| 摘要 |
<p>A gravity shutter for a roof unit has hinge pin (28) for a pair of shutter blades (22) engaged in helical tracks (30) so as to cause a twisting movement of the shutter when the blades lift by air pressure and laterally disengage pawls from catch unit (32) to release the blades to fly to a Vee position for opening. In closing, the reversed movement aligns the catch pawls which may ratchet on rack teeth to return the parts to the closed position.</p> |
