Abstract: A housing including longitudinally extending tubular members interconnected to allow controlled relative bending thereof, during a drilling operation, a rotary drive transmitting torsion bar extending generally longitudinally within the housing to controllably bend in response to relative bending of said members, a rotary drill bit operatively connected to said torsion bar to be rotated as the bar rotates, a rotary drive operatively connected to the torsion bar to rotate the bar, means for controlling relative bending of the said members during torsion bar rotation and as a function of such rotation.

Abstract: A housing including longitudinally extending tubular members interconnected to allow controlled relative bending thereof, during a drilling operation, a rotary drive transmitting torsion bar extending generally longitudinally within the housing to controllably bend in response to relative bending of said members, a rotary drill bit operatively connected to said torsion bar to be rotated as the bar rotates, a rotary drive operatively connected to the torsion bar to rotate the bar, means for controlling relative bending of the said members during torsion bar rotation and as a function of such rotation.

Abstract: A down hole apparatus for measure while drilling usage comprising, in combination, a housing including one or more housing unit sections along apparatus, and defining an axis length, a motor stator for a motor driven by drilling fluids, a motor rotor for said motor driven by drilling fluid, a bent subassembly at the lower end of said downhole apparatus, said subassembly providing a relatively small angular deviation between said housing unit axis and an axis defined by said bent subassembly, an output shaft extending within said bent subassembly for use in driving a drill bit, a bearing assembly to support said output shaft for rotation within said housing, a torsion bar or flexible shaft connecting said motor rotor to said output shaft, said torsion bar or flexible shaft accommodating both eccentric motion of said rotor and the bend and relative motion between the said main housing axis and the bent subassembly axis, and a sensor and data transmission assembly located on the main housing in a parallel relati

Abstract: For use in a wellbore containing a rotary drill string and a drill bit, the combination comprising, a rotary mandrel containing a through opening to pass drilling fluid downwardly from the interior of the drill string, and toward the bit, a non-rotary housing extending about the mandrel, a plenum or plenums in the housing in communication with the interior of the mandrel through an opening to receive fluid pressure used to actuate means associated with drilling activity in the well, and a controlled fluid gap proximate the housing, to slowly leak drilling fluid to the annulus outside the string.