# Split pins (cotter pins) ISO 1234 / DIN 94, 0.6–20: hole size, wire diameter d, a, b, c and the bolt and clevis-pin size each one serves

> What size split pin (cotter pin) goes with a given clevis pin or bolt, and what are its d, a, b and c?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: Westfield Fasteners' DIN 94 sheet (nominal 0.6 to 20 mm, d, a, b, c, plus the pin and bolt ranges per size), roymech's DIN 94 / ISO 1234 / BS 1574 table (agrees on every value it prints); numbers only
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**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- Split pins (cotter pins) are sized by the hole they fit: the nominal size equals the hole diameter (Westfield: 'cotter pin holes match the nominal diameter'). Columns in mm: nominal size = hole, d (the wire section, max / min), a (the prong extension, max / min), b (eye length), c (eye outside, min / max), the length range roymech lists (l), the bolt diameter range the size serves (over x up to y) and the clevis-pin diameter range, and v min as printed in Westfield's application table (it does not define v). Westfield's sheet names DIN 94; roymech names DIN 94, ISO 1234 and BS 1574 together; the ISO 1234 text itself was not read, so the ISO match rests on roymech's statement and on identical d, a, b and c in the two tables.
- roymech does not list 0.6 and 16 mm and has no bolt ranges; where both print a value (0.8 to 13 mm) d max, a max, b and c agree. roymech's 8 mm row prints c max as '15,' (incomplete) and Westfield 15; the Westfield value is shown. Length tolerance on the shank (Westfield, DIN 94): 4 to 6 mm ±0.6, 8 to 10 ±0.75, 12 to 18 ±0.9, 20 to 28 ±1.0, 32 to 50 ±1.25, 56 to 80 ±1.5, 90 to 112 ±1.75, 125 to 180 ±2.0, 200 to 250 ±2.3, 280 ±2.6 mm.
- Use: a split pin goes through a cross hole in a clevis pin, bolt or shaft and its two halves are bent apart. Pick the size from the clevis pin's hole (ISO 2341 form B: d1 per size on clevis-pins-iso-2341). The ranges in the table are Westfield's application table; for clevis pins they match ISO 2341's hole for all 26 sizes (d 3 to 100). ISO 2341 also says to use the next larger pin and hole where alternating transverse forces act (iTeh's page for ISO 2341).
- No file: the pin is two half-round wires with a rolled eye; the cross-section and the eye form are not published as numbers in the sources read. Hairpin-style R-clips: r-clips-hairpin-cotters-din-11024. The existing page pins-clevises-and-joints lists a few model-work sizes.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| nominal size = hole | 0.6, 0.8, 1, 1.2, 1.6, 2, 2.5, 3.2, 4, 5, 6.3, 8, 10, 13, 16, 20 mm; d max 0.5 to 19.3 mm | cross hole of that diameter in a clevis pin (ISO 2341 B d1) or bolt in the range of the table (Westfield) | slide | all |
| clevis pin range served | 2 mm split pin: clevis pins over 6 up to 8 mm; 3.2: over 9 up to 12; 5: over 17 up to 23; 8: over 29 up to 44; 13: over 69 up to 110 mm | ISO 2341 clevis pin of that d on clevis-pins-iso-2341 (the table matches d1 for all 26 sizes) | designed | all |

## Sizes

| nominal size = hole (mm) | d max / min | a max / min | b | c min / max | length range l (roymech) | bolt d range, over to up to (mm) | clevis pin d range, over to up to (mm) | v min |
|---|---|---|---|---|---|---|---|---|
| 0.6 | 0.5 / 0.4 | 1.6 / 0.8 | 2 | 0.9 / 1 | — | — to 2.5 | — to 2 | 3 |
| 0.8 | 0.7 / 0.6 | 1.6 / 0.8 | 2.4 | 1.2 / 1.4 | 6–12 | 2.5 to 3.5 | 2 to 3 | 3 |
| 1 | 0.9 / 0.8 | 1.6 / 0.8 | 3 | 1.6 / 1.8 | 6–12 | 3.5 to 4.5 | 3 to 4 | 4 |
| 1.2 | 1 / 0.9 | 2.5 / 1.25 | 3 | 1.7 / 2 | 6–40 | 4.5 to 5.5 | 4 to 5 | 5 |
| 1.6 | 1.4 / 1.3 | 2.5 / 1.25 | 3.2 | 2.4 / 2.8 | 6–40 | 5.5 to 7 | 5 to 6 | 5 |
| 2 | 1.8 / 1.7 | 2.5 / 1.25 | 4 | 3.2 / 3.6 | 6–50 | 7 to 9 | 6 to 8 | 6 |
| 2.5 | 2.3 / 2.1 | 2.5 / 1.25 | 5 | 4 / 4.6 | 8–50 | 9 to 11 | 8 to 9 | 6 |
| 3.2 | 2.9 / 2.7 | 3.2 / 1.6 | 6.4 | 5.1 / 5.8 | 8–63 | 11 to 14 | 9 to 12 | 8 |
| 4 | 3.7 / 3.5 | 4 / 2 | 8 | 6.5 / 7.4 | 16–100 | 14 to 20 | 12 to 17 | 8 |
| 5 | 4.6 / 4.4 | 4 / 2 | 10 | 8 / 9.2 | 20–100 | 20 to 27 | 17 to 23 | 10 |
| 6.3 | 5.9 / 5.7 | 4 / 2 | 12.6 | 10.3 / 11.8 | 25–125 | 27 to 39 | 23 to 29 | 12 |
| 8 | 7.5 / 7.3 | 4 / 2 | 16 | 13.1 / 15 | 40–140 | 39 to 56 | 29 to 44 | 14 |
| 10 | 9.5 / 9.3 | 6.3 / 3.2 | 20 | 16.6 / 19 | 50–140 | 56 to 80 | 44 to 69 | 16 |
| 13 | 12.4 / 12.1 | 6.3 / 3.2 | 26 | 21.7 / 24.8 | 71–140 | 80 to 120 | 69 to 110 | 20 |
| 16 | 15.4 / 15.1 | 6.3 / 3.2 | 26 | 21.7 / 24.8 | — | 120 to 170 | 110 to 160 | 25 |
| 20 | 19.3 / 19 | 6.3 / 3.2 | 40 | 33.8 / 38.6 | — | 170 to — | 160 to — | 32 |

## Where the files are

- Westfield Fasteners: [DIN 94 split (cotter) pins, nominal 0.6 to 20: d max / min, a max / min, b, c min / max, length tolerances, bolt and clevis-pin ranges per size with v min](https://westfieldfasteners.co.uk/Standards/Pin-Cotter.pdf) — web — Reference page; numbers only
- roymech: [Split cotter pins (DIN 94 / ISO 1234 / BS 1574): nominal size = hole, d, a, b, c and length range l](https://roymech.org/Useful_Tables/Circlips/Split_Cotter_Pins.html) — web — Reference page; numbers only
- ISO: [ISO 1234:1976: Split pins, metric series (title as listed by ISO) (standard body catalogue page; the standard itself is paid)](https://www.iso.org/ics/21.060.50.html) — web — Standard body catalogue page

## Questions

**What split pin for an 8 mm clevis pin?**

A 2 mm split pin: Westfield's application table puts clevis pins of 6 to 8 mm in the 2 mm size (hole Ø2); ISO 2341's hole for d 8 is 2 mm.

**Is the split pin size the pin diameter or the hole?**

The hole: nominal size equals the hole diameter, and the wire diameter d is a little smaller (for 3.2 mm, d is 2.9 / 2.7 mm).

**What is the eye length of a 4 mm split pin?**

b is 8 mm, with the eye outside c 6.5 to 7.4 mm (Westfield and roymech).

## Fits with

- [Clevis pins with head, ISO 2341 (DIN 1444) forms A and B, d 3–100: head diameter and height, split-pin hole, le, radius + example pin models](https://xemstudio.com/objects/clevis-pins-iso-2341/)
- [R-clips, spring cotters and hairpin cotter pins: wire diameter, pin / shaft range, length (DIN 11024, McMaster hairpin sizes)](https://xemstudio.com/objects/r-clips-hairpin-cotters-din-11024/)
- [Clevis pins ISO 2341 B, Ø3 to Ø8](https://xemstudio.com/objects/clevis-pins/)
- [Spring pins: slotted (ISO 8752, ASME B18.8.2) and coiled (ISO 8750): diameter, wall, chamfer, hole size, shear + hole gauges](https://xemstudio.com/objects/spring-pins-iso-8752-8750-asme-b18-8-2/)
- [E-clips DIN 6799 for Ø2 to Ø10 shafts](https://xemstudio.com/objects/e-clips-din-6799/)
- [Retaining rings DIN 471 (external, for shafts): ring dimensions and groove diameter d2 × width m, 3 to 100 mm](https://xemstudio.com/objects/retaining-rings-din-471-external/)