Lock nut for fastening bearings for machine tool shafts / ball screws. It has metric threads and four equally spaced slots located around their circumference to accommodate a spanner. It is locked by a lock washer to prevent loosening.
DIN981 is a technical specification for lock nuts of rolling bearings in the German Industrial Standard (Deutsches Institut für Normung), mainly used to fix the inner ring of bearings and prevent axial displacement. This standard stipulates the dimensions, materials, mechanical properties and surface treatment requirements of round nuts, ensuring their reliability and interchangeability in mechanical transmission systems.
