Tube coupling

Claim 1

A tube coupling comprising a centrally bored body having a rear end and a forward end into which a tube may be received, with the forward end portion of the bore being of greater diameter than the rear end portion; a cup-shaped cap removably fastened to the forward end portion of the body and having a centrally apertured base covering the body forward end; a grab ring formed of thin springy sheet metal shaped as a flat outer flange, frictionally squeezed and held between the cap base and body forward end, and with an integral, central frustoconical rearwardly extending portion whose inner free edge defines an annular tube-gripping edge; a U-shaped in cross section resilient sealing ring having an outer leg in face-to-face contact with the wall defining the bore forward end portion, an inner leg normally arranged in face-to-face contact with the tube, and a base having its forward face formed in a frustoconical shape corresponding to and receiving in face-to-face contact the grab ring frustoconical portion, and with the sealing ring being axially shorter than the axial length of the bore forward end portion; whereby a tube may be slipped through the cap base aperture, grab ring and sealing ring to the bore rear end portion for being gripped by said grab ring-gripping edge, and so that fluid pressure caused by fluid entering the bore forward end portion forces the sealing ring tube-contacting leg into tighter contact with the tube, and forces the sealing ring base to press the grab ring frustoconical portion towards the tube wherein its annular gripping edge more tightly grips the tube.