| 摘要 |
PURPOSE:To better the flow of sediment to reduce excavation resistance by providing space on both sides of spokes radially extending to the front end of a center shaft, and providing a ramp at the front end of the center shaft. CONSTITUTION:A plurality of spokes 11 radially extending to a center bit 14 located at the center of the front end of a center shaft 2 are formed on the front face of a cutter frame 4 end notched portions 12 are provided on both sides of the plurality of spokes 11, to form space 13 that leads to the center bit 14. In the space 13 position, a ramp 16 is provided which slopes as the space 13 portion leads from near the front end of the center shaft to the front end. The cutter frame 4 is rotary driven and a natural ground ahead is excavated by a cutter bit 15 and earth and sand excavated are smoothly transferred through the space 13 end the inclined portion 16 and discharged. Thus excavation resistance is reduced without lowering the support strength of the cutter frame. |
