To solve problems wherein overhang beams 21 and 24 for supporting a cab from the under side are formed as beams forming a hollow structure for securing sufficient rigidity for supporting the cab having large weight from the under side, and the hollow structure causes resonance in a certain frequency by the size and a shape, and increases in vibration and noise.
By arranging partition wall members 36A, 36B, 37A, and 37B for defining a plurality of closed spaces S1 to S3, and S5 to S7 in the overhang beams 21 and 24 forming the hollow structure, the size of the closed spaces in the overhang beams 21 and 24 changes, and a resonance causing frequency changes to thereby avoid an overlap of a resonance frequency of the overhang beams and a frequency of the propagating vibration and noise as well as to prevent an increase in the vibration and the noise.
NISHIMORI HIROYUKI
TAKESHITA SEIICHIRO
