  34  respectively and are preferably located to align with a U-bolt such as U-bolt  32 C shown in  FIG. 1A . As can be seen in  FIG. 1A , U-bolt  32 C fits around forward wheel support member  6 A which is fastened and clamped in place by nuts  32 C 1  and  32 C 2  on the threaded ends of U-bolt  32 C. A generally symmetrically identical U-bolt arrangement is present on the opposite side of frame  5  but is now shown in  FIGS. 1 and 1A . Back flange  36  of counterweight support structure  20 , in this example, is arranged to be fastened to transverse frame member  7 . Generally, it is sufficient that counterweight support structure  20  is either part of frame  5  or is otherwise fixed to frame  5 . Weight support structure  20 , in this example, may be fashioned from sheet steel parts that are cut out and, for some of the above described features, brake formed and subsequently welded together using processes that are well known to those skilled in the art. 
     Each counterweight  50  is configured to be handled by an operator and is designed such that its weight is manageable by an operator. Preferably, each counterweight  50  may weigh approximately 40 Lbs. or may have some other suitable weight depending on the amount of counter-weighting needed. Accordingly, with the example embodiment shown in  FIGS. 1 and 2 , if such embodiment includes weights weighing 40 Lbs. each, counterweight apparatus  10  may be used to provide a balancing force of approximately 40, 80, 120 or 160 pounds depending on whether one, two, three or four counterweights  50  are mounted to counterweight support structure  20 . In this example, counterweights  50  are sufficiently identical so that counterweights  50  can be used interchangeably. Preferably, each counterweight  50  is fashioned from cast iron or a similar dense cast material. 
       FIGS. 3A-3D  provide various views of a counterweight  50 . Direction arrows are given in  FIG. 3A  to show the orientation of counterweight  50  when it is placed in counterweight support structure  20 . As can be best seen in  FIGS. 3A-3D , each counterweight  50  has a body portion  52 , an upper ledge portion  62 , an anchor portion  64  and a handle  76 . Upper ledge portion  62  projects back from the top of body portion  52 . In this example, anchor portion  64  projects rearwardly from body portion  52  and down from upper ledge portion  62 . In this example, each body portion  52  of each counterweight  50  preferably has a front face  54 , a back face  56 , a bottom face  58 , a top face  59  and parallel sides  60  extending between the front, back, bottom and top faces  54 ,  56 ,  58  and  59 . Preferably, sides  60  are generally parallel so that a plurality of counterweights  50  may be fit side by side into bay recesses  23 A and  23 B described above. In this example, handle  76  extends from top face  59  to facilitate handling. Front, back and bottom faces  54 ,  56  and  58  are arranged to generally fit the inside surfaces of each recess  23 A and  23 B of counterweight support structure  20  as shown in  FIGS. 6 ,  7 ,  9 A and  9 B. 
     As noted above anchor portion  64  extends from back face  56  and downwardly from upper ledge portion  62 . Anchor portion  64  includes a lower portion that is spaced away from back face  56  so that the lower portion of anchor portion  64  and back face  56  define a downwardly opening transverse, upright slot  66  which can be best seen in  FIG. 3D . Upright slot  66  is given a width sufficient for receiving the exposed edge portion  26 A of back wall  22 D of weight tray  22  as can be best seen in  FIGS. 6 ,  7  and  9 A. As can be seen in  FIG. 6 , the vertical dimension of back wall  22 D at anchor opening  26  indicated as dimension D is generally slightly greater than dimension C indicated on counterweight  50 . Moreover, as shown in  FIG. 6 , the longitudinal dimension B between the front surface of back wall  22 D and the back edge of anchor opening  26 , in this example, is preferably slightly larger than dimension A indicated in  FIG. 6  as extending between back surface  56  and the back surface of anchor portion  64 . Also, dimension K given in  FIG. 4  indicating the width of opening  26  must be sufficiently large to allow passage of anchor portion  64  having a width indicated by dimension L in  FIG. 8 . Thus, dimension K must be equal to or greater than dimension L. Accordingly, anchor portion  64  of each counterweight  50  is shaped and sized to fit into one the above described anchor openings  26  of bay portion  22  such that slot  66  of counterweight  50  receives the exposed edge portion  26 A of back wall  22 D of bay portion  22  as counterweight  50  rests in one of bay recesses  23 A or  23 B. Still further, in this example, the width of anchor portion  64  as indicated by dimension L in  FIG. 8  is preferably sized to be slightly less than the width of anchor opening  26  as indicated by dimension K shown in  FIG. 4 . The skilled reader may note that a portion of anchor portion  64  immediately above slot  66  also has a width corresponding with dimension L shown in  FIG. 8  and that at least this portion of anchor portion  64  fits the portion of anchor opening  26  common to back wall  22 D of bay portion  22 . Accordingly, when counterweight  50  is received by weight tray  22 , because the forward, back and bottom faces of counterweight  50  generally fit into bay portion  22  as described above and because anchor portion  64  is received by an anchor opening  26  as described above, counterweight  50  is constrained from moving forward or backward, and, in this example, is also constrained from moving side to side. 
     In this example, anchor portion  64  of each counterweight  50  is reduced in its transverse width to define a neck region  68  that can be best seen in  FIGS. 3C and 3D . This neck region  68  presents two generally horizontal, longitudinal anchor slots  68 A and  68 B which are most clearly indicated in  FIG. 3C . In particular slots  68 A and  68 B present retaining plate surfaces  68 S 1  and  68 S 2  respectively which define the lower surfaces of slots  68 A and  68 B. When a counterweight  50  is seated in one of bay recesses  23 A or  23 B of counterweight support structure  20 , retaining plate surfaces  68 S 1  and  68 S 2  of anchor slots  68 A and  68 B respectively are preferably generally co-planar with the upper surface of the horizontal ledge flange  24  of counterweight support structure  20 . The purpose for this alignment will be explained immediately below. 
     The purpose of retaining plate  80 , is to engage the features of anchor slots  68 A and  68 B of counterweight  50  in order to constrain counterweight  50  from moving up relative to counterweight support structure  20 . This is an important function because a riding lawnmower often encounters uneven terrain. While it is useful to be able to quickly install and remove a counterweight  50 , it is even more useful to be able to quickly slide retaining plate  80  into place in order to secure a counterweight  50 . 
     Retaining plate  80  includes a horizontal flange  82  that is designed to lie on top of the upper surface of ledge flange  24  of the counterweight support structure  20 . Retaining plate  80 , in this example, has an upwardly projecting flange  84  to impart structural rigidity to retaining plate  80 . Horizontal flange  82  is profiled to have a series of shaped portions, which, in this example, are cutouts  86 . Each cutout  86  of retaining plate  80  is arranged and located such that when a counterweight  50  is placed in a recess  23  of support structure  20  as shown in  FIG. 4  and retaining plate  80  is in the advanced position as shown in  FIG. 9 , one of cutouts  86  will engage neck region  68  of anchor portion  64  of a counterweight  50 . As a neck region  68  of counterweight  50  is received by cutout  86 , the material on either side of cutout  86  is also received by anchor slots  68 A and  68 B of counterweight  50 . Still further, in this example, the generally flat lower surface  80 S of retaining plate  80  (indicated as  80 S in  FIG. 10A ), if placed on the upper surface of ledge flange  24 , registers with retaining plate surfaces  68 S 1  and  68 S 2  (indicated in  FIGS. 3C ,  3 D and  8 ) defining the lower walls of slots  68 A and  68 B (indicated in  FIGS. 3C ,  3 D,  8  and  9 B). Thus, if retaining plate  80  is in the advanced position shown in  FIGS. 9 and 9A  cutouts  86  (shown in  FIG.1 ) receive the material between slots  68 B 1  and  68 B 2 , counterweight  50  is constrained from moving (at least by any significant distance) if retaining plate  80  is secured to counterweight support structure  20  as will be described below. 
     In this example, retaining plate  80  is releasably secured to ledge flange  24  of support structure  90  by a pair of threaded clamp bolts  90  which are attached at opposite ends of ledge flange  24 . Clamp bolts  90  are threaded into corresponding threaded holes  24 A and  24 B. Retaining plate  80 , at its opposite ends, presents a correspondingly spaced pair of clamp slots  88 . Accordingly, when retaining plate  80  is in the advanced position shown in  FIGS. 9 and 9A  and clamp bolts  90  which are captured by clamp slots  88  are tightened, retaining plate  80  is secured in the advanced position and a counterweight  50 , if present in support structure  20  as shown in  FIG. 9 , will be secured in support structure  20 . When clamp bolts  90  are loosened, retaining plate  80  may be slid to the retracted position shown in  FIGS. 10 and 10A  as slots  88  slide relative to clamp bolts  90 . When retaining plate  80  is in the retracted position shown in  FIGS. 10 and 10A , a counterweight  50  may be either added to or removed from support structure  20 . 
     As can be understood from the above description, counterweight apparatus  10  provides a way to balance a vehicle when various attachments are added to the vehicle causing an unbalanced condition. The configuration of counterweight apparatus  10  provides a structure for receiving and securing a series of counterweights ranging from one counterweight  50  to four counterweights  50 , and, in this example, ranging between 40 lbs. and 160 lbs. Further, counterweight apparatus  10  provides a way to quickly install or remove counterweights  50  while providing a way to secure installed counterweights  50 . 
     It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.