Patent ID: 8181396

Claim:
A counterbalance system for counterbalancing the weight of a window sash in a window frame, said system comprising: a guide track coupled to said window frame, said guide track having a mounting slot formed therein; a coil spring of steel ribbon wound into a coiled configuration, said coil spring having one end bent into an anchor configuration, wherein said anchor configuration includes a first ninety degree bend in said steel ribbon causes said steel ribbon to radially extend from said coiled configuration, and a second ninety degree bend in said steel ribbon, wherein said first ninety degree bend and said second ninety degree bend are bent in opposed directions and a lateral section of said steel ribbon extends between said first ninety degree bend and said second ninety degree bend, and wherein said anchor configuration passes into, and is retained by, said mounting slot, therein anchoring said one end of said coil spring to said mounting slot; and a spring carriage coupled to said window sash and extending between said window sash and said guide track, wherein said spring carriage retains said coiled configuration of said coil spring between said window sash and said guide track so that said coil spring moves with said window sash in said guide track as said window sash is moved up and down causing said coil spring to wind and unwind.