Why cotter pins are important.

While conducting a CDL  vehicle inspection, all front end suspension parts are to examined to make sure they safe and will not cause problems while driving.

One item that may have been mentioned during many hours of classroom training is to inspect all cotter pins. A cotter pin is important. It has a role in the safety and integatity of the vehicle it was installed.

Cotter pins serve an important function and are most often used on the front end suspension on parts that have movement and wear. Purpose is to stop a threaded nut from backing away from the item that might loosen over miles of traffic and hundreds of hours of service life. The nut will not be permitted to back away.

You should be able to point out and explain it’s purpose. Often used with a “castle nut” they lock together for secure years of service. As seen in the above image, the cotter pin goes through the suspension end and castle nut. The split end of the cotter pin is bent around and spread open. A school bus front end suspension takes a lot of abuse from potholes and part movement, it is possible for the castle nut to loosen. The cotter pin insures that the nut can not loosen.