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Technifast's range of split cotter pins are stocked in diameters of 1mm to 13mm in mild steel (usually zinc plated), stainless steel A4 and brass. Our specifications follow DIN 94, which is equivalent to ISO 1234 and BS 1574. Due to the loose fit required for cotter pins, the metric range doubles for inch sizes. For detailed on how to measure a cotter pin, please view our cotter pin measurement guide.

Cotter pins are designed to be easy to insert into pre-drilled components, such as a clevis pin and can also be applied around a shaft. The cotter pin prongs can then be spread to hold the assembly in position.  We hold large stocks of all the popular cotter pins sizes for next day shipping at competitive prices- get a quote today!


Cotter Pins

Technifast provides split pins which are used in conjunction with clevis pins and other types of free fitting pinned assemblies within general applications.

We have large stock of split cotter pins available to the following standards:


  • Cotter Pin ISO 1234
  • Cotter Pin DIN 94
  • Cotter Pin BS 1574


  • Mild Steel, Zinc Plated
  • Stainless Steel A4
  • Brass

The type of cotter pin we supply are produced and formed from a single strand of wire, with a loop at one end to create the head. This is then used as part of a mating assembly with a clevis pin or other type of shaft.  The cotter pin becomes a locking mechanism once the two prongs are bent apart.



 Cotter Pin Size Chart

We stock a wide variety of split cotter pins as detailed in the table below. Read our cotter pin measurement guide for details on how to choose the correct size pin.

Nominal Diameter 1 1.2 1.6 2 2.5 3.2 4 5 6.3 8 10 13

Dimension d1 (Max / Min)

0.9 / 0.8 1.0 / 1.09 1.4 / 1.3 1.8 / 1.7 2.3 / 2.1 2.9 / 2.7 3.7 / 3.5 4.6 / 4.4 5.9 / 5.7 7.5 / 7.3 9.5 / 9.3 12.4 / 12.1
Dimension a (Max / Min) 1.8 / 1.6 2.0 / 1.7  2.8 / 2.4 3.6 / 3.2 4.6 / 4.0 5.8 / 5.1  7.4 / 6.5 9.2 / 8.0 11.8 / 10.3 15.0 / 13.1 19.0 / 16.6 24.8 / 21.7
6mm length Y                      
8mm length Y                      
10mm length Y Y Y Y                
12mm length Y Y Y Y                
16mm length Y Y Y Y Y Y Y Y        
18mm length Y Y Y Y Y Y Y Y        
20mm length Y Y Y Y Y Y Y Y Y      
22mm length Y Y Y Y Y Y Y Y Y      
25mm length Y Y Y Y Y Y Y Y Y      
28mm length Y Y Y Y Y Y Y Y Y      
32mm length Y Y Y Y Y Y Y Y Y Y Y  
36mm length Y Y Y Y Y Y Y Y Y Y Y  
40mm length     Y Y Y Y Y Y Y Y Y  
45mm length       Y Y Y Y Y Y Y Y Y
50mm length       Y Y Y Y Y Y Y Y Y
56mm length         Y Y Y Y Y Y Y Y
63mm length         Y Y Y Y Y Y Y Y
71mm length         Y Y Y Y Y Y Y Y
80mm length             Y Y Y Y Y Y
90mm length             Y Y Y Y Y Y
100mm length             Y Y Y Y Y Y
112mm length             Y Y Y Y Y Y
125mm length             Y Y Y Y Y Y
140mm length                 Y Y Y Y
160mm length                   Y Y Y



How To Measure A Split Cotter Pin

Split cotter pins are a type of mechanical fastener designed to couple two components together.  They’re formed from semi-circular wire bent to create a looped head, with two tines that can be spread to create a locking mechanism to keep the pin securely in place.

Cotter pins are designed to be easy to insert into pre-drilled components and due to their compatibility with clevis pins they are often used in construction, marine and agricultural industries.

The pins are very easy to install and remove and are meant for single use only, which means they offer a reliable fastening solution for light-duty applications where permanent fasteners might be an unacceptable choice.

Our cotter pins are supplied in a choice of mild steel, stainless steel or brass in wide a range of sizes. It is important to note that the nominal diameter of the pin is larger than the actual diameter. For example a pin with a nominal diameter of 5mm will have an actual diameter of 4.4 – 4.6mm. The nominal diameter is the same as the recommended hole size.

Here’s our step-by-step guide to measuring a cotter pin:

1.       Measure the diameter of the hole in which the pin will be inserted

2.       Measure the diameter of the two tines of the cotter pin when held closed.

3.       Select a cotter pin with a diameter which is very similar to the hole.

4.       Measure the length of the hole

5.       Choose a cotter pin with enough length to penetrate the hole and allow the prongs to be splayed to keep the pin secure. The nominal length of a cotter pin is the length of the shorter leg, not counting the head

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