Image Number 5 for United States Patent #5393172.
A shield tunneling machine comprises a shield body having a soil chamber, an inside chamber and a partition wall. The soil chamber has a conical peripheral surface converging gradually rearward. A crankshaft having an eccentric portion is rotatably supported by the partition wall at the center of the partition wall corresponding to the axis of the shield body. A cutter disc with roller bits is secured to a front end of the crankshaft, and a conical rotor is rotatably mounted on the eccentric portion of the crankshaft behind the cutter disc. Since the cutter disc is rotated at an increased rotary velocity by five to ten times as many as that of a cutter disc in a conventional shield tunneling machine, crushing of gravel can be efficiently carried out by the cutter disc with roller bits in cooperation with the conical rotor mounted on the crankshaft.