Abstract: In a window frame track, a U-shaped channel having a front wall connecting a pair of side walls includes a block, a cam rotatably mounted in the block, an axial opening in the cam generally concentric with an opening through the front wall, a sash attached to the cam by a bar extending through the opening through the front wall into the axial opening in the cam, a plate extendable from the block axially against said track contacting the cam prevents vertical movement of the U-shaped cannel in the track when the sash is rotated out of the window frame.