| 摘要 |
PURPOSE:To prevent the collapse of a working face and take a proper quantity of the excavated earth by exerting the earth retaining effect of the working face in excavating the ground having a large content of boulders and gravel and a small quantity of fine grains and easy to collapse. CONSTITUTION:Multiple spokes 11 are provided at the tip of a conical rotor 10 provided at the tip of a main body l, and a face plate 12 is selectively provided between the spokes 11. An outer periphery bit 11a and a bit 11b are fixed to the spokes 11, and an outer periphery bit 12a is fixed to the face plate 12. A working face is earth-retained by the face plate 12 to prevent its collapse. The opening section of a crushing chamber 14 is reduced by the face plate 12, a large quantity of boulders and gravel is prevented from being taken into the crushing chamber 14 simultaneously when the ground having a large content of boulders and gravel and a small quantity of fine grains is excavated. The collapse of the working face is prevented, and a good excavation state can be maintained. |
