What is a Cotter Pin?

What is a Cotter Pin?

7th Apr 2023

image of six cotter pins of various sizes on a white background, automotive tool, cotter pin

It’s a type of fastener invented a long time ago but not by anyone named Cotter.

Ira J. Young of St. Louis, MO gets credited with creating the cotter pin. In 1912, he applied for a patent on a machine that made split cotter pins. People aren’t sure where the “cotter” name comes from. (It might come from the word “cotterel,” which is a pin or bolt used to hang pots over fires.) Generally speaking, cotter pins are fasteners used to secure bolts in place. There are at least two types of cotter pins, each specific use. We’ll take a closer look at two popular types of these metal fasteners and more.

Split Pin AKA Split Cotter Pin

assortment of split pins and cotter pins from titan tools in a bin on a white background

This is often called a “Cotter pin,” but it is a specific fastener. These pins are made out of a single piece of thick but soft wire. The metal is cut down the middle and ends in a loop. These pins are inserted into small holes designed to hold them, such as rods with washers. Once you insert a split pin, you bend its two ends apart to lock it into place. When deployed, a split pin looks somewhat like a capital letter Y turned upside down.

If you need these unique cotter pins, you’re in luck. JB Tools carries a variety of assorted split pin kits from Titan Tools. Among them, you’ll find a 555-piece split pin set, a 144-piece assortment of large-sized split cotter pins, and a 1,000-piece split pin assortment. You can also search our inventory for more split cotter pin assortments.

Hitch Pin Clip AKA Hairpin Cotter Pin

set of Titan Tools hairpin cotter pins in a plastic container on a white background

This type of cotter pin has a more unique look than split pins. They look like a hairpin or even the letter “R.” Some people call these fasteners R-clips or R-pins. By the name “hitch pin clip,” you can probably guess one of the uses of this cotter pin. That’s right, it’s used to help hold hitch pins in place. With a forceful shove into the hole, these R-clips lock into place between the grooves on the bent side. These cotter pins are also used to secure axles and clevis pins.

Do you need hairpin cotter pins? JB Tools carries a 150-piece hitch pin clip assortment. If you regularly use several hairpin cotter pins in your line of work, this kit comes in handy. It’s made by Titan Tools and the various sizes of cotter pins come in a resealable plastic case.

Spring Pin AKA Roll Pin

Set of Tekz Roll Pins in a plastic container with labels of sizes, spring pin, roll pin

These are not cotter pins but we’ve included them here because they are useful fasteners. These pins are coiled pieces of metal that are wider than the holes in which they’re inserted. They’re able to fill these narrow spaces by compressing as they’re inserted. This makes for a tight fit that holds together two or more pieces of machinery.

Anyone who’s worked with spring pins knows that you never need just one. To help you, JB Tools offers two choices of roll pin assortments. There is the 120-piece spring pin kit from K Tool and the 120-piece roll pin assortment from Titan Tools. Find exactly what you need in our well-stocked online inventory!

Get Cotter Pins And More From JB Tools

We’re known for our selection of hand tools, air tools, and diagnostic equipment. Truth be told, our online inventory is stocked with many other useful things. At JB Tools, we take pride in everything we carry because we know it’s what you need. We’re also proud to offer everything at rock-bottom prices. That, plus our free shipping on most orders, makes us the best place to buy cotter pins and so much more!