Abstract:
An arbor guide shoe assembly for slidably interconnecting an arbor top plate or bottom plate with a pair of spaced rails. The guide shoe assembly has a rail contacting channel which defines a plurality of operable rail capturing distances, and an elongate slot for orienting the guide shoe assembly with a plurality of orientations with respect to the counterweight arbor.

Description:
FIELD OF THE INVENTION 
     The present invention relates to rigging systems including those for theaters, studios, concert halls, arenas, television studios, casino showrooms and cruise ships, and more particularly, to a counterweight arbor guide shoe assembly having a curvilinear rail contacting surface and elongated slots for operably engaging the guide shoe assembly and the counterweight arbor in a plurality of operable positions. 
     BACKGROUND OF THE INVENTION 
     Counterweight systems are often employed for balancing battens and loaded battens in a stage environment. In principal, the counterweight is set to generally match the combined load of the batten and any attached load, such as scenery, lighting or sound equipment. The counterweights are releasably connected to the counterweight arbors or carriages. The conventional counterweight arbor has a top and a bottom between which the weights are selectively disposed. The counterweight arbor (carriage) is slidably translated along vertically extending rails. The slidable interconnection of the counterweight arbor and the rails is accommodated by a multi component structure specifically sized for the specific spacing of the rails in a respective counterweight arbor. 
     However, the need exists for a counterweight arbor guide shoe assembly that can be utilized for a variety of rail spacings, without requiring separate construction of the guide shoes. The need further exists for a counterweight arbor guide shoe assembly that can be adjusted to accommodate tolerances derived from manufacture of the rail, the arbor or installation of the counterweight system. 
     SUMMARY OF THE INVENTION 
     The present invention provides a counterweight arbor guide shoe assembly for slidably interconnecting a counterweight arbor and a guide rail. The present guide shoe assembly can be disposed to accommodate guide rail systems having differing spacing between the guide rails. That is, the present guide shoe assembly can be utilized in rail systems having six, eight or tern inch centers, as well as intermediate spacings. 
     In a first configuration, the guide shoe assembly includes a guide shoe having a curvilinear rail bearing surface and a curvilinear arbor mounting slot. In one construction, the counterweight arbor includes a pair of mounting apertures or pins disposed along an inclined line. The corresponding mounting slots in the guide shoe assembly are selected to allow the guide shoe assembly to be mounted relative to the counterweight arbor at a plurality of orientations. Preferably, the guide shoe assembly can be operably connected to the counterweight arbor at and between 90° orientations. 
     In a further configuration, the guide shoe assembly is constructed of a pair of identical interlocking guide plates, wherein the guide plate includes a pair of arbor mounting slots and a curvilinear rail contacting surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a counterweight arbor assembly employing the present guide shoe assembly. 
         FIG. 2  is a perspective view of a guide shoe assembly. 
         FIG. 3  is a partial cutaway of perspective view of a guide shoe assembly showing structural features. 
         FIG. 4  is a top plan view of a guide shoe assembly. 
         FIG. 5  is a top plan view of a guide plate. 
         FIG. 6  is a side elevational view of the inside surface of a guide plate. 
         FIG. 7  is a perspective view of the inside surface of a guide plate. 
         FIG. 8  is a side elevational view of the outside surface of a guide plate. 
         FIG. 9  is a cross sectional view taken along lines  9 - 9  of FIG.  8 . 
         FIG. 10  is a cross sectional view taken along lines  10 - 10  of FIG.  8 . 
         FIG. 11  is a perspective view of the outside surface of a guide plate. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the guide shoe assembly  10  of the present invention is employed in a counterweighted rigging system, such as a stage or theater rigging. However, the invention is independent of the specific location or application of the rigging system. The rigging system usually includes a plurality of variable counterweights for balancing loads attached to corresponding battens, wherein the battens are to be raised and lowered relative to a stage. 
     The counterweight system includes a plurality of counterweight arbors  20  that are raised and lowered along corresponding vertical rails or flanges  30 . The counterweight arbor usually includes or are connected to an arbor guide for guiding the counterweight arbor relative to the rails. The counterweight arbor  20  includes an arbor top  22  and an arbor bottom  24 . Preferably, each of the arbor top  22  and the arbor bottom  24  include a pair of mounting apertures  25  for operable alignment with the guide shoe assembly  10 . In previous systems, the arbor top  22  and arbor bottom  24  included a single mounting hole to engage fastener for coupling to the guide shoe. In some systems, two vertically aligned mounting holes. While such mounting holes can be accommodated in the present invention, one configuration employs the mounting holes  25  of the arbor top  22  and the arbor bottom  24  disposed along a line inclined 45° from vertical. 
     Typically, the rails  30  are spaced at predetermined intervals along a wall  32  or frame to which the counterweight system is attached. Typical spacings of the rails  30  are 6, 8 or 10 inch centers. However, within a system spacing of a given distance, installation and manufacturing tolerances result in variances along the length of the rails  30 . Although the term rail  30  is used the description, it encompasses flanges along which the counterweight arbor  20  is to be guided. 
     The rail  30  can be any of a variety of configurations and typically includes the projecting flange for engaging the arbor guide assembly. Thus, the rail  30  may have a variety of cross sectional profiles including L, T, U, I, H, C and still employ the present invention. 
     The guide shoe assembly  10  operably interconnects the counterweight arbor  20  and a rail  30 . Preferably, the guide shoe assembly  10  engages a pair of consecutive spaced apart rails  30  and the counterweight arbor  20 . 
     The guide shoe assembly  10  includes a rail contacting surface  40  and an arbor mounting slot  50 . The guide shoe assembly  10  defines a major axis  12  extending along a longer dimension of the assembly and a transverse minor axis  14  extending along a lesser coplanar dimension. As shown in  FIG. 2 , the major axis  12  and the minor axis  14  intersect at a central point of the guide shoe assembly  10 . 
     Although the guide shoe assembly  10  is shown as having a generally obround periphery, it is understood the rail contacting surface  40  can be a circular arc, a portion of an ellipse, hyperbola or other curvilinear segment. 
     The rail contacting surface  40  defines that portion of the guide shoe assembly  10  that engages the rails  30  to retain and guide the counterweight arbor  20  relative to the rails. The rail contacting surface  40  preferably defines channel that can contact three sides of the rail  30  such as the front, the exposed edge and the back. The rail contacting surface  40  can have any of a variety of cross sections such as C, U or even V shaped. It is desired the channel have a sufficient depth (that the legs of the cross sectional profile have a sufficient length) to accommodate tolerances and variations within a given rail system spacing. 
     The rail contacting surface  40  defines a rail capture distance, or span that is the distance between any two points that are diametrically opposed across the center of the guide shoe assembly. As the rail contacting surface  40  is curvilinear, the rail capture distance depends upon the orientation of the guide shoe assembly  10  relative to the counterweight arbor  20  and the rail  30 . 
     The rail contacting surface  40  is selected such that as the guide shoe assembly  10  is rotated relative to the counterweight arbor  20  (and the rails  30 ), the horizontal distance between the extremes of the rail contacting surfaces is varied. That is, as the guide shoe assembly  10  is rotated relative to the counterweight arbor and the rails, the rail capture distance varies. Thus, as the guide shoe assembly  10  is disposed with the major axis horizontal, the rail contacting surface  40  spans the greatest rail capture distance. In contrast, as the guide shoe assembly  10  is disposed to locate the minor axis horizontal, the rail contacting surface  40  defines a minimum rail capture distance. Preferably, the spanned distance of the rail contacting surfaces  40  continuously varies from the maximum distance along the major axis to a minimum distance along the minor axis. However, it is understood the spanned distance can vary incrementally rather than continuously, wherein the increments are selected to operably engage any of a variety of rail spacings. That is, preferably, the rail contacting surface  40  is curvilinear or sufficiently multi-faceted to permit a plurality of operable orientations of the guide shoe assembly relative to the rails. 
     As shown, the present rail contacting surface  40  defines a generally obround profile. That is, the rail contacting surface  40  has a curvilinear section  42  and a straight section  44 . In one configuration, the section of the rail contacting surface  40  extending between the maximum rail capture distance and the minimum rail capture distance is curvilinear, or sufficiently faceted to allow a discrete stepwise function that accommodates the anticipated tolerances in the rail system. In the configuration of  FIGS. 1-3 , as the guide shoe assembly  10  is disposed with the major axis being horizontal, the portion of the rail contacting surface  40  which contacts the rails  30  is curvilinear. In contrast, as the guide shoe assembly  10  is disposed with the minor axis being horizontal, the portion of the rail contacting surface  40  engaging the rails  30  is substantially straight, wherein the intermediate orientations of the guide shoe assembly expose a curvilinear (or incrementally faceted) rail contacting surface to the rails. 
     However, it is understood these are predominately design choices and so long as the arbor guide assembly has rail contacting surfaces  40  which can be operably located at the desired spacing by rotation of the guide shoe assembly  10  relative to the arbor top plate  22  or arbor bottom plate  24 , the rail contacting surface can be thus selected. 
     Referring to  FIGS. 2 ,  3 ,  6  and  7 , the guide shoe assembly  10  includes a pair of arbor mounting slots  50 . The arbor mounting slots  50  are selected to allow the guide shoe assembly  10  to rotate relative to the counterweight arbor  20  and the rails  30 . It is this rotation that allows varying the rail capture distance presented by the guide shoe assembly  10 . 
     Preferably the arbor mounting slots  50  are arcuate and define an approximately 90° arc, thus allowing the guide shoe assembly  10  to rotate between presenting the maximum rail capture distance to the minimum rail capture distance. However, it is understood the rotation of the guide shoe assembly  10  can be accomplished with a pivot point and a single slot, or other equivalent structures. 
     In a preferred configuration, the guide shoe assembly  10  is formed of a pair of identical interlocking guide plates  60 . Although the guide shoe assembly  10  is shown as a pair of interlocking guide plates  60 , it is understood the guide shoe assembly can be formed of a single piece of material. In alternative configurations, the guide plates can be uniquely formed. The benefit of identical guide plates  60  is reduction in inventory requirements and manufacturing considerations. 
     The guide plate  60  includes the arbor mounting slot  50  and a part of the rail contacting surface  40 . Referring to  FIGS. 1-4 , the guide plate  60  defines one leg of a U shaped rail contacting channel and a portion of the closed end of the rail contacting channel. The fully defined channel cross section is formed upon the engagement of two guide plates  60 . 
     Operable engagement of a pair of guide plates  60  is provided by interlocking tabs and recesses. In one configuration, the guide plate  60  includes a spaced apart tab  62  and slot  63  for receiving a corresponding guide plate  60  in an interlocking manner. Preferably, the guide plate  60  includes a pair of tabs  62  and a pair of spaced apart slots  63 . The tabs  62  and slots  63  are symmetrically located on the guide plate  60  to allow two identical guide plates  60  to interlock. 
     It is understood that any of a variety of interlocking mechanisms can be employed, such as snap fits and friction fits. Further, the guide plates  60  may be temporarily retained by manual retention prior to operable engagement with the counterweight arbor  20 . 
     Although the guide shoe assembly  10  is shown as formed of identical interlocking guide plates  60 , it is understood that one of the guide plates can include or define the rail contacting surface, such as the channel and the remaining plate serve as forming the shoulder upon operable engagement with the first plate. Thus, the guide&#39;s plates can be unique. 
     Any of a variety of interconnecting mechanisms can be used to interconnect the guide shoe assembly  10  and the arbor top  22 , and the arbor bottom  24 . The interconnecting mechanisms include, but are not limited to screws, threads, bolts, rods, or pins. For purposes of simplicity and description, the configuration employing a bolt for is disclosed. 
     In contrast to prior systems, which employ a single bolt for interconnecting the arbor top plate  22  and the guide shoe assembly  10 , and the arbor bottom plate  24  and the guide shoe assembly, the present arbor top plate  22  and arbor bottom plate  24  includes a pair of mounting apertures located along an inclined line. Preferably, the mounting apertures lie upon a line 45° from vertical and horizontal. The arbor mounting slots  50  are selected to operably align with the corresponding mounting apertures in the arbor top plate  22  and the arbor bottom plate  24 . 
     Installation and Operation 
     To operably interconnect to the counterweight arbor  20  and the rail  30 , a pair of guide plates  60  is interlocked by engaging the corresponding tabs  62  and slots  63 . The guide shoe assembly  10  is then rotated to be dispose the rail contacting channel  40  between opposing rails  30 . The guide shoe assembly  10  is then rotated in the opposite direction to contact or abut the rail contacting surface  40  with the corresponding portion of the rail  30 . The guide shoe assembly  10  can be disposed with the major axis  12  being horizontal or vertical, or any orientation therebetween (assuming the rail contacting surface is continuous—it is understood if the rail contacting surface is multi-faceted, there will be discrete orientations intermediate the horizontal and vertical disposition of the major axis). 
     Upon the guide shoe assembly  10  being rotated to operably dispose a portion of the rails  30  within the rail contacting channel and contact the rail contacting surface, mounting bolts are passed through the arbor mounting slots  50  in the guide plates  60  and into the corresponding offset apertures in the arbor top plate  22 , or arbor bottom plate  24 , and tightened to thus locate the guide shoe assembly  10  relative to the counterweight arbor  20  and rail  30 . 
     While the invention has been described in conjunction with specific embodiments thereof, 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, the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.