Abstract: An operating mechanism for an overhead door has a drive pulley mounted on the door. A drive motor is coupled to the pulley. An arm pivotally mounted on the door extends from the upper portion of the door generally in the direction of opening movement of the door. A guide cable is mounted on the end of the arm. A drive cable strung above the door extends in a path from the front of the building, around the guide pulley, around the drive pulley, and over the guide pulley to the rear of the building. The guide pulley prevents contact between the top of the door and the cable. The drive motor may be movably mounted in the operating mechanism for performing a variety of control functions.

Abstract: The present invention provides a friction gear comprising a drive pulley operated by a motor, a driven ring disposed around the drive pulley and forming a friction zone between the inside surface of the ring and the pulley. A flexible tractive member, such as a rope, cable, chain or belt, extends around the outside periphery of the ring and is in frictional connection therewith, suitably in a groove, the member producing a pressure in the friction zone proportional to the tension in the tractive member. The gear operates in an analogous manner in both directions of rotation of the ring and may be used for example as an extremely simple garage door operator installed on the inside of the door per se. Disengagement between the drive pulley and the driven ring is possible in a simple manner by actuating from the outside of the gear an opposite movement to the pivoting ring.