| 摘要 |
A self-contained heavy duty constant force sliding sash counterbalance assembly embodying a stacked plurality of coil springs each having a uniform coiling and recoiling force throughout all of the various coils irrespective of the individual coil spring positions of extension or contraction, wherein the counterbalance assembly structure is provided with an elongated U-shaped housing adapted to adjustably accommodate the addition or removal of individual spring elements as necessary in order to achieve the proper counterbalance effect for the weight of the particular sash to be supported so that over the raising and lowering range of that sash to which the counterbalance assembly is affixed, and at all adjustably set sash opening elevations and corresponding coil spring positions of extension and contraction therebetween, there is a substantially constantly uniform counterbalance force effect exerted on the sash.
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