Abstract: A retractable roof structure for crop protection includes pitched sections of roof defined by a retractable membrane. The membrane is moved by cables connected to a drive tube with a spring to regulate minimum tension of the cable. The drive system ensures that the membrane adjacent to the drive tube is able to travel the same distance as the second membrane from the drive tube. The rafter contains profiles to allow the stationary end of said membrane to be attached continuously to the rafters to provide a water tight connection. The rafter also contains clips which inhibit vertical, lateral and horizontal movement of the guide wires used to suspend the membrane. The guide wires are supported by flexible cables or nodes. A secondary clear membrane is installed below a white upper retractable membrane.

Abstract: A retractable roof structure for crop protection includes pitch sections of roof defined by a retractable membrane. The membrane is moved by cables connected to a drive tube with a spring regulate minimum tension of the cable. The drive system ensures that the membrane adjacent to the drive tube is able to travel the same distance as the second membrane from the drive tube. The rafter contains profiles to allow the stationary end of said membrane to be attached continuously to the rafters to provide a water tight connection. The rafter also contains clips which inhibit vertical, lateral and horizontal movement of the guide wires used to suspend the membrane. The guide wires are supported by flexible cables or rods. A secondary clear membrane is installed below a white upper retractable membrane.

Abstract: A hook for suspending from a support, such as a rod or wire, a retractable roof covering such as that used for greenhouses, comprises a generally C-shaped body including a pin for engaging the covering, a cavity for retaining the rod or wire, an opening for the cavity, and a means for locking the pin opposite of the opening.