Abstract: In a piston actuated valve, means for determining the position of the operating piston by means of at least one insulated contact probe which is inserted through the wall of the cylinder. Two or more can be used, one in each extreme position of the piston. As the piston moves into its extreme position, contact is made with the probe and a suitable signal is sent, indicating that the piston is in that extreme position.

Abstract: In a rotary drilling system for drilling deep, large-diameter bore holes in the earth, using multiple lengths of drill pipe joined together by threaded tool joints, the improvement in means to prevent relative rotation while joining and unjoining the two parts of the threaded-together tool joints, after the tool joints has been made to a desired torque, comprises a retaining cylinder or ring, of somewhat larger diameter than the diameter of the tool joints, positioned to surround a tool joint with an annular space of a selected radial dimension. There is at least one pair of longitudinally slidable cams or wedges that slide within longitudinal grooves on the inside surface of the retainer ring. Hydraulic means are provided to move the pair of wedges longitudinally toward each other, along the sloping grooves until they are wedged between the retaining ring and the outer surface of the tool joint, one wedge opposite each part of the tool joint.