The invention concerns a locking device comprising: an adjustable fixing element (7) provided with a recess (16); a fixed contour (9) having a contact surface (12); a pin (8) arranged mobile in said recess (16), capable of being subjected to an axial elastic force generated by a pressure spring (21) and comprising a rod head (14) projecting relative to the recess (16) of the fixing element (7) and coupled by contact with the contact surface (12); at least one centering device (18) arranged between the pin (8) and the fixing element (7). The inventive locking device is characterized in that itcomprises at least one centering device (18) including at least one elastically deformable ring (19) which: is arranged in the recess (16) between the pin (8) and the fixing element (7); is adapted to be mobile in the recess (16); comprises a surface (22) having a cross-section tapering in the direction opposite to that of the pressure spring (21) force, and which is in contact with a complementary surface (23) at the rod (8).