Abstract: A two-piece anti-loosening nut assembly includes a nut and a washer. The nut is configured to threadedly engaged with a bolt and has a main body including an annular outer flange extending outwardly and radially from an end periphery thereof. The annular outer flange has an annular flange surface formed with a cam structure. The washer is fixedly disposed on the nut, and has a lower ring surface facing the annular flange surface and formed with a cam structure engaged with the cam structure of the annular flange surface, and an upper ring surface opposite to the lower ring surface and formed with a serrated structure configured to bite into a surface of a workpiece.

Abstract: A two-piece anti-loosening nut assembly includes a nut and a washer. The nut is configured to threadedly engaged with a bolt and has a main body including an annular outer flange extending outwardly and radially from an end periphery thereof. The annular outer flange has an annular flange surface formed with a cam structure. The washer is fixedly disposed on the nut, and has a lower ring surface facing the annular flange surface and formed with a cam structure engaged with the cam structure of the annular flange surface, and an upper ring surface opposite to the lower ring surface and formed with a serrated structure configured to bite into a surface of a workpiece.

Abstract: A two-piece anti-loosening screw assembly includes a screw and a washer. The screw includes a shank, and a head connected to one end of the shank and having a lower surface formed with a cam structure. The washer is sleeved on the screw, and includes inner and outer peripheral surfaces radially spaced apart from each other, an upper ring surface interconnecting upper peripheries of the inner and outer peripheral surfaces and formed with a cam structure engaging with the cam structure of the lower surface of the head, and a lower ring surface interconnecting lower peripheries of the inner and outer peripheral surfaces and formed with a serrated structure configured to bite into a surface of a workpiece.