Abstract: The device is composed of a conical section located on the edge of the disk rim. The greatest radius of the conical section is at least equal to the radius of the circumference passing through the bottom of the axial grooves into which the blade roots are inserted. A groove is formed in the end of the lower part of the root, this groove having a right angle triangular section. A locking part has one face pressed against the bearing and two other faces against the sides of the groove in the root. A blade extending longitudinally in the locking part works together with a groove in the slot of the blade root to keep the locking part in place.