Pivot corner for a sash window
TECHNICAL FIELD 
     The invention relates to a pivotable sash window and, more particularly, to a flush-mounted pivot corner having a pivot pin extending from a housing and operatively engaged in a sash balance brake assembly, wherein the pivot pin rotates relative to the housing upon application of a torque greater than a predetermined amount. 
     BACKGROUND PRIOR ART 
     Double-hung window assemblies having pivotal sashes are well known in the art. Typically each of the sashes includes a pair of opposing pivot pins which outwardly extend into respective rotatable members in the side jambs. The rotatable members are each coupled to a sash balance assembly which provides an upward force to counteract, and thus balance, the gravitational force of the particular sash. 
     When pivoting the window, the center of gravity of the window is moved out of line with the force of the sash balance assembly, which can cause the sash balance assemblies to force the sash up. To counteract this force, the rotatable member often includes a rotatable brake assembly which locks the sash balance when the sash is pivoted. The brake assembly is typically actuated by rotation of the pivot pin when the sash is pivoted. Occasionally, the brake assembly jams and fails to rotate upon rotation of the pivot pin. When this happens, the pivot pin can twist and potentially break causing a catastrophic failure. Specifically, if the pivot pin breaks the sash can potentially fall out of the window frame. 
     The present invention is provided to solve this and other problems. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a flush-mounted pivot corner adapted for operative engagement with a sash balance brake assembly of a pivotable sash window. 
     In accordance with the invention, the pivot corner comprises a housing and a pivot pin. The housing includes an axial bore. The pivot pin has a first pin portion disposed within the bore and a second pin portion extending outwardly therefrom and adapted for operative engagement with the brake assembly. The axial bore and the first pin portion are complementarily octagonal in cross-section. The first pin portion has a cross-section sufficiently smaller than the cross-section of the axial bore to permit non-destructive rotation of the pin relative to the housing upon application of a predetermined torque. Thus in the event the brake assembly jams and fails to rotate, the pin will rotate in the housing rather than twisting and breaking. 
     Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawing. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of a double-hung window assembly including a pivot corner in accordance with the invention; 
     FIG. 2 is an exploded perspective view of the pivot corner and a brake assembly; 
     FIG. 3 is a perspective view of the pivot corner; 
     FIG. 4 is a section of the pivot corner taken along lines 4--4 of FIG. 3; and 
     FIG. 5 is similar to FIG. 4, but with the sash window pivoted. 
    
    
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiment illustrated. 
     A pivot corner, generally designated 10, adapted for operative engagement with a sash balance brake assembly 12 of a pivotable sash window 14 is illustrated in FIG. 1 The pivotable sash window 14 includes a top header 14a, two side stiles 14b and a base 14c. 
     The pivot corner 10 is shown in greater detail in FIGS. 2 and 3. The pivot corner 10 comprises a housing 16 and a pivot pin 18. The housing 16 is molded of Nylon 6 and the pin 18 is molded of glass filled (30%) Nylon 6. The housing 16 is flush mounted along the bottom surface of the sash base 14c. 
     The housing 16 has an axial bore 20 having an octagonal cross-section. The pivot pin 18 has a first, octagonal portion 18a disposed within the bore 20 and a second, rectangular portion 18b extending outwardly therefrom. 
     The sash window 14 typically includes two of the brake assemblies 12, one installed in each of the side stiles 14b. A sash balance assembly, generally designated 19, is coupled to each of the brake assemblies 12. 
     The brake assembly 12 includes a generally oval drum 12a having a rectangular cavity 12b and rotatably disposed in a shoe 12c. As is well known, the drum 12a forms a camming surface with the inner surface of the shoe 12c, such that rotation of the drum 12a expands the shoe 12c. As is well known, expansion of the shoe 12c locks the brake assembly in the respective stiles 14b, locking the sash balance assembly in place. 
     The second rectangular portion 18b of the pin 18 is inserted into the rectangular cavity 12b. Thus when the sash 14 is pivoted, the housing 16 rotates the pin 18, which rotates the drum to cam open the shoe 12c. 
     The octagonal first pin portion 18a has eight equal sides of 0.240&#34;. The octagonal bore 20 has four major sides of 0.270&#34; and four minor sides of 0.250&#34;. Thus when the first octagonal portion of 18a of the pin 18 is inserted in the octagonal bore 20, there is an interference fit so that rotation of the housing 16 causes the pin 18 to rotate. However, if the drum 12a fails to rotate, the pin 18 will deform and, thereby, rotate in the housing 16, rather than twist and break, as illustrated in FIGS. 4 and 5. The brake assembly can be then repaired, the pin 18 can be reset properly in the bore 20, and the window assembly will be as good as new. 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.