| 摘要 |
A back reamer for underground bores, more particularly for use in directional horizontal drilling. The back reamer comprises a head with a cylindrical wall which is attached, by means of struts, on a central tube and is provided, at one end, with soil loosening means and with spraying nozzles for a drilling liquid, whilst the ends of the central tube are provided with means for coupling the tube to a drill string. At least some of the struts are arranged according to the surface of a cone, the apex of which points into the direction of travel of the reamer. |
