| 摘要 |
A drive system for a movable closure member movable along rail sets carried on opposed sides of the frame of a structure includes a rail set on each side of at least one pair of opposed sides of the frame. Each rail set includes first and second laterally offset toothed sections. Each first section includes a horizontal segment and an inclined segment whereas each second segment includes a vertical segment and an inclined segment which has at least a portion thereof in juxtaposed side-by-side relation with the inclined segment of the first section. An electric motor has a drive shaft that extends transversely of the rail sets and carries a first gear wheel coaxially therewith at each end. Each first gear wheel carries a second and smaller gear wheel eccentrically thereon. The first and second gear wheels have a common point of tangency. The first gear wheels are cooperable with the first sections of the respective rail sets and the second gear wheels are cooperable with the second sections of the respective rail sets. The respective rail sections and gear wheels are dimensioned to provide for transfer of driving force between the first and second gear wheels when the common point of tangency therebetween falls within the juxtaposed side-by-side portions of the respective inclined segments of the rail sets.
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