Constant force balance

Question

For Kolbe & Kolbe double hung windows. The most common of the window sashes weighs in at 18 lbs. The dimensions of the parts are shown in the photos.

Tom · Accepted Answer

Thanks for contacting us. Your pivot shoe looks like our 15-177, which is designed to be used with our Series 152 spring. If your sash weighs 18 pounds, then you'd want to distribute that weight between each spring supporting the sash. I would recommend using one S152-4 (4 pounds) and one S152-5 (5 pounds) on each side of the window. That will add up to 18 pounds of support.