| 摘要 |
A rotary drill rig includes an elongated mast, a pulldown head disposed for linear traversal along the mast and connected to mechanism for effecting pulldown and hoisting movements on a drill string, and a rotary drive unit adapted to be connected to the pulldown head for unitary movement therewith to form a rotary top drive drilling head. The rotary drive unit may be detached from the pulldown head and disposed at the lower end of the mast for performing joint breakout operations on the sectional drill string members and for performing drilling operations as a rotary table drive. A pair of parallel tracks are disposed on the mast for guiding the pulldown head and the rotary drive unit. The tracks are turned inward into the mast near the top end thereof to provide for parking the pulldown head out of the way of a block and tackle which may be used to raise relatively long drill strings from the drill hole. |
