Threaded couplings with locking

A method of assembling a threaded coupling, the threaded coupling comprising:

• a first coupling member, comprising a cylindrical portion which is internally threaded around an axis of rotational symmetry of the cylindrical portion and comprises an open end that defines an opening with an annular rim, the annular rim comprising at least one projection that projects in a generally axial direction parallel to the axis of rotational symmetry of the cylindrical portion and that comprises a side surface that at least partially defines a gap in the annular rim;
• a second coupling member comprising an externally threaded portion and at least one key cavity;
• and
• a locking assembly comprising:
• a locking member comprising a pin portion fixed to a flexible cable portion;
• and
• a lock nut;
• wherein the method comprises:
• threading the lock nut onto the second coupling member;
• threadedly engaging the first coupling member onto the second coupling member to couple the first coupling member to the second coupling member;
• positioning the locking member such that the pin portion is seated in the at least one key cavity and confined by an inner surface of the annular rim and the flexible cable portion extends from the pin portion through the gap in the annular rim in a generally radial direction adjacent to the side surface of the at least one projection;
• and
• positioning the lock nut so as to restrict axial movement of the pin portion.

A threaded coupling comprising:

• a first coupling member, comprising a cylindrical portion which is internally threaded around an axis of rotational symmetry of the cylindrical portion and comprises an open end that defines an opening with an annular rim, the annular rim comprising at least one timing through-hole that extends through the rim in a generally radial direction perpendicular to the axis of rotational symmetry of the cylindrical portion;
• a second coupling member comprising an externally threaded portion and at least one key cavity;
• and
• a locking assembly comprising:
• a locking member comprising a pin portion fixed to a flexible cable portion;
• wherein the externally threaded portion is arranged to be received through the opening to be threadedly engaged with the internally threaded cylindrical portion, to couple the first coupling member to the second coupling member;
• and
• wherein, when the first coupling member is coupled to the second coupling member:
• the pin portion is arranged to be seated in the at least one key cavity and be confined by an inner surface of the annular rim so as to restrict radial movement of the pin portion;
• the flexible cable portion is arranged to extend from the pin portion in a generally radial direction through the at least one timing through-hole so as to restrict circumferential and axial movement of the flexible cable portion.