Cotter Pin

A cotter pin is a split pin with two tines that are bent apart after insertion to lock it in place. It is used to secure a nut or to hold a clevis pin.

A cotter pin passes through a hole in a bolt or pin and its legs are bent back to stop the fastener turning or coming loose. It is often matched with a castellated nut or a drilled shank. A split pin can be opened and reused a few times, but the legs work-harden and it is usually replaced after removal.

Plain finish means the pin has no added coating. It is often used where corrosion is not a concern or where a coating could interfere with fit.

Cotter pins are often made in steel, stainless steel 304, or stainless steel 316. Stainless steel grades give better corrosion resistance than plain steel.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a certificate of conformance for the material and dimensions. On receipt, check the tine spread, length, and that the pin fits the hole without excessive play.