| 摘要 |
<p>The horizontal trap door, which is opened manually and closes automatically, comprises a panel (1) articulated about a horizontal axis (4) and capable of opening above the horizontal plane containing this axis (4); it comprises a hydraulic device (7) forming a brake on the shutting of the trap door, and a stop element (18, 19) limiting the angle of opening of the trap door to a value of less than 90 DEG so that the panel (1) is permanently subjected, under the effect of gravity, to a closing moment.</p> |
