| 摘要 |
<p>The manhole cover (4, 5) is made of cast stell with reinforcement ribs (6) on its underneath face, the top surface being smooth. The frame (1) has two steel side pieces (2a, 2b) welded to two longitudinal members (3a, 3b) which have horizontal flanges forming supports for the cover. The stabilizing lock element is a T-section, the main part (10) being an angle section to which is welded an arm (11) having at the opposite end to the angle a mass (12) forming a counter-weight. This element is placed at the end of the frame on the horizontal flanges of the longitudinal members (3a, 3b), the angle (10) running parallel to and touching the side pieces of the frame. Once the manhole cover is in place, the mass (12) is lowered, causing the angle-piece (10) to rotate, resulting in horizontal pressure displacing the cover, locking it in position.</p> |
