Method and apparatus for forming inverts in manhole assemblies, and the like

A method for producing a manhole base of a manhole assembly in a single pour operation comprising the steps of:

• providing a mold having a hollow interior space for forming the manhole base to be cast therein;
• mounting rings within the interior space of said mold to define openings to be provided in the sidewalls of the manhole base being cast in said mold, said rings having central openings defining the central axis of the openings to be formed in the manhole base being cast;
• disposing in said mold a mold member defining an interior surface of a floor of the manhole base being cast and having raised portions supported thereon defining an invert to be provided in the floor of the manhole base, said mold member having openings at the end walls of the raised portions, the centers of said openings lying on a line parallel to the longitudinal axis of its associated raised portion;
• and
• actuating a reciprocating activating means to slidably extend movable alignment members through each opening in said invert forming mold member and through an opening in an associated one of said mounting rings to precisely align the center of each ring along the longitudinal axis of a respective one of said raised portions preparatory to casting.

Apparatus for forming a manhole base comprising:

• inner and outer mold members defining an interior volume having a cylindrical shape;
• an invert forming member supported on said inner mold member;
• said invert forming member having an elongated invert forming projection;
• at least a pair of retainer rings positioned between said inner and outer mold members each having an opening;
• the opposing ends of said elongated projection having openings;
• first and second alignment means adjacent to the ends of each elongated projection, each being slidable to a first position to extend through the openings in an associated end of said projection and the opening in the adjacent retainer ring to align said projection and said retainer rings and slidable to a second position removed from one of the openings in said retainer ring and said projection to enable said retainer rings and said base member to be separated from one another after casting of the manhole base, and a reciprocable actuating means connected with said alignment means to extend and retract said alignment means.