Apparatus for forming inverts and manhole assemblies

Abstract

Apparatus for forming inverts in a manhole base using a single pour or double pour technique. In the single pour technique, the invert is formed simultaneously with the formation of the manhole base using a mold member having a channel-shaped projection defining the invert. Alignment members simply, and precisely, align the mold member having the channel-shaped projection with the members forming the base member sidewall openings to form a manhole base having an invert in precise alignment with associated sidewall openings. In the two pour technique, the manhole base is initially formed. Thereafter, channel invert forms are aligned with sidewall openings by alignment members arranged within the manhole openings to assure precise alignment therebetween, wherein the invert formed within the manhole base by pouring the casting material into the base member forms an invert which is in precise alignment with associated sidewall openings. The apparatus for both single and double pour techniques incorporates at least one adjustably positionable channel-forming assembly for forming an invert communicating between associated sidewall openings each having a central axis and whose intersecting central axes define an angle different from 180.degree.. Flexible members join the ends of the invert form. Alignment members on the inverts and a flexible internal member, either alone, or in cooperation with a joining bar and a clamp, assure precise alignment between the channel-shaped projections forming the invert and prevent flotation of the invert form during formation. A method and apparatus is disclosed for producing resilient, flexible inverts.