| 摘要 |
PURPOSE:To successively enable excavation with a spare cutter, even if main cutters wear. CONSTITUTION:In a shield excavator which is provided with a cutter head 2 being turned by a cutter head motor 3 (not shown) in the front of the shield body 1 (not shown) and also in which a large number of main cutters 4 are radially fitted in the front of the face plate 2a of the cutter head 2, a spare cutter bit 7b capable of being retracted or protracted in the front of the face plate 2a is provided inside the face plate 2a. Thus, even if the main cutters 4 wear, excavation can be successively carried out with a spare cutter bit 7b, and even in the case of long distance excavation, the need of cutter replacement in the course of excavation can be dispensed with, so that the period of construction can be reduced. |
