Patent ID: 7669284

Claim:
A block and tackle window balance device adapted for traveling with a window sash, the block and tackle window balance device comprising: a channel; a top guide secured proximate a top end of the channel; a bottom guide secured proximate a bottom end of the channel, the bottom guide comprising a substantially vertical portion adapted to guide the balance device with a window sash along a rear wall of a window jamb surface when installed in a window jamb; a fixed pulley block fixed relative to the channel; a translatable pulley block unit moveable within the channel; a spring comprising a first end and a second end, wherein the first end is fixed relative to the channel and the second end is connected to the translatable pulley block unit; a cord comprising a first cord end and a second cord end; and a roller for dispensing the cord, wherein at least a portion of the roller is located below the substantially vertical portion of the bottom guide when installed in a window jamb, and wherein the cord is threaded through the translatable pulley block unit and the fixed pulley block unit and extends around the roller, the first cord end being attached to the translatable pulley block unit and the second cord end being attachable to a jamb.