Lightweight positive lock coupling

A threaded coupling apparatus for interconnected ends of first and second fluid-carrying conduit members in a fixed releasable locking relationship, said apparatus comprising:

• first and second coupling members, each having a peripheral surface, circumferentially engageable with the ends of the conduit members to hold them in fluid communication, said coupling members being rotatable with respect to each other in a locking direction to a locked position and in an opposite unlocking direction to an unlocked position to unfasten said coupling apparatus;
• a first complementary locking element located on said first coupling member;
• a second complimentary locking element located on said second coupling member having a plurality of protrusions angularly spaced about said second coupling member a distance equal to the spacing of said plurality of reliefs so that when said protrusions are aligned with said reliefs said lock ring is movable axially to snap said protrusions into said reliefs to positively lock said first and second coupling members in the fixed rotational position;
• external threads on said first coupling member forming alternating ridges and valleys, said ridges having a first larger diameter and said valleys having a second smaller diameter, said first coupling member having a peripheral flange spaced from said external threads;
• internal threads on said second coupling member for cooperative engagement with said external threads, said threads being angularly oriented with said complementary locking elements so that said complimentary locking elements become aligned only when said coupling members are rotated with respect to each other to said locked position;
• an annular resilient member positioned on said first coupling member for urging said complimentary locking elements toward each other so that they make contact with each other and subsequently interlock during rotation in the locking direction when said complimentary locking elements become aligned to hold said first and second coupling members in a fixed rotational and locked position;
• a lock ring including a first locking element, said resilient member being mounted within and supporting said lock ring and being attached to said first coupling member to urge said first locking element toward said second locking element, said lock ring further including a peripheral facing surface having a plurality of angularly spaced reliefs thereon;
• and
• a plurality of peripherally spaced fingers extending longitudinally from said facing surface toward said peripheral flange of said first coupling member, each said finger having an inturned lip extending radially inward and engageable with said peripheral flange to limit movement of said lock ring toward said external threads by said wavy spring.