Types of Cotter Pins and Dimensional Standards

Types of Cotter (Split) Pins

Cotter pins come in three types: forked (split) type, spring-wire type, and wedge type. Of these, the forked (split) type cotter pin is the most commonly used. The other cotter pin types are rarely found on the market.

types of cotter pins — Types of cotter pins and their TS numbers

Cotter pin material varies according to the intended use, but materials such as mild steel, stainless steel, copper-zinc alloys, copper-alloy spring steel, copper, and aluminum are used to make cotter pins. They can also be made from other materials on request. Chrome-nickel plating can be applied if needed.

Role as a Safety Pin

A cotter pin is a simple but effective safety pin that prevents parts such as castellated nuts from loosening and rotating.

Standard Diameter Range

Depending on their intended use, cotter pins are generally produced in diameters ranging from 1 mm to 20 mm.

Single-Use Nature

Since a removed cotter pin has been bent, it shouldn’t be reused with the same strength — it should be replaced with a new one.

Cotter Pin Dimensions and Standards

The table above gives standard cotter pin dimensions according to TS 2339/1. On matters not specified, and on shaping, the manufacturer is free to decide.

cotter pin dimensions according to Turkish standards

Cotter pin TS 2339/2-5.6×97-Fe

cotter pin and castellated nut assembly technical drawing

Cotter pin 5×50 TS 2339/1 and its assembly drawing. The picture on the right shows a castellated nut being secured with a cotter pin. (above)

Standard Designation of a Cotter Pin

As an example of a cotter pin’s standard designation: the short designation for a cotter pin with a nominal diameter of 6.3, a length of 100 mm, made of spring steel, is as follows:
Cotter Pin TS 2339/2–A – 6.3 x 100 – Spring steel

In this machine elements article, we covered the standard cotter pin dimensions table and cotter pin standard designation. See you in upcoming articles.

Related Questions

After the nut is fitted, the cotter pin is passed through a special hole in the bolt, and its ends are bent. This bent pin physically blocks the nut from rotating in the loosening direction.

Because the cotter pin’s ends are bent when it’s installed, removing it causes permanent weakening in that area. Since it can no longer provide the same level of protection, it needs to be replaced with a new one every time it’s removed.