| 摘要 |
<p>Door re-inforcements (14, 15, 16) are automatically positioned and removed by the door's (8) closing and opening movements, respectively. A roll-up, sliding or retractable door (8) is strengthened in its closed position by an arrangement of bars (14, 15, 16) held in position by brackets (17, 18, 19, 20 21, 22) on the door frame. The door (8) by its opening movement, progressively and sequentially catches and removes the bars (14, 15, 16) to a location wherein they will not obstruct the doorway thereby opened. Conversely, the bars (14, 15, 16) are progressively and sequentially replaced by the door's (8) closing movement.</p> |
