Abstract: An operator for a rolling door having a curtain barrel shaft rotatable for actuating the door and including a drive gear adapted for connection to one end of the curtain barrel shaft and a second gear adapted for connection to one end of an idler roller. The idler roller in use engages one surface of the door and extends horizontally across the top of the door opening. A third gear is rotatably mounted in the region of the drive gear and the second gear and an electric motor is provided to rotate this third gear. In one version of the invention there is a moveable fourth gear in meshing engagement with the third gear and driven thereby. The fourth gear can be swung from a first position where it is in meshing engagement with the second gear to a second position where it is in meshing engagement with the drive gear. A chain loop connectable to the door is driven when the second gear and the idler roller rotate and it is provided to close the door even under pressure.