Plug and coupling assembly

A coupling assembly, comprising:

• a plug having a cavity, a front opening and a rear opening respectively located at opposite ends of the cavity, the plug comprising:
• a plug main body comprising a circumferential hook protruding from an outer surface of the plug main body, wherein the front opening defines a front end surface of the plug main body;
• a plug rear terminal connected to the plug main body, and the rear opening being located at an end of the plug rear terminal away from the plug main body;
• and
• a piston disposed in the cavity, the piston comprising a piston main body, a piston head, and at least two extending portions, wherein the piston main body has a cone surface, the piston head is disposed on the piston main body, and the at least two extending portions are connected to the cone surface of the piston main body, wherein the at least two extending portions extend from the cone surface of the piston main body away from the piston head, and a notch is defined between the at least two extending portions at a side of the piston main body away from the piston head;
• and
• a socket coupled with the plug, the socket comprising:
• a socket main body accommodating the plug main body;
• a clip ring movably disposed on the socket main body, and a portion of the clip ring being located in the socket main body;
• a sleeve disposed in the socket main body, and the plug main body abutting against the sleeve;
• and
• a stem disposed in the socket main body, and the sleeve surrounding the stem, wherein the piston abuts against the stem.