A nut with several lugs protruding from one end making it look like the turrets on the top of the wall of a castle. This nut is used on a shaft with a hole drilled in it. It is secured to the shaft by passing a cotter pin through an opening in the nut and through the shaft hole.
CASTELLATED NUT
Meaning of CASTELLATED NUT in English
English dictionary of automotive terms. Английский словарь автомобильных терминов. 2012