1) Lock ring 2) Lock washer 3) Washer 
a ring, usually metal, of varying design, that serves to retain a component in place.
A lock ring is a threaded washer used to prevent components from becoming loose during rotation. They are found on an adjustable bottom bracket and a track hub of a bicycle. Lokring is another form of fastener used in the automotive and air condition industries. These fittings are often confused with lockrings. ...
[n] - washer that prevents a nut from loosening
lock ring noun washer that prevents a nut from loosening