Manhole cover made from cast iron - has concrete filling contg. embedded cast iron scrap to ensure stability of cover under traffic load

摘要

The dished cover plate cavity in the diagram is filled with concrete into which heavy broken cast iron scrap, heavy iron ore or other heavy fillers are embedded. The weight of the filling stabilises the manhole cover so that this cover does not rock under the wheels of the vehicles which pass over this cover plate. The cast iron shell of the cover plate in the diagram is filled with heavy concrete. This filling whose density is about four to six times that of water is cheaper than solid cast iron.