A brick forming machine comprising an upper vacuum room mounted on a frame lifting up and down and enclosing an upper piston therein, an upper sealing ring mounted on the frame for sealing contact to an upper face of a mold, a lower vacuum room mounted on a truck and encircling a lower piston and giving...http://www.google.ca/patents/US4417864?utm_source=gb-gplus-sharePatent US4417864 - Vacuum type brick forming machine
