| 摘要 |
A ground drill system (10) has a drill string 14 which forms first and second mutually isolated fluid paths (16 and 18) respectively. The drill string (14) has an up hole end (20) coupled to a dual circulation rotation head (22) and a down hole end (24) which is coupled to a drilling tool (12). The drilling tool (12) is operated by the flow of fluid delivered through the first flow path (16). A second fluid outlet (26) is provided intermediate the up hole end (20) and the drilling tool (12). The outlet (26) is in fluid communication with the second fluid flow path (18) and located a constant or fixed distance from the drilling toll (2). The second fluid outlet (26) discharges a flushing fluid flowing through the flushing flow path (18) into a hole being drilled by the drilling system (10). The rotation head (22) provides torque to the drill string (14) and thus the drilling tool (12). |
