The valve 1 comprises: a body 2 having a through-channel 3 for the fluid, a rotary control shaft 4 having a seal for the channel, mounted in a passage 10 of the body, bearings 6, 7 provided in said passage between the body and the rotary control shaft, and axial locking of the shaft in said body. According to the invention, the axial locking of the shaft is achieved by at least one cylindrical ring 15 mounted in a rotationally constrained manner on said shaft 4 and having an external surface 20 orientated towards one of the bearings 6 and contacting a transverse face thereof.