A castellated nut is held in place using which securing item?

A castellated nut, known for its notched pattern, is specifically designed to be secured in place using a cotter pin. The purpose of the cotter pin is to pass through a hole in the bolt or shaft that the castellated nut is threaded onto, effectively preventing the nut from loosening due to vibration or rotational movement. This mechanism is crucial in maintaining looseness-free assembly in applications such as aircraft components where safety and reliability are paramount.

While washers, lock nuts, and screws also serve various securing functions in mechanical assemblies, they do not provide the same direct locking function as a cotter pin does for a castellated nut. A washer can distribute the load on the nut but does not secure it against rotation. A lock nut is designed to resist loosening on its own but is not typically used with a castellated nut. Screws are fastening devices themselves and do not have a role in securing a castellated nut. Thus, the cotter pin is the correct and most effective choice for securing a castellated nut.