In the absence of such a tool, the cotter pin is installed by tapping it with a hammer. Special tools were once available to insert and remove these cotter pins. Installing the pin wedges the shaft against the sides of the hole and prevents it from turning. The cotter pin is inserted so that its flat faces the axle's flat. The axle is inserted into the hole so that the axle's flat is parallel to and facing the overlap. The crank has two holes, one for the axle and another at right angles to it for the cotter pin, with a slight, specified overlap. That particular use will be the basis of this description. They are used to secure a piece with a bored hole to a flatted shaft having the same diameter, for example, formerly, to hold the cranks of bicycles to their axle. In military standards, MS24665 has replaced AN380 and AN381.Ĭrank cotter pins are short shafts, threaded on one end, with a flat tapered so that the low end of the flat is at the threaded end of the pin. This error has led to deaths.Įxamples of industrial accidents involving cotter pins. Because cotter pins are so readily available, workers are often tempted to replace some special pin that has failed with an.In general, when a fastener must be safetied, properly installed safety wire is preferable to a cotter pin.

Always use the largest cotter pin that will fit the hole.

In some applications, the spread prongs can be a problem because they can catch on such things as pant legs. The prongs of hammerlock pins are spread by striking the head with a hammer. NominalĬotter pins are ordinarily secured by spreading the prongs. Which lengths are actually available varyīy, for example, the material from which the pin is made.

for all other styles, at the end of the shorter prong.

for hammerlock ends, at the farthest point of the longer prong.

for pins with miter or bevel point ends, at the end of the farthest point of both prongs.

The measurement begins at the point where the large end meets the hole into which the pin is inserted. The way the length of a cotter pin is measured depends on the style of the points. The sizes below 5/16 inch are intended to fit a hole 1/64 inch larger than the pin size for pins larger than that the pin and hole size are the same. Hammer lock cotter pins require a hammer to install, which will close the ends of the prongs together.American standard cotter pin sizes are in nominal fractional inches, starting at 1/32. R-clip cotter pins feature a curved prong that wraps around the side of components. Extended prong cotter pins are bent around the back of components manually. Each type, though, works in a different way. They all consist of a single piece of bent metal with two prongs. As you strike the head with a hammer, the ends of the prongs will close together.Įxtended prong, R-clip and hammer lock are some of the most common cotter pins. You can use a hammer lock cotter pin by inserting it into a hole and then striking it with a hammer. The end of the long prong curved inward towards the opposite, shorter prong. The only difference is that hammer lock cotter pins are curved on the end. They look like extended prong cotter pins. Hammer lock cotter pins are a type of locking fastener that, as the name suggests, requires a hammer to install. The curved prong should then wrap around the side of the cylindrical-shaped component Hammer Lock To use an R-clip cotter pin, you’ll need to insert the straight prong into a hole. The other prong on an R-clip cotter pin is curved.

They feature two prongs - just like extended prong cotter pins. R-shaped cotter pins are used around cylindrical-shaped components, such as tooling balls. Rather, R-clip cotter pins feature an R-shaped design. They don’t feature the same U-shaped design as extended prong cotter pins. R-clip cotter pins are made of metal as well, but they are shaped differently. Bending the ends of the prongs will secure the cotter pin and, thus, the component with which it’s used. You can then bend the ends of the prongs around the back of the component. To use an extended prong cotter pin, simply insert it into a hole. One of the prongs is slightly longer than the other prong. As shown in the adjacent photo, extended prong cotter pins feature two long and narrow parallel prongs. One of the most common types of cotter pins is extended prong. While all cotter pins function as metal fasteners, though, they are available in different types. And you can typically remove cotter pins by pulling them out of the hole. You can insert a cotter pin into a hole to secure a component. Also known as split pins, they are designed for use in holes. Cotter pins are fasteners consisting of a piece of metal.

Humpback cotter pins