Thursday 21st September 2017
Slotted nuts are often called castellated nuts. They have slots cut into one side. Typically there are a total of 6 opposing slots, but this number can vary - in very large nuts 8 are common, as well as 2 in smaller nuts.The name comes from the nut's resemblance to the parapet of a typical medieval castle.
The slots are designed to align with holes in a mated bolt to accept a cotter pin, a split pin, R-clip or even safety wire to be inserted, which then locks the nut in place and prevents it from loosening and turning.
Don't confuse castle nuts with slotted nuts. Castle nuts have a round reduced section formed on the section where the slots are, this allows a cotter pin to be pressed closer to the margins of the nut itself.