| 摘要 |
<p>An upwardly acting sectional door system including, a door (D) having a plurality of hinged door sections (16-18) movable between a closed vertical position and an open horizontal position, a drive tube (31) mounted above th e door in the closed vertical position, an operator (11) selectively directionally rotatably driving the drive tube, cable drums (35) mounted on the drive tube for rotation therewith by the operator, springs (60) mounted in operative relation to the cable drums, and counterbalance cables (75) reeved about the cable drums and interconnecting the springs and the door to counterbalance the door when moving between the closed vertical position and the open horizontal position.</p> |
