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You are an expert at summarizing long articles. Proceed to summarize the following text: 
TECHNICAL FIELD 
       [0001]    Locking shoes for tilt sash. 
       BACKGROUND 
       [0002]    The invention of this application improves on an assembly of a brake or locking element in a tilt shoe that includes a cam to actuate the brake when a sash tilts. The previous assembly is illustrated and described in published U.S. patent application 2005/00229492, application Ser. No. 11/101,202, which represents the closest known prior art. 
       SUMMARY 
       [0003]    The previous lock and shoe assembly encountered difficulties when the marketplace demanded narrower lock shoes running in narrower shoe channels. The tilt shoe assembly that is the subject of this application was able to meet the demand for narrower shoes without compromising the reliability of the assembly and without adding to the cost of manufacture. 
         [0004]    The new assembly uses brake retaining tabs that hold the brake or locking element within the shoe while allowing a pair of brake pads to expand and lock or retract and unlock. The tabs are spaced from a guide wall along which a bearing wall of the locking element moves as the brake operates. A portion of the bearing wall fits between the tabs and the guide wall to retain the locking element in place. 
         [0005]    A tilt cam that spreads the brake pads apart when a sash tilts is disposed between the brake pads for this purpose. When the sash untilts or returns to vertical, the brake pads retract with the tilt cam. This is accomplished by a resilient element connecting the brake pads and holding them against cam surfaces. 
         [0006]    Movement of the brake pads in response to the tilt cam does not separate the pads by enough to allow bearing walls of the locking element to escape from the retainer tabs. The resilient element, however, allows the brake pads to be spread far enough to escape, and this possibility can be used to assemble the locking element into the shoe before the shoe is arranged within a shoe channel. Thereafter, the locking element cannot escape from the shoe and yet is free and effective in its movements in response to the tilt cam to lock and unlock as the sash tilts. 
     
    
     
       DRAWINGS 
         [0007]      FIG. 1  is an elevational view of a preferred embodiment of the inventive assembly. 
           [0008]      FIG. 2  is a side elevational view of the shoe of  FIG. 1 . 
           [0009]      FIG. 3  is a side elevational view similar to the view of  FIG. 2 , with a locking element and cam removed from the shoe. 
           [0010]      FIG. 4  is an elevational view similar to the view of  FIG. 1  with the locking element and cam removed from the shoe. 
           [0011]      FIG. 5  is a plan view of the locking element removed from the shoes of  FIGS. 3 and 4 . 
           [0012]      FIG. 6  is a fragmentary cross-sectional view of the assembly of  FIG. 1 , taken along the line  6 - 6  thereof. 
           [0013]      FIG. 7  is an exploded perspective view of the shoe and cam of  FIGS. 1 and 2  showing the locking element separated from the shoe. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Shoe  10 , as shown in the drawings, can have many forms that are preferably molded of resin material and dimensioned to slide up and down within a shoe channel (not shown) of a tilt sash (also not shown). Shoe  10  connects to a counter balance that is not illustrated because it can be formed in a variety of ways to exert an upward force against shoe  10  to counterbalance a sash to which the shoe is connected. The operation of locking shoes generally is well understood in the window sash counterbalance art, and is explained in published U.S. Patent application No. 2005/00229492. 
         [0015]    Shoe  10  contains tilt cam  15  that rotates when a sash tilts. Locking element  20  is actuated by cam  15  to lock shoe  10  within a shoe channel whenever the sash tilts. Conversely, when a sash untilts and returns to a vertical position within a window jamb, cam  15  rotates to a position releasing locking element  20  to allow shoe  10  to move freely up and down in a shoe channel as a sash moves. 
         [0016]    Locking element  20  is formed with a pair of opposed brake pads  21  that are inter-connected by a resilient element  25 , which holds brake pads  21  against surfaces of cam  15 . When cam  15  rotates in response to a sash tilt, this forces brake pads  21  apart, against the resilience of element  25 , to lock shoe  10  within a shoe channel. Conversely, when a sash untilts and rotates cam  15  to an unlocked position, resilient element  25  draws brake pads  21  back toward each other to release the sash brake. 
         [0017]    The assembly of brake  21  within shoe  10  for operative movement in response to cam  15  is preferably accomplished by retainer tabs  30 . These are spaced from a guide or groove wall  31 , which intersects recess  35  that receives cam  15 . Tabs  30 , besides being spaced from guide wall  31 , are preferably located adjacent cam recess  35 . 
         [0018]    Brake element  20  has a pair of bearing walls  32  that move along guide wall  31  of shoe  10  as brake  20  moves between locked and unlocked positions. Portions  33  of bearing walls  32  of brake  20  fit between retainer tabs  30  and guide wall  31  to retain brake  20  in place while it moves between locked and unlocked positions. Bearing wall portions  33  slide outward and inward while trapped behind retainer tabs  30 . 
         [0019]    Surfaces of cam  15  are configured so that they do not spread brake pads  21  far enough apart so that bearing surface portions  33  can escape from behind retainer tabs  30 . This ensures that brake  20  remains assembled to shoe  10  while it moves between locked and unlocked positions. 
         [0020]    Resilient element  25 , which biases brake pads  21  toward each other and into engagement with surfaces of cam  15 , does allow brake pads  21  to be spread farther apart than the locked position produced by cam  15 . This can occur, however, only when shoe  10  is not confined within a shoe channel. This allows assembly and disassembly of brake element  20  and shoe  10  when shoe  10  is not confined within a jamb channel. In other words, cam  15  can never dislodge locking element  20  from its movably trapped position behind retainer tabs  30 , but resilient element  25  allows brake pads  21  to be spread farther apart during assembly or disassembly of bearing wall portions  33  into retained positions behind tabs  30  when shoe  10  is not confined within a jam channel. Initial assembly of lock  20  to shoe  10  is accomplished simply by spreading brake pads  21  apart far enough to position bearing walls  32  against guide wall  31  and then allow resilient element  25  to retract brake pads  21  toward each other and move bearing wall portions  33  in behind tabs  30  where brake element  20  is permanently retained for movement between locked and unlocked positions. 
         [0021]    The assembly of a shoe, locking element, and tilt cam, as explained above, allows shoe  10  to be made narrower than previous shoes have been made to fit in narrower shoe channels, as desired by window manufacturers. Positioning retainer tabs  30  close to cam recess  35  allows shoe  10  to retain bearing wall portions  33  effectively and operatively without requiring much shoe width. 
         [0022]    Arranging tabs  30  to engage both upper and lower portions of bearing wall projections  33  is also preferred for secure and reliable retention of lock  20 . This may not be essential in practice, however. While the preferred embodiment, as illustrated, suggests  4  retainer tabs  30 , a single pair of tabs may be arranged with one retainer tab on each side of cam recess  35  to accomplish the necessary retention. Other variations are also possible in adapting shoe  10  to different counterbalance systems, and different shoe channel dimensions and configurations.

Summary:
An assembly of a cam and a tilt lock in a shoe for a tilt sash includes retainer tabs disposed near the cam to trap movable brake pads between the tabs and a shoe wall so that the brake pads can move apart in response to pivoting of the cam to a locked position and can move back toward each other to an unlocked position while remaining effectively retained by the tabs.