| 摘要 |
A boom-operated mechanism, suitable for driving up-and-over doors of the canopy and non-protruding types, comprises an elongated straight track (13;43) for mounting in a generally horizontal position extending rearwardly from the top (7) of the doorway, a carriage (14) mounted upon said track, drive means to move said carriage along said track, a link (19;39), rigidly attached to said carriage (14) and adapted for pivotal attachment (22; 45,46) to a point adjacent to the upper edge of a door (4;30) and a pair of guide tracks (10,11; 33,34), adapted for mounting in a generally vertical position at the sides (5,6) of the doorway and to engage rollers located on the respective sides of a door, said guide tracks being curved rearwardly in a region adjacent to their upper sides (29,30; 35,360). |
