A tilt sash window system has a counterbalance spring mounted for movement with the sliding sash. A releasable securing catch projects into a jamb channel containing the spring and its end hanger and clears the latter. A tilt-action shoe is connectible to the spring by an endwise snap action and by laterally outward movement therebetween. A movable lock member provides security against disconnection. In the tilted position of the sash, a stay counterbalances the overhung weight. In a vertical tilt axis embodiment the moving spring body locates below the upper pivot shoe. The spring end is connected to the vertical jamb channel by a screwless self-fixing hanger having a tilt action under spring tension forces.
