PROBLEM TO BE SOLVED: To provide a tunnel excavator having a rectangular section capable of continuously excavating while preventing the collapse of a face ground, at the same time, also facilitating the directional control and smoothly and efficiently carrying excavated earth and sand out.;SOLUTION: The tunnel excavator having the rectangular section is so constituted that excavation means formed by projecting a plurality of arms putting excavation edges on the front ends to a rotational shaft in a state to change directions at right angles to each other every certain interval are successively arranged to the inside of the front end in an opening of a cylindrical body having a rectangular section to continuously excavate the face ground taken inside of the end in the opening of the cylindrical body with the excavation edges by rotation of the rotational shaft, at the same time, an opening bottom section is provided to the lower surface of the cylindrical boy to excavate the ground exposed to the opening bottom section by moving the whole excavation means below and that the excavated earth and sand are pushed backward with the excavation edges to direcly throw down to a belt conveyor.;COPYRIGHT: (C)2001,JPO
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