Drilling tool for sinking wells in underground rock formations

摘要

The present invention provides an apparatus for orienting a drilling tool in a borehole, and which employs drilling mud pressure to selectively hydraulically move force-transmitting elements associated with pressure members on the exterior of the tool against the wall of the borehole, or to radially shift the drive shaft of the drilling tool in the tool casing. The tool may also include a drilling mud powered centering mechanism for maintaining the tool or the drive shaft within the tool in a centered basic position. A tool may include both pressure members and a shiftable drive shaft, as well as centering mechanisms to act on both the pressure members and the drive shaft.