| 摘要 |
<p>The farm building with a corrugated fibre cement roof has a ventilation system which raises a separate panel(1) clear of the roof ridge. The panel(1) is attached to a mobile frame on the underside of the roof. This frame has rollers which run in sloping guides of a second framework which runs in a horizontal guide. When this second framework is moved horizontally, the roof panel is lifted clear of the roof. The panel is guided in the vertical direction by pairs of hinged links at each end.</p> |
