| 摘要 |
The manhole cover or gully grating comprises a frame 12 and a plurality of cover or grating parts 14a-d with the parts all being hinged to the same side of the frame and each having a generally triangular shape. Each cover part is preferably in a three point contact with the frame and there are preferably an even number of cover parts. Adjacent cover parts may be loosely connected or one cover part may include a formation 64 which overlaps an adjacent cover part so that two or more cover parts can be lifted together. The cover parts are preferably arranged to sit on seats 34,36 on the frame and one seat may support corners of a number of cover parts. Preferably at least one cover part can be locked to the frame and the seats and hinges are preferably arranged outside the clear opening of the frame. Each hinge is preferably formed from only two elements, a fork which receives a boss, that are integral to the frame and cover parts. The boss and fork may be shaped so that the cover part moves downwards after a certain angle of movement and an element on the cover part then engages a part of the frame to inhibit movement in the return direction. A portion of the boss may have a non-rounded engagement surface, preferably a flat while the fork may include a rounded surface to engage the boss. The fork is preferably on the cover part and the boss on the frame. |
