What type of pin is classified as a safety fastener?

The cotter pin is classified as a safety fastener because it is specifically designed to secure other fasteners, such as bolts or nuts, preventing them from loosening during operation. When inserted through a hole in a shaft or a pin, the ends of the cotter pin are typically bent or spread apart, creating a secure connection that minimizes the risk of slippage or disconnection. This characteristic makes cotter pins particularly reliable in maintaining the integrity of assemblies in various mechanical systems, where safety is paramount.

In contrast, the other types of pins, such as screw pins, quick pins, and chain lock pins, do not fulfill the same safety fastening role. While they may provide various types of connections or adjustments, they do not offer the same level of assurance against loosening or accidental disconnection as a cotter pin does.