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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a window operating mechanism for opening and closing a casement window.  
           [0003]    2. Discussion of the Prior Art  
           [0004]    Casement windows have been in existence for a great many years. In the last forty or fifty years, operating or activating mechanisms have become standard equipment in casement window assemblies. Casement windows commonly open in one or two directions, depending upon whether the hinges are mounted on the left or the right hand side of the window. Typical operators for such windows are described in Canadian Patent No. 1,301,202, issued to D. A. Nolte et al on May 19, 1992; and in U.S. Pat. No. 3,044,311, issued to G. W. Gagnon on Jul. 17, 1962.  
           [0005]    A problem inherent to existing window operating mechanisms is reversibility, i.e. the ability to adapt the mechanism to windows opening in the opposite directions. In existing devices, it is necessary to disassemble and then reassemble a substantial portion of the devices in order to be able to use the devices with windows opening in opposite directions.  
         GENERAL DESCRIPTION OF THE INVENTION  
         [0006]    An object of the present invention is to provide a solution to the above-identified problem in the form of a relatively simple window operating mechanism which can be quickly and easily modified for use on windows opening in opposite directions.  
           [0007]    Accordingly, the invention relates to an operating mechanism for a casement window comprising:  
           [0008]    (a) a hollow, closed housing for mounting on a casement window frame, said housing including:  
           [0009]    (i) an opening in one side thereof;  
           [0010]    (b) a worm shaft rotatable in said housing for manual actuation of the mechanism;  
           [0011]    (c) an inner gear in said housing for rotation by said worm shaft;  
           [0012]    (d) an annular outer gear in said housing for rotation by said inner gear, said outer gear including  
           [0013]    (i) a flange extending out of said opening in the housing;  
           [0014]    (e) spaced apart pins on said flange; and  
           [0015]    (f) a crank arm releasably mounted on said pins for extending in one of two opposed directions,  
           [0016]    whereby the operating mechanism can be readily adapted to windows opening in opposite directions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The invention is described below in greater detail with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention, and wherein:  
         [0018]    [0018]FIG. 1 is an isometric view of a window operating mechanism in accordance with the invention as seen from above and an outer end;  
         [0019]    [0019]FIG. 2 is an isometric view of the mechanism of FIG. 1 with parts removed;  
         [0020]    FIGS.  3  to  5  are isometric views of a cover used on the mechanism of FIGS. 1 and 2 as seen from above (FIGS. 3 and 4) and below (FIG. 5);  
         [0021]    [0021]FIG. 6 is a top view of the mechanism of FIGS. 1 and 2;  
         [0022]    [0022]FIG. 7 is a cross section taken generally along line  7 - 7  of FIG. 6;  
         [0023]    [0023]FIG. 8 is an inner end view of the mechanism of FIGS. 1 and 2;  
         [0024]    [0024]FIG. 9 is a cross section taken generally along line  9 - 9  of FIG. 8;  
         [0025]    [0025]FIG. 10 is an exploded, isometric view of interior elements of the mechanism of FIGS. 1 and 2; and  
         [0026]    [0026]FIG. 11 is a cross section taken generally along line  11 - 11  of FIG. 6. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    With reference to FIGS. 1 and 2 of the drawings, a window operating mechanism in accordance with the present invention includes a hollow, one-piece housing indicated generally at  1 , which is covered by a cover  2 .  
         [0028]    The one-piece hollow cover  2  (FIGS.  3  to  5 ) is defined by a top wall  4 , an outer end wall  5 , side walls  6  and a flange  7  extending upwardly from the inner end of the top wall  4  and outwardly from the side walls  6 . A sleeve  8  extends upwardly from the top wall  4 , and a hole  9  (FIG. 3) is provided in the otherwise closed top end of the sleeve.  
         [0029]    The housing  1  (FIG. 2, where the cover  2  is omitted) includes a top wall  10 , a bottom wall  11 , an outer end wall  12  and side walls  13  extending between the top and bottom walls  10  and  11 ; respectively. The inner end  14  of the housing  1  is open for receiving various elements of the mechanism as described below. The bottom wall  11  extends outwardly a substantial distance beyond the open inner end  14  of the housing  1 . A plurality of holes  15  are provided in the outer end  16  of the bottom wall  11  for receiving screws (not shown) for securely mounting the housing  1  on the ledge of a window in the conventional manner. Because a large number of window frames are made of plastic, it is sometimes necessary to use many screws to ensure a secure mounting of the operating mechanism. When mounting the mechanism on a window frame, the outer end  16  of the bottom wall  11  and the inner free ends of the top and side walls of the housing  1  are housed in a socket (not shown) in the window frame. A flange  18  near the inner end of the housing  1  limits movement of the housing into the socket. Actually, the flange  18  bears against a vertical surface of the window frame around the socket to stabilize the mechanism, i.e. reduce or eliminate torque on the screws holding the housing  1  in position during operation of the mechanism.  
         [0030]    Rectangular notches  20  and  21  are provided in the centers of the interiors of the top and bottom walls  10  and  11 , respectively of the housing for slidably receiving rectangular projections  22  and  23  on the top and bottom ends, respectively of a core body  27  of the mechanism. When the core body  27  is mounted in the housing  1 , mating of the projections  22  and  23  with the notches  20  and  21  prevents rotation of the core body in the housing. As best shown in FIGS.  8  to  10 , the core body  27  is generally-cylindrical for rotatably supporting an annular outer gear or gear ring  29  which is sandwiched between annular upper and lower spacers  30  and  31 , respectively. The upper spacer  30  is seated on a shoulder  32  on the core body  27 . The outer gear  29  has a larger interior diameter than the lower spacer  31 . Inclined teeth  34  extend around the interior of the outer gear  29  for meshing with similarly shaped and inclined teeth  35  on an inner, disc-shaped gear  36 , which is, in effect, a sun gear.  
         [0031]    The inner gear  36  is rotatably mounted on a pin  38  on the flat base  39  of a semicircular recess  40  in one side of the core body  27 . Rotation of the inner gear  36  results in a corresponding rotation of the outer gear  29  around the longitudinal axis of the core body  27 . The recess  40  intersects an inclined passage  42  through the center of the core body  27 . The inner gear  36  is rotated by a worm shaft  43  which is rotatably mounted in the passage  42 . Helical threads  44  on the shaft  43  mesh with the inner gear  36 . The cylindrical bottom end  46  of the shaft  43  is rotatable in an inclined recess  47  in the bottom wall  10  of the housing  1 . The shaft  43  is held in the housing  1  by a cylindrical lock screw  49 , which bears against a shoulder  50  on the shaft  43 . External threads on the screw  49  engage the threaded upper end of a passage  51  through an inclined projection  53  on the center of the housing top wall  9 .  
         [0032]    A handle assembly, which is indicated generally at  55 , is mounted on the splined upper end  56  of the shaft  43 . The assembly  55  includes a base  57  with a splined socked  58  for mounting on the shaft  43 , and a handle  60  pivotally connected to the base  57  by a pin  61 . A convex, transversely extending rib  62  on the cylindrical, body end of the handle  60  limits rotation of the handle when the latter is rotated from a non-use, storage position (not shown) on the base  57  to the use position (FIGS. 1, 6 and  7 ). A knob  64  secured to the outer, free end  65  of the handle  60  by a screw  66  facilitates manual manipulation of the handle.  
         [0033]    Immediately prior to mounting the handle assembly  55  on the housing  1 , the thin, plastic rover  2  is mounted on the housing. An arm  66 , which forms part of a conventional lever system (not shown) for opening and closing a window, is mounted on a rectangular projection  67  on the outer gear  29 . The projection  67  extends outwardly from the open end  14  of the housing  1 . Spaced apart snap pins  69  on the projection  67  mate with holes in the arm  66 .  
         [0034]    Snap rings  70  placed in annular grooves  72  (FIG. 11) near the outer free ends of the pins  69  hold the arm  66  on the outer gear  29 . Obviously, it is a simple matter to reverse the arm  66  on the pins  69 . The arm is lifted off the pins  69  causing the snap rings  71  to compress and then expand, the arm is rotated 180°, and the arm  66  is again placed on the pins  69 . When the arm  66  is reinstalled, the rings  71  compress and again expand to hold the arm on the pins  69 . This process applies to a retrofit situation. Normally, the operating mechanism is installed in a window frame when a window is being produced. Depending upon the intended opening direction, i.e. which side of the window sash carries the hinges, the arm  66  is installed to point in the appropriate direction.  
         [0035]    Thus, it will be appreciated that the above described mechanism is much simpler in terms of structure than other assemblies intended for the same purpose. Moreover, the mechanism of the present invention makes it substantially easier to change the direction of window opening.

Summary:
An operating mechanism of a casement window includes a handle for rotating a worm shaft, which in turn rotates an inner gear, an annular gear and a crank arm to open a window. The crank arm is mounted on spaced apart pins on a flange or extension of the outer gear, so that the arm can be reversed on the pins to change the direction of window opening.