|Threads Per Inch:
|Imperial - BSW
Self locking nuts work by using increased friction between the threads of the two mating faces to cause a slight distortion of the threads. They are frequently used in areas where vibration is experienced.
Self locking nuts can be re-used, but only a few times before they lose their inherent locking qualities.
Stiff nuts, jam nuts and bent beam nuts are all terms that are used to describe self-locking nuts.
BSW (British Standard Whitworth) is an imperial coarse thread first used in standard production by Joseph Whitworth during the industrial revolution. Whilst it is still used in engineering applications all across the world it is less common in the UK where metric threads have generally taken over.