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What is a cotter pin?

Time : 2023-03-27 Hits : 54

What is a split pin?

A cotter pin is a mechanical component used to prevent loosening of threaded connections. 

After tightening the nut, insert the cotter pin into the nut slot and bolt tail hole, and pull the

 cotter pin tail apart to prevent the relative rotation of the nut and bolt. To avoid damaging the 

hole wall, grease and lubricating oil can be added to the pin hole. The production of this part 

requires the use of high-quality steel and rigid materials with good elasticity.


Pull the cotter pin apart and clamp any part of its leg into the inspection mold (no flattening 

should occur); Then bend the cotter pin by 90 °, one round trip being one bend. The test speed

 shall not exceed 60 times/min. The inspection mold should have a semicircular slot hole with

a diameter that is the nominal size of the cotter pin. The jaw should have a rounded corner 

of r=0.5 mm.

Insert a cotter pin through a hole in one part and a slot in another part and separate the threaded

 end to prevent relative movement of the part.

Installation method


There is no hole at the end of the bolt, so it needs to be punched first


Insert the cotter pin into the cylindrical pin by hand or pliers, and do not use a hammer to

 drive the cotter pin in


Use pliers to break off the cotter pin.


The angle for breaking off the split pin is in principle 60 °. If it collides with the workpiece, 

roll up the cotter pin and make the separated parts straight and symmetrical.


Confirm that the nut and bolt will not rotate relative to each other, and then the installation 

未标题-3is completed.

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