Abstract:
A winch with adjustable arms allowing the length to be adjusted. The winch can have a very thin drum to allow it to fit in confined spaces.

Description:
[0001]    This application claims priority from provisional application Ser. No. 61/061,403, filed Jun. 13, 2008, the entire contents of which are herewith incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Winches can be used to move various objects and scenery, especially in a stage lighting environment. In some applications for a winch, the distances over which force application are carried out can vary. 
         [0003]    For example, when lifting scenery on a stage, the width of the scenery depends on the specific scenery being lifted. This width correspondingly sets the width over which the lifting needs to occur, e.g., when lifting is carried out by the two far sides. 
         [0004]    Also, the supports for the lifting may be separated by varying widths. 
       SUMMARY 
       [0005]    The present application describes a winch with movable end parts that allow it extend across variable length supports and to carry out lifting across those variable lengths. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1A-1C  show the “tab” winch in multiple extended positions with different distances between the pulling areas; 
           [0007]      FIG. 2  illustrates a “tab” drum used according to an embodiment; and 
           [0008]      FIG. 3  illustrates the way that variable width lifting. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    According to an embodiment, a winch is described which can vary in width and hence can vary the locations of its outer extent. 
         [0010]    Another embodiment describes special operations which enable a reduced-thickness winch. This can facilitate the use of this winch in certain applications, such as overhead and in limited space areas. 
         [0011]    The basic diagram of the winch in multiple different configurations is shown in  FIGS. 1A-1C . 
         [0012]    The main part of the winch includes a special drum for unwinding cable from two different locations at the same time. The inventors call this a yoyo drum  100 . The yoyo drum  100  has a power plant that causes its rotation. Two extendable arms  110 ,  120  are coupled to the yoyo drum  100  and can be extended relative thereto. Each arm  110 ,  120  has an idler at its very end. The arm  110  has the idler  111 , and the arm  120  has the idler  121 . 
         [0013]    In operation, the cable pays onto and off of the drum  100  at two different locations simultaneously. One cable goes along arm  110  to idler  111 , and is raised or lowered by the idler. The other cable goes along arm  120  to idler  121 , and is simultaneously and synchronously raised or lowered from both spots. 
         [0014]      FIG. 2  shows a detail of the yoyo drum from its side, illustrating the two tabs in the drum and those tabs can each hold their own supply of cable. The yo-yo drum  100  includes two different tabs,  202   05 . Each tab forms a slot that holds a stack of cable such as  210 . The cable can be stacked in each slot up from one side of the driven element, while simultaneously fed or taken up on the other tab from the driven element. 
         [0015]    The special design allows the yoyo drum to hold cable only within a “tab” in the drum, and hence allows the drum to be very thin, even though it is a double cable supply drum. In the embodiment, the drum can be about the same thickness as the arms that extend and retract, so that the drum can fit within whatever thickness the arms can fit in. In one embodiment the drum is no thicker than the arms. In another embodiment, the drum is no more than 1.5 times the thickness of the arm. 
         [0016]    The embodiment enables reconfiguring between multiple different crossbar sizes. For example, the crossbar elements such as  110  includes two portions  115 ,  116 , which slide relative to one another. The portion  116  is smaller in outer cross section than the portion  115 , and hence the portion  116  fits within the portion  115 . Fasteners such as screws and nuts  117  hold the portion  115  relative to the portion  116 . 
         [0017]    Other ways of holding the two arm parts together can also be used. For example, a clamp system could be used to hold the parts relative to each other. A threaded system could be used where one rod is threaded within the other. 
         [0018]    Thus the lengths of the arms can each be independently adjusted to any desired length. Hence, this winch can be reconfigured between any desired set of crossbar lengths. 
         [0019]      FIG. 3  illustrates how the distance  310  between the arms  315 ,  316  can be reconfigured. The distance W is based on the distance between holding portions  351 ,  352  on the item to be lifted  350 . The movement of the winch cable causes the item  350  to go up and down. 
         [0020]    Although only a few embodiments have been disclosed in detail above, other embodiments are possible and the inventors intend these to be encompassed within this specification. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way. This disclosure is intended to be exemplary, and the claims are intended to cover any modification or alternative which might be predictable to a person having ordinary skill in the art. For example, other sizes, materials and connections can be used. Other structures can be used to receive the magnetic field. In general, an electric field can be used in place of the magnetic field, as the primary coupling mechanism. Other kinds of antennas can be used. Also, the inventors intend that only those claims which use the-words “means for” are intended to be interpreted under 35 USC 112, sixth paragraph. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims. 
         [0021]    Where a specific numerical value is mentioned herein, it should be considered that the value may be increased or decreased by 20%, while still staying within the teachings of the present application, unless some different range is specifically mentioned. Where a specified logical sense is used, the opposite logical sense is also intended to be encompassed.