Concrete shaft bottom for sewers etc. has inward-facing ring-shaped section integral with side wall to act as tread with step surface

摘要

The shaft bottom has a side wall (14) with an inward facing tread (25) having a top step (26). The tread has an inward facing ring-shaped section (27), which is an integral part of the side wall. Its top step extends at a distance above connection apertures (21,23,24) for intake and outlet. The section acts as support for a tread component, and/or forms the top step. The top step surface is mainly flat, or is slightly inclined inwards. The ring section has a width of approx. 100mm.