How it all works

OS cremone handle and mechanism are mounted to the frame. At 0º window is closed and the locking points are secured. When the cremone handle is turned, the locking points release in the first 60º of handle rotation. At 180º the machanism pushes the sash fully open. As the cremone handle rotates back to the closed position, the machanism brings the vent back to the frame and engages the locking points. 

 

Additionally, since all this functionality begins with a frame-mounted handle, removable flyscreens can be fixed to the inside.