| 摘要 |
PURPOSE:To prevent noises due to vibration by a mechanism wherein safety frames are formed by using hollow members, and a sound insulating material is filled into the cavity portions of the hollow members of interest. CONSTITUTION:A sound insulating material 18 is filled into the cavity portions of safety frames 10, 11. etc., whose frames are molded, and the movement of air remaining in the cavity portions is prevented by the sound insulating material 18. Consequently, when noises due to the vibration of an engine 21 supported to a front frame 1 and a transmission case 22 are transmitted to an upper frame 15 from a front lower frame 3, etc., the noises are not reflected in the cavity portions, and echo sounds are not generated. Thus, since the cavity portions are filled with the sound insulating material 18, the resonance frequency of the hollow members lowers. As a result, high trembling noises due to vibration can be prevented. |
