A locking device comprising: - a shaft comprising a first external thread , and - a nut and a ring to be assembled on the shaft ; the nut comprising a first internal thread adapted to mate with the first external thread of the shaft, said first internal and external threads defining a first radial clearance (J1); the nut further comprising a second internal thread in the opposite direction to the first internal thread , the first and second internal threads being coaxial, an outer surface of the ring comprising a second external thread adapted to mate with the second internal thread of the nut, said second internal and external threads defining a second radial clearance (J2); an inner surface of said ring having a third internal thread adapted to mate with the first external thread of the shaft, said first external and third internal threads defining a third radial clearance (J3); characterised in that : - the first , second and third internal threads and the first and second external threads have an identical and constant thread pitch (P); and - each of the second (J2) and third (J3) radial clearances is greater than the first radial clearance (J1). - a shaft comprising a first external thread , and - a nut and a ring to be assembled on the shaft ; the nut comprising a first internal thread adapted to mate with the first external thread of the shaft, said first internal and external threads defining a first radial clearance (J1); the nut further comprising a second internal thread in the opposite direction to the first internal thread , the first and second internal threads being coaxial, an outer surface of the ring comprising a second external thread adapted to mate with the second internal thread of the nut, said second internal and external threads defining a second radial clearance (J2); an inner surface of said ring having a third internal thread adapted to mate with the first external thread of the shaft, said first external and third internal threads defining a third radial clearance (J3); characterised in that : - the first , second and third internal threads and the first and second external threads have an identical and constant thread pitch (P); and - each of the second (J2) and third (J3) radial clearances is greater than the first radial clearance (J1). the nut further comprising a second internal thread in the opposite direction to the first internal thread , the first and second internal threads being coaxial, an outer surface of the ring comprising a second external thread adapted to mate with the second internal thread of the nut, said second internal and external threads defining a second radial clearance (J2); an inner surface of said ring having a third internal thread adapted to mate with the first external thread of the shaft, said first external and third internal threads defining a third radial clearance (J3); characterised in that : - the first , second and third internal threads and the first and second external threads have an identical and constant thread pitch (P); and - each of the second (J2) and third (J3) radial clearances is greater than the first radial clearance (J1). - the first , second and third internal threads and the first and second external threads have an identical and constant thread pitch (P); and - each of the second (J2) and third (J3) radial clearances is greater than the first radial clearance (J1). <EOS>