Weight and chain windows employ a counterbalance system that is quite simple. On a basic level, the weight and chain window system involves a pulley, a chain, and a weight. This highly efficient system leverages mechanical advantage to harness a simple machine to make everyday life easier, especially when operating weight and chain windows.
Operable window sashes can be quite heavy, especially so with larger windows. Some sashes can weigh as much as 20 pounds, or more, depending on the size of the window and whether they have single pane or double pane glass. Opening these larger windows without assistance would require quite a bit of effort
However, operating weight and chain windows is made much easier due to the use of counterbalanced weights. These weights can be made of lead, cast iron, or even brass. Which material the weights are made of is less importance than what they weigh.
The total weight of the window sash weights is equal to the total weight of each operable sash. The load is distributed evenly on either side of the window. For example, if a sash weighed ten pounds, one five-pound weight would be attached to each side of the sash.
The sash weights are attached to either a metal sash chain or a sash cord, made of twisted fiber, which is then attached to the window sash with a piece of hardware called a chain attachment spiral. A 5/8" hole is bored into the wooden window stile and the small, metal spiral, which resembles a spring, is then embedded in the window frame.
The weights ride in a hollow sash weight pocket on each side of the window, which is concealed by the jamb. When both the upper and lower sashes are operable, there are two, independent weights housed side-by-side in the same sash pocket. The sash weights ride freely up and down, counterbalancing the weight of the sash as it is raised and lowered. These weights are installed in such a way that they cannot ever touch or interfere with each other.
Considering that weight and chain windows have been in use in America since it was a British colony, the stability and efficiency of the counterbalance system has long been proven by the test of time.
- Linda Childers