| 摘要 |
A telescoping sub ( 50 ) for mining operations and the like. The telescoping sub ( 50 ) includes a rotor ( 94 ) portion coupleadle to the rotary head of a drilling rig, and a stator ( 74 ) portion that is coupleable to a drill rod. The rotor ( 94 ) portion is slideadly coupled to the stator ( 74 ) portion and is moveable with respect thereto between an extended position and a retracted position. With the telescoping sub ( 50 ) in the retracted position, the drilling rig is operated to drill to a first depth. The drilling rig is then operated to move the rotor ( 94 ) portion to the extended position, and the drilling rig is operated to drill to a second depth that is greater than the first depth.
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