Mechanical coupling

Claim 1

A RELEASABLE COUPLING COMPRISING, IN COMBINATION: (A) A RECEIVER PART HAVING A SOCKET HAVING A PROJECTION FIXED IN THE SOCKET, SAID PROJECTION HAVING PORTIONS SPACED FROM THE SIDE WALLS OF THE SOCKET, THEREBY PROVIDING AN INTERVENING SPACE BETWEEN THE PROJECTION PORTIONS AND THE SOCKET SIDE WALL, (B) A PLUG PART INSERTABLE IN THE RECEIVER PART, HAVING A PROTUBERANT SIDE WALL PORTION INSERTABLE IN SAID INTERVENING SPACE AND ENGAGEABLE WITH A SIDE OF THE SAID PROJECTION, SAID PROTUBERANT SIDE WALL PORTION BEING SHAPED TO NEST THE PROJECTION WHEN THE PLUG PART IS INSERTED IN THE SOCKET AND THE PROTUBERANT SIDE WALL PORTION IS MOVED SIDEWISE IN SAID INTERVENING SPACE TO BRING THE SIDE WALL PORTION INTO ENGAGEMENT WITH THE PROJECTION, AND (C) A COLLAR AXIALLY MOVABLE ON AND CLOSELY FITTING AROUND THE PLUG PART, SAID COLLAR BEING ARRANGED TO OCCUPY AN ADVANCED POSITION WHEREIN IT CLOSELY AND SLIDABLY FITS INTO THE SOCKET IN A POSITION ADJOINING SAID INTERVENING SPACE WHILE STILL ON THE PLUG PART, AND AFTER INSERTION OF THE SAME INTO THE SOCKET AND AFTER COMPLETION OF SAID SIDEWISE MOVEMENT, SAID COLLAR PREVENTING AN OPPOSITE SIDEWISE MOVEMENT OF THE PLUG PART IN THE SOCKET AND THEREBY EFFECTING A LOCKING OF THE SIDE WALL PORTION OF THE PLUG PART IN SAID INTERVENING SPACE BY THE NESTING ENGAGEMENT OF THE PROJECTION AND SIDE WALL PORTION.