| 摘要 |
An overhead door assembly for opening and closing a door opening comprises a plurality of door sections (10) having hinges (12) for hingedly joining the door sections (10) together. A pivot (26) on an upper end region of each door section (10) pivotally connects a tandem arm (28). Each tandem arm (28) has at opposite ends thereof a rotatably mounted roller (20). A lowermost door section has a roller (21) rotatably mounted at the lowermost region of the door section. Two lead arms (29) each have a first end pivotally connected to the pivot (26) of the uppermost door section and an opposite end having a rotatably mounted roller (25). An axle (14) is rotatably mounted above the door opening (22) and having springs (16) for urging the axle (14) to rotate in opposite senses. Drums (15) are fixedly mounted on the axle (14) and aligned with each side of the door opening (22). Two cables (19), each extend from the lowermost door section about the drum (15) and extending to the opposite end of the lead arm (29). Two guides (24) extend upwardly along each side of the door opening (22) for guiding the door sections (10) as the door travels to open and close the door opening (22). A motor (32) drives the axle (14) in one sense tensioning the cable (19) extending from the lowermost door section for opening the door and for driving the axle (14) in an opposite sense tensioning the cable (19) extending at the opposite end of the lead arm (29) for closing the door. |
