Abstract: An adapter unit for mechanically driven doors of the type such as garage doors are driven by a motor and guided at the sides thereof by guide rails mounted to a frame that defines the door opening. The adapter unit comprises an elongated member adapted to be mounted to the back side of the door receiving channel of one of the guide rails. The elongated member defines an elongated inverted U-shaped channel in which a chain is slidably received. A sprocket is rotatably mounted in the elongated member within a circular recess defined in the channel for engagement with the chain. The sprocket is further adapted to centrally engage a shaft of the motor to thus rotate therewith. A door drive mechanism is mounted at one end of the chain and is adapted to be removably coupled to a bracket provided on an inner lower part of the door. The sprocket and chain are adapted to remain engaged between the two extreme positions of the chain which correspond with the open and closed positions of the door.

Abstract: A universal load sensing gearbox integrating a safety mechanism for use, for instance, with motor driven closures, such as garage doors, barriers and gates, includes a housing which encases a worm slidably mounted on an input shaft and adapted for rotation therewith. The input shaft is connected with the motor driving the closure. The worm is engaged with a worm gear which is mounted on an output shaft which is connected with the closure. Dished washers are provided generally around the input shaft at both ends of the worm to urge the worm in a central meshed engagement with the worm gear. A motion transmission device is provided on the worm and is adapted to slide therewith to detect a longitudinal movement thereof and to transmit this movement to an actuating device which is adapted to stop and/or reverse the motor.