PROBLEM TO BE SOLVED: To provide a parent/offspring shield machine which is useful, economical, and suitable for construction of a shifting part between a single track part and a double track part by arranging sub-cutters capable of projecting from the outer circumference on the main cutters of a parent machine and a offspring machine. ;SOLUTION: An offspring machine 2 is housed in the interior of a parent machine 1, and integrated excavation by the parent machine 1 together with the offspring machine 2 and single excavation by only the offspring machine 2 departing from the inside of the parent machine 1 are made possible. In this parent/offspring shield machine, the sectional outer of the shell of the parent machine 1 is constructed into an elliptical form, and the main cutters 13, 23 of the parent machine 1 and the offspring machine 2 are arranged so as not to interfere with the end part in the excavation direction of the parent machine 1. Sub-cutters 3,... capable of projecting from the outer circumference are arranged on the main cutters 13, 23, and hence the parts which can not be excavated by the main cutters 13, 23 in the sectional outer shape of the shell of the parent machine 1 can be excavated. Hereby, useful and economical execution is made possible, and in addition it can be suitable even for a shifting part between a single track part and a double track part.;COPYRIGHT: (C)1998,JPO
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