Abstract: A magnetic coupling for substantially synchronously transferring linear motion through a non magnetic barrier from a first movable element to a second movable element. The coupling comprises magnets disposed at spaced apart locations along the first element. The magnets each have a magnetization direction substantially perpendicular to a direction of motion of the first element along the non magnetic barrier. The coupling includes magnets disposed at spaced apart locations along the second element at locations corresponding to locations of the magnets op the first element. Each of the magnets on the second element has a magnetization direction inclined at an oblique angle with respect to the magnetization direction of the corresponding magnet so as to capture magnetic flux from the magnets on the first element when either of the elements is moved along the barrier.

Abstract: A well logging instrument string including a first section adapted to be operated substantially in contact with a wall of a wellbore, a coupling connected at one end to one end of the first section. The coupling includes first and second flexible joints for enabling relative angular deflection between the first section and a second section. The coupling includes a biasing mechanism for urging at least one of either the first or the second flexible joints, or both, to assume their positions of maximum angular deflection. The instrument string includes a second section connected to the other end of the coupling. The second section is adapted to be operated spaced apart from the wellbore wall.