ISO 1234 Cotter Pins (Split Pins)

What Are ISO 1234 Cotter Pins?

ISO 1234 split pins (or “spring pins” or “ cotter pins”) are made from bent metal wire, forming a pin structure with a forked end. During installation, the split pin is inserted through a pre-drilled hole, and the forked end is bent open to securely fix it in the hole, thereby preventing nuts, bolts, or other fasteners from accidentally loosening or falling off.

Characteristics

Quick and easy installation without special tools
Reliable anti-loosening performance
Reusable in certain applications
Cost-effective locking solution
Suitable for high vibration environments

ISO 1234 Dimensions & Size Chart

Equivalent standards: DIN 94; GB/T 91; CSN 021781; PN 82001; UNI 1336; NF E25-774.

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size (mm)	d max	d min	a max	a min	c max	c min
Φ0.6	0.5	0.4	1.6	0.8	1.0	0.9
Φ0.8	0.7	0.6	1.6	0.8	1.4	1.2
Φ1	0.9	0.8	1.6	0.8	1.8	1.6
Φ1.2	1.0	0.9	2.5	1.25	2.0	1.7
Φ1.6	1.4	1.3	2.5	1.25	2.8	2.4
Φ2	1.8	1.7	2.5	1.25	3.6	3.2
Φ2.5	2.3	2.1	2.5	1.25	4.6	4.0
Φ3.2	2.9	2.7	3.2	1.6	5.8	5.1
Φ4	3.7	3.5	4.0	2.0	7.4	6.5
Φ5	4.6	4.4	4.0	2.0	9.2	8.0
Φ6.3	5.9	5.7	4.0	2.0	11.8	10.3
Φ8	7.5	7.3	4.0	2.0	15.0	13.1
Φ10	9.5	9.3	6.3	3.15	19.0	16.6
Φ13	12.4	12.1	6.3	3.15	24.8	21.7
Φ16	15.4	15.1	6.3	3.15	30.8	27.0
Φ20	19.3	19.0	6.3	3.15	38.5	33.8

ISO 1234 Cotter Pins Suppliers

Advantages:

✔ Full size range available (standard & custom)
✔ Materials: carbon steel, stainless steel, brass
✔ Advanced surface treatment options
✔ Strict quality control (ISO-certified production)
✔ OEM & custom packaging support
✔ Fast delivery & global export experience