| 摘要 |
A power drive moves a movable closure (D) between an open position and a closed position with respect to a portal defining a passage through a barrier. The power drive can include an elongated drive member (34) connected to the movable closure and a ball nut drive assembly (64) for selectively moving the drive member longitudinally. The elongated drive member (34) can be a compound drive member having at least one gear or tooth-like member extending helically around in uniformly spaced turns about a core of the drive member to form a rigid or resilient screw-like portion (88) capable of being driven by operable engagement with the recirculating ball nut drive assembly (64). A flexible portion, such as a push/pull cable (90) can be attached to one end of the screw-like member to allow the power drive to move a movable closure along a curved or other non-linear path. |
