| 摘要 |
An overhead door with rollers on its sides is provided with a pair of elevated, non-vertical tracks into which the rollers move as the door is moved to the open position. The door is opened by cables that extend from a pair of drums, to pulleys at the distal ends of the tracks, and then to the top corners of the door. Provision is made for transitioning curved portions of the tracks, and, in some cases, vertical portions below the curved portions, by a plurality of links provided between the cable ends and the door upper corners.
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