Abstract: Locking device made as a nut (111) provided with an axial threaded seat or bore (115) or as a bolt (11) provided with a cylindrical axial threaded stem (15), comprising a body (13; 113; 213) in which a guide portion (17; 217) is defined, which may also be an engaging portion, for an actuating wrench for rotating the nut or bolt when the device is to be engaged onto a threaded stem or into a threaded seat or bore, respectively, wherein the guide portion (17; 217) comprises a hollow cap (19; 219), and wherein the guide portion (17; 217) comprises at least one face (27) which is concave relative to a transverse plane and in that the cap (19; 219) comprises in its inside at least one complementary convex face (29).

Abstract: Locking device made as a nut (111) provided with an axial threaded seat or bore (115) or as a bolt (11) provided with a cylindrical axial threaded stem (15), comprising a body (13; 113; 213) in which a guide portion (17; 217) is defined, which may also be an engaging portion, for an actuating wrench for rotating the nut or bolt when the device is to be engaged onto a threaded stem or into a threaded seat or bore, respectively, wherein the guide portion (17; 217) comprises a hollow cap (19; 219), and wherein the guide portion (17; 217) comprises at least one face (27) which is concave relative to a transverse plane and in that the cap (19; 219) comprises in its inside at least one complementary convex face (29).