Nut-locking device and associated assembly unit

Assembly for a locking device, extending along a main axis (X) and comprising:

• a nut comprising a first and a second coaxial and opposite-direction tappings;
• and
• a ring;
• an inner surface of said ring comprising a third tapping;
• the first and third tappings being capable of cooperating with a same first thread;
• an outer surface of said ring comprises a second thread capable of cooperating with the second tapping of the nut;
• the assembly being characterised in that it further comprises a washer configured so as to be inserted around one of the nut and of the ring, in a rotationally fixed manner with respect to said nut or to said ring,
• the washer comprises a means of elastic engagement with the other of the ring and of the nut in an installation position of the assembly, so as to prevent rotation relative to the other of the ring and the nut from said installation position.