Torque actuated brake mechanism for spring balanced window sash

摘要

A brake mechanism utilizes the tension of a spring acting upwardly and the weight of a window acting downwardly to produce a force couple for applying a frictional force to hold a window sash in a preselected position in a sash run. The mechanism is utilized in combination with a jamb liner defining an elongated sash run provided with a C-shaped guide channel in its plow region. The channel has co-planar, laterally spaced, flanges defining a longitudinally extending slot therebetween. A brake component has a pair of shoe portions disposed in the channel adjacent respective internal flange surfaces. The brake component rotates in the channel to move the shoe portions into frictional engagement with the internal flange surfaces. A columnar element rigid with the brake component extends through the slot and presents means disposed outside the channel for applying a torque to rotate the brake component inside the channel. A support platform for a window sash and a balance spring are connected to respective spaced points on the columnar element outside the channel. The connection points are offset so that the tension of the spring acting upwardly and the weight of the sash acting downwardly impose a torque on the element to rotate the brake component and move the brake shoe elements into frictional contact with the internal flange surfaces.