Coupling device of a plug-in coupling and plug-in coupling with such a coupling device

A coupling device of a plug-in coupling, the coupling device comprising:

• a tubular coupling receptacle of metal having a receiving end and a matching tubular coupling insert configured to be received via the receiving end in the coupling receptacle in a coupling position for connecting two components conveying a fluid;
• the coupling receptacle having two lateral slots positioned diametrically opposite one another and having a longitudinal extension in a direction perpendicular to a longitudinal center axis of the coupling receptacle;
• a U-shaped, elastic securing bracket seated externally on the coupling receptacle and having two legs extending parallel to the two lateral slots and projecting into the lateral slots, respectively;
• the coupling insert having an outer peripheral securing rib, wherein the legs of the U-shaped, elastic securing bracket snap into place behind the securing ring when the coupling insert and the coupling receptacle are in the coupling position;
• at least one sealing ring arranged in the interior of the coupling receptacle;
• a securing bushing arranged in the interior of the coupling receptacle, wherein the securing bushing has a first end and a second end, the first end facing the sealing ring and the second end resting against a radially outer surface of the securing rib and projecting past the lateral slots;
• wherein the securing bushing has two transverse slots aligned with the two lateral slots and configured such that the two legs of the U-shaped, elastic securing bracket engage the two transverse slots, respectively.