Double-walled lid with concrete filling

摘要

There are lids for manhole covers made of cast iron with a cast-iron surface with fluting and lids of cast iron with concrete filling. The latter are established in standards. In some cases, a lid with a cast-iron surface is required for various reasons, e.g. for paving surfaces. On account of the greater cast weight, however, this lid is more expensive than a lid of cast iron with concrete filling. The innovation shows a lid of cast iron with a cast-iron surface and at the same time a concrete filling. Apart from a thin cast-iron surface, this lid construction has a cast tub underneath with an opening for placing the concrete filling. This lid combines the advantages of a lid with concrete filling with the advantages of a lid with a cast-iron surface with fluting. Since the portion of cast material is only slightly higher, the price relationship is also positive.