DIN 94 Split Cotter Pins (ISO 1234)
We supply DIN 94 / ISO 1234 split cotter pins in zinc plated steel, A2 and A4 stainless steel, brass, copper and phosphor bronze, from 1mm to 13mm diameter in lengths to 180mm. The pin is formed from half-round wire folded back on itself, with an eye that stops against the hole and two legs that bend apart to lock nuts, clevis pins and shaft fittings in place.
Also known as: split pin, cotter pin, cotter, hair pin, split cotter pin, iso 1234, bs 1574, bs 7724, din 94.
DIN 94 (ISO 1234) dimensions
| Nominal size (hole diameter) | Shank diameter max | Shank diameter min |
|---|---|---|
| 1mm | 0.9mm | 0.8mm |
| 1.2mm | 1.0mm | 0.9mm |
| 1.6mm | 1.4mm | 1.3mm |
| 2mm | 1.8mm | 1.7mm |
| 2.5mm | 2.3mm | 2.1mm |
| 3.2mm | 2.9mm | 2.7mm |
| 4mm | 3.7mm | 3.5mm |
| 5mm | 4.6mm | 4.4mm |
| 6.3mm | 5.9mm | 5.7mm |
| 8mm | 7.5mm | 7.3mm |
| 10mm | 9.5mm | 9.3mm |
| 13mm | 12.4mm | 12.1mm |
Materials & strength
Nominal size is the hole size
A split pin's nominal diameter is the hole it fits - the pin itself is made undersize so it passes through freely before the legs are spread.
Eye and staggered legs
The folded eye acts as a stop against the hole face, and the two legs are cut to unequal lengths so they separate easily for bending.
Stainless for exposed service
Electro-plating cannot be relied on between the closed legs of a folded pin, so where corrosion matters a stainless pin is the sounder route than a plated one.
Related specificationsWhat size split pin fits my hole?
Order the nominal size matching the hole diameter - a 3.2mm pin fits a 3.2mm hole. The shank is made a little under nominal so it slides in without force.
How should a split pin be fitted?
Pass the pin through until the eye seats, then bend the legs apart around the nut or shaft - one leg back over the bolt end and one against the flat is the common pattern. Treat the pin as a consumable and fit a new one at each re-assembly.
What is the difference between A2 and A4 stainless split pins?
A2 covers general outdoor and industrial exposure; A4 adds molybdenum for salt water and chemical environments. Both grades are carried across the size range.
Are DIN 94, ISO 1234 and the BS split pin standards interchangeable?
The UK metric split pin standard is BS EN ISO 1234, which is the direct adoption of ISO 1234. BS 7724 is an older separate British metric standard — where a drawing specifies either, send us the requirement and we will confirm the appropriate product.
Need DIN 94 (ISO 1234) in a non-standard size or material?
Send us your drawing — specials quoted within 24 hours.