Patent ID: 9689212
Date: 2017-06-27
CPC Classifications: E21B

Claim:
1. A coupling sub for coupling a first drill string section to a second drill string section in a directional drilling system, the coupling sub comprising: a first end connectable to the first drill string section; a second end connectable to the second drill string section; a hinge member between the first end and the section end allowing hinging of the second end relative to the first end; and locking means, operable between a hinge mode, allowing hinging of the first end with respect to the second end, and a locking mode for locking the hinge member to prevent hinging of the second end relative to the first end, wherein the locking means comprise: a locking sleeve which is moveable in axial direction with respect to the first drill string section between a locking mode and a hinge mode, and being provided with at least one sleeve lock surface; at least one locking surface being provided on an end part of the second drill string section and being complementary to the sleeve lock surface, wherein in the hinge mode of the locking sleeve said sleeve lock surface is located at a distance from the locking surfaces enabling the first drill string section to hinge with respect to the second drill string section, and wherein in the locking mode said sleeve lock surface engages said locking surface to prevent hinging of the first drill string section with respect to the second drill string section.