Patent ID: 8074402

Claim:
A combination of a curl spring and a holder used in a window sash counterbalance system, the holder comprising: a holder body being formed of a first material having a first coefficient of friction to hold curled coils of the curl spring and permit uncurled lengths of the curl spring to pass out of and into the holder; and a bearing surface of the holder engaged by the curled coils of the curl spring substantially when a sash is lowered thereby uncurling the curl spring, the bearing surface being formed of a frictional material having a second coefficient of friction greater than the first coefficient of friction and within a range of about 0.30 to about 0.55; wherein at least a portion of the uncurled length of the curl spring can engage the first material of the holder when passing into the holder with a first frictional resistance and wherein the bearing surface provides a second frictional resistance, based on the second coefficient of friction and greater than the first frictional resistance of the holder body, to an uncurling of the curl spring when the at least a portion of the uncurled length of the curl spring is passing out of the holder and thereby resists sash drop.