Pressure-tight plug coupling

A plug coupling for providing a pressure-sealed flow connection to a conduit member provided with an essentially cylindrical, radially outwardly protruding rim for engagement with said plug coupling, comprising:

• a tube-like support element having a longitudinal axis, a rear portion with an inlet part and a front portion for receiving the cylindrical rim of the conduit member;
• elongated clamping jaws having rear and front ends, the rear ends being linked to said front portion of said support element and extending in a generally axial direction, said clamping jaws being concentrically arranged around the longitudinal axis of said support element, said front ends of said clamping jaws being radially displaceable;
• a sleeve essentially surrounding said support element and shiftable parallel to said longitudinal axis relative to said support element between a released position and an engaged position;
• means for radially displacing said front ends of said clamping jaws upon shifting said sleeve into said released position;
• means for holding said sleeve in said engaged position;
• and
• a sealing cylinder separated from said support element, shiftable parallel to said longitudinal axis relative to said support element and biased in a direction from the rear portion to the front portion of said support element by a spring supported between said support element and said sealing cylinder, said sealing cylinder being sealed against said support element by a sealing ring;
• said sealing cylinder being provided with radial openings for permitting a pressure fluid which flows through said plug coupling to flow into a pressure space formed between said support element and said sealing cylinder, said sealing cylinder having a wall portion extending into the pressure space formed between said sealing cylinder and said support element, said wall portion of said sealing cylinder acting as a piston area loaded with the pressure fluid for securing the pressure-sealed connection of said plug coupling to the conduit member.