Lock nut, 10 x 18 x 4 mm, M10 x 0.75 thread, BTC.

Lock nuts are used to locate bearings onto a shaft. Additionally, they can be used to mount bearings with a tapered bore onto tapered shaft seats and adapter sleeves, and to dismount bearings from withdrawal sleeves. Lock nuts have to be secured to prevent unintentional loosening. This is done, either by a locking device that engages a key way in the shaft or key slot in the adapter sleeve, or by a locking mechanism integrated in the nut. Lock nuts are frequently used to secure gears, belt pulleys and other machine components.