A connection assembly which comprises: - a socket provided with connection pins; - a plug provided with matching connection pins and suitable for being inserted on the socket; - a means for locking the plug relative to the socket while the matching pins (18, 24) are engaged; comprising: a bolt secured either to the plug or the socket, said bolt comprising a barrel provided with balls movable between a locking position projecting in relation to the barrel and a position retracted inside the barrel, and a rod for retaining the balls in the locking position thereof, said rod being movable relative to the barrel between a position in which the balls are released and a position in which the balls are retained in the locked and projecting position thereof, a shaft arranged in the other one of the plug or the socket, said shaft being suitable for at least partially receiving the bolt and having a groove for receiving the balls in the locked and projecting position thereof, and it comprises a spring for returning the rod toward the ball-retaining position thereof, and the rod has a cam surface suitable for pushing the balls back into the locked position thereof when the spring urges the rod towards the retaining position thereof, characterized in that each connection pin of the plug is constituted by an elastic piston contact, and in that the plug comprises - a sealing ring surrounding the complementary pins (18, 24) gripped between the socket and the plug when they are coupled, and in which the elastic piston contacts and the sealing ring apply combined a separating force between the plug and the socket, the spring is such that, when the rod is moved in order to release the balls, the return force exerted by the spring is less than the said separating force exerted between the plug and the socket by the elastic piston contacts and the sealing ring. - a socket provided with connection pins; - a plug provided with matching connection pins and suitable for being inserted on the socket; - a means for locking the plug relative to the socket while the matching pins (18, 24) are engaged; comprising: a bolt secured either to the plug or the socket, said bolt comprising a barrel provided with balls movable between a locking position projecting in relation to the barrel and a position retracted inside the barrel, and a rod for retaining the balls in the locking position thereof, said rod being movable relative to the barrel between a position in which the balls are released and a position in which the balls are retained in the locked and projecting position thereof, a shaft arranged in the other one of the plug or the socket, said shaft being suitable for at least partially receiving the bolt and having a groove for receiving the balls in the locked and projecting position thereof, and it comprises a spring for returning the rod toward the ball-retaining position thereof, and the rod has a cam surface suitable for pushing the balls back into the locked position thereof when the spring urges the rod towards the retaining position thereof, characterized in that each connection pin of the plug is constituted by an elastic piston contact, and in that the plug comprises a bolt secured either to the plug or the socket, said bolt comprising a barrel provided with balls movable between a locking position projecting in relation to the barrel and a position retracted inside the barrel, and a rod for retaining the balls in the locking position thereof, said rod being movable relative to the barrel between a position in which the balls are released and a position in which the balls are retained in the locked and projecting position thereof, a shaft arranged in the other one of the plug or the socket, said shaft being suitable for at least partially receiving the bolt and having a groove for receiving the balls in the locked and projecting position thereof, and it comprises a spring for returning the rod toward the ball-retaining position thereof, and the rod has a cam surface suitable for pushing the balls back into the locked position thereof when the spring urges the rod towards the retaining position thereof, characterized in that each connection pin of the plug is constituted by an elastic piston contact, and in that the plug comprises - a sealing ring surrounding the complementary pins (18, 24) gripped between the socket and the plug when they are coupled,