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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS RUNNER CONNECTOR AND MAIN RUNNER RECEIVING HOLE 
       [0001]    This application claims the priority of U.S. Provisional Application No. 61/532,755, filed Sep. 9, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to suspended ceiling grid and, more particularly, to cross runner connections. 
       PRIOR ART 
       [0003]    Suspended ceiling grid is typically constructed with main runners that are relatively long and cross runners that intersect the main runners and are relatively short. The main runners are formed with holes along their length strategically spaced to receive connectors on the ends of the cross runners. Typically, the grid runners are referred to as tees because of their most common cross-sectional shape. U.S. Pat. Nos. 5,517,796 and 5,761,868 illustrate examples of cross runner end connectors. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention provides an improved cross runner connector or clip and main tee connector receiving hole. The connector and receiving hole achieve a single runner joint that has a much higher pull out or tensile resistance than prior art systems and can be easily disassembled from either a single or double runner connection. 
         [0005]    The invention utilizes a unique locking tab that greatly improves single runner connection performance. The geometry of the inventive tab resists buckling or folding of the tab when the associated runner is subjected to high tensile loads. Additionally, the inventive tab, by virtue of its geometry and spring characteristics reduces free play in a joint. The single connection joint made by the inventive connector is less prone to accidental release in a cantilever condition where only one end of a cross runner is supported. 
         [0006]    The geometry of the connector and receiving hole permits the connector to be easily released from either a single connector joint or a connector-to-connector joint. The release can be effected without damage or physical alteration to either the main runner or the cross runner. This non-destructive, non-altering release allows a cross runner to be disassembled and reconnected multiple times without loss of function. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective side view of the connector of the invention; 
           [0008]      FIG. 2  is a fragmentary side view of a main or through runner having a connector receiving hole of the invention; 
           [0009]      FIG. 3  is a side view of the connector and an end portion of a cross runner; 
           [0010]      FIG. 4  is a perspective fragmentary view of a pair of opposed connectors assembled in a common hole in a main runner; 
           [0011]      FIG. 5  is a side view of a pair of joined connectors; 
           [0012]      FIG. 6  is a top view of the pair of joined connectors; and 
           [0013]      FIG. 7  is an end view of a connector assembled in a main runner hole with an opposed connector. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    A connector or clip  10  of the invention is permanently assembled on an end of a cross runner or tee  11  and is effective to join the cross tee to a main runner or tee  12  at a hole  13  of the invention in the main tee. The connector  10  is also capable of joining with an identical connector of an opposed cross runner or tee  11  inserted in a hole  13  from an opposite side of the main runner  12 . As is customary, main runners  12  are arranged on parallel lines spaced apart by a plurality of cross runners  11  spaced along the main runners on centers determined by the location of the holes  13  on the main runners. Typically, the runners  11 ,  12  are manufactured by roll forming sheet metal into the desired cross section. A cross runner  11  has an identical connector  10  fixed on each of its ends. The connectors or clips  10  are mounted to a web  15  of the cross runner  11  that extends between a lower flange  16  and an upper hollow reinforcing bulb  17 . The main runner  12  has holes  13  located along its length spaced at, for example, 6 inches, or the industry metric equivalent thereof, and are used to establish a corresponding grid module of 2 foot or 4 foot. In 2 foot by 2 foot modules, a 4 foot cross runner, as is customary, can serve as a main or through runner for a 2 foot cross runner; a hole  13  is located at the mid-length of the 4 foot through (cross) runner. 
         [0015]    The connector  10  is stamped from high strength, hard sheet metal and exhibits spring characteristics. The side profile of the connection  10  is roughly rectangular, having a length greater than its height. Upper and lower margins  21 ,  22  of the connector  10  are offset from a major central plane of the connector to impart stiffness. Two holes  23  through the body of the connector  10  receive material of a cross runner that is folded or crimped over edges of the holes to fix the connector onto an end of a cross runner  11 . 
         [0016]    The connector  10  has a pair of opposed projections  26 ,  27  spaced by an opening that forms edges  28 ,  29 . The projections  26  are arranged to receive a strip or band  31  of material at the leading edge of an identical clip. A D-shaped hole  32  is proportioned to receive a forward projection  26  of a mating connector. Additionally, where the connector  10  is joined to an identical connector, the edge  29  of the rearward projection  27  engages a lead end  34  of the identical clip to resist compressive longitudinal forces in the associated runners  11 . 
         [0017]    An embossment  36  in the lead or forward end of a connector  10  facilitates coupling of a pair of clips being forced together in a common hole  13 , as discussed below, by riding over the forward projection  26  of the opposed connector  10 . 
         [0018]    A locking tab  41  is stamped and permanently bent out of a main plane of the clip body to a side opposite that on which the projections  26 ,  27  exist. The tab  41 , which in the illustrated arrangement is planar, is attached to the main clip body at a bend line  42  which is inclined forwardly from bottom to top. A generally rearwardly facing free edge of the tab is stepped or offset so that an upper part of the edge  43  lies forward of a lower part  44 . The upper part or zone  43  of the edge is inclined forwardly from bottom to top. The connector  10  has a generally vertical notch  46  on its forward upper edge, each side of the notch diverging, for example, at about 5 degrees from the vertical. The lower part  44  of the free edge of the locking tab  41  is rearward of an imaginary vertical plane, transverse to the plane of the main body of the connector  10 , that is tangent to a forward edge  47  of the notch  46 . A rearward edge  48  of the notch  46  lies generally in a vertical plane transverse to the connector body common with a vertical lower abutment edge  49  of the connector profile. 
         [0019]    The cross runner connector receiving hole  13  is stamped in the web  15  of the through or main runner  12 . The hole  13  has a shape similar to the capital letter A, being symmetrical about a vertical axis. A narrow top  51  of the hole  13  has a width adequate to receive the thickness of two connectors  10  with moderate clearance. A notch or shallow slot  52  at the bottom of the hole  13 , between a pair of abutments  53  is similarly proportioned to receive a double thickness of a connector body with moderate clearance. The distance between the top  51  of the hole  13  and the top of the abutments  53  is greater than the distance between the bottom of a connector notch  46  and a lower edge  54  of a forward end of the connector  10 . Opposite sides or edges  56  of the hole  13  are arcuate and convex. 
         [0020]    A cross runner or tee  11  is assembled to a main runner or tee  12  by inserting its end connector  10  in an appropriate hole  13 . The body of the connector  10  is inserted in the center of the hole  13  so that its lower edge  54  is in the central notch  52 . The cross runner  11  is pushed towards the main runner  12  until the connector profile edges  48  and  49  abut the surface of the web  15  surrounding the hole  13 . This insertion motion causes the tab  41  to be forced towards the main body of the connector  10  by a camming action developed by interference between the tab and a side  56  of the hole  13 . Before the connector edges  48  and  49  contact the web  15 , the forwardmost part of the first tab edge  43  will reach the far side of the web  15  and the tab  41  will spring towards its free state. This spring action drives the forward part of the edge  47  outward of the boundary of the adjacent side  56  of the hole  13  thereby locking the connector  10  in the hole. The tab  41  is proportioned so that its trailing part behind the forward edge  43  and including the rearward edge  44  cannot pass through the hole  13  before motion of the connection is stopped by abutment of the edges  48  and  49  with the main runner web  15 . The resilient spring action of the tab  41  causes the slightly inclined forward edge  43  at the free edge of the tab  41  working against the convex hole side  56  to draw the connector  10  tight against the main runner  12 . 
         [0021]    The distal trailing part of the tab  41 , since it cannot pass through the hole  13  and is laterally confined by the hole prevents the tab from buckling or folding outward, i.e. overbending from the main body of the connector  10  when even a high tensile load is applied to the associated cross runner  11 . The connector  10  has demonstrated a resistance to such tensile loads of  5  or more times than that of currently available prior art products. 
         [0022]    Circumstances occur where the opposite end of a cross runner  11  is unsupported so that the cross runner is in a cantilever condition. This condition can occur, for example, where an opposite end was improperly or not fully installed on a parallel main tee and then falls off the parallel main tee. Another circumstance occurs where an installer inserts a connector  10  in a main runner hole  13  and allows the cross runner to hang with its opposite end temporarily unsupported during erection of a grid. In these circumstances, the notch  46  serves to cooperate with the locking tab  41  to maintain the joint or coupling of the cross runner with a more reliable coupling than is experienced with prior art connectors. 
         [0023]    A second connector  10  of an opposing cross runner  11  can be assembled in a hole  13  from the side opposite the first connector. A second connector  10  is placed laterally against the lead end of the first connector and pushed into the center hole slot  52  until its abutment edges  48  and  49  contact the web  15  of the main runner  12 . In this position, the connectors  10  establish a strong connector-to-connector lock with the forward band  31  of each connector captured in the pocket between opposing projections  26 ,  27  of the other connector. The locking tab  41  of the second connector  11  works as previously described. The lateral compression on both locking tabs  41 , developed by their confinement in the hole  13 , serves to maintain the connectors in mutual inter-engagement. 
         [0024]    The connector  10  can be easily released from a hole  13  without tools whether or not coupled to an opposing connector. This release is accomplished by holding the main runner  12  in one hand, raising the cross runner to be released so that the top edge of the hole  13  is fully received in the cantilever notch  46  on the top of the associated connector  10  and then twisting the cross runner  11  so that the connector pivots in the hole  13  away from any opposed connector. This pivoting motion moves the connector  10  towards the hole side  56  compressing the associated tab  41 . The convex character of the hole side  56  focuses the reaction force developed by the hole side on the trailing portion of the tab  41 . The tab  41  is forced towards the plane of the main body of the connector  10  until the locking edge  43  is free of the main runner web area at the edge of the hole  13 . In this orientation of the connector  10 , the locking strips or bands  31  of any opposed connectors  10  are released from the restriction of opposing projections  26 ,  27 . The twisted connector  10  can now be withdrawn from the hole  13  to release its cross runner  11 . No damage or permanent deformation is incurred either by the connector  10  or the main runner  12 . The connector  10  can, therefore, be reassembled and disassembled repeatedly. 
         [0025]    It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.

Summary:
A cross runner connector receivable in a through runner hole that locks with an identical opposed connector and locks with the through runner hole with increased tensile strength, both locks being releasable without tools by manipulation of the associated cross runner.