Cotter pin per GOST

A cotter pin per GOST 397-79 is a type of metal fastening element. It is made from a half-round rod that is bent in half.

On one side there are two blunt ends, and on the other a rounded eye. In appearance it resembles a kind of paperclip.

Product features

According to the GOSTs, developed back in the Soviet Union, cotter pins are made of low-carbon steel with a carbon content not exceeding 0.2%. The fastener is coated with a special finish:

• zinc
• zinc with chromating;
• cadmium with chromating;
• phosphate with oil impregnation.

According to the GOST, the coating thickness must be within 6-12 micrometers.

The GOSTs also specify the permissible dimensions of cotter pins. In diameter they range from 0.8 to 13 millimeters, and in length from 5 to 250 millimeters.

Application and installation rules

Cotter pins are used to secure lightweight parts. For this, a hole is made in the parts, into which the fastener is inserted until the eye fits snugly against the surface. On the opposite side, for reliable fastening, the two ends of the cotter pin are spread apart in different directions.

Cotter pins are also used to prevent nuts from spontaneously unscrewing. The installation method is the same – insert the fastener into the hole and spread its ends apart. This method is often found in machine building and shipbuilding, and even in the space industry.