Spring loaded block and tackle window sash balance assembly

A unitary, spring loaded, block and tackle balance assembly adapted for providing vertical support for a window sash running in an elongated, generally upright sash run having a guide channel comprising flange means defining a longitudinal slot extending along a plow region of the sash run, said assembly comprising:

• an elongated, generally U-shaped housing having a pair of generally parallel, laterally spaced side walls and an outer wall interconnecting the side walls, said outer wall and said side walls together defining an elongated chamber having an open side located across from said outer wall;
• block and tackle spring balance means in said chamber and adapted for being operably connected to said sash in supporting relationship thereto;
• first securing means discrete from said housing and including first slide means configured for slidably interengaging said guide channel;
• means for mounting said first securing means in said chamber in a generally fixed longitudinally position with said first slide means adjacent said open side of the chamber;
• second securing means discrete from the housing and fixed in said chamber in longitudinal spaced relationship to said first securing means, said second securing means including second slide means disposed adjacent said open side of the chamber and configured for slidably interengaging said guide channel;
• and
• support means for holding said assembly in a fixed longitudinal position relative to said guide channel during running of the window sash in the sash run,
• whereby said assembly may be slidably received in said sash run during attachment in the latter and thereby mounted in the said fixed position relative to the guide channel for supporting a window sash with said block and tackle spring balance means covered by said housing.