This coupling (R) comprises a male element (A) with a stepped outer groove (20), a female element (B) with locking balls (7), a locking ring (9) provided with a front inner notch and a rear inner notch axially separated by an inner rim, a spring that pushes the locking ring (9) back into the forward position, and a valve movable in the female element (B) and pushed by a spring (14) back to the closed position. The male element (A) comprises a valve movable in an inner channel (200) of the male element (A) and a spring (48) that pushes the valve of the male element (A) back toward a closed position of the inner channel (200).