| 摘要 |
A cover made of polymeric material is essentially pot-shaped and includes stiffening ribs on the inside of the cover top. The stiffening ribs are arranged in a crisscross formation, whereby the criss-cross formation is at least partly interrupted by gaps in the stiffening ribs. After straightening-out of the cover, the stiffening rib ends respectively adjacent one of the gaps are interconnected by a secondary connecting element. The finished cover has essentially the same torsional strength as a conventional cover molded in one step with an uninterrupted stiffening rib formation, but is substantially free of any warp and can be easily installed without damage to the cover or any gasket used. |
