| 摘要 |
PROBLEM TO BE SOLVED: To alter the quantity of a cutter bit projected during propulsion, to improve excavation efficiency by soil and to lengthen the lifetime of the abraded cutter bit by installing the cutter bit to a cutter spoke in a manner that the quantity of projection can be changed. SOLUTION: L-shaped bit movable support members 28 are welded and fixed mutually back to back at both end sections of the facing 27 side section of a cutter spoke 24 constituting a cutter 23 rotatably mounted at the front end of a shield frame respectively. The thinned rear end sections of cutter bits 30 are inserted between two pin plates 29 integrally set up to each bit movable support member 28 respectively. Sections among the rear end sections 31 and the pin plates 29 are pivotally attached rotatably by rotary central pins 32 parallel with the cutter spoke 24, the front ends of each cutter bit 30 are supported so as to be able to be projected and retracted to and from the facing 27, and the quantities of the cutter bits 30 projected to the cutter spoke 24 can be changed. |
