Abstract: A winding rod is mounted for rotation in winding and unwinding directions about a fixed axis of rotation. An elongated flexible member has one end affixed to the winding rod. A traction device is operatively connected to the flexible member for selectively pulling the flexible member at a predetermined speed in the winding and unwinding directions. A first driving device is rotatable in normal and reverse directions and includes a torque motor for driving the winding rod. A clutch operatively couples the driving device to the winding rod and is maintained in a disengaged state during the unwinding operation of the winding rod by making the speed of rotation of the driving device in the reverse direction higher than the speed of rotation of the winding rod in the unwinding direction.

Abstract: Apparatus for opening and closing a flexible screen in a greenhouse or the like includes a winding rod mounted for rotation about a fixed axis and to which an end edge of an elongated flexible screen is fixed, first driving apparatus for constantly applying a torque to the winding rod tending to rotate the same such that the flexible screen would be wound thereon, and traction apparatus including elongated flexible members, each of which has its two ends secured to a rotatably mounted driving shaft with respective end portions thereof oppositely coiled on the driving shaft and having two portions guided along a predetermined path of travel with one of the portions being operatively connected to the other end edge of the flexible screen, and second driving apparatus for selectively rotating the driving shaft in a normal or reverse direction.

Abstract: Apparatus for opening and closing the flexible screen of a greenhouse or the like include an elongated driving shaft rotatably mounted about a fixed axis of rotation, a prime mover such as a reversible motor for selectively rotating the driving shaft in either one of the normal and reverse directions, transmission gear apparatus operatively connected to the driving shaft, an elongated flexible driving shaft operatively connected at one end to the transmission gear apparatus adapted to be rotated through the transmission gear apparatus upon the rotation of the driving shaft, reduction gear apparatus operatively connected to the other end of the elongated flexible driving shaft and a winding rod operatively connected at one end to the reduction gear apparatus and adapted to be rotated through the reduction gear apparatus upon rotation of the flexible driving shaft.